Astigmatism induced by conventional spherical ablation after PRK and LASIK in myopia with astigmatism < 1.00 D.

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Christiansen, Steven M; Mifflin, Mark D; Edmonds, Jason N; Simpson, Rachel G; Moshirfar, Majid

2012-01-01

The purpose of this study was to evaluate surgically-induced astigmatism after spherical ablation in photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK) for myopia with astigmatism PRK or LASIK for the correction of myopia with minimal astigmatism of PRK, average cylinder increased from 0.39 ± 0.25 (0.00-0.75) preoperatively to 0.55 ± 0.48 (0.00-1.75) postoperatively (P = 0.014), compared with an increase in LASIK eyes from 0.40 ± 0.27 (0.00-0.75) preoperatively to 0.52 ± 0.45 (0.00-2.00) postoperatively (P = 0.041). PRK eyes experienced an absolute value change in cylinder of 0.41 ± 0.32 (0.00-1.50) and LASIK eyes experienced a change of 0.41 ± 0.31 (0.00-1.50, P = 0.955). Mean surgically-induced astigmatism was 0.59 ± 0.35 (0.00-1.70) in PRK eyes, with an increase in surgically-induced astigmatism of 0.44 D for each additional 1.00 D of preoperative cylinder; in LASIK eyes, mean surgically-induced astigmatism was 0.55 ± 0.32 (0.00-1.80, P = 0.482), with an increase in surgically-induced astigmatism of 0.29 D for each 1.00 D of preoperative cylinder. Spherical ablation can induce substantial astigmatism even in eyes with less than one diopter of preoperative astigmatism in both PRK and LASIK. No significant difference in the magnitude of surgically-induced astigmatism was found between eyes treated with PRK and LASIK, although surgically-induced astigmatism was found to increase with greater levels of preoperative astigmatism in both PRK and LASIK.

Eye growth and myopia development: Unifying theory and Matlab model.

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Hung, George K; Mahadas, Kausalendra; Mohammad, Faisal

2016-03-01

The aim of this article is to present an updated unifying theory of the mechanisms underlying eye growth and myopia development. A series of model simulation programs were developed to illustrate the mechanism of eye growth regulation and myopia development. Two fundamental processes are presumed to govern the relationship between physiological optics and eye growth: genetically pre-programmed signaling and blur feedback. Cornea/lens is considered to have only a genetically pre-programmed component, whereas eye growth is considered to have both a genetically pre-programmed and a blur feedback component. Moreover, based on the Incremental Retinal-Defocus Theory (IRDT), the rate of change of blur size provides the direction for blur-driven regulation. The various factors affecting eye growth are shown in 5 simulations: (1 - unregulated eye growth): blur feedback is rendered ineffective, as in the case of form deprivation, so there is only genetically pre-programmed eye growth, generally resulting in myopia; (2 - regulated eye growth): blur feedback regulation demonstrates the emmetropization process, with abnormally excessive or reduced eye growth leading to myopia and hyperopia, respectively; (3 - repeated near-far viewing): simulation of large-to-small change in blur size as seen in the accommodative stimulus/response function, and via IRDT as well as nearwork-induced transient myopia (NITM), leading to the development of myopia; (4 - neurochemical bulk flow and diffusion): release of dopamine from the inner plexiform layer of the retina, and the subsequent diffusion and relay of neurochemical cascade show that a decrease in dopamine results in a reduction of proteoglycan synthesis rate, which leads to myopia; (5 - Simulink model): model of genetically pre-programmed signaling and blur feedback components that allows for different input functions to simulate experimental manipulations that result in hyperopia, emmetropia, and myopia. These model simulation programs

Strabismus-associated myopia. Review.

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Hernández Martínez, P; Rodríguez Del Valle, J M

2017-12-01

The treatment of strabismus associated with myopia is often a therapeutic challenge for the ophthalmologist. The strabismus associated with myopia has certain peculiarities and there are even certain types of strabismus that occur exclusively in myopia, such as strabismus fixus, requiring treatments with specific surgical techniques. It is important to make a correct differential diagnosis, because there are many conditions described with this association. A review is presented of strabismus associated with myopia, together with its treatment adjusted to refractive error. Measurements of strabismus may be altered by the prismatic effect of the spectacles. Surgical results may be unpredictable if myopia is not taken into account. Better results were obtained with the techniques of anatomical replacement described by Yokoyama than with traditional retro-insertion-resection. For the diagnosis and appropriate treatment of strabismus, it is important to make a correct measurement of the angle of deviation, and perform image tests prior to surgery in certain cases. The anatomical characteristics of the myopic eye should also be taken into account during surgery. Copyright © 2017 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

Oseltamivir (Tamiflu-induced bilateral acute angle closure glaucoma and transient myopia

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Ji Woong Lee

2014-01-01

Full Text Available A 27-year-old woman developed bilateral acute angle closure glaucoma (AACG and transient myopia after taking oseltamivir for four days. On the fourth day, she received systemic and topical intraocular pressure (IOP-lowering agents, and IOP decreased in both eyes. However, her visual acuity was unchanged. A myopic shift of -5.25 D OD and -5.0 D OS was estimated to have occurred in the acute phase. A-scan ultrasonography and Pentacam showed markedly shallow anterior chambers and increased lens thickness. Ultrasound biomicroscopy revealed an annular ciliochoroidal effusion with forward displacement of the lens-iris diaphragm. Ciliochoroidal effusion and transient myopia were resolved after discontinuation of oseltamivir.

Intermittent Episodes of Bright Light Suppress Myopia in the Chicken More than Continuous Bright Light

OpenAIRE

Lan, Weizhong; Feldkaemper, Marita; Schaeffel, Frank

2014-01-01

PURPOSE: Bright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens. METHODS: Eight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8) was kept under office-like illuminance (500 lux) at a 10:14 light:dark cycle. Episodes of bright light (15 000 lux) were super-imposed on this background as follows....

Analysis of the factors affecting the occurrence of myopia in children with myopia

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Can Zhao

2017-10-01

Full Text Available AIM: To analyze the electronic product use time, writing time, playing piano time and outdoor activity time and the distribution of myopia in 586 cases of school age children in our hospital. METHODS: A retrospective analysis of 586 cases of children aged 6 to 12 years old in the outpatient department was established. Personalized files were used to record the uncorrected visual acuity, optometry, slit lamp, fundus mirror and strabismus. The cumulative use time of electronic products(including computer, mobile phone, iPad, writing time, whether to play the piano and outdoor activities time with the eye situation were recorded. Statistical analysis of the age group of myopia, the cumulative use of electronic age in different age groups, writing time, whether playing piano and outdoor activities and the distribution of myopia occurred.RESULTS:(1With the increasing of age, the distribution of uncorrected eyesight was in children mostly mild myopia, and the proportion of mild myopia was significantly higher than that of moderate and high myopia.(2Electronic products use time distribution: the proportion of playing electronic products(including mobilephone, computers, iPadaccounted for 76.8%, of which 9 years old, 10 years old the cumulative use of electronic products with a long time was higher than other age groups.(3Distribution of writing time: the proportion of write homework ≤1h was significantly lower than the proportion of writing homework> 1h(37.2% vs 62.8%, of which 9 and 10 years old children cumulative write time was higher than other age group.(4Distribution of playing the piano: the proportion of playing piano time less than 1h was significantly higher than the proportion of playing piano time more than 1h(89.1% vs 10.9%.(5Distribution of outdoor activities: the proportion of outdoor activities ≤1h in children at school age was significantly higher than that of outdoor activities > 1h(91.8% vs 8.9%. CONCLUSION: With the age exposure

Oxidative Stress in Myopia

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Bosch-Morell Francisco

2015-01-01

Full Text Available Myopia affected approximately 1.6 billion people worldwide in 2000, and it is expected to increase to 2.5 billion by 2020. Although optical problems can be corrected by optics or surgical procedures, normal myopia and high myopia are still an unsolved medical problem. They frequently predispose people who have them to suffer from other eye pathologies: retinal detachment, glaucoma, macular hemorrhage, cataracts, and so on being one of the main causes of visual deterioration and blindness. Genetic and environmental factors have been associated with myopia. Nevertheless, lack of knowledge in the underlying physiopathological molecular mechanisms has not permitted an adequate diagnosis, prevention, or treatment to be found. Nowadays several pieces of evidence indicate that oxidative stress may help explain the altered regulatory pathways in myopia and the appearance of associated eye diseases. On the one hand, oxidative damage associated with hypoxia myopic can alter the neuromodulation that nitric oxide and dopamine have in eye growth. On the other hand, radical superoxide or peroxynitrite production damage retina, vitreous, lens, and so on contributing to the appearance of retinopathies, retinal detachment, cataracts and so on. The objective of this review is to suggest that oxidative stress is one of the key pieces that can help solve this complex eye problem.

Controlling myopia progression in children and adolescents

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Smith MJ

2015-08-01

Full Text Available Molly J Smith, Jeffrey J WallineThe Ohio State University College of Optometry, Columbus, OH, USAAbstract: Myopia is a common disorder, affecting approximately one-third of the US population and over 90% of the population in some East Asian countries. High amounts of myopia are associated with an increased risk of sight-threatening problems, such as retinal detachment, choroidal degeneration, cataracts, and glaucoma. Slowing the progression of myopia could potentially benefit millions of children in the USA. To date, few strategies used for myopia control have proven to be effective. Treatment options such as undercorrection of myopia, gas permeable contact lenses, and bifocal or multifocal spectacles have all been proven to be ineffective for myopia control, although one recent randomized clinical trial using executive top bifocal spectacles on children with progressive myopia has shown to decrease the progression to nearly half of the control subjects. The most effective methods are the use of orthokeratology contact lenses, soft bifocal contact lenses, and topical pharmaceutical agents such as atropine or pirenzepine. Although none of these modalities are US Food and Drug Administration-approved to slow myopia progression, they have been shown to slow the progression by approximately 50% with few risks. Both orthokeratology and soft bifocal contact lenses have shown to slow myopia progression by slightly less than 50% in most studies. Parents and eye care practitioners should work together to determine which modality may be best suited for a particular child. Topical pharmaceutical agents such as anti-muscarinic eye drops typically lead to light sensitivity and poor near vision. The most effective myopia control is provided by atropine, but is rarely prescribed due to the side effects. Pirenzepine provides myopia control with little light sensitivity and few near-vision problems, but it is not yet commercially available as an eye drop or

Environmental Factors and Myopia: Paradoxes and Prospects for Prevention.

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Rose, Kathryn Ailsa; French, Amanda Nicole; Morgan, Ian George

The prevalence of myopia in developed countries in East and Southeast Asia has increased to more than 80% in children completing schooling, whereas that of high myopia has increased to 10%-20%. This poses significant challenges for correction of refractive errors and the management of pathological high myopia. Prevention is therefore an important priority. Myopia is etiologically heterogeneous, with a low level of myopia of clearly genetic origins that appears without exposure to risk factors. The big increases have occurred in school myopia, driven by increasing educational pressures in combination with limited amounts of time spent outdoors. The rise in prevalence of high myopia has an unusual pattern of development, with increases in prevalence first appearing at approximately age 11. This pattern suggests that the increasing prevalence of high myopia is because of progression of myopia in children who became myopic at approximately age 6 or 7 because age-specific progression rates typical of East Asia will take these children to the threshold for high myopia in 5 to 6 years. This high myopia seems to be acquired, having an association with educational parameters, whereas high myopia in previous generations tended to be genetic in origin. Increased time outdoors can counter the effects of increased nearwork and reduce the impact of parental myopia, reducing the onset of myopia, and this approach has been validated in 3 randomized controlled trials. Other proposed risk factors need further work to demonstrate that they are independent and can be modified to reduce the onset of myopia.

Nearwork in early-onset myopia.

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Saw, Seang-Mei; Chua, Wei-Han; Hong, Ching-Ye; Wu, Hui-Min; Chan, Wai-Ying; Chia, Kee-Seng; Stone, Richard A; Tan, Donald

2002-02-01

To determine the relationship of nearwork and myopia in young elementary school-age children in Singapore. A cross-sectional study of 1005 school children aged 7 to 9 years was conducted in two schools in Singapore. Cycloplegic autorefraction, keratometry, and biometry measurements were performed. In addition, the parents completed a detailed questionnaire on nearwork activity (books read per week, reading in hours per day and diopter hours [addition of three times reading, two times computer use, and two times video games use in hours per day]). Other risk factors, such as parental myopia, socioeconomic status, and light exposure history, were assessed. In addition to socioeconomic factors, several nearwork indices were associated with myopia in these young children. The multivariate adjusted odds ratio of higher myopia (at least -3.0 D) for children who read more than two books per week was 3.05 (95% confidence interval [CI], 1.80-5.18). However, the odds ratios of higher myopia for children who read more than 2 hours per day or with more than 8 diopter hours (1.50; 95% CI, 0.87-2.55 and 1.04; 95% CI, 0.61-1.78, respectively) were not significant, after controlling for several factors. Children aged 7 to 9 years with a greater current reading exposure were more likely to be myopic. This association of reading and myopia in a young age cohort was greater than the strength of the reading association generally found in older myopic subjects. Whether these results identify an association of early-onset myopia with nearwork activity or other potentially confounding factors is discussed.

Juvenile myopia progression, risk factors and interventions.

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Myrowitz, Elliott H

2012-07-01

The development and progression of early onset myopia is actively being investigated. While myopia is often considered a benign condition it should be considered a public health problem for its visual, quality of life, and economic consequences. Nearly half of the visually impaired population in the world has uncorrected refractive errors, with myopia a high percent of that group. Uncorrected visual acuity should be screened for and treated in order to improve academic performance, career opportunities and socio-economic status. Genetic and environmental factors contribute to the onset and progression of myopia. Twin studies have supported genetic factors and research continues to identify myopia genetic loci. While multiple myopia genetic loci have been identified establishing myopia as a common complex disorder, there is not yet a genetic model explaining myopia progression in populations. Environmental factors include near work, education levels, urban compared to rural location, and time spent outdoors. In this field of study where there continues to be etiology controversies, there is recent agreement that children who spend more time outdoors are less likely to become myopic. Worldwide population studies, some completed and some in progress, with a common protocol are gathering both genetic and environmental cohort data of great value. There have been rapid population changes in prevalence rates supporting an environmental influence. Interventions to prevent juvenile myopia progression include pharmacologic agents, glasses and contact lenses. Pharmacological interventions over 1-2 year trials have shown benefits. Peripheral vision defocus has been found to affect the emmetropization process and may be affected by wearing glasses or contacts. Accommodation accuracy also has been implicated in myopia progression. Further research will aim to assess both the role and interaction of environmental influences and genetic factors.

Birth order and myopia.

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Guggenheim, Jeremy A; McMahon, George; Northstone, Kate; Mandel, Yossi; Kaiserman, Igor; Stone, Richard A; Lin, Xiaoyu; Saw, Seang Mei; Forward, Hannah; Mackey, David A; Yazar, Seyhan; Young, Terri L; Williams, Cathy

2013-12-01

An association between birth order and reduced unaided vision (a surrogate for myopia) has been observed previously. We examined the association between birth order and myopia directly in four subject groups. Subject groups were participants in (1) the Avon Longitudinal Study of Parents and Children (ALSPAC; UK; age 15 years; N = 4401), (2) the Singapore Cohort Study of Risk Factors for Myopia (SCORM; Singapore; age 13 years; N = 1959), (3) the Raine Eye Health Study (REHS; Australia; age 20 years; N = 1344), and (4) Israeli Defense Force Pre-recruitment Candidates (IDFC; Israel; age 16-22 years; N = 888,277). The main outcome was odds ratios (OR) for myopia in first-born versus non-first-born individuals after adjusting for potential risk factors. The prevalence of myopia was numerically higher in first-born versus non-first-born individuals in all study groups, but the strength of evidence varied widely. Adjusted ORs (95% confidence intervals, CIs) were: ALSPAC, 1.31 (1.05-1.64); SCORM, 1.25 (0.89-1.77); REHS, 1.18 (0.90-1.55); and IDFC, 1.04 (1.03-1.06). In the large IDFC sample, the effect size was greater (a) for the first-born versus fourth- or higher-born comparison than for the first-born versus second/third-born comparison (p 4000 participants provided strong statistical support for the association. The available evidence suggested the relationship was independent of established risk factors such as time outdoors/reading, and thus may arise through a different causal mechanism.

cAMP level modulates scleral collagen remodeling, a critical step in the development of myopia.

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Yijin Tao

Full Text Available The development of myopia is associated with decreased ocular scleral collagen synthesis in humans and animal models. Collagen synthesis is, in part, under the influence of cyclic adenosine monophosphate (cAMP. We investigated the associations between cAMP, myopia development in guinea pigs, and collagen synthesis by human scleral fibroblasts (HSFs. Form-deprived myopia (FDM was induced by unilateral masking of guinea pig eyes. Scleral cAMP levels increased selectively in the FDM eyes and returned to normal levels after unmasking and recovery. Unilateral subconjunctival treatment with the adenylyl cyclase (AC activator forskolin resulted in a myopic shift accompanied by reduced collagen mRNA levels, but it did not affect retinal electroretinograms. The AC inhibitor SQ22536 attenuated the progression of FDM. Moreover, forskolin inhibited collagen mRNA levels and collagen secretion by HSFs. The inhibition was reversed by SQ22536. These results demonstrate a critical role of cAMP in control of myopia development. Selective regulation of cAMP to control scleral collagen synthesis may be a novel therapeutic strategy for preventing and treating myopia.

Insight into high myopia and the macula.

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Kumar, Atul; Chawla, Rohan; Kumawat, Devesh; Pillay, Ganesh

2017-02-01

The incidence of myopia is constantly on the rise. Patients of high myopia and pathological myopia are young and can lose vision due to a number of degenerative changes occurring at the macula. With the emergence of new technologies such as swept-source optical coherence tomography (OCT) and OCT angiography, our understanding of macular pathology in myopia has improved significantly. New conditions such as myopic traction maculopathy have been defined. Early, noninvasive detection of myopic choroidal neovascularization and its differentiation from lacquer cracks is possible with a greater degree of certainty. We discuss the impact of these new exciting and promising technologies and management of macular pathology in myopia. Incorporation of OCT in the microscope has also improved macular surgery. New concepts such as fovea-sparing internal limiting membrane peeling have emerged. A review of literature and our experience in managing all these conditions are discussed.

Phenotypic and genotypic correlation between myopia and intelligence

NARCIS (Netherlands)

Williams, Katie M.; Hysi, Pirro G.; Yonova-Doing, Ekaterina; Mahroo, Omar A.; Snieder, Harold; Hammond, Christopher J.

2017-01-01

Myopia, or near-sightedness, is our most common eye condition and the prevalence is increasing globally. Visual impairment will occur if uncorrected, whilst high myopia causes sight-threatening complications. Myopia is associated with higher intelligence. As both are heritable, we set out to examine

Wnt signaling in form deprivation myopia of the mice retina.

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Mingming Ma

Full Text Available BACKGROUND: The canonical Wnt signaling pathway plays important roles in cellular proliferation and differentiation, axonal outgrowth, cellular maintenance in retinas. Here we test the hypothesis that elements of the Wnt signaling pathway are involved in the regulation of eye growth and prevention of myopia, in the mouse form-deprivation myopia model. METHODOLOGY/PRINCIPAL FINDINGS: (1 One hundred twenty-five C57BL/6 mice were randomly distributed into form-deprivation myopia and control groups. Form-deprivation myopia (FDM was induced by suturing the right eyelid, while the control group received no treatment. After 1, 2, and 4 weeks of treatment, eyes were assessed in vivo by cycloplegic retinoscopic refraction and axial length measurement by photography or A-scan ultrasonography. Levels of retinal Wnt2b, Fzd5 and β-catenin mRNA and protein were evaluated using RT-PCR and western blotting, respectively. (2 Another 96 mice were divided into three groups: control, drugs-only, and drugs+FDM (by diffuser. Experimentally treated eyes in the last two groups received intravitreal injections of vehicle or the proteins, DKK-1 (Wnt-pathway antagonist or Norrin (Wnt-pathway agonist, once every three days, for 4 injections total. Axial length and retinoscopic refraction were measured on the 14th day of form deprivation. Following form-deprivation for 1, 2, and 4 weeks, FDM eyes had a relatively myopic refractive error, compared with contralateral eyes. There were no significant differences in refractive error between right and left eye in control group. The amounts of Wnt2b, Fzd5 and β-catenin mRNA and protein were significantly greater in form-deprived myopia eyes than in control eyes.DKK-1 (antagonist reduced the myopic shift in refractive error and increase in axial elongation, whereas Norrin had the opposite effect in FDM eyes. CONCLUSIONS/SIGNIFICANCE: Our studies provide the first evidence that the Wnt2b signaling pathway may play a role in the

Incremental retinal-defocus theory of myopia development--schematic analysis and computer simulation.

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Hung, George K; Ciuffreda, Kenneth J

2007-07-01

Previous theories of myopia development involved subtle and complex processes such as the sensing and analyzing of chromatic aberration, spherical aberration, spatial gradient of blur, or spatial frequency content of the retinal image, but they have not been able to explain satisfactorily the diverse experimental results reported in the literature. On the other hand, our newly proposed incremental retinal-defocus theory (IRDT) has been able to explain all of these results. This theory is based on a relatively simple and direct mechanism for the regulation of ocular growth. It states that a time-averaged decrease in retinal-image defocus area decreases the rate of release of retinal neuromodulators, which decreases the rate of retinal proteoglycan synthesis with an associated decrease in scleral structural integrity. This increases the rate of scleral growth, and in turn the eye's axial length, which leads to myopia. Our schematic analysis has provided a clear explanation for the eye's ability to grow in the appropriate direction under a wide range of experimental conditions. In addition, the theory has been able to explain how repeated cycles of nearwork-induced transient myopia leads to repeated periods of decreased retinal-image defocus, whose cumulative effect over an extended period of time results in an increase in axial growth that leads to permanent myopia. Thus, this unifying theory forms the basis for understanding the underlying retinal and scleral mechanisms of myopia development.

Incidence and progression of myopia and associated factors in urban school children in Delhi: The North India Myopia Study (NIM Study.

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Rohit Saxena

Full Text Available To evaluate the incidence and progression of myopia and factors associated with progression of myopia in school going children in Delhi.Prospective longitudinal study of 10,000 school children aged 5 to 15 years screened after an interval of 1 year to identify new myopes (Spherical Equivalent≤ -0.5D and progression of myopia in previously diagnosed myopic children. Association between risk factors and progression was analyzed using adjusted odds ratio.Of the 9,616 children re-screened (97.3% coverage, annual incidence of myopia was 3.4%with mean dioptric change of -1.09 ± 0.55. There was a significant higher incidence of myopia in younger children compared to older children (P = 0.012 and among girls compared to boys (P = 0.002. Progression was observed in 49.2%children with mean dioptric change of -0.27 ± 0.42 diopters. The demographic and behavioral risk factors were analyzed for children with progression (n = 629 and adjusted odds ratio values were estimated. Hours of reading-writing/week (p 2 hours in a day were protective with an inverse association with progression of myopia (P< 0.001.Myopia is an important health issue in India and is associated with long hours of reading and screen time with use of computers and video games. An annual eye vision screening should be conducted, and outdoor activities be promoted to prevent the increase of myopia among school children.

Astigmatism induced by conventional spherical ablation after PRK and LASIK in myopia with astigmatism < 1.00 D

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Christiansen SM

2012-12-01

Full Text Available Steven M Christiansen,1 Mark D Mifflin,1 Jason N Edmonds,1 Rachel G Simpson,2 Majid Moshirfar11John A Moran Eye Center, University of Utah, Salt Lake City, UT, 2The University of Arizona College of Medicine, Phoenix, AZ, USABackground: The purpose of this study was to evaluate surgically-induced astigmatism after spherical ablation in photorefractive keratectomy (PRK and laser-assisted in situ keratomileusis (LASIK for myopia with astigmatism < 1.00 D.Methods: The charts of patients undergoing spherical PRK or LASIK for the correction of myopia with minimal astigmatism of <1.00 D from 2002 to 2012 at the John A Moran Eye Center in Salt Lake City, UT, were retrospectively reviewed. Astigmatism was measured by manifest refraction. The final astigmatic refractive outcome at 6 months postoperatively was compared with the initial refraction by Alpins vector analysis.Results: For PRK, average cylinder increased from 0.39 ± 0.25 (0.00–0.75 preoperatively to 0.55 ± 0.48 (0.00–1.75 postoperatively (P = 0.014, compared with an increase in LASIK eyes from 0.40 ± 0.27 (0.00–0.75 preoperatively to 0.52 ± 0.45 (0.00–2.00 postoperatively (P = 0.041. PRK eyes experienced an absolute value change in cylinder of 0.41 ± 0.32 (0.00–1.50 and LASIK eyes experienced a change of 0.41 ± 0.31 (0.00–1.50, P = 0.955. Mean surgically-induced astigmatism was 0.59 ± 0.35 (0.00–1.70 in PRK eyes, with an increase in surgically-induced astigmatism of 0.44 D for each additional 1.00 D of preoperative cylinder; in LASIK eyes, mean surgically-induced astigmatism was 0.55 ± 0.32 (0.00–1.80, P = 0.482, with an increase in surgically-induced astigmatism of 0.29 D for each 1.00 D of preoperative cylinder.Conclusion: Spherical ablation can induce substantial astigmatism even in eyes with less than one diopter of preoperative astigmatism in both PRK and LASIK. No significant difference in the magnitude of surgically-induced astigmatism was found between eyes

Protection Myopia

DEFF Research Database (Denmark)

Laursen, Keld; Salter, Ammon; Li, Cher

from having an orientation towards legal appropriability, we conjecture that protection myopia may lead some firms to allocate too much attention to legal appropriability, in particular when the behavioral and structural contingencies are unfavorable. Examining a panel of three successive waves...

Pathology of Macular Foveoschisis Associated with Degenerative Myopia

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Johnny Tang

2010-01-01

Full Text Available This is a clinicopathological paper on the histologic findings in myopia-associated macular foveoschisis. The findings on ophthalmic pathological study of a 73-year-old woman with high myopia are reviewed. Multiple retinoschisis cavities involving both the macula and retinal periphery were disclosed. Our paper offers tissue evidence and supports recent ocular coherence tomography reports of eyes with high myopia and associated macular foveoschisis.

Effects of electroacupuncture on the levels of retinal gamma-aminobutyric acid and its receptors in a guinea pig model of lens-induced myopia.

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Sha, F; Ye, X; Zhao, W; Xu, C-L; Wang, L; Ding, M-H; Bi, A-L; Wu, J-F; Jiang, W-J; Guo, D-D; Guo, J-G; Bi, H-S

2015-02-26

Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter of the retina and affects myopic development. Electroacupuncture (EA) is widely utilized to treat myopia in clinical settings. However, there are few reports on whether EA affects the level of retinal GABA during myopic development. To study this issue, in the present study, we explored the changes of retinal GABA content and the expression of its receptor subtypes, and the effects of EA stimulation on them in a guinea pig model with lens-induced myopia (LIM). Our results showed that the content of GABA and the expression of GABAA and GABAC receptors of retina were up-regulated during the development of myopia, and this up-regulation was inhibited by applying EA to Hegu (LI4) and Taiyang (EX-HN5) acupoints. Moreover, these effects of EA show a positional specificity. While applying EA at a sham acupoint, no apparent change of myopic retinal GABA and its receptor subtypes was observed. Taken together, our findings suggest that LIM is effective to up-regulate the level of retinal GABA, GABAA and GABAC receptors in guinea pigs and the effect may be inhibited by EA stimulation at LI4 and EX-HN5 acupoints. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

BILATERAL ACUTE ANGLE CLOSURE GLAUCOMA AND MYOPIA INDUCED BY LOW DOSAGE TOPIRAMATE

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Busra S. Arica

2014-09-01

Full Text Available Introduction: Topiramate, a sulfamate-substituted monosaccharide, has been shown to be effective in the treatment of epilepsy and migraine prophylaxis. However, acute secondary angle closure glaucoma and myopia has been shown to develop, especially during the first two weeks of treatment, in a small subset of patients. Case presentation: In the current case report, a 23 year old female patient developed acute myopia and angle closure glaucoma after one week topiramate treatment (25 mg/day for prophylaxis of migraine without aura. The patient was found to have significant conjunctival hyperemia, shallow anterior chamber, and bulging iris in both eyes. Grade 1 acute angle was detected in both eyes during gonioscopic examination. There was no pupillary block and intraocular pressure was 40 mmHg in both eyes. Refraction values were measured at -7.00 and -8.00 in the right and left eye, respectively. The patient and #8217;s visual acuity was at 0.1 to 0.2. Topiramate treatment was promptly discontinued, topical antiglaucomatous treatment was initiated, and laser peripheral iridotomy was performed on each eye. Intraocular pressure has declined to normal limits, refractive values were zero in both eyes and patient and #8217;s visual acuity has restored at follow-up period at 10 days after treatment. Conclusion: Side effects associated with topiramate treatments are known to disappear without long-term damage when the discontinuation of therapy and effective interventions are started early. Therefore, patients and their physicians should be alert for symptoms associated with acute secondary angle closure glaucoma and myopia; especially in the first weeks of topiramate treatment also with low dosage. [J Contemp Med 2014; 4(3.000: 168-171

Exome sequencing identifies ZNF644 mutations in high myopia.

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Yi Shi

2011-06-01

Full Text Available Myopia is the most common ocular disorder worldwide, and high myopia in particular is one of the leading causes of blindness. Genetic factors play a critical role in the development of myopia, especially high myopia. Recently, the exome sequencing approach has been successfully used for the disease gene identification of Mendelian disorders. Here we show a successful application of exome sequencing to identify a gene for an autosomal dominant disorder, and we have identified a gene potentially responsible for high myopia in a monogenic form. We captured exomes of two affected individuals from a Han Chinese family with high myopia and performed sequencing analysis by a second-generation sequencer with a mean coverage of 30× and sufficient depth to call variants at ∼97% of each targeted exome. The shared genetic variants of these two affected individuals in the family being studied were filtered against the 1000 Genomes Project and the dbSNP131 database. A mutation A672G in zinc finger protein 644 isoform 1 (ZNF644 was identified as being related to the phenotype of this family. After we performed sequencing analysis of the exons in the ZNF644 gene in 300 sporadic cases of high myopia, we identified an additional five mutations (I587V, R680G, C699Y, 3'UTR+12 C>G, and 3'UTR+592 G>A in 11 different patients. All these mutations were absent in 600 normal controls. The ZNF644 gene was expressed in human retinal and retinal pigment epithelium (RPE. Given that ZNF644 is predicted to be a transcription factor that may regulate genes involved in eye development, mutation may cause the axial elongation of eyeball found in high myopia patients. Our results suggest that ZNF644 might be a causal gene for high myopia in a monogenic form.

Darkness and near work: myopia and its progression in third-year law students.

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Loman, Jane; Quinn, Graham E; Kamoun, Layla; Ying, Gui-Shuang; Maguire, Maureen G; Hudesman, David; Stone, Richard A

2002-05-01

To evaluate myopia prevalence, myopia progression, and various potential myopia risk factors in third-year law students. Cross-sectional study and survey. One hundred seventy-nine third-year law students at the University of Pennsylvania. We administered a questionnaire to assess the prevalence of myopia, myopia progression, and risk factors, including near work, family history, and daily light/dark exposure. We conducted a screening eye examination to ascertain myopia status. Myopia was defined as the mean spherical equivalent of the two eyes of school. (1) prevalence of myopia, (2) progression of myopia. Seventy-nine percent of the class participated (n = 179, two were excluded for amblyopia leaving 177 students). Fifty-eight percent were male, 75% were Caucasian, and the mean age was 27 years. Seventy-nine percent reported parental myopia. The mean amount of near work was 7.4 hours/day; mean sleep was 7.9 hours/day; mean darkness was 5.3 hours/day. Sixty-six percent of the students were myopic. Of 96 participants myopic before law school, myopia increased in 83 (86%) during law school. Among 75 students not myopic at the beginning of law school, 14 (19%) became myopic. The onset of myopia could not be determined for 6 patients. There were trends for higher myopia prevalence among those with a parental myopia history (P = 0.14) and for increased myopia progression among those reporting more daily near work (P = 0.18). Students with 5.6 hours of darkness per day (95% vs. 80%, P = 0.07). To account for possible confounding effects of risk factors with myopia progression, logistic regression with categorization of the continuous exposure variables (hours of near work, sleep, and darkness) above or below median values weakened the near work association (odds ratio 1.8, 95% confidence interval 0.5-6.7, P = 0.35) but continued to identify darkness association with daily hours of darkness (odds ratio 4.8, 95% confidence interval 1.0 >/= 23.3, P students with myopia

[Modern aspects of surgical treatment of myopia].

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Beliaev, V S; Dushin, N V; Barashkov, V I; Frolov, M A; Gonchar, P A; Kravchinina, V V

1997-01-01

Problems in complex surgical treatment of myopia are discussed. Extensive clinical data and long follow-up of the patients permitted the authors to develop a well-based system of care which helps not only arrest the progress of myopia, but correct it within a rather wide range. The pathogenesis of tissue process in progressive myopia is discussed basing on the regularities revealed experimentally. The main modern operations on the cornea and sclera are described. Data on the inter-layer transplantation of the cornea, developed at the Chair of Ophthalmic Diseases of the Russian University of Peoples' Friendship are presented.

Choroidal thickness in eyes with different degrees of myopia

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Yuriy Sergeyevich Astakhov

2013-12-01

Full Text Available 66 healthy people (124 eyes with different degrees of myopia and emmetropia were examined using enhanced depth imaging optical coherence tomography (EDI-OCT using the “Spectralis OCT”. It was found that the choroid in subjects with medium and high degrees of myopia was significantly thinner than that in the control group. In the study, a negative correlation was found between the subfoveal choroidal thickness and the degree of myopia (r = -0.75, p < 0.0001. It was also found that the subfoveal choroidal thickness decreased for each diopter of myopia by approximately 18.03 μm.

Education-Related Parameters in High Myopia: Adults versus School Children.

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Jost B Jonas

Full Text Available Since high myopia in the younger generation may differ etiologically from high myopia in older generations, we examined whether education-related parameters differ between high myopia in today´s school children and high pathological myopia in today´s elderly generation.The investigation included the adult populations of the population-based Beijing Eye Study (BES (3468 adults;mean age:64.6±9.8years;range:50-93years and Central India Eye and Medical Study (CIEMS (4711 adults;age:49.±13.2years;range:30-100years, and the children and teenager populations of the Shandong Children Eye Study (SCES (6026 children;age:9.7±3.3years;range:4-18years;cycloplegic refractometry, Gobi Desert Children Eye Study (1565;age:11.9±3.5years;range:6-21 years;cycloplegic refractometry, Beijing Pediatric Eye Study (681 children;age:7.7±1.6years;range:5-13 years;non-cycloplegic refractometry,calculation of axial length to corneal curvature radius ratio, Beijing Children Eye Study (15066 children;age:13.2±3.4years;range:7-18years;non-cycloplegic refractometry, Beijing High School Teenager Eye Study (4677 children;age:16.9±0.7years;range:16-18years;non-cycloplegic refractometry.In the BES and CIEMS, educational level did not differ significantly between, or was significantly lower in the highly myopic group (myopic refractive error ≥6 diopters than in the non-highly myopic group. In all non-adult study populations, higher prevalence of high myopia was significantly associated with higher degree of education related parameters such as attendance of high-level schools, and more time spent for indoors near work versus time spent outdoors.Comparing associations of old or genetic high myopia in adults with new or acquired high myopia in school children revealed that education-related parameters did not show a clear association with old or genetic high myopia, while in contrast, new high myopia showed strong associations with education. It confirms previous studies

Dopamine signaling and myopia development: What are the key challenges.

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Zhou, Xiangtian; Pardue, Machelle T; Iuvone, P Michael; Qu, Jia

2017-11-01

In the face of an "epidemic" increase in myopia over the last decades and myopia prevalence predicted to reach 2.5 billion people by the end of this decade, there is an urgent need to develop effective and safe therapeutic interventions to slow down this "myopia booming" and prevent myopia-related complications and vision loss. Dopamine (DA) is an important neurotransmitter in the retina and mediates diverse functions including retina development, visual signaling, and refractive development. Inspired by the convergence of epidemiological and animal studies in support of the inverse relationship between outdoor activity and risk of developing myopia and by the close biological relationship between light exposure and dopamine release/signaling, we felt it is timely and important to critically review the role of DA in myopia development. This review will revisit several key points of evidence for and against DA mediating light control of myopia: 1) the causal role of extracellular retinal DA levels, 2) the mechanism and action of dopamine D1 and D2 receptors and 3) the roles of cellular/circuit retinal pathways. We examine the experiments that show causation by altering DA, DA receptors and visual pathways using pharmacological, transgenic, or visual environment approaches. Furthermore, we critically evaluate the safety issues of a DA-based treatment strategy and some approaches to address these issues. The review identifies the key questions and challenges in translating basic knowledge on DA signaling and myopia from animal studies into effective pharmacological treatments for myopia in children. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Study of the relationship between myopia and personality.

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Rodríguez Uña, I; Pérez Bartolomé, F; Urriés Ortiz, M; Arriola Villalobos, P; Bermúdez Vallecilla, M; Fernández-Vega Cueto, L; Martín Villaescusa, C; Marticorena Álvarez, P

2015-08-01

To study the correlation between the myopic refractive error and certain personality traits, and to determine whether there is a correlation between the degree of myopia and an increased frequency in personality disorders. Cross-sectional observational multicenter study conducted on 82 subjects (26 men, 56 women) age over 18 years with myopia (spherical defect ≤ -0.5 D), with 30 subjects having high myopia (de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

Role of Educational Exposure in the Association Between Myopia and Birth Order.

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Guggenheim, Jeremy A; Williams, Cathy

2015-12-01

Visual impairment due to myopia is an important public health issue. A prior analysis of population-based cohorts aged 15 to 22 years recruited from the United Kingdom and Israel suggested myopia and high myopia were approximately 10% more common in first-born compared with later-born children. To examine whether myopia was associated with birth order in an earlier generation than studied previously and, if so, whether the association was attenuated after adjusting for education exposure, as predicted by the hypothesis that the education of children with later birth orders is less intense. Cross-sectional study of UK Biobank participants recruited from 2006 to 2010. Analysis was restricted to participants aged 40 to 69 years who had a vision assessment, self-reported white ethnicity, and no history of eye disorders (N = 89,120). Myopia and high myopia were defined as autorefraction of -0.75 diopters (D) or less and -6.00 D or less, respectively. Birth order and information on potential confounders including highest educational qualification ascertained using a structured questionnaire. Odds ratios (ORs) for myopia and high myopia by birth order, using logistic regression and adjusting for age and sex (model 1) or age, sex, and highest educational qualification (model 2). In model 1 (no adjustment for education), birth order was associated with both myopia and high myopia (eg, comparing first- vs second-born individuals; OR, 1.12; 95% CI, 1.08-1.16; P = 1.40E-11 and OR, 1.21; 95% CI, 1.11-1.30; P = 3.60E-06 for myopia and high myopia, respectively). The risk for myopia became progressively lower for later birth orders, suggesting a dose response. In model 2 (after adjusting for education), the effect sizes were attenuated by approximately 25% (OR, 1.09; 95% CI, 1.05-1.12; P = 1.30E-06 and OR, 1.15; 95% CI, 1.06-1.25; P = 4.60E-04 for myopia and high myopia, respectively) and the apparent dose response was abolished. These data suggest that the

Facts about Myopia

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... an international team of vision scientists, discovered 24 new genetic risk factors for myopia. 1 Some of these genes are involved in nerve cell function, metabolism, and eye development. Alone, each gene has a small influence ...

Induction methods and formation process of experimental myopia in guinea pigs

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Mi-Duo Chen

2016-03-01

Full Text Available Myopia, especially high myopia, is one of the most important eye diseases in the world. For many years the researchers established a variety of animal models and animal experiments to explore the mechanism of development of myopia. Guinea pig is one of the most commonly used myopia models in recent years. It has obvious advantages in many aspects, and it is a kind of experimental animals which is worth to be further applied to different kinds of myopic experiments and to be studied thoroughly. This article reviews the induction methods and the forming process of the guinea pig myopia model.

Increasing Prevalence of Myopia in Europe and the Impact of Education

DEFF Research Database (Denmark)

Williams, Katie M; Bertelsen, Geir; Cumberland, Phillippa

2015-01-01

PURPOSE: To investigate whether myopia is becoming more common across Europe and explore whether increasing education levels, an important environmental risk factor for myopia, might explain any temporal trend. DESIGN: Meta-analysis of population-based, cross-sectional studies from the European Eye...... a range of median ages from 44 to 78 years. METHODS: Noncycloplegic refraction, year of birth, and highest educational level achieved were obtained for all participants. Myopia was defined as a mean spherical equivalent ≤-0.75 diopters. A random-effects meta-analysis of age-specific myopia prevalence...... was performed, with sequential analyses stratified by year of birth and highest level of educational attainment. MAIN OUTCOME MEASURES: Variation in age-specific myopia prevalence for differing years of birth and educational level. RESULTS: There was a significant cohort effect for increasing myopia prevalence...

Childhood myopia and parental smoking.

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Saw, S-M; Chia, K-S; Lindstrom, J M; Tan, D T H; Stone, R A

2004-07-01

To examine the relation between exposure to passive parental smoke and myopia in Chinese children in Singapore. 1334 Chinese children from three schools in Singapore were recruited, all of whom were participants in the Singapore Cohort study Of the Risk factors for Myopia (SCORM). Information on whether the father or mother smoked, number of years smoked, and the number of cigarettes smoked per day during the child's lifetime were derived. These data were correlated with contemporaneously obtained data available in SCORM. The children's cycloplegic autorefraction, corneal curvature radius, and biometry measures were compared with reported parental smoking history. There were 434 fathers (33.3%) and 23 mothers (1.7%) who smoked during their child's lifetime. There were no significant trends observed between paternal smoking and refractive error or axial length. After controlling for age, sex, school, mother's education, and mother's myopia, children with mothers who had ever smoked during their lifetime had more "positive" refractions (adjusted mean -0.28 D v -1.38 D) compared with children whose mother did not smoke (p = 0.012). The study found no consistent evidence of association between parental smoking and refractive error. There was a suggestion that children whose mothers smoked cigarettes had more hyperopic refractions, but the absence of a relation with paternal smoking and the small number of mothers who smoked in this sample preclude definite conclusions about a link between passive smoking exposure and myopia.

Subfoveal choroidal thickness measured by Cirrus HD optical coherence tomography in myopia

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Li-Li Chen

2014-09-01

Full Text Available ATM: To measure the subfoveal choroidal thickness(SFCTin myopia using Cirrus HD optical coherence tomography(OCT, and to explore the relationship between the SFCT, axial length and myopic refractive spherical equivalent.METHODS: One-hundred thirty-three eyes of 70 healthy volunteers were recruited, and were divided into emmetropia group, low-degree myopia, middle-degree myopia and high-degree myopia group. SFCT were measured by Cirrus HD OCT, and the relationship between the SFCT, axial length and myopic refractive spherical equivalent were evaluated.RESULTS: 1Average SFCT was(275.91±55.74μm in normals, that in emmetropia group, low-degree myopia, middle-degree myopia and high-degree myopia group were(290.03±34.82μm,(287.64±51.51μm,(274.95±56.83μm,(248.37±67.98μm; 2the SFCT of high-degree myopia group was significant thinner than that of emmetropia group(PPPCONCLUSION: the SFCT is inversely correlated with increasing axial length and myopic refractive error.

What causes myopia? : Complex genetics and epidemiology of a common condition

NARCIS (Netherlands)

V.J.M. Verhoeven (Virginie)

2015-01-01

markdownabstract__Abstract__ Myopia (nearsightedness) is a highly common eye condition that is predominantly caused by an axial elongation of the eye. Myopia can usually be corrected with negative glasses, contact lenses, and/or laser refractive surgery. Unfortunately, however, high myopia (-6

TGIF1 is a potential candidate gene for high myopia in ethnic Kashmiri population.

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Ahmed, Ishfaq; Rasool, Shabhat; Jan, Tariq; Qureshi, Tariq; Naykoo, Niyaz A; Andrabi, Khurshid I

2014-03-01

High myopia is a complex disorder that imposes serious consequences on ocular health. Linkage analysis has identified several genetic loci with a series of potential candidate genes that reveal an ambiguous pattern of association with high myopia due to population heterogeneity. We have accordingly chosen to examine the prospect of association of one such gene [transforming growth β-induced factor 1 (TGIF1)] in population that is purely ethnic (Kashmiri) and represents a homogeneous cohort from Northern India. Cases with high myopia with a spherical equivalent of ≥-6 diopters (D) and emmetropic controls with spherical equivalent within ±0.5 D in one or both eyes represented by a sample size of 212 ethnic Kashmiri subjects and 239 matched controls. Genomic DNA was genotyped for sequence variations in TGIF1 gene and allele frequencies tested for Hardy-Weinberg disequilibrium. Potential association was evaluated using χ(2) or Fisher's exact test. Two previously reported missense variations C > T, rs4468717 (first base of codon 143) changing proline to serine and rs2229333 (second base of codon 143) changing proline to leucine were identified in exon 10 of TGIF1. Both variations exhibited possibly significant (p population. In silico predictions show that substitutions are likely to have an impact on the structure and functional properties of the protein, making it imperative to understand their functional consequences in relation to high myopia. TGIF1 is a relevant candidate gene with potential to contribute in the genesis of high myopia.

Alcohol myopia and goal commitment

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A. Timur Sevincer

2014-03-01

Full Text Available According to alcohol-myopia theory, acute alcohol consumption leads people to disproportionally focus on the salient rather than the peripheral aspects of a situation. We summarize various studies exploring how myopic processes resulting from acute alcohol intake affect goal commitment. After consuming alcohol student participants felt strongly committed to an important personal goal even though they had low expectations of successfully attaining the goal. However, once intoxicated participants were sober again (i.e., not myopic anymore they failed to act on their goal commitment. In line with alcohol-myopia theory, strong goal commitment as a result of alcohol intake was mediated by intoxicated (vs. sober participants disproportionally focusing on the desirability rather than the feasibility of their goal. Further supporting alcohol-myopia theory, when the low feasibility of attaining a particular goal was experimentally made salient (either explicitly or implicitly by subliminal priming, intoxicated participants felt less committed than those who consumed a placebo. We discuss these effects of acute alcohol intake in the context of research on the effects of chronic alcohol consumption on goal commitment.

High myopia in Greater Beijing School Children in 2016.

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Yin Guo

Full Text Available To assess prevalence and associated factors of myopia and high myopia in schoolchildren in Greater Beijing.The school-based, cross-sectional Greater Beijing School Children Myopia study was carried out in the year 2016 in 54 schools randomly selected from 15 districts in Beijing. Non-cycloplegic auto-refractometry of the right eyes was performed.The study included 35,745 (99.4% out of 35,968 eligible pupils with a mean age of 12.6±3.4 years (range 6-18 years. Prevalence of myopia defined as myopic refractive error of ≥-0.50 diopters (D,≥-1D,≥-6D,≥-8D and ≥-10D was 70.9%(95% confidence intervals (CI:70.5,71.4, 60.9% (95%CI:60.4,61.4, 8.6%(95%CI:8.4,8.9, 2.2%(95%CI:2.0,2.4, and 0.3% (95%CI:0.3,0.4, respectively. The frequency of high myopia (≥-6D, ≥-8D, ≥-10D increased from 1.5% (95%CI:1.0,2.0, 0.4% (95%CI:0.1,0.6 and 0.1% (95%CI:0.00,0.02, respectively in 10-year-olds to 19.4% (95%CI:17.3,21.6, 5.2% (95%CI:4.0,6.4 and 0.9% (95%CI:0.4,1.5, respectively, in 18-year-olds. Mean refractive error in the 18-year-olds was -3.74±2.56D (median:-3.63D;range:-19.6D to + 6.25D. Higher prevalence of high myopia (≥-6D and ≥-8D was correlated (all P<0.001 with older age (OR:1.18, and 1.15, respectively, female gender (OR: 1.44 and 1.40, respectively, higher body mass index (OR: 1.02 and 1.03, respectively, taller body height (OR: 1.03 and 1.02, respectively, urban region of habitation (OR: 1.26 and 1.33, respectively and higher school type (OR:1.57 and 2.22, respectively. Prevalence of severe high myopia (≥-10D was associated only with older age (P<0.001; OR: 1.44; 95%CI: 1.31, 1.59 but not with any education-related parameter such as higher school type (P = 0.48, urban region of habitation (P = 0.07 or female gender (P = 0.37.In this most recent survey, prevalence of high myopia (≥-6D:19.4%;≥-8D:5.2%;≥-10D:0.9% in 18-year-old school children was higher than in previous surveys from mainland China. In contrast to minor high myopia

Abstracts from the 15th International Myopia Conference

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Alexandra Benavente-Perez

2016-11-01

Full Text Available Table of contents O1 Changes in peripheral refraction associated with decreased ocular axial growth rate in marmosets Alexandra Benavente-Perez, Ann Nour, Tobin Ansel, Kathleen Abarr, Luying Yan, Keisha Roden, David Troilo O2 PPARα activation suppresses myopia development by increasing scleral collagen synthesis--a new drug target to suppress myopia development Chanyi Lu, Miaozhen Pan, Min Zheng, Jia Qu, Xiangtian Zhou O3 Evidence and possibilities for local ocular growth regulating signal pathways Christine F Wildsoet O4 Myopia researches at Eye Hospital of Wenzhou Medical University Fan Lu, Xiangtian Zhou, Jie Chen, Jinhua Bao, Liang Hu, Qinmei Wang, Zibing Jin, Jia Qu O5 Color, temporal contrast and myopia Frances Rucker, Stephanie Britton, Stephan Hanowsky, Molly Spatcher O6 The impact of atropine usage on visual function and reading performance in myopic school children in Taiwan Hui-Ying Kuo, Ching-Hsiu Ke, I-Hsin Kuo, Chien-Chun Peng, Han-Yin Sun O7 Increased time outdoors prevents the onset of myopia: evidence from randomised clinical trials Ian G Morgan O8 Environmental risk factors and gene-environment interactions for myopia in the ALSPAC cohort Jeremy A. Guggenheim, Rupal L. Shah, Cathy Williams O9 Retinal metabolic profiling identifies declines in FP receptor-linked signaling as contributors to form-deprived myopic development in guinea pigs Jinglei Yang, Peter S. Reinach, Sen Zhang, Miaozhen Pan, Wenfeng Sun, Bo Liu, Xiangtian Zhou O10 The study of peripheral refraction in moderate and high myopes after one month of wearing orthokeratology lens Jun Jiang, Haoran Wu, Fan Lu O11 Axial length of school children around the earth’s equatorial area and factors affecting the axial length Kazuo Tsubota, Hiroko Ozawa, Hidemasa Torii, Shigemasa Takamizawa, Toshihide Kurihara, Kazuno Negishi O12 Processing of defocus in the chicken retina by retinal ganglion cells Klaus Graef, Daniel Rathbun, Frank Schaeffel O13 Blue SAD light protects

Myopia prevalence in Chinese-Canadian children in an optometric practice.

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Cheng, Desmond; Schmid, Katrina L; Woo, George C

2007-01-01

The high prevalence of myopia in Chinese children living in urban East Asian countries such as Hong Kong, Taiwan, and China has been well documented. However, it is not clear whether the prevalence of myopia would be similarly high for this group of children if they were living in a Western country. This study aims to determine the prevalence and progression of myopia in ethnic Chinese children living in Canada. Right eye refraction data of Chinese-Canadian children aged 6 to 12 years were collated from the 2003 clinical records of an optometric practice in Mississauga, Ontario, Canada. Myopia was defined as a spherical equivalent refraction (SER) equal or less than -0.50 D. The prevalence of myopia and refractive error distribution in children of different ages and the magnitude of refractive error shifts over the preceding 8 years were determined. Data were adjusted for potential biases in the clinic sample. A questionnaire was administered to 300 Chinese and 300 Caucasian children randomly selected from the clinic records to study lifestyle issues that may impact on myopia development. Optometric records of 1468 children were analyzed (729 boys and 739 girls). The clinic bias adjusted prevalence of myopia increased from 22.4% at age 6 to 64.1% at age 12 and concurrently the portion of the children that were emmetropic (refraction between -0.25 and +0.75 D) decreased (68.6% at 6 years to 27.2% at 12 years). The highest incidence of myopia for both girls ( approximately 35%) and boys ( approximately 25%) occurred at 9 and 10 years of age. The average annual refractive shift for all children was -0.52+/-0.42 D and -0.90+/-0.40 D for just myopic children. The questionnaire revealed that these Chinese-Canadian children spent a greater amount of time performing near work and less time outdoors than did Caucasian-Canadian children. Ethnic Chinese children living in Canada develop myopia comparable in prevalence and magnitude to those living in urban East Asian

[Interlamellar circular keratoplasty for correction of high myopia].

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Beliaev, V S; Dushin, N V; Gonchar, P A; Frolov, M A; Barashkov, V I; Kravchinina, V V; Balikoev, T M

1995-01-01

A new method is proposed for the correction of high myopia: Interlamellar circular keratoplasty. This method has been used in 15 patients (17 eyes) aged 18 to 54 with 9 to 17 diopters myopia. Vision acuity attained was at least 0.5 in 10 (60.3%) patients; in 7 (35.2%) patients vision acuity was 0.3 without correction, that is, was equal to the maximal vision acuity with the optimal correction. The highest refraction effect was 15.0 diopters. The patients were followed up for 3 months to 16 years. The proposed method for the correction of high myopia is highly effective, simple, and is recommended for clinical practice.

Astigmatism and myopia in Tohono O'odham Native American children.

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Twelker, J Daniel; Miller, Joseph M; Sherrill, Duane L; Harvey, Erin M

2013-11-01

To describe change in spherical equivalent (M) in a longitudinal sample of Tohono O'odham students ages 3 to 18 years and to test the hypothesis that astigmatism creates complex cues to emmetropization, resulting in increased change in M in the direction of increasing myopia and increased occurrence of myopia. Subjects were 777 Tohono O'odham Native American children on whom cycloplegic right eye autorefraction was measured on at least two study encounters between ages 3 and 18 years (first encounter prior to age 5.5 years, final encounter ≥3 years later). Regression lines were fit to individual subjects' longitudinal M data to estimate rate of change in M (regression slope, D/yr). Regression was also used to predict if a subject would be myopic (≤-0.75 D M) by age 18 years. Analysis of covariance was used to assess the relation between M slope and magnitude of baseline M and astigmatism. Chi-square analyses were used to assess the relation between predicted myopia onset and magnitude of baseline M and astigmatism. Mean M slope was significantly more negative for hyperopes (M ≥ +2.00) than for myopes (M ≤ -0.75) or for subjects neither hyperopic nor myopic (NHM, M > -0.75 and < +2.00), but there was no significant difference between the myopic and NHM groups. Chi-square analysis indicated that final myopia status varied across level of baseline astigmatism. Subjects with high astigmatism were more likely to be predicted to have significant myopia by age 18 years. The association between greater shift in M towards myopia with age in subjects who were hyperopic at baseline is consistent with continued emmetropization in the school years. Results regarding predicted myopia development imply that degradation of image quality due to refractive astigmatism creates complex cues to emmetropization, resulting in increased occurrence of myopia.

Wavefront-guided laser-assisted subepithelial keratectomy in low myopia, myopic astigmatism and high myopia

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Seyed Javad Hashemian

2015-02-01

Full Text Available AIM: To compare the safety, efficacy, predictability, stability and complications of wavefront-guided laser-assisted subepithelial keratectomy(LASEKin low myopia, myopic astigmatism and high myopia correction.METHODS: A retrospective analysis of 416 eyes were assigned to 3 groups: 159 eyes with low myopia(LMand mean refractive spherical equivalent(MRSEof -3.68±1.33 dioptre(D; 161 eyes with myopic astigmatism(MAand MRSE of -5.99±2.24D and mean cylinder of 2.41±1.07D; and 96 eyes with high myopia(HMand MRSE of -7.41±0.80D. After an epithelial flap creation, a wavefront-based excimer laser ablation was performed. Safety, efficacy, predictability and stability were evaluated at day 10, 2, 6 and 12mo postoperatively.RESULTS:At 12mo, the MRSE was -0.36±0.31D in LM group, 0.15±0.41D in MA group and 0.58±0.68D in HM group. The uncorrected visual acuity(UCVAwas 20/20 in 90.60% of patients in LM group, 78.90% in MA group and 67% in HM group. Efficacy indices were 0.98, 1.04 and 0.92 in LM, MA and HM groups, respectively. Safety indices were 1.00, 1.07 and 1.05 in LM, MA and HM respectively. Five eyes(3.1%in the LM group gained 1 line. Forty-four eyes(27.3%in MA gained 1-3 lines and eighteen eyes(19.2%of HM group gained 1-2 lines of BSCVA. Only 2 eyes in LM group developed corneal haze. There were not statistically significant differences in efficacy and safety indices amongst three groups. CONCLUSION: Wavefront-guided LASEK is an effective and safe procedure for the treatment of LM, MA, and HM.although in myopic astigmatism the predictability, efficacy and safety indices had been better.

Investigation of junior school student myopia in high-altitude Tibetan areas in Qinghai Province

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Xia Han

2014-05-01

Full Text Available AIM: To know the rate of students' myopia in junior school and factors affecting its occurrence in high altitude Tibetan areas in Qinghai, and provide basis for the prevention of myopia. METHODS: Totally 2 209 junior school students were extracted as respondent with stratified cluster sampling method. The gender, age, ethnicity, grade, eye behavior, physical activity and parental visual conditions were collected by self-made questionnaire, and the curvature of the cornea, anterior chamber depth and axial length were detected. RESULTS: The prevalence of myopia was 48.02%, including the mild myopia, moderate myopia and high myopia were 40.74%, 35.31% and 23.96% respectively. Curvature of the cornea, anterior chamber depth and axial length had statistical difference between normal vision and different degrees of myopia(PPCONCLUSION: Incorrect sitting posture, parental myopia, visual near distance <20cm, incorrect eye exercises and less time for outdoor activities are the main reasons that cause myopia of junior students. The effective prevention and controlled measures should be taken for these factors.

Evaluation the COL9A2 gene with high myopia

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Zhang, Dingding; Huang, Maomin

2017-11-01

This paper investigates the association of the COL9A2 gene between high myopia and normal controls in the Han Chinese population. It shows that the frameshift mutation (D281fs) in the COL9A2 gene is not associated with high myopia in the Han Chinese population, and the two novel variants(c.143G＞C and c.884G＞A) may contribute to the development of high myopia.

[Myopia: frequency of lattice degeneration and axial length].

Science.gov (United States)

Martín Sánchez, M D; Roldán Pallarés, M

2001-05-01

To evaluate the relationship between lattice retinal degeneration and axial length of the eye in different grades of myopia. A sample of 200 eyes from 124 myopic patients was collected by chance. The average age was 34.8 years (20-50 years) and the myopia was between 0.5 and 20 diopters (D). The eyes were grouped according to the degree of refraction defect, the mean axial length of each group (Scan A) and the frequency of lattice retinal degeneration and the relationship between these variables was studied. The possible influence of age on our results was also considered. For the statistical analysis, the SAS 6.07 program with the variance analysis for quantitative variables, and chi(2) test for qualitative variables with a 5% significance were used. A multivariable linear regression model was also adjusted. The highest frequency of lattice retinal degeneration occurred in those myopia patients having more than 15 D, and also in the group of myopia patients between 3 and 6 D, but this did not show statistical significance when compared with the other myopic groups. If the axial length is assessed, a greater frequency of lattice retinal degeneration is also found when the axial length is 25-27 mm and 29-30 mm, which correspond, respectively, to myopias between 3-10 D and more than 15 D. When the multivariable linear regression model was adjusted, the axial length showed the existence of lattice retinal degeneration (beta 0.41 mm; p=0.08) adjusted by the number of diopters (beta 0.38 mm; plattice retinal degeneration was found for myopias with axial eye length between 29-30 mm (more than 15 D), and 25-27 mm (between 3-10 D).

A study of fundus status in myopia

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Christina Samuel, Sundararajan D

2014-07-01

Full Text Available Background: The most important sensory organ for a human is the eye. Any damage to the retina can cause diminution or loss of vision. One of the most important refractive errors of the eye is Myopia apart from hypermetropia and astigmatism. It is one of the commonest conditions seen in everyday practice. Myopic degeneration is one of the common causes of decreased visual acuity. Aim: The aim of this clinical study is to observe the fundus changes associated with Myopia. Methods: A prospective study of 100 cases of myopia were included in this study. Detailed anterior segment and good posterior segment examination after achieving mydriasis was done with a direct ophthalmoscope and indirect ophthalmoscope with 20D lens. Result: In our study, we found that males were more commonly affected than females with myopia (54%. 50% of the cases affected belonged to the student community. 53.68% had positive changes in the retina suggestive of degenerative changes in the fundus. Conclusion: Degenerative changes of fundus are most commonly seen in myopic patients of which Tessellated fundus was about 90.20%. Vitreous degenerative changes for 70.59%. Crescent formation was 87.25%. Dull foveal reflex in 82.35% and lattice degeneration accounted for 40%.

Exome Sequence Analysis of 14 Families With High Myopia

DEFF Research Database (Denmark)

Kloss, Bethany A.; Tompson, Stuart W.; Whisenhunt, Kristina N.

2017-01-01

Purpose: To identify causal gene mutations in 14 families with autosomal dominant (AD) high myopia using exome sequencing. Methods: Select individuals from 14 large Caucasian families with high myopia were exome sequenced. Gene variants were filtered to identify potential pathogenic changes. Sang...

Visual function of cataract with high myopia

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Jian-Tao Ren

2013-09-01

Full Text Available Cataract with high myopia is research priority associated with the large amount of high myopia patients. The unaided visual acuity and the best-corrected visual acuity are partial for the visual acuity of the patients with cataract. The mechanism and clinical significance of modern visual function measurements associated with cataract and high myopia, including accommodation and convergence, stereoscopic vision, contrast sensitivity, have been introduced. These measurements could be of great value in early diagnosis of cataract, assessment of surgical indication, customized intraocular lens(IOLselection and evaluation of visual performance after IOL implantation. They could also be helpful to the analysis of postoperative impaired visual function and its management. Having an adequate understanding of the contents and significance of visual function was helpful to the improvement of cataract surgery techniques and postoperative visual acuity.

Evaluation of high myopia complications prevention program in university freshmen

OpenAIRE

Tseng, Gow-Lieng; Chen, Cheng-Yu

2016-01-01

Abstract High myopia is a global eye health problem because of its high incidence of sight-threatening complications. Due to the role of awareness, self-examination, and preventive behavior in prevention of morbidity of high myopia complications, promoting knowledge, capabilities, and attitude of high myopic personnel are required in this regard. In this quasi-experiment study, 31 freshmen with high myopia in a national university were enrolled in 2014. The data were collected by validated an...

Study and development of retinal dopamine nervous system in experimental myopia

International Nuclear Information System (INIS)

Zhao Juan; Liu Xingdang

2007-01-01

Myopia is the most familiar ametropia. Animal experimental models include form deprivation myopia and defocus myopia. Experimental animals we often use are chicken and mammals. The retinal dopamine system and vision experience have close relations with the regulation of eyeball's growth after birth, while the change of dopamine transporter may reflect the change of dopamine in the synaptic cleft more directly. (authors)

Relation Between Near Work and Myopia Progression in Student Population

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Muhamedagic, Lejla; Muhamedagic, Belma; Halilovic, Emina Alimanovic; Halimic, Jasmina Alajbegovic; Stankovic, Aleksa; Muracevic, Bedrana

2014-01-01

Aim To determine relation between near work and myopia progression in student population. Causes of myopia occurrence are not sufficiently explained. Methods This retrospective-prospective, descriptive research included 100 students with verified myopia up to -3 Dsph. Ophthalmological examination and measurement diopter-hours variable (Dh) were done twice, in the period from January 2011 until January 2012. Results A multivariate regression analysis of impact on the difference of distance visual acuity without correction to the right and left eye and difference of automatic computer refractometry in cycloplegia of both eyes indicates that, diopter-hours variable (Dh) had statistically significant impact on increase of distance visual acuity difference (right eye OR: I measurement–Dh 1.489, II measurement–Dh 1.544, prefractometry in cycloplegia (right eye OR: I measurement 1.361, II measurement 1.493, p<0.05; left eye OR: I measurement 0.931, II measurement 1.019, p<0.05) during both measurements. Conclusion Near work cause the increase of myopia. This research opened a perspective for other researches on the impact of near work on myopia. PMID:24944532

Oculometry findings in high myopia at adult age: considerations based on oculometric follow-up data over 28 years in a cohort-based Danish high-myopia series

DEFF Research Database (Denmark)

Fledelius, Hans C; Goldschmidt, Ernst

2010-01-01

PURPOSE: To present and discuss oculometry data in a series of adults with high myopia followed between the ages of 26 and 54 years. Emphasis is on axial length (AL) findings and corneal curvature radius (Crad). METHODS: Thirty-four out of the 39 individuals recruited as teenagers from a Copenhagen...... 1948 birth cohort with myopia of at least 6 D have had current follow-up exams, to include AL measurements (by ultrasound, 1974-2002; the latter year also with the Zeiss IOLMaster) and keratometry. The cross-sectional and longitudinal analyses are based primarily on the eyes with high myopia; however......, the fellow eye is also assessed in unilateral cases. RESULTS: At age 54 years, the maximum myopia in the series was -26 D; the highest AL value was 35.4 mm. The myopia had increased in most, with an increase from the 26-year oculometry baseline averaging 1.0 D [standard deviation (SD) 1.84]. Ultrasound...

Interventions to slow progression of myopia in children.

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Walline, Jeffrey J; Lindsley, Kristina; Vedula, Satyanarayana S; Cotter, Susan A; Mutti, Donald O; Twelker, J Daniel

2011-12-07

Nearsightedness (myopia) causes blurry vision when looking at distant objects. Highly nearsighted people are at greater risk of several vision-threatening problems such as retinal detachments, choroidal atrophy, cataracts and glaucoma. Interventions that have been explored to slow the progression of myopia include bifocal spectacles, cycloplegic drops, intraocular pressure-lowering drugs, muscarinic receptor antagonists and contact lenses. The purpose of this review was to systematically assess the effectiveness of strategies to control progression of myopia in children. To assess the effects of several types of interventions, including eye drops, undercorrection of nearsightedness, multifocal spectacles and contact lenses, on the progression of nearsightedness in myopic children younger than 18 years. We compared the interventions of interest with each other, to single vision lenses (SVLs) (spectacles), placebo or no treatment. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 10), MEDLINE (January 1950 to October 2011), EMBASE (January 1980 to October 2011), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (http://clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 11 October 2011. We also searched the reference lists and Science Citation Index for additional, potentially relevant studies. We included randomized controlled trials (RCTs) in which participants were treated with spectacles, contact lenses or pharmaceutical agents for the purpose of controlling progression of myopia. We excluded trials where participants were older than 18 years at baseline or participants had less than -0.25 diopters (D) spherical equivalent myopia. Two review authors

Chondrogenesis in scleral stem/progenitor cells and its association with form-deprived myopia in mice.

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Wu, Pei-Chang; Tsai, Chia-Ling; Gordon, Gabriel M; Jeong, Shinwu; Itakura, Tatsuo; Patel, Nitin; Shi, Songtao; Fini, M Elizabeth

2015-01-01

Previously, we demonstrated that scleral stem/progenitor cells (SSPCs) from mice have a chondrogenic differentiation potential, which is stimulated by transforming growth factor-β (TGF-β). In the present study, we hypothesized that chondrogenesis in the sclera could be a possible mechanism in myopia development. Therefore, we investigated the association of form-deprivation myopia (FDM) with expressions in mice sclera representing the chondrogenic phenotype: collagen type II (Col2) and α-smooth muscle actin (α-SMA). The mRNA levels of α-SMA and Col2 in cultured murine SSPCs during chondrogenesis stimulated by TGF-β2 were determined by real-time quantitative RT-PCR (qRT-PCR). The expression patterns of α-SMA and Col2 were assessed by immunohistochemistry in a three dimensional pellet culture. In an FDM mouse model, a western blot analysis and immunofluorescence study were used to detect the changes in the α-SMA and Col2 protein expressions in the sclera. In the RPE-choroid complex, qRT-PCR was used to detect any changes in the TGF-β mRNA expression. The treatment of SSPCs in vitro with TGF-β2 for 24 h at 1 or 10 ng/ml led to increased levels of both the α-SMA and Col2 expressions. In addition, we observed the formation of cartilage-like pellets from TGF-β2-treated SSPCs. Both α-SMA and Col2 were expressed in the pellet. In an in-vivo study, the α-SMA and Col2 protein expressions were significantly increased in the sclera of FDM eyes in comparison to contralateral control eyes. Similarly, the levels of TGF-β in the RPE-choroid complex of an FDM eye were also significantly elevated. Based on the concept of stem cells possessing multipotent differentiation potentials, scleral chondrogenesis induced by SSPCs may play a role in myopia development. The increased expressions of the cartilage-associated proteins Col2 and α-SMA during scleral chondrogenesis may be potential markers for myopia development. In addition, the increased levels of TGF-β mRNA in

Myopia in premature babies with and without retinopathy of prematurity.

OpenAIRE

Nissenkorn, I; Yassur, Y; Mashkowski, D; Sherf, I; Ben-Sira, I

1983-01-01

One hundred and fifty-five premature infants weighing 600-2000 g were followed up during 1974-80 for the presence of retinopathy of prematurity (ROP) and for the existence of myopia. 50% of the premature infants who had ROP were myopic, while only 16% myopic premature infants were found among those who did not have ROP. There was a positive correlation between the degree of myopia and the severity of cicatricial ROP. No difference existed in the frequency and degree of myopia between prematur...

Intermittent episodes of bright light suppress myopia in the chicken more than continuous bright light.

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Weizhong Lan

Full Text Available PURPOSE: Bright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens. METHODS: Eight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8 was kept under office-like illuminance (500 lux at a 10:14 light:dark cycle. Episodes of bright light (15 000 lux were super-imposed on this background as follows. Paradigm I: exposure to constant bright light for either 1 hour (n = 5, 2 hours (n = 5, 5 hours (n = 4 or 10 hours (n = 4. Paradigm II: exposure to repeated cycles of bright light with 50% duty cycle and either 60 minutes (n = 7, 30 minutes (n = 8, 15 minutes (n = 6, 7 minutes (n = 7 or 1 minute (n = 7 periods, provided for 10 hours. Refraction and axial length were measured prior to and immediately after the 5-day experiment. Relative changes were analyzed by paired t-tests, and differences among groups were tested by one-way ANOVA. RESULTS: Compared with the reference group, exposure to continuous bright light for 1 or 2 hours every day had no significant protective effect against deprivation myopia. Inhibition of myopia became significant after 5 hours of bright light exposure but extending the duration to 10 hours did not offer an additional benefit. In comparison, repeated cycles of 1:1 or 7:7 minutes of bright light enhanced the protective effect against myopia and could fully suppress its development. CONCLUSIONS: The protective effect of bright light depends on the exposure duration and, to the intermittent form, the frequency cycle. Compared to the saturation effect of continuous bright light, low frequency cycles of bright light (1:1 min provided the strongest inhibition effect. However, our quantitative results probably might not be directly translated into humans, but rather need further amendments in clinical studies.

Intermittent episodes of bright light suppress myopia in the chicken more than continuous bright light.

Science.gov (United States)

Lan, Weizhong; Feldkaemper, Marita; Schaeffel, Frank

2014-01-01

Bright light has been shown a powerful inhibitor of myopia development in animal models. We studied which temporal patterns of bright light are the most potent in suppressing deprivation myopia in chickens. Eight-day-old chickens wore diffusers over one eye to induce deprivation myopia. A reference group (n = 8) was kept under office-like illuminance (500 lux) at a 10:14 light:dark cycle. Episodes of bright light (15 000 lux) were super-imposed on this background as follows. Paradigm I: exposure to constant bright light for either 1 hour (n = 5), 2 hours (n = 5), 5 hours (n = 4) or 10 hours (n = 4). Paradigm II: exposure to repeated cycles of bright light with 50% duty cycle and either 60 minutes (n = 7), 30 minutes (n = 8), 15 minutes (n = 6), 7 minutes (n = 7) or 1 minute (n = 7) periods, provided for 10 hours. Refraction and axial length were measured prior to and immediately after the 5-day experiment. Relative changes were analyzed by paired t-tests, and differences among groups were tested by one-way ANOVA. Compared with the reference group, exposure to continuous bright light for 1 or 2 hours every day had no significant protective effect against deprivation myopia. Inhibition of myopia became significant after 5 hours of bright light exposure but extending the duration to 10 hours did not offer an additional benefit. In comparison, repeated cycles of 1:1 or 7:7 minutes of bright light enhanced the protective effect against myopia and could fully suppress its development. The protective effect of bright light depends on the exposure duration and, to the intermittent form, the frequency cycle. Compared to the saturation effect of continuous bright light, low frequency cycles of bright light (1:1 min) provided the strongest inhibition effect. However, our quantitative results probably might not be directly translated into humans, but rather need further amendments in clinical studies.

Near work, education, family history, and myopia in Greek conscripts.

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Konstantopoulos, A; Yadegarfar, G; Elgohary, M

2008-04-01

To investigate potential factors associated with the presence of myopia in a cohort of young adult men carrying out their military service in Greece. A nested case-control study of 200 conscripts (99 myopes and 101 non-myopes). The cohort consisted of approximately 1000 conscripts in compulsory national service. All cohort members had been screened for refractive errors by Snellen visual acuity measurement at presentation to military service; individuals not achieving visual activity 6/6 underwent noncycloplaegic refraction. The study sample consisted of the first 99 myopic and 101 nonmyopic conscripts who attended the study. In-person interviews of these 200 conscripts were conducted to obtain information on family history, occupation, level of education, near-work activities, and sleeping behaviour. chi(2) and Mann-Whitney tests were used as univariate analysis methods to identify the potential factors associated with the presence of myopia. Multiple logistic regression was used to estimate the adjusted relative risk of myopia. Univariate analysis showed that parental family history (Pfamily history (OR=3.39, 95% CI 1.56-7.36) were independently associated with myopia. In young Greek conscripts, parental family history, older age, and education level are independently associated with myopia.

Correlative study between myopia and ocular relative accommodation

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Qiao-Ya Lin

2015-07-01

Full Text Available AIM: To research the characteristics of positive relative accommodation(PRA, negative relative accommodation(NRAand PRA/NRA ratio in myopes. To analyze the relationship among PRA, NRA, PRA/NRA ratio, spherical equivalent degree, years and habbits of wearing glasses, myopia development, and pupil diameter.METHODS: Aretrospective study of ninety eyes in the 180th Hospital of Quanzhou from August 2014 to December 2014. PRA, NRA and PRA/NRA ratio were compared among low, moderate, high myopes and emmetropes. The correlation were analyzed among PRA, NRA, PRA/NRA ratio, spherical equivalent degree, years and habbits of wearing glasses, myopia development and pupil diameter. PRA, NRA, PRA/NRA ratio, years and habbits of wearing glasses and pupil diameter were compared between progress group and non-progress group.RESULTS:(1Without statistical differences in age, sex and intraocular pressure, PRA and PRA/NRA ratio of myopes were lower than emmetropes, while NRA was higher.(2Without statistical differences in age, sex and intraocular pressure, PRA, PRA/NRA ratio and NRA had no statistical differences while years and habbits of wearing glasses had statistical differences among low, moderate, high myopes.(3With longer years of wearing glasses, PRA, PRA/NRA ratio were larger and NRA, pupils were smaller.(4Without statistical differences in age, diopter and intraocular pressure, one group which were not easy to deepen degree had more often-wear-glasses myopia patiens and longer years of wearing glasses, the other group which were easy to deepen degree had more seldom-wear-glasses myopia patiens and shorter years of wearing glasses.CONCLUSION: PRA and PRA/NRA ratio of myopes were lower than emmetropes, while NRA was higher. No correlated relation was detected among PRA, NRA, PRA/NRA ratio, spherical equivalent degree and myopia development. It suggests the onset and progress of myopia are related to many factors. Wearing-glass timely and accurately can

Physical activity in relation to development and progression of myopia

DEFF Research Database (Denmark)

Suhr Thykjær, Anne; Lundberg, Kristian; Grauslund, Jakob

2017-01-01

. The objective of this study was to make a systematic review regarding the correlation between physical activity and myopia. A total of 263 papers were identified in a systematic database search of PubMed/Medline and Embase. Five steps of screening removed studies of a low evidence quality and animal studies......On a global scale, myopia is one of the most common causes of visual impairment. Given the increasing prevalence of myopia, it is vital to understand the pathogenesis and to identify potential interventions. Some studies have described physical activity as a potential correlation for myopia....... Studies included had refractive error and physical activity (as measured by questionnaires, accelerometers and cycle ergometers) as separate, well-defined outcomes. Nine studies (six cross-sectional, two cohorts and one case-control study) with a total of 17 634 subjects were included. Six studies...

Early diagnosis and research of high myopia with primary open angle glaucoma

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Yan Guo

2014-04-01

Full Text Available People with high myopia are high risk populations to have primary open angle glaucoma. Clinically, we found that patients with primary open angle glaucoma and high myopia is closely related. So to understand the clinical features of high myopia with primary open angle glaucoma and the importance of early diagnosis, to avoiding missed diagnosis or lower misdiagnosed rate, can help to improve the vigilance and level of early diagnosis of the clinicians. In this paper, high myopia with clinical features of primary open angle glaucoma, and the research progress on the main points of early diagnosis were reviewed.

A Clinical and Confocal Microscopic Comparison of Transepithelial PRK and LASEK for Myopia

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Safak Korkmaz

2014-01-01

Full Text Available Purpose. To compare the clinical and confocal microscopic results of transepithelial PRK versus LASEK for correction of myopia. Materials and Methods. Twelve patients with myopia received transepithelial PRK in one eye and LASEK in the other. In transepithelial PRK-treated eyes, the corneal epithelium was removed with 40 microns of excimer laser ablation and in LASEK-treated eyes with 25-second application of 18% ethanol. Time to epithelial healing, ocular discomfort, uncorrected and best corrected visual acuities, manifest refraction, haze, greyscale value, and keratocyte apoptosis in confocal microscopy were recorded. Results. The mean time to epithelial healing was significantly longer after LASEK (4.00 ± 0.43 versus 3.17 ± 0.6 days. On day 1, ocular discomfort was significantly higher after transepithelial PRK. The grade of haze, keratocyte apoptosis, and greyscale value in confocal microscopy were significantly higher in transepithelial PRK-treated eyes at 1 month. All transepithelial PRK- and LASEK-treated eyes achieved 20/25 or better UCVA and were within ±1.00 D of emmetropia at final visits. Conclusions. Both transepithelial PRK and LASEK offer effective correction of myopia at 1 year. However, LASEK appeared to induce less discomfort and less intense wound healing in the early postoperative period.

A Clinical and Confocal Microscopic Comparison of Transepithelial PRK and LASEK for Myopia.

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Korkmaz, Safak; Bilgihan, Kamil; Sul, Sabahattin; Hondur, Ahmet

2014-01-01

Purpose. To compare the clinical and confocal microscopic results of transepithelial PRK versus LASEK for correction of myopia. Materials and Methods. Twelve patients with myopia received transepithelial PRK in one eye and LASEK in the other. In transepithelial PRK-treated eyes, the corneal epithelium was removed with 40 microns of excimer laser ablation and in LASEK-treated eyes with 25-second application of 18% ethanol. Time to epithelial healing, ocular discomfort, uncorrected and best corrected visual acuities, manifest refraction, haze, greyscale value, and keratocyte apoptosis in confocal microscopy were recorded. Results. The mean time to epithelial healing was significantly longer after LASEK (4.00 ± 0.43 versus 3.17 ± 0.6 days). On day 1, ocular discomfort was significantly higher after transepithelial PRK. The grade of haze, keratocyte apoptosis, and greyscale value in confocal microscopy were significantly higher in transepithelial PRK-treated eyes at 1 month. All transepithelial PRK- and LASEK-treated eyes achieved 20/25 or better UCVA and were within ±1.00 D of emmetropia at final visits. Conclusions. Both transepithelial PRK and LASEK offer effective correction of myopia at 1 year. However, LASEK appeared to induce less discomfort and less intense wound healing in the early postoperative period.

[Displacement of the posterior part of the eyeball in myopia].

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Akizawa, Yasuko; Masahiro, Ida

2006-12-01

The principal aim of this study was to investigate displacement of the posterior part of the eyeball within the muscle cone in myopic eyes, particularly in moderately myopic subjects as well as in high myopes. Secondly, the correlation of the amount of displacement and the outer axial length of the globe was studied. The direction of displacement was also examined to clarify whether the eyeball tends to shift toward a certain direction. Seven patients with moderate myopia (moderate myopia group), fifteen patients with high myopia without esotropia (high myopia group), five patients with high myopia and esotropia (myopic esotropia group), and twenty-two controls (control group) were examined. Using magnetic resonance imaging, the outer axial length and the displacement of the posterior portion of the eyeball in the muscle cone were measured. In order to eliminate interindividual differences in the facial configuration, the coronal scanning was done perpendicularly to the orbital axis. The displacement was measured in a plane 4 mm anterior to the globe-optic nerve junction. The displacement was represented by the distance and direction of the globe center from the center of the muscle cone. In the moderate myopia group, there was no displacement of the posterior part of the eyeball in the muscle cone. It was the same as in the control group. But among the three groups, the displacement (mean standard deviation) was significantly greater in the myopic esotropia group (1.53 +/- 0.49 mm) and the high myopia group (0.94 +/- 0.52 mm) than in the control group (0.11 +/- 0.18 mm) (one way ANOVA and multiple comparison). The outer axial length and the distance of the displacement in all cases was significantly correlated (r = 0.87, p = 0.01). Moreover, the posterior part of the eyeball of the myopic esotropia group and the high myopia group was displaced superiorly and temporally. The posterior part of the eyeball of myopic eyes was displaced superotemporally in the muscle

Interconnection between several eye biomechanical and biometric parameters in children with axial and refractive mild myopia

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T. Ye. Tsybulskaya

2016-08-01

Full Text Available Aim – to study the relationship of biometric and biomechanical indicators of corneoscleral capsule of the eye in children with axial and refractive mild myopia. Materials and methods. Axial myopia was diagnosed in 32 children (64 eyes, refractive myopia – 18 (36 eyes. The control group – 16 children without ophthalmic diseases (32 eyes. Eye examination: visometry, automated refractometry, biomicroscopy, ophthalmoscopy, determination of the axial length of the eyeball and corneal hysteresis. Results. Significant differences were determined in the indicators of dioptric power of the cornea: 42.2 dpt in patients with axial and 44.7 dpt with refractive myopia (p<0.05, and also difference between patients with refractive myopia and the control group, in which the diopter power of cornea was 42.6 (p<0.05. There are also significant differences in the indicators of the axial length of eyes between axial and refractive myopia – 24.5±0.64 mm and 23.1±0.43 mm (p<0.05. Significant difference with the control group in the axial length marked only in eyes with axial myopia 22.7±0.33 mm and 24.5±0.64 mm, respectively (p<0.05. Corneal hysteresis determined significantly reduced on eyes with both the axial and refractive myopia, which was significantly lower than in the indicators of emmetropic eyes of the control group 13.7 (p<0.05. Corneal hysteresis is inversely related to the axial length of the eyeball: in patients with axial myopia r -0.32, p<0.05; with refractive myopia r -0.36, p<0.05. Сorrelation between diopter power of cornea and axial length of the eyeball: r -0.53, р<0.05 in eyes with axial myopia and r -0.42, p<0.05 refractive myopia. Comparative analysis showed no significant differences between the corneal hysteresis, the axial length of the eye and the spherical component of myopia. Conclusions. In patients with axial and refractive mild myopia corneal hysteresis is reduced on average in 1.2 and 1.1 times, in comparison with

Prevalence and associated factors of myopia in high-school students in Beijing.

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Li Juan Wu

Full Text Available To evaluate prevalence and associated factors for myopia in high school students in Beijing.Grade 10 and 11 high school students were randomly selected from nine randomly selected districts of Beijing. The students underwent non-cylcoplegic auto-refractometry and an interview.Out of 4798 eligible students, 4677 (93.4% students (mean age:16.9±0.7years;range:16-18 years participated. Mean refractive error of right eyes and left eyes was -2.78±2.29 diopters and -2.59±2.50 diopters, respectively. Prevalence of myopia (defined as ≤ -1.00 diopters in the worse eye was 80.7% (95% Confidence Interval (CI: 79.6-81.8%. Out of 3773 students with myopia, 1525 (40.4% wore glasses daily. In multiple logistic regression analysis, a higher prevalence of myopia was associated with female sex (odds ratio (OR = 1.31;95%CI:1.11-1.55, Han ethnicity (OR = 1.64;95%CI:1.28-2.11, attending key schools (OR = 1.48;95%CI:1.24,1.77, higher family income (OR = 1.37;95%CI:1.09-1.71, longer time spent for near work (OR = 1.43;95%CI:1.06-1.93, shorter near work distance (OR = 1.87;95%CI:1.55-2.26, lower frequency of active rest during studying (OR = 1.40;95%CI:1.16-1.70, and parental myopia (OR = 2.28;95%CI:1.80-2.87. The interaction between distance from near work and time spent for near work was statistically (P = 0.03 significant. In multiple logistic regression analysis, higher prevalence of high myopia (≤-6.0 diopters was associated with studying in key schools (OR = 1.38;95%CI:1.05,1.81, lower frequency of active rest during studying (OR = 1.40;95%CI:1.09,1.79, and a higher number of myopic parents (OR = 2.66;95%CI:2.08,3.40.A prevalence of about 80% for myopia and a prevalence of about 10% for high myopia in students aged 16 to 18 years and attending classes of grade 10 and 11 in a Chinese metropolitan region is another example of the high prevalence of moderate and high myopia in metropolitan areas of China. With this young myopic generation getting older, myopia

Efficiency analysis of orthokeratological correction in the treatment of progressive myopia in childhood

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Dolgova Е.А.

2017-06-01

Full Text Available Objective: to evaluate the effectiveness of orthokeratological correction in the treatment of progressive myopia in children. Material and methods. A retrospective study correction of myopia orthokeratology lenses of 100 patients (178 eyes with an established diagnosis of myopia of an average degree, undergoing treatment at the Clinic of eye diseases of SSMU. Group I consisted of 50 patients who received OK-correction lenses "Emerald" by Euclid Systems Corporation (USA. The wear time is 2 years. Group II included 50 people (87 eyes, using spectacle correction during the same time. Patients underwent visual acuity testing, biomicroscopy, refractometry, determination of reserves of accommodation, ultrasonic biometry (IOL-Master, CarlZeiss is a measurement of the size of the front-sadayoshi eyeball, survey after 2 years of using the selected correction. Results. Comparative analysis showed that the use of OK lenses for patients with myopia of an average degree resulted in a significant reduction in the rate of progression of myopia. In the background wearing OK lenses for 2 years has been the increase PZO, PZO dynamics were 0.09±0.05 mm. For the correction of progressive myopia spectacle lens changes were more significant, the dynamics of early school leaving amounted to 0,36±0,11 mm. Conclusion. The identified inhibitory effect of OK-lenses on myopia progression, confirmed by the indices of refraction and ultrasound biometry within 2 years of the study. The data allow us to recommend OK-therapy, as an effective tool for progressive myopia.

Iris colour in relation to myopia among Chinese school-aged children.

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Pan, Chen-Wei; Qiu, Qin-Xiao; Qian, Deng-Juan; Hu, Dan-Ning; Li, Jun; Saw, Seang-Mei; Zhong, Hua

2018-01-01

Understanding the association of iris colour and myopia may provide further insights into the role of the wavelength of lights in the pathophysiology of myopia. We aim to assess the association of iris colour and myopia in a school-based sample of Chinese students. Two thousand three hundred and forty-six Year 7 students from 10 middle schools (93.5% response rate) aged 13-14 years in Mojiang, a small county located in Southwestern China, participated in the study. We obtained standardised slit lamp photographs and developed a grading system assessing iris colour (higher grade denoting a darker iris). Refractive error was measured after cycloplegia using an autorefractor by optometrists or trained technicians. An IOLMaster (www.zeiss.com) was used to measure ocular biometric parameters including axial length (AL). Of all the study participants, 693 (29.5%) were affected by myopia with the prevalence estimates being higher in girls (36.8%; 95% confidence interval [CI]: 34.0, 39.6) than in boys (22.8%; 95% CI: 20.4, 25.1) (p iris colour tended to have a higher prevalence of myopia, a more myopic refraction and a longer AL. Dose-response relationships were observed in all regression models (p for trend iris colour was associated with more myopic refractive errors and longer ALs among Chinese school-aged children and this association was independent of other known myopia-related risk factors. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Displacement of the posterior part of the eyeball in myopia

International Nuclear Information System (INIS)

Akizawa, Yasuko; Ida, Masahiro

2006-01-01

The principal aim of this study was to investigate displacement of the posterior part of the eyeball within the muscle cone in myopic eyes, particularly in moderately myopic subjects as well as in high myopes. Secondly, the correlation of the amount of displacement and the outer axial length of the globe was studied. The direction of displacement was also examined to clarify whether the eyeball tends to shift toward a certain direction. Seven patients with moderate myopia (moderate myopia group), fifteen patients with high myopia without esotropia (high myopia group), five patients with high myopia and esotropia (myopic esotropia group), and twenty-two controls (control group) were examined. Using magnetic resonance imaging, the outer axial length and the displacement of the posterior portion of the eyeball in the muscle cone were measured. In order to eliminate interindividual differences in the facial configuration, the coronal scanning was done perpendicularly to the orbital axis. The displacement was measured in a plane 4 mm anterior to the globe-optic nerve junction. The displacement was represented by the distance and direction of the globe center from the center of the muscle cone. In the moderate myopia group, there was no displacement of the posterior part of the eyeball in the muscle cone. It was the same as in the control group. But among the three groups, the displacement (mean±standard deviation) was significantly greater in the myopic esotropia group (1.53±0.49 mm) and the high myopia group (0.94±0.52 mm) than in the control group (0.11±0.18 mm) (one way ANOVA and multiple comparison). The outer axial length and the distance of the displacement in all cases was significantly correlated (r=0.87, p=0.01). Moreover, the posterior part of the eyeball of the myopic esotropia group and the high myopia group was displaced superiorly and temporally. The posterior part of the eyeball of myopic eyes was displaced superotemporally in the muscle cone

Development of myopia as a hazard for workers in pneumatic caissons

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Onoo, A; Kiyosawa, M; Takase, H; Mano, Y

2002-01-01

Background/aim: Pneumatic caisson engineering has been developed for large civil engineering constructions. Because of complaints of blurred vision by personnel working in pneumatic caissons, the development of myopia was suspected. The aim of this study was to determine the cause of the blurred vision and the mechanism underlying the changes. Methods: 12 caisson workers underwent a complete ophthalmological examination after completing up to 11 weeks of work (4 days/week) in a pneumatic caisson. Six months later, nine of the workers were examined again. Results: Nine subjects were myopic at the initial examination, and seven of these were considered to have developed the myopia after starting to work in the pneumatic caisson. Six months after completion of the work, the mean refractive change was significantly towards hyperopia. Conclusions: The blurred vision in pneumatic caisson workers was in all likelihood due to the development of myopia. The refractive shift towards hyperopia after completion of work in the pneumatic caisson supports this and demonstrates that the changes were temporary. The myopia is similar to the myopia seen in patients treated by hyperbaric oxygen. Careful monitoring of the refraction of caisson workers should be performed for industrial health control. PMID:12386088

[Study on relationship between outdoor activities and self-reported myopia among middle school students].

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Zhai, L L; Wu, X Y; Xu, S J; Wan, Y H; Zhang, S C; Xu, L; Liu, W; Ma, S S; Zhang, H; Tao, F B

2017-09-06

Objective: To examine the relationship between the prevalence of self-reported myopia and outdoor activities among middle school students and to explore the influence factors of the self-reported myopia. Methods: A total of 12 979 participants were recruited from junior and senior middle school students in in Shenzhen, Nanchang, Zhengzhou and Shenyang by random cluster sampling method between December 2015 and March 2016. All participants completed an anonymous questionnaire to collect the information of demographic characteristics, self-reported myopia, outdoor activities, etc. 12 603 out of 12 979 copies of questionnaire were valid. The prevalence of self-reported myopia was compared among middle school students with different characteristics. Logistic regression models were used to analyze the relationship between myopia and outdoor activities. Results: The prevalence of self-reported myopia among middle school students was 69.6% (8 766/12 603); which was separately 52.1% (1 216/2 335) in seventh grader, 61.6% (1 459/2 369) in eighth grader, 69.0%(1 470/2 129) in ninth grader, 80.0% (1 812/2 265) in freshmen, 79.4% (1 622/2 042) in sophomore, and 81.1%(1 187/1 463) in junior. The prevalence of self-reported myopia showed an increasing trend with the increase of grade (χ(2)=639.67, Pmiddle school students ( OR= 1.58, 95 %CI: 1.36-1.82). The risk of self-reported myopia were significantly decreased by always physical exercise and recreational activities after school among middle school students: the ORs were separately 0.67 (95 %CI: 0.57-0.78) for physical exercise and 0.77 (95 %CI: 0.64-0.92) for recreational activities. After stratified analysis by the parents' myopia status, in non-myopic parents group, exercise and recreational activities after school among middle school students decreased the risk of myopia: the ORs were separately 0.68 (95 %CI: 0.55-0.82) for physical exercise and 0.76 (95 %CI: 0.61-0.95) for recreational activities; in either myopic parent

Form-deprivation myopia induces decreased expression of bone morphogenetic protein-2, 5 in guinea pig sclera

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Qing Wang

2015-02-01

Full Text Available AIM: To identify the presence of various bone morphogenetic proteins (BMPs and their receptors in normal sclera of human, rat and guinea pigs, and to determine whether their expression changed with form-deprivation myopia (FDM in guinea pig sclera. METHODS: The expression of BMPs and BMP receptors were detected using reverse transcription polymerase chain reaction (RT-PCR and immunofluorescence. Two-week-old guinea pigs were monocularly form-deprived with a translucent lens. After fourteen days induction of FDM, total RNA was isolated and subjected to RT-PCR to examine the changes of BMPs and BMP receptors in tissues from the posterior sclera. Western blotting analysis was used to investigate their changes in protein levels. RESULTS: Human sclera expressed mRNAs for BMP-2, -4, -5, -7, -RIA, -RIB and BMP-RII. Conversely, rat sclera only expressed mRNA for BMP-7 and BMP-RIB, while the expression of BMPs and BMP receptors in guinea pigs were similar to that of humans. Human sclera also expresses BMP-2, -4, -5,-7 in protein level. Fourteen days after the induction of myopia, significant decreased expressions for BMP-2 and BMP-5 in the posterior sclera of FDM-affected eyes (PCONCLUSION: Various BMPs were expressed in human and guinea pig sclera. In the posterior sclera, expressions of BMP-2 and BMP-5 significantly decreased in FDM eyes. This finding indicates that various BMPs as components of the scleral cytokines regulating tissue homeostasis and provide evidence that alterations in the expression of BMP-2 and BMP-5 are associated with sclera remodeling during myopia induction.

Prevalence and related factors investigations of myopia among multi-ethnic adolescents in Linxia Prefecture

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Mei-Ling Qian

2018-06-01

Full Text Available AIM: To investigate the prevalence of juvenile myopia and factors affecting its occurrence in Linxia Prefecture. METHODS: Totally 8 683 juvenile students who were 6-18 years old were extracted as respondent with stratified cluster sampling method. The eyesight, diopter and axial length were detected, and the gender, age, ethnicity, eye behavior were collected by self-made questionnaire. RESULTS: The prevalence of myopia was 42.80%. The myopic rates of all ethnic groups were as follows: Tibetan Nationality: 59.05%, Han Nationality: 46.71%, Dongxiang Nationality: 46.36%, Tu Nationality: 45.24%, Sala Nationality: 41.30%, Baoan nationality: 40.61%, Hui Nationality: 31.97%. Myopia rate between each ethnic groups had statistical difference(χ2=44.08, P=0.007. Multivariate analyses revealed that outdoor activities during the break was the protect factor for myopia; age, using electronic products on weekends and holidays, using the same lighting in room while studying were risk factors for myopia. CONCLUSION: The prevalence of myopia increase with age in Linxia. The prevalence in different ethnic groups is different. Education department and family should make joint efforts to increase the outdoor time, improve the environment for teenagers to reduce the occurrence and development of myopia.

Is myopia a public health problem in India?

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Rohit Saxena

2013-01-01

Full Text Available Myopia, a form of refractive error is a leading cause of visual disability throughout the world. In India uncorrected refractive errors are the most common cause of visual impairment and second major cause of avoidable blindness. Due to this the public health and economic impact of myopia is enormous. Although school vision screening programme is very successful in many states, still a significant number of school going children remain unidentified and the unmet need for correcting refractive errors in children appears to be significant.

Bio-environmental factors associated with myopia: An updated review.

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Galvis, V; Tello, A; Camacho, P A; Parra, M M; Merayo-Lloves, J

2017-07-01

Experimental studies in animals, as well as observational and intervention studies in humans, seem to support the premise that the development of juvenile myopia is promoted by a combination of the effect of genetic and environmental factors, with a complex interaction between them. The very rapid increase in myopia rates in some parts of the world, such as Southeast Asia, supports a significant environmental effect. Several lines of evidence suggest that humans might respond to various external factors, such as increased activity in near vision, increased educational pressure, decreased exposure to sunlight outdoors, dietary changes (including increased intake of carbohydrates), as well as low light levels indoors. All these factors could be associated with a higher prevalence of myopia. Copyright © 2017 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

Bidirectional Expression of Metabolic, Structural, and Immune Pathways in Early Myopia and Hyperopia

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Nina Riddell

2016-08-01

Full Text Available Myopia (short-sightedness affects 1.45 billion people worldwide, many of whom will develop sight-threatening secondary disorders. Myopic eyes are characterized by excessive size while hyperopic (long-sighted eyes are typically small. The biological and genetic mechanisms underpinning the retina’s local control of these growth patterns remain unclear. In the present study, we used RNA sequencing to examine gene expression in the retina/RPE/choroid across 3 days of optically-induced myopia and hyperopia induction in chick. Data were analysed for differential expression of single genes, and Gene Set Enrichment Analysis (GSEA was used to identify gene sets correlated with ocular axial length and refraction across lens groups. Like previous studies, we found few single genes that were differentially-expressed in a sign-of-defocus dependent manner (only BMP2 at 1 day. Using GSEA, however, we are the first to show that more subtle shifts in structural, metabolic, and immune pathway expression are correlated with the eye size and refractive changes induced by lens defocus. Our findings link gene expression with the morphological characteristics of refractive error, and suggest that physiological stress arising from metabolic and inflammatory pathway activation could increase the vulnerability of myopic eyes to secondary pathologies

Prevalence of myopia and its risk factors in urban school children in Delhi: the North India Myopia Study (NIM Study.

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Rohit Saxena

Full Text Available Assess prevalence of myopia and identify associated risk factors in urban school children.This was a cross-sectional study screening children for sub-normal vision and refractive errors in Delhi. Vision was tested by trained health workers using ETDRS charts. Risk factor questionnaire was filled for children with vision 11 years children (p 5 hours per day (p 2 hours / day (p 2 hours in a day.Myopia is a major health problem in Indian school children. It is important to identify modifiable risk factors associated with its development and try to develop cost effective intervention strategies.

Prevalence of myopia and its risk factors in urban school children in Delhi: the North India Myopia Study (NIM Study).

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Saxena, Rohit; Vashist, Praveen; Tandon, Radhika; Pandey, R M; Bhardawaj, Amit; Menon, Vimala; Mani, Kalaivani

2015-01-01

Assess prevalence of myopia and identify associated risk factors in urban school children. This was a cross-sectional study screening children for sub-normal vision and refractive errors in Delhi. Vision was tested by trained health workers using ETDRS charts. Risk factor questionnaire was filled for children with vision 11 years) children (phistory (p 5 hours per day (p 2 hours / day (p video/mobile games (p 2 hours in a day. Myopia is a major health problem in Indian school children. It is important to identify modifiable risk factors associated with its development and try to develop cost effective intervention strategies.

Changes of subfoveal choroidal thickness after treated by Ranibizumab for choroidal neovascularization secondary to pathologic myopia

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Jian-Shu Yuan

2016-05-01

Full Text Available AIM:To observe the change of subfoveal choroidal thickness(SFCTafter intravitreal injections of anti-vascular endothelial growth factor monoclonal antibody Ranibizumab in patients with choroidal neovascularization(CNVsecondary to pathologic myopia(PMand to research the relation between visual acuity and SFCT.METHODS:This was a prospective, contrast, open-label study.Fifty pathologic myopia patients with CNV(50 eyeswere recruited in this study. Before the injection,best-corrected visual acuity detected by visual chart from Early Treatment of Diabetic Retinopathy Study(ETDRS,non-contact tonometer,ophthalmoscope,fundus photography, fundus fluorescein angiograph(FFAand optical coherence tomography(OCTexamination were necessary. All affected eye were treated with intravitreal ranibizumab 0.05mL. Following up for 12mo, the changes of visual acuity and SFCT were compared before and after treatment, also the relation between them. RESULTS:All eyes received an average of 2.47±2.23 injections,the final vision of follow-up increased by 13.62±8.98 letters than that before(t=6.69,Pt=0.95, P>0.05.While after 6 and 12mo,the differences were significant(t=2.34, 2.61; PPP>0.05.There were no serious systemic or local side effects during the follow up.CONCLUSION:Intravitreal ranibizumab for CNV secondary to pathologic myopia is safe and can improve the visual acuity.Intravitreal injections of ranibizumab can induce SFCT reduction for CNV secondary to pathologic myopia.We hypothesized that increase of SFCT may be one of evaluation index for CNV activity.

Physical activity and myopia in Danish children-The CHAMPS Eye Study

DEFF Research Database (Denmark)

Lundberg, Kristian; Suhr Thykjær, Anne; Søgaard Hansen, Rasmus

2018-01-01

PURPOSE: To determine associations between physical activity (PA) and myopia in Danish school children and investigate the prevalence of myopia. METHODS: This is a prospective study with longitudinal data on PA in a Danish child cohort. Physical activity (PA) was measured objectively by repeated....... The ophthalmologic examination was conducted at the mean age of 15.4 ± 0.7 years and included cycloplegic autorefraction and biometry. RESULTS: A total of 307 children participated in the Childhood Health, Activity, and Motor Performance School (CHAMPS) Eye Study. The cycloplegic spherical equivalent (SE) was 0...... PA and myopia, in this first of its kind study based on objective and repeated PA data....

[Role of cerebral hemodynamics in the mechanism of development of acquired myopia in schoolchildren].

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Iastrebtseva, T A; Demidova, T E; Polikarpova, V E

2008-01-01

Rheoencephalography was used to study cerebral venous circulation in 199 schoolchildren aged 12-15 years who had emmetropia, pseudomyopia, and myopia. Tonometry was carried out in 39 persons. Cerebral venous hemodynamic dysfunction was more frequently encountered in schoolchildren with myopia than in those with emmetropia. Intraocular pressure was significantly higher only in schoolchildren with high myopia than in the controls.

Risk factors for incident myopia in Australian schoolchildren: the Sydney adolescent vascular and eye study.

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French, Amanda N; Morgan, Ian G; Mitchell, Paul; Rose, Kathryn A

2013-10-01

To examine the risk factors for incident myopia in Australian schoolchildren. Population-based, longitudinal cohort study. The Sydney Adolescent Vascular and Eye Study (SAVES) was a 5- to 6-year follow-up of the Sydney Myopia Study (SMS). At follow-up, 2103 children were reexamined: 892 (50.5%) from the younger cohort and 1211 (51.5%) from the older cohort. Of these, 863 in the younger cohort and 1196 in the older cohort had complete refraction data. Cycloplegic autorefraction (cyclopentolate 1%; Canon RK-F1; Canon, Tokyo, Japan) was measured at baseline and follow-up. Myopia was defined as a spherical equivalent refraction of ≤-0.50 diopters (D). Children were classified as having incident myopia if they were nonmyopic at baseline and myopic in either eye at follow-up. A comprehensive questionnaire determined the amount of time children spent outdoors and doing near work per week at baseline, as well as ethnicity, parental myopia, and socioeconomic status. Incident myopia. Children who became myopic spent less time outdoors compared with children who remained nonmyopic (younger cohort, 16.3 vs. 21.0 hours, respectively, Phours, respectively, P=0.001). Children who became myopic performed significantly more near work (19.4 vs. 17.6 hours; P=0.02) in the younger cohort, but not in the older cohort (P=0.06). Children with 1 or 2 parents who were myopic had greater odds of incident myopia (1 parent: odds ratio [OR], 3.2, 95% confidence interval [CI], 1.9-5.2; both parents: OR, 3.3, 95% CI, 1.6-6.8) in the younger but not the older cohort. Children of East Asian ethnicity had a higher incidence of myopia compared with children of European Caucasian ethnicity (both Pwork, parental myopia, and ethnicity to the model significantly improved the predictive power (Pwork and parental myopia were additional significant risk factors for myopia only in the younger cohort. The author(s) have no proprietary or commercial interest in any materials discussed in this article

Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci.

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Claire L Simpson

Full Text Available Refractive error (RE is a complex, multifactorial disorder characterized by a mismatch between the optical power of the eye and its axial length that causes object images to be focused off the retina. The two major subtypes of RE are myopia (nearsightedness and hyperopia (farsightedness, which represent opposite ends of the distribution of the quantitative measure of spherical refraction. We performed a fixed effects meta-analysis of genome-wide association results of myopia and hyperopia from 9 studies of European-derived populations: AREDS, KORA, FES, OGP-Talana, MESA, RSI, RSII, RSIII and ERF. One genome-wide significant region was observed for myopia, corresponding to a previously identified myopia locus on 8q12 (p = 1.25×10(-8, which has been reported by Kiefer et al. as significantly associated with myopia age at onset and Verhoeven et al. as significantly associated to mean spherical-equivalent (MSE refractive error. We observed two genome-wide significant associations with hyperopia. These regions overlapped with loci on 15q14 (minimum p value = 9.11×10(-11 and 8q12 (minimum p value 1.82×10(-11 previously reported for MSE and myopia age at onset. We also used an intermarker linkage- disequilibrium-based method for calculating the effective number of tests in targeted regional replication analyses. We analyzed myopia (which represents the closest phenotype in our data to the one used by Kiefer et al. and showed replication of 10 additional loci associated with myopia previously reported by Kiefer et al. This is the first replication of these loci using myopia as the trait under analysis. "Replication-level" association was also seen between hyperopia and 12 of Kiefer et al.'s published loci. For the loci that show evidence of association to both myopia and hyperopia, the estimated effect of the risk alleles were in opposite directions for the two traits. This suggests that these loci are important contributors to variation of

Myopia and radial keratotomy: a survey among Norwegian ophthalmologists.

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Midelfart, A

1990-10-01

One hundred and eighty-nine of 200 ophthalmologists in Norway responded to a survey requesting them to report their age, sex, refractive state, use of corrective lenses, and if myopic, their view on radial keratotomy as a possible method to correct their own myopia. According to the answers, 32 (17%) females and 154 (82%) males, with mean age of 49 years, were registered. The reported refractive state was 26.5% emmetropy and 72.0% ametropy. The prevalence of myopia was 45%. The mean refractive status (equivalent sphere) in the right eye was -1.02 +/- 2.28 D with a range from -8.5 D to +7.25 D (n = 184). Of the ametropes, 64.8% used spectacles, 15.3% used both spectacles and contact lenses, whilst 3.6% used only contact lenses for distance vision. With the exception of one, all myopes used corrective lenses. Only 2 myopic ophthalmologists responded positively to the question of whether they would consider having radial keratotomy to correct their own myopia.

Information Myopia

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Nadi Helena Presser

2016-04-01

Full Text Available This article reflects on the ways of appropriation in organizations. The notion of Information Myopia is characterized by the lack of knowledge about the available informational capabilities in organizations, revealing a narrow view of the information environment. This analysis has focused on the process for renewing the software licenses contracts of a large multinational group, in order to manage its organizational assets in information technology. The collected, explained and justified information allowed to elaborate an action proposal, which enabled the creation of new organizational knowledge. In its theoretical dimension, the value of information was materialized by its use, in a collective process of organizational learning.

Retinal sensitivity and choroidal thickness in high myopia.

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Zaben, Ahmad; Zapata, Miguel Á; Garcia-Arumi, Jose

2015-03-01

To estimate the association between choroidal thickness in the macular area and retinal sensitivity in eyes with high myopia. This investigation was a transversal study of patients with high myopia, all of whom had their retinal sensitivity measured with macular integrity assessment microperimetry. The choroidal thicknesses in the macular area were then measured by optical coherence tomography, and statistical correlations between their functionality and the anatomical structuralism, as assessed by both types of measurements, were analyzed. Ninety-six eyes from 77 patients with high myopia were studied. The patients had a mean age ± standard deviation of 38.9 ± 13.2 years, with spherical equivalent values ranging from -6.00 diopter to -20.00 diopter (8.74 ± 2.73 diopter). The mean central choroidal thickness was 159.00 ± 50.57. The mean choroidal thickness was directly correlated with sensitivity (r = 0.306; P = 0.004) and visual acuity but indirectly correlated with the spherical equivalent values and patient age. The mean sensitivity was not significantly correlated with the macular foveal thickness (r = -0.174; P = 0.101) or with the overall macular thickness (r = 0.103; P = 0.334); furthermore, the mean sensitivity was significantly correlated with visual acuity (r = 0.431; P < 0.001) and the spherical equivalent values (r = -0.306; P = 0.003). Retinal sensitivity in highly myopic eyes is directly correlated with choroidal thickness and does not seem to be associated with retinal thickness. Thus, in patients with high myopia, accurate measurements of choroidal thickness may provide more accurate information about this pathologic condition because choroidal thickness correlates to a greater degree with the functional parameters, patient age, and spherical equivalent values.

SCLERAL AND CHOROIDAL THICKNESS IN SECONDARY HIGH AXIAL MYOPIA.

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Shen, Ling; You, Qi Sheng; Xu, Xiaolin; Gao, Fei; Zhang, Zhibao; Li, Bin; Jonas, Jost B

2016-08-01

To assess differences in scleral and choroidal thickness between eyes with secondary high axial myopia caused by congenital glaucoma, eyes with primary high axial myopia, and nonhighly myopic eyes. The study consisted of 301 Chinese individuals with a mean age of 23.9 ± 22.6 years and mean axial length of 24.8 ± 4.2 mm. It included the "secondary highly myopic group" (SHMG) because of congenital glaucoma (n = 20 eyes; axial length >26.0 mm), the "primary highly myopic group" (PHMG) (n = 73; axial length >26.0 mm), and the remaining nonhighly myopic group (NHMG). The secondary highly myopic group versus the primary highly myopic group had significantly thinner sclera in the pars plana region (343 ± 71 μm versus 398 ± 83 μm; P = 0.006), whereas scleral thickness in other regions did not differ significantly between both highly myopic groups and was significantly thinner in both highly myopic groups than in the NHMG. Mean total scleral volume did not differ significantly (P > 0.20) between any group (SHMG: 659 ± 106 μm; PHMG: 667 ± 128 μm; NHMG: 626 ± 135 μm). Choroidal thickness was significantly thinner in both highly myopic groups than in the NHMG, with no significant differences between both highly myopic groups. Choroidal volume did not differ significantly (P > 0.40) between any of the groups (SHMG: 43 ± 12 μm; PHMG: 43 ± 13 μm; NHMG: 46 ± 17 μm). In secondary high axial myopia, the sclera gets thinner anterior and posterior to the equator; whereas in primary high axial myopia, scleral thinning is predominantly found posterior to the equator. Because volume of sclera and choroid did not differ between any group, scleral and choroidal thinning in myopia may be due to a rearrangement of tissue and not due to the new formation of tissue.

Automatic classification of pathological myopia in retinal fundus images using PAMELA

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Liu, Jiang; Wong, Damon W. K.; Tan, Ngan Meng; Zhang, Zhuo; Lu, Shijian; Lim, Joo Hwee; Li, Huiqi; Saw, Seang Mei; Tong, Louis; Wong, Tien Yin

2010-03-01

Pathological myopia is the seventh leading cause of blindness. We introduce a framework based on PAMELA (PAthological Myopia dEtection through peripapilLary Atrophy) for the detection of pathological myopia from fundus images. The framework consists of a pre-processing stage which extracts a region of interest centered on the optic disc. Subsequently, three analysis modules focus on detecting specific visual indicators. The optic disc tilt ratio module gives a measure of the axial elongation of the eye through inference from the deformation of the optic disc. In the texturebased ROI assessment module, contextual knowledge is used to demarcate the ROI into four distinct, clinically-relevant zones in which information from an entropy transform of the ROI is analyzed and metrics generated. In particular, the preferential appearance of peripapillary atrophy (PPA) in the temporal zone compared to the nasal zone is utilized by calculating ratios of the metrics. The PPA detection module obtains an outer boundary through a level-set method, and subtracts this region against the optic disc boundary. Temporal and nasal zones are obtained from the remnants to generate associated hue and color values. The outputs of the three modules are used as in a SVM model to determine the presence of pathological myopia in a retinal fundus image. Using images from the Singapore Eye Research Institute, the proposed framework reported an optimized accuracy of 90% and a sensitivity and specificity of 0.85 and 0.95 respectively, indicating promise for the use of the proposed system as a screening tool for pathological myopia.

[The relationship between eyeball structure and visual acuity in high myopia].

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Liu, Yi-Chang; Xia, Wen-Tao; Zhu, Guang-You; Zhou, Xing-Tao; Fan, Li-Hua; Liu, Rui-Jue; Chen, Jie-Min

2010-06-01

To explore the relationship between eyeball structure and visual acuity in high myopia. Totally, 152 people (283 eyeballs) with different levels of myopia were tested for visual acuity, axial length, and fundus. All cases were classified according to diopter, axial length, and fundus. The relationships between diopter, axial length, fundus and visual acuity were studied. The mathematical models were established for visual acuity and eyeball structure markers. The visual acuity showed a moderate correlation with fundus class, comus, axial length and diopter ([r] > 0.4, P eyeball structure markers. The visual acuity should decline with axial length extension, diopter deepening and pathological deterioration of fundus. To detect the structure changes by combining different kinds of objective methods can help to assess and to judge the vision in high myopia.

Photorefractive keratectomy for post-penetrating keratoplasty myopia and astigmatism.

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Bilgihan, K; Ozdek, S C; Akata, F; Hasanreisoğlu, B

2000-11-01

To determine the safety, effectiveness, and predictability of photorefractive keratectomy (PRK) for the correction of myopia and astigmatism after penetrating keratoplasty. Gazi University, Medical School, Department of Ophthalmology, Ankara, Turkey. Photorefractive keratectomy was performed in 16 eyes of 16 patients with postkeratoplasty myopia and astigmatism who were unable to wear glasses due to anisometropia and were contact lens intolerant. They were examined for uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and corneal transplant integrity before and after surgery. The mean follow-up after PRK was 26.0 months +/- 15.7 (SD) (range 12 to 63 months). The mean preoperative spherical equivalent refraction of -4.47 +/- 1.39 diopters (D) was -3.39 +/- 1.84 D (P >.05) at the last postoperative visit and the mean preoperative cylinder of -5.62 +/- 2.88 D was -3.23 +/- 1.70 D (P <.05); refractive regression correlated with the amount of ablation performed. The BSCVA decreased in 3 eyes (18.8%), and the UCVA decreased in 2 (12.5%). Six eyes (37.5%) had grade 2 to 3 haze, which resolved spontaneously in 4 eyes within a relatively long time but caused a decrease in BSCVA in 2 (12.5%). Two of the eyes (12.5%) had a rejection episode after PRK and were successfully treated with topical steroids. Photorefractive keratectomy to correct postkeratoplasty myopia and astigmatism appears to be less effective and less predictable than PRK for naturally occurring myopia and astigmatism. Corneal haze and refractive regression are more prevalent, and patient satisfaction is not good.

Myopia: Prevalence and Progression

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1989-01-01

final solutions (pp. 39-41). 1 Introduction Myopia is the visual condition in which only nearby objects appear in focus, much like a camera ...permanently focused at a close distance. In a "normal" or emmetropic eye, distant objects are naturally in focus, like a camera focused at infinity. That is...Versammlung d. ophth. gesel . 16, Heidelberg. Houston, J.W. 1972 A Comparison of New Cadets at U.S. Military Academy With Entering Freshmen at Other

Evaluation of diopter after cataract surgery in high myopia combined cataract

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Wan-Qi Zhang

2015-02-01

Full Text Available AIM: To observe the diopter after cataract surgery for vision gain in high myopia and its effect on visual outcomes. METHODS: Sixty(120 eyeshigh myopia combined with cataract cases received phacoemulsification and intraocular lens implantation in our hospital were retrospective studied. The patients were divided into three groups based on postoperative diopter: -1.0～-2.0D(group A, -2.25～-3.0D(group Band -3.25～-4.0D(group C. The uncorrected distance visual acuity(UCDVA, best corrected distant visual acuity(BCDVA, uncorrected near visual acuity(UCNVAand questionnaire of Activities of Daily Vision Scale(ADVSwere collected to assess the vision gain at 3mo after cataract surgery. RESULTS: At 3mo after surgery, UCDVA of group A was better than that of group B, and UCDVA of group B was better than that of group C. There were no differences in BCDVA among groups. There were significant differences between the three groups' UCNVA, it was best for the group C, followed by the group B, group A was the worst. For questionnaire, no difference was observed in patients' satisfactory for surgical results, but a significant difference was detected in postoperative glasses wearing frequency between groups. CONCLUSION:For cataract surgery in high myopia combined cataract, postoperative diopter should be calculated based on patients' daily requirements. For patients had not used to wearing glasses and near distant working condition, it's appropriated to reserve a minor degree of myopia. Conversely, for patients require near distant working and received wearing moderate and low hyperopia mirror, higher degree of myopia can be reserved.

Analysis of the factors affecting the occurrence of myopia in children with myopia

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Can Zhao; Qiu-Jie Xue; Xiao-Fen Liu; Wen-Jie Cao; Li-Li Sun

2017-01-01

AIM: To analyze the electronic product use time, writing time, playing piano time and outdoor activity time and the distribution of myopia in 586 cases of school age children in our hospital. METHODS: A retrospective analysis of 586 cases of children aged 6 to 12 years old in the outpatient department was established. Personalized files were used to record the uncorrected visual acuity, optometry, slit lamp, fundus mirror and strabismus. The cumulative use time of electronic products(includin...

[Prevalence of myopia and influencing factors among primary and middle school students in 6 provinces of China].

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Zhou, Jia; Ma, Yinghua; Ma, Jun; Zou, Zhiyong; Meng, Xiangkun; Tao, Fangbiao; Luo, Chunyan; Jing, Jin; Pan, Dehong; Luo, Jiayou; Zhang, Xin; Wang, Hong; Zhao, Haiping

2016-01-01

To understand the prevalence of myopia in primary and middle school students in 6 provinces and the possible influencing factors. Primary and middle school students were selected through multistage cluster sampling in 60 primary and middle schools in 6 provinces in China. The questionnaire survey and eyesight test were conducted among all the students selected according to the national student's physique and health survey protocol. Pearson chi-square test and binary multivariate logistic regression analysis were done to identify the influencing factors for myopia in students. The prevalence of myopia among primary and middle school students surveyed was 55.7%, the gender specific difference was statistically significant (59.7% for girls, 51.9% for boys) (Psleep time, average outdoor activity time during last week, school sport activities in the afternoon, the size of television set at home, time spent on watching TV and playing computer were the influencing factors for myopia. The prevalence of myopia is till high in primary and middle school students. Myopia is associated with both genetic factors and individual eye health related behaviors.

[Outdoor activity and myopia among 681 primary students in urban and rural regions of Beijing].

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Guo, Yin; Liu, Lijuan; Xu, Liang; Lü, Yanyun; Tang, Ping; Feng, Yi

2014-01-21

To explore the association between outdoor activity and myopia among 681 primary students from Beijing. School-based, cross-sectional investigation. Eye examination includes the visual acuity test, auto-refractor, slit lamp, ocular biometry and non-mydriatic fundus camera. Questionnaire includes regular items, near work, outdoor activity and social-economic status. The mean time spent outdoors was 1.6 ± 0.8 hours daily. Time spent on outdoor sports and outdoor leisure were 0.7 ± 0.1 hours daily, 1.0 ± 0.8 hours daily, respectively. Mean time of outdoor activity in urban was 1.1 ± 0.4 hours daily, compared with 2.2 ± 0.8 hours daily in rural (P = 0.000). In grade-1, total time spent outdoors is significantly different between myopia and non-myopia (1.4 ± 0.6 vs 1.8 ± 0.8 hours daily, P = 0.000), similar to outdoor leisure (0.8 ± 0.6 vs 1.1 ± 0.9 hours daily, P = 0.000). The same trend was also found in grade-4. The mean time spent outdoors was 1.6 ± 0.8 hours daily. Myopia spent a lower outdoor activity compared with non-myopia. More outdoor activity, e.g., in schools, may potentially be helpful to reduce the high prevalence of myopia in the young generation.

[The optimization of a surgical intervention to stabilize progressive myopia].

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Gonchar, P A; Dushin, N V; Beliaev, V S; Kravchinina, V V; Barashkov, V I; Frolov, M A

1999-01-01

Results of 236 sclera-fortifying surgeries are followed up for more than 25 years. Progressive myopia stabilized in 95.8% cases after bandaging scleroplasty and in 87.03% cases after chondroplasty. Clinical refraction and posteroanterior axis of the eye did not increase after surgery; visual functions stabilized, and brightness sensitivity threshold was lowered. The technique of operation and clinical course of the postoperative period are described. Based on analysis of the clinical material, the authors propose the optimal approach to scleroplastic operations aimed at stabilization of progressive myopia.

SCREENING FOR SIMPLE MYOPIA AMONG HIGH SCHOOL CHILDREN IN HYDERABAD CITY

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Vundi Krishna

2016-03-01

Full Text Available BACKGROUND Refractive error is one of the most common causes of visual impairment around the world and the second leading cause of treatable blindness. Due to the high magnitude of uncorrected refractive errors, myopia is considered as one of the important public health problems, especially in the urban population in India. It has been given high priority under the National Programme for Control of Blindness. AIM The aim of the present study is to know the prevalence of myopia and assess the degree of myopia among school going children. SETTINGS AND DESIGN Cross-sectional study done for one year. METHODS AND MATERIAL Age group of children 13-15 years, a total of 1600 were included in the study. Refractive error was tested using Snellen’s chart, Pin hole test, Occluder, Retinoscope. Statistical Analysis was done using the Epi Info version 7. RESULTS The prevalence of refractive errors was more in private schools (28.6% than in government schools (23%. It was observed that myopia was the major refractive error (89.8% among total refractive errors, followed by astigmatism (6.1% and hypermetropia (4.1%. In myopic children, both eyes were involved in 71.5%, right eye alone in 16.4%. Only 60% (478 and 98.4% (788 have undergone eye checkups yearly once, 36% and 0.3% didn’t have eye checkups so far in private and government schools respectively. CONCLUSION We conclude that prevalence of refractive errors more in private schools than government schools and myopia is the major among refractive errors. In most of them both the eyes are involved. Bitot’s spots were more in government schools, suggesting the need of vitamin A supplementation.

The increasing prevalence of myopia in junior high school students in the Haidian District of Beijing, China: a 10-year population-based survey.

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Li, Yan; Liu, Jia; Qi, Pengcheng

2017-06-12

Myopia is a leading cause of preventable blindness. Although, multiple cross-sectional epidemiological studies have confirmed that there is a high prevalence of myopia in high school-aged students in China. However, few longitudinal studies have been performed to assess junior high school students. In the present study, we investigate changes in the prevalence of myopia in third year junior high school (grade 9) students in the Haidian District of Beijing, China, from 2006 to 2015. A retrospective, longitudinal cohort study was performed over 10 years. A total of 37,424 third-year middle school (grade 9) students from 8 junior high schools in Haidian district, Beijing, were included. Participants underwent a comprehensive ophthalmic examination in which they were evaluated using autorefraction under cycloplegia and submitted to retinoscopy to assess accuracy. According to the spherical equivalent refraction (SER) of the right eye, subjects were separated into the following groups: non-myopia, -0.5 ≤ SER diopters (D); low myopia, -3.0 ≤ SER  -6.0 D. The following characteristics were measured: refractive error; the proportion of subjects with non- myopia, low myopia, moderate myopia and high myopia; and the difference in the prevalence of myopia between male and female subjects. From 2006 to 2015, the prevalence of non-myopia (from 44.05% to 34.52%) and low myopia (from 32.27% to 20.73%) decreased, while the prevalence of moderate myopia (from 19.72% to 38.06%) and high myopia (from 3.96% to 6.69%) significantly increased. For refractive error, the worse eye was -2.23 ± 2.42 D (median, -1.75; range - 12.75 to +8.50) in 2006 and -3.13 ± 2.66 D (median, -2.75; range - 12.75 to +8.50) in 2015. When the entire population was considered, the overall prevalence of myopia increased from 55.95% in 2005 to 65.48% in 2015. There was a significant positive relationship between the year and the prevalence of myopia in both girls and boys. Girls were more

Changes in myopia with low-Dk hydrogel and high-Dk silicone hydrogel extended wear.

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Jalbert, Isabelle; Stretton, Serina; Naduvilath, Thomas; Holden, Brien; Keay, Lisa; Sweeney, Deborah

2004-08-01

This study compared changes in myopia between wearers of high-oxygen permeability (Dk) silicone hydrogel lenses and low-Dk hydrogel lenses after 1 year of extended wear (EW). Ninety-two adult subjects were randomly assigned to a lens type. Subjective refraction and autokeratometry were performed at baseline and at 6 and 12 months. After 6 months of EW, myopia (spherical equivalent) regressed by 0.18 +/- 0.33 D (p Dk silicone hydrogel group and progressed by -0.23 +/- 0.36 D (p Dk hydrogel group. There were no further changes after 12 months. Previous lens wear history, baseline refractive error, and age and gender did not have an impact on the change in myopia, and only 35% of the variation could be accounted for by changes in corneal curvature and lens type. Soft contact lens type significantly affects the direction of change in myopia during EW. We hypothesize that these changes are driven by pressure-related redistribution of corneal tissue in high-Dk silicone hydrogel lens wearers and by hypoxia-associated corneal thinning in low-Dk hydrogel wearers. More long-term studies are required to confirm whether the effects of high-Dk silicone hydrogel lens wear on myopia are permanent.

Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus

NARCIS (Netherlands)

Nio, YK; Jansonius, NM; Wijdh, RHJ; Beekhuis, WH; Worst, JGF; Noorby, S; Kooijman, AC

Purpose. To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction. Setting: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. Methods: Three groups of patients with low myopia correction

Study on the prevalence and underlying factors of myopia among the students of a medical college in Kerala

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Shiny George, Biju Baby Joseph

2014-04-01

Full Text Available Background: Few decades earlier, wearing spectacles was a province of adults over 40 years of age. Now we see more children and adolescents with spectacles/contact lenses. Various studies in Asian population show a dramatic increase in refractive error, especially myopia among school and college students. More advanced levels of education like medical education that involves extensive near work such as reading and writing have been repeatedly associated with greater myopia prevalence Objective: To study the prevalence and the underlying factors of myopia in MBBS students of a Medical college in Kerala. Research methodology: One hundred and sixty two MBBS students (2009 – 2012 batches were examined. 40 students were selected from each class by systematic random sampling technique, their visual acuity was checked using Snellen’s Chart and Diopters were obtained. Details of factors were obtained using a questionnaire. Results: Prevalence of myopia was observed as 39.5%. First and second year students had a greater percentage of myopia with 40% & 52.5% respectively. 40.6% of myopics had positive family history of myopia (p = 0.003. Duration of TV watching and computer use showed a significant relation with myopia. (p = 0. 033, 0.009. Reading hours, type of light used, playing or texting with cell phone and sleeping habits of students were not significant. Conclusion: Prevalence of myopia was high among medical students (39.5%. Significance of genetic predisposition was well appreciated in our study.

Total flight hours, irritated and burning eye and risk of mild myopia in civilian pilots in Indonesia

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Pritha Maya Savitri

2016-07-01

Full Text Available Latar belakang: Miopia merupakan kelainan refraksi yang sering terjadi di antara penerbang. Penelitianini bertujuan mengidentifikasi beberapa faktor risiko dominan terhadap miopia ringan pada penerbang sipildi Indonesia.Metode: Subyek adalah penerbang sipil pria berusia 21-45 tahun yang dipilih secara purposif di antara yangsedang melaksanakan pemeriksaan kesehatan berkala di Balai Kesehatan Penerbangan Jakarta. Data tajampenglihatan dan gula darah didapatkan dari rekam medik. Miopia ringan adalah subyek dengan penurunantajam penglihatan dengan koreksi lensa -0,25 sampai dengan -0,30. Analisis data dengan regresi Coxmenggunakan Stata 10.Hasil: Persentase miopia ringan dalam penelitian ini sebesar 36%. Faktor risiko dominan terhadap myopiaringan adalah jam terbang total, riwayat orang tua myopia, dan gejala iritasi dan gatal mata. Subyekdengan dibandingkan dengan yang kurang dari 1000 jam terbang 28% lebih tinggi berisiko myopia ringan[risiko relatif suaian (RRa = 1,28; 95% interval kepercayaan (CI =1,00-1,64; P = 0,047]. Subyek dengandibandingkan ttanpa riwayat orang tua myopia 32% lebih tinggi berisiko myopia ringan (RRa = 5,32; 95%CI = 3,75-7,55; P = 0,000. Sedangkan subyek dengan dibandingkan tanpa gejala iritasi mata 48% lebihbesar berisiko miopia ringan RRa = 1,48; 95% CI = 1,19-1,85; P = 0,001. Subyek dengan dibandingkantanpa gejala iritasi mata 46% lebih berisiko miopia ringan (RRa = 0,46; 95% CI = 0,26-0,83; P = 0,009.Kesimpulan: Jam terbang total lebih dari 1000 jam, riwayat orang tua miopia, iritasi mata merupakanfaktor risiko dominan terhadap miopia ringan pada penerbang sipil di Indonesia. (Health Science Journalof Indonesia 2016;7:49-53Kata kunci: miopia ringan, penerbang sipil, jam terbang, Indonesia Background: Spatial orientation is the main problem to pilots that determined by visual, vestibuler andpropioseptif. This study aims to identify several dominant risk factors related to mild myopia in civilianpilots in Indonesia

Genetic and environmental-genetic interaction rules for the myopia based on a family exposed to risk from a myopic environment.

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Wenbo, Li; Congxia, Bai; Hui, Liu

2017-08-30

To quantitatively assess the role of heredity and environmental factors in myopia based on the family with enough exposed to risk from myopic environment for establishment of environmental and genetic index (EGI). A pedigree analysis unit was defined as one child (university student), father, and mother. Information pertaining to visual acuity, experience in participating in the college entrance examination in mainland of China (regarded as a strong environmental risk for myopia), and occupation for pedigree analysis units were obtained. The difference between effect of both genetic and environmental factors (myopia prevalence in children with two myopic parents) and environmental factors (myopia prevalence in children of whom neither parent was myopic) was defined as the EGI. Multiple regression analysis was performed for 114 pedigree using diopters of father, mother, average diopters in parents, maximum and minimum diopters in father and mother as variables. A total of 353 farmers and 162 farmer families were used as a control group. A distinct difference in myopia rate (96.2% versus 57.7%) was observed for children from parents with myopia and parents without myopia (EGI=0.385). The maximum diopter was included to regression equation which was statistically significant. The prevalence of myopia was 9.9% in the farmer. The prevalence in children is similar between the farmer and other families. A new genetic rule that myopia in children was directly related with maximum diopters in father and mother may be suggested. Environmental factors may play a leading role in the formation of myopia. Copyright © 2017 Elsevier B.V. All rights reserved.

Levodopa inhibits the development of form-deprivation myopia in guinea pigs.

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Mao, Junfeng; Liu, Shuangzhen; Qin, Wenjuan; Li, Fengyun; Wu, Xiaoying; Tan, Qian

2010-01-01

It has been shown that visual deprivation leads to a myopic refractive error and also reduces the retinal concentration of dopamine. Exogenously 3,4-dihydroxy-L-phenylalanine (levodopa, L-DOPA) can be converted into dopamine in vivo, which safely and effectively treats Parkinson disease. Moreover, L-DOPA was also used in the treatment of amblyopia in clinical studies. However, the effect of L-DOPA on the development of myopia has not been studied. The aim of this study was to investigate whether intraperitoneal injection of L-DOPA could inhibit form-deprivation myopia in guinea pigs and to explore a new strategy for drug treatment of myopia. Sixty guinea pigs, at age of 4 weeks, were randomly divided into six groups: normal control, L-DOPA group, saline group, deprived group, deprived plus L-DOPA group, and deprived plus saline group. Form deprivation was induced with translucent eye shields on the right eye and lasted for 10 days. L-DOPA was injected intraperitoneally into the guinea pig once a day. The corneal radius of curvature, refraction, and axial length were measured in all animals. Subsequently, retinal dopamine content was evaluated by high-performance liquid chromatography with electrochemical detection. Ten days of eye occlusion caused the form-deprived eyes to elongate and become myopic, and retinal dopamine content to decrease, but the corneal radius of curvature was not affected. Repeated intraperitoneal injection of L-DOPA could inhibit the myopic shift (from -3.62 +/- 0.98 D to -1.50 +/- 0.38 D; p < 0.001) due to goggles occluding and compensate retinal dopamine (from 0.65 +/- 0.10 ng to 1.33 +/- 0.23 ng; p < 0.001). Administration of L-DOPA to the unoccluded animals had no effect on its ocular refraction. There was no effect of intraperitoneal saline on the ocular refractive state and retinal dopamine. Systemic L-DOPA was partly effective in this guinea pig model and, therefore, is worth testing for effectiveness in progressing human myopes.

Alcohol myopia and goal commitment

OpenAIRE

Sevincer, A. Timur; Oettingen, Gabriele

2014-01-01

According to alcohol myopia theory, acute alcohol consumption leads people to disproportionally focus on the salient rather than the peripheral aspects of a situation. We summarize various studies exploring how myopic processes resulting from acute alcohol intake affect goal commitment. After consuming alcohol student participants felt strongly committed to an important personal goal even though they had low expectations of successfully attaining the goal. However, once intoxicated participan...

Myopia correction in children: a meta-analysis.

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Cui, Yanhui; Li, Li; Wu, Qian; Zhao, Junyang; Chu, Huihui; Yu, Gang; Wei, Wenbin

2017-06-26

The purpose of this study was to conduct a meta-analysis comparing rigid gas permeable lenses (RGP) with soft contact lenses (SCL), spectacles and orthokeratology (OK) lenses for myopia control with respect to axial length elongation, spherical equivalent and measures of corneal curvature. Medline, Cochrane, EMBASE, and Google Scholar databases were searched to September 29, 2015 using the following keywords: rigid gas permeable contact lens; refractive error; and refractive abnormalities. Randomized controlled trials, two-arm prospective studies and retrospective studies of children with myopia treated with RGP lenses compared with spectacles, SCL, and OK lenses were included. Outcome measures were changes of axial length, spherical equivalent, flatter meridian, steeper meridian and corneal apical radius. Five studies were included. Three studies reported axial length change after 2-3 years of treatment with RGP lenses and SCL/spectacles and no difference between the groups was noted (pooled mean difference = -0.077, 95% confidence interval [CI]: -0.120 to 0.097, p = 0.840). Two studies reported a change of spherical equivalent after 2-3 years of treatment with RGP lenses and SCL/spectacles, and no difference between the groups was noted (pooled mean difference = 0.275, 95% CI: -0.390 to 0.941, p = 0.417). Two studies compared corneal curvature measures between RGP and OK lenses after 3-6 months of treatment and no differences in any measures of corneal curvature were seen. The effect of RGP lenses and SCL/spectacles on axial length elongation and spherical equivalent and of RGP and OK lenses on corneal curvature in children with myopia was similar.

Correlation analysis of electronic products with myopia in preschool and school aged children

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Li-Li Sun

2016-02-01

Full Text Available AIM: To explore the influence of electronic products on myopia in preschool and school aged children, and the development regularities of myopia, to formulate reasonable guidelines for using eyes healthily, and lay a solid foundation for the prevention and control work. METHODS: This retrospective analysis enrolled 900 3～12 years old children from outpatients department, and all of them were established individualized archives, recording: uncorrected visual acuity, optometry, slit lamp, ophthalmoscopy, strabismus inspection results; recording eye usage condition on TVs, computers, mobile phones, iPad, homework, extra-curricular books. Statistical analyze the refractive status of each age group, the use of electronic products of different age groups and their correlation with refractive status. RESULTS: The number of preschool children with normal uncorrected visual acuity was more than that of early school-age children, and the difference was statistically significant(PP>0.05; the number of children aged 7～12(early school aged childrenwith myopia was more than that of children aged 3～6(preschool childrenand the difference was statistically significant(PCONCLUSION: For preschool children, it is necessary to conduct early screening, health guidance, the establishment of personalized medical records and one-to-one personalized guidance; it is also needed to avoid the arduous learning task with the stacking usage of eyes, to fight for myopia and to control the development of myopia. Therefore, to reduce the use of electronic products has become a topic worthy of further study.

Prevalence and risk factors for myopia and other refractive errors in an adult population in southern India.

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Joseph, Sanil; Krishnan, Tiruvengada; Ravindran, Ravilla D; Maraini, Giovanni; Camparini, Monica; Chakravarthy, Usha; Ravilla, Thulasiraj D; Hutchings, Andrew; Fletcher, Astrid E

2018-05-01

To investigate prevalence and risk factors for myopia, hyperopia and astigmatism in southern India. Randomly sampled villages were enumerated to identify people aged ≥40 years. Participants were interviewed for socioeconomic and lifestyle factors and attended a hospital-based ophthalmic examination including visual acuity measurement and objective and subjective measurement of refractive status. Myopia was defined as spherical equivalent (SE) worse than -0.75 dioptres (D), hyperopia as SE ≥+1D and astigmatism as cylinder <-0.5. The age-standardised prevalences of myopia, hyperopia and astigmatism were 35.6% (95% CI: 34.7-36.6), 17.0% (95% CI: 16.3-17.8) and 32.6 (29.3-36.1), respectively. Of those with myopia (n = 1490), 70% had advanced cataract. Of these, 79% had presenting visual acuity (VA) less than 6/18 and after best correction, 44% of these improved to 6/12 or better and 27% remained with VA less than 6/18. In multivariable analyses (excluding patients with advanced cataract), increasing nuclear opacity score, current tobacco use, and increasing height were associated with higher odds of myopia. Higher levels of education were associated with increased odds of myopia in younger people and decreased odds in older people. Increasing time outdoors was associated with myopia only in older people. Increasing age and female gender were associated with hyperopia, and nuclear opacity score, increasing time outdoors, rural residence and current tobacco use with lower odds of hyperopia. After controlling for myopia, factors associated with higher odds of astigmatism were age, rural residence, and increasing nuclear opacity score and increasing education with lower odds. In contrast to high-income settings and in agreement with studies from low-income settings, we found a rise in myopia with increasing age reflecting the high prevalence of advanced cataract. © 2018 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of

Single-step transepithelial photorefractive keratectomy in myopia and astigmatism: 18-month follow-up.

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Adib-Moghaddam, Soheil; Soleyman-Jahi, Saeed; Salmanian, Bahram; Omidvari, Amir-Houshang; Adili-Aghdam, Fatemeh; Noorizadeh, Farsad; Eslani, Medi

2016-11-01

To evaluate the long-term quantitative and qualitative optical outcomes of 1-step transepithelial photorefractive keratectomy (PRK) to correct myopia and astigmatism. Bina Eye Hospital, Tehran, Iran. Prospective interventional case series. Eyes with myopia with or without astigmatism were evaluated. One-step transepithelial PRK was performed with an aberration-free aspheric optimized profile and the Amaris 500 laser. Eighteen-month follow-up results for refraction, visual acuities, vector analysis, higher-order aberrations, contrast sensitivity, postoperative pain, and haze grade were assessed. The study enrolled 146 eyes (74 patients). At the end of follow-up, 93.84% of eyes had an uncorrected distance visual acuity of 20/20 or better and 97.94% of eyes were within ±0.5 diopter of the targeted spherical refraction. On vector analysis, the mean correction index value was close to 1 and the mean index of success and magnitude of error values were close to 0. The achieved correction vector was on an axis counterclockwise to the axis of the intended correction. Photopic and mesopic contrast sensitivities and ocular and corneal spherical, cylindrical, and corneal coma aberrations significantly improved (all P < .001). A slight amount of trefoil aberration was induced (P < .001, ocular aberration; P < .01, corneal aberration). No eye lost more than 1 line of corrected distance visual acuity. No eye had a haze grade of 2+ degrees or higher throughout the follow-up. Eighteen-month results indicate the efficacy and safety of transepithelial PRK to correct myopia and astigmatism. It improved refraction and quality of vision. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Under-correction of human myopia – Is it myopigenic?: A retrospective analysis of clinical refraction data

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Balamurali Vasudevan

2014-07-01

Conclusion: Under-correction of myopia produced a small but progressively greater degree of myopic progression than did full correction. The present finding is consistent with earlier clinical trials and modeling of human myopia.

Phacoemulsificatıon in eyes wıth cataract and high myopia

OpenAIRE

Cetinkaya,Servet; Acir,Nursen Oncel; Cetinkaya,Yasemin Fatma; Dadaci,Zeynep; Yener,Halil İbrahim; Saglam,Faik

2015-01-01

ABSTRACTPurpose:To evaluate the outcomes and complications following phacoemulsification surgery in eyes with cataract and high myopia.Methods:We retrospectively evaluated the data of 43 eyes of 28 consecutive patients (12 males, 16 females) with cataract and high myopia who had undergone phacoemulsification and intraocular lens (IOL) implantation. The mean [± standard deviation (range)] age of the patients was 59.20 ± 11.08 (39-77) years.Results:The frequency of nuclear cataract was signific...

Near Work Related Parameters and Myopia in Chinese Children: the Anyang Childhood Eye Study.

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Shi-Ming Li

Full Text Available To examine the associations of near work related parameters with spherical equivalent refraction and axial length in Chinese children.A total of 1770 grade 7 students with mean age of 12.7 years were examined with cycloplegic autorefraction and axial length. Questions were asked regarding time spent in near work and outdoors per day, and near work related parameters.Multivariate models revealed the following associations with greater odds of myopia: continuous reading (> 45min, odds ratio [OR], 1.4; 95% confidence interval [CI], 1.1-1.8; close television viewing distance (≤ 3m, OR, 1.7; 95% CI, 1.2-2.3; head tilt when writing, OR, 1.3; 95% CI, 1.1-1.7, and desk lighting using fluorescent vs. incandescent lamp, OR, 1.5; 95% CI, 1.2-2.0. These factors, together with close reading distance and close nib-to-fingertip distance were significantly associated with greater myopia (P<0.01. Among near work activities, only reading more books for pleasure was significantly associated with greater myopia (P=0.03. Television viewing distance (≤ 3 m, fluorescent desk light, close reading distance (≤20 cm and close nib-to-fingertip distance (≤ 2 cm were significantly associated with longer axial length (P<0.01. Reading distance, desk light, and reading books for pleasure had significant interaction effects with parental myopia.Continuous reading, close distances of reading, television viewing and nib-to-fingertip, head tilt when writing, reading more books for pleasure and use of fluorescent desk light were significantly associated with myopia in 12-year-old Chinese children, which indicates that visual behaviors and environments may be important factors mediating the effects of near work on myopia.

Ethnic variations in myopia and ocular biometry among adults in a rural community in China: the Yunnan minority eye studies.

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Pan, Chen-Wei; Chen, Qin; Sheng, Xun; Li, Jun; Niu, Zhiqiang; Zhou, Hua; Wei, Tao; Yuan, Yuansheng; Zhong, Hua

2015-05-01

To determine the prevalence of myopia and ocular biometry in population-based samples of ethnic Yi and Han people living in an inland rural community in China. A random cluster sampling strategy was used to select ethnic Han and Yi adults aged 50 years or older living in Yunnan. Refractive error was determined by subjective refraction and ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD), and lens thickness (LT), which were measured using an Echoscan. Adults of Yi ethnicity had lower prevalence of myopia (10.3% vs. 8.1%; P = 0.02) and high myopia (2.3% vs. 1.6%; P = 0.10) than their counterparts of Han ethnicity. The prevalence of myopia increased with age (P for trend ethnic groups (both P for trend > 0.05). In multivariate analysis, time spent outdoors was associated with myopia (P = 0.003) and AL (P ethnicity and other risk factors on myopia (all P > 0.05). Adjustment for lens nuclear opacity score reduced the excess prevalence of myopia in Han ethnicity by 37.5%. There was little evidence showing that ethnic disparities existed in the prevalence and risk factors between the major and minor ethnic groups living in the same communities in rural China. The "cohort effect" on myopia observed in many other populations was not seen in this study.

Looking into aqueous humor through metabolomics spectacles - exploring its metabolic characteristics in relation to myopia.

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Barbas-Bernardos, Cecilia; Armitage, Emily G; García, Antonia; Mérida, Salvador; Navea, Amparo; Bosch-Morell, Francisco; Barbas, Coral

2016-08-05

Aqueous humor is the transparent fluid found in the anterior chamber of the eye that provides the metabolic requirements to the avascular tissues surrounding it. Despite the fact that metabolomics could be a powerful tool in the characterization of this biofluid and in revealing metabolic signatures of common ocular diseases such as myopia, it has never to our knowledge previously been applied in humans. In this research a novel method for the analysis of aqueous humor is presented to show its application in the characterization of this biofluid using CE-MS. The method was extended to a dual platform method (CE-MS and LC-MS) in order to compare samples from patients with different severities of myopia in order to explore the disease from the metabolic phenotype point of view. With this method, a profound knowledge of the metabolites present in human aqueous humor has been obtained: over 40 metabolites were reproducibly and simultaneously identified from a low volume of sample by CE-MS, including among others, a vast number of amino acids and derivatives. When this method was extended to study groups of patients with high or low myopia in both CE-MS and LC-MS, it has been possible to identify over 20 significantly different metabolite and lipid signatures that distinguish patients based on the severity of myopia. Among these, the most notable higher abundant metabolites in high myopia were aminooctanoic acid, arginine, citrulline and sphinganine while features of low myopia were aminoundecanoic acid, dihydro-retinoic acid and cysteinylglycine disulfide. This dual platform approach offered complementarity such that different metabolites were detected in each technique. Together the experiments presented provide a whelm of valuable information about human aqueous humor and myopia, proving the utility of non-targeted metabolomics for the first time in analyzing this type of sample and the metabolic phenotype of this disease. Copyright © 2016 Elsevier B.V. All rights

Does the level of physical activity in university students influence development and progression of myopia? - A 2-year prospective cohort study

DEFF Research Database (Denmark)

Jacobsen, Niels; Jensen, Hanne; Goldschmidt, E.

2008-01-01

PURPOSE. To study whether physical activity has a protective effect on the development and progression of myopia in medical students. METHODS. In a 2-year longitudinal cohort study, 156 Caucasian first-year medical students from the University of Copenhagen were enrolled. The baseline examination...... with a refractive change toward myopia, whereas physical activity was inversely associated with a refractive change toward myopia (P = 0.015). Myopic eyes progressed significantly more than did emmetropic and hyperopic eyes (P = 0.002). CONCLUSIONS. An association between physical activity and myopia was observed......, suggesting a protective effect of physical activity on the development and progression of myopia in university students. The results confirm that intensive studying is a risk factor of myopia and that myopic progression or development is more likely in medical students in their early 20s than in their late...

[Comparative results evaluation of residual myopia and astigmatism correction after radial keratotomy by photorefraction keratectomy and laser specialized keratomileusis].

Science.gov (United States)

Dias-Martines, T E; Sheludchenko, V M; Kurenkov, V V

1999-01-01

The results of correction of residual myopia by photorefraction keratectomy (PRK) (51 eyes) and laser specialized keratomileusis (LASIK) (36 eyes) after radial keratotomy (RK) are compared. The patients were observed for up to 12 months. After PRK, 7.3% patients developed late fleur of the cornea, evaluated by at least 2 points. The incidence of fleur directly depended on the value of residual myopia. After LASIK none of the patients developed such fleur. The best visual acuity (0.5 and higher without correction) was attained in 70.73% after PRK and RK, vs. 100% after LASIK. The results of photorefraction operations and severity of residual myopia after RK correlated. In residual myopia of up to -3 diopters the results of correction by PRK and LASIK were virtually the same. In residual myopia higher than -3 diopters, LASIK is preferable.

Factors associated with myopia in school children in China: the Beijing childhood eye study.

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Qi Sheng You

Full Text Available PURPOSE: To assess factors associated with myopia in school children in rural and urban parts of Greater Beijing. METHODS: The Beijing Pedriatic Eye Study was a population-based cross-sectional study, in which one school of each level (primary, junior high, senior high was randomly selected from nine randomly selected districts out of 18 districts of Greater Beijing. The children underwent non-cylcoplegic refractometry and their parents an interview. RESULTS: Of 16,771 eligible students, 15,066 (89.8% children (7,769 (51.6% girls participated, with 8,860 (58.8% participants living in the rural region. Mean age was 13.2±3.4 years (range:7-18 years. In multivariate analysis, prevalence of myopia (defined as ≤-1.00 diopters was associated with higher age (Odds ratio(OR:1.37; 95% confidence interval(CI:1.35,1.39, female gender (OR:1.35;95%CI:1.25,1.47, key school type (OR:0.77;95%CI: 0.70,0.85, higher family income (OR:1.04;95%CI:1.01,1.07, parental myopia (OR:1.46;95%CI:1.40,1.53, dim reading illumination (OR:0.93;95%CI: 0.88,0.98, longer daily studying duration (OR:1.10;95%CI:1.06,1.15, shorter duration of watching television (or computer (OR:0.93;95%CI:0.89,0.97, higher self-reported protein intake (OR:0.94;95%CI:0.90,0.99, feeling well about life and status (OR:0.93;95%CI:0.89,0.98, and feeling tired or dizzy (OR:0.94;95%CI:0.91,0.97. Prevalence of high myopia (defined as ≤-6.00 diopters was associated with higher age (OR:1.43;95%CI:1.38, 1.48, key school type (OR:0.61;95%CI:0.49,0.74, family income (OR:1.07;95%CI:1.02,1.13, parental myopia (OR:1.65;95%CI:1.54,1.76, dim reading illumination (OR:0.86;95%CI:0.77,0.96, less rest during studying (OR:1.18;95%CI:1.10,1.27, feeling well about life and studying (OR:0.88;95%CI: 0.81,0.96 and feeling dizzy or tired (OR:0.93;95%CI:0.87,0.99. Prevalence of high myopia (defined as ≤-8.00 diopters was significantly associated with higher age (OR:1.39;95%CI:1.31,1.48;, key school type (OR:0.61;95%CI:0

A prospective bilateral comparison of epi-LASIK and LASEK for myopia.

Science.gov (United States)

Hondur, Ahmet; Bilgihan, Kamil; Hasanreisoglu, Berati

2008-11-01

To compare the clinical and confocal microscopic results of mechanical (epi-LASIK) versus alcohol-assisted laser epithelial keratomileusis (LASEK) for the correction of myopia. Twenty-five patients with myopia received epi-LASIK in one eye and LASEK in the other. The difference of spherical equivalent refraction of myopia and astigmatism was less than 1.00 diopter (D) in two eyes of each case. Mechanical separation of the epithelium was performed with the Lasitome epithelial separator and alcohol-assisted separation with 25 second application of 18% alcohol. Ablation was performed with the ESIRIS laser. Patients were seen daily until epithelial closure, and at 1, 3, 6, and 12 months. Time to epithelial healing, uncorrected visual acuity (UCVA), manifest refraction, haze, and grey scale value in confocal microscopy were recorded. Preoperative myopic spherical equivalent refraction was -3.95+/-1.49 D in the epi-LASIK and -3.91+/-1.39 D in the LASEK-treated eyes. The mean time to epithelial healing was slightly longer after epi-LASIK (4.86+/-0.64 vs 4.18+/-0.58 days). Of both epi-LASIK and LASEK-treated eyes, 92% achieved 20/20 or better UCVA and were within +/-0.50 D of emmetropia at 12 months. The grade of haze and mean grey scale value in confocal microscopy were similar in epi-LASIK and LASEK-treated eyes at all postoperative periods. One eye treated with epi-LASIK suffered a minor stromal cut. Epi-LASIK and LASEK offer effective correction of myopia with comparable results at 1 year.

Development and validation of the Alcohol Myopia Scale.

Science.gov (United States)

Lac, Andrew; Berger, Dale E

2013-09-01

Alcohol myopia theory conceptualizes the ability of alcohol to narrow attention and how this demand on mental resources produces the impairments of self-inflation, relief, and excess. The current research was designed to develop and validate a scale based on this framework. People who were alcohol users rated items representing myopic experiences arising from drinking episodes in the past month. In Study 1 (N = 260), the preliminary 3-factor structure was supported by exploratory factor analysis. In Study 2 (N = 289), the 3-factor structure was substantiated with confirmatory factor analysis, and it was superior in fit to an empirically indefensible 1-factor structure. The final 14-item scale was evaluated with internal consistency reliability, discriminant validity, convergent validity, criterion validity, and incremental validity. The alcohol myopia scale (AMS) illuminates conceptual underpinnings of this theory and yields insights for understanding the tunnel vision that arises from intoxication.

Physical activity in childhood and the association with myopia in adolescence – The CHAMPS Eye Study

DEFF Research Database (Denmark)

Lundberg, Lars Kristian; Vestergaard, Anders Højslet; Jacobsen, Nina

Purpose: Myopia is the most frequent eye disease globally and is usually caused by increasing axial growth of the eye during childhood and adolescence. Lifestyle changes such as reduced physical activity (PA) are thought to be the driving force behind the rapid increase of myopia worldwide....... The purpose of this study was to investigate the effect of PA on the development of myopia in a Danish cohort of schoolchildren. The hypothesis was that decreased PA during childhood is associated with increased axial length and myopia. Methods: A prospective study of 198 children from the CHAMPS-study DK...... cohort (Childhood Health, Activity, and Motor Performance School Study Denmark). PA was assessed with GT3X accelerometer (ActiGraph, Florida, USA) worn for 7 full consecutive days at the period August to October 2010: mean intensity was estimated as counts/min (CPM); and cut off-points for sedentary (SED...

[Binocular fusion method for prevention of myopia].

Science.gov (United States)

Xu, G D

1989-03-01

When looking at a far object with two eyes, relaxation of convergence and accommodation occurred and accompanied by binocular fusion. Using this phenomenon a method of binocular fusion of targets was designed, that is the distance between two targets are just the same as the distance between two visual lines, while looking at a far object. During the images of the targets are fused, the accommodation and convergence are relaxed concomitantly; thus a result of correction of pseudomyopia and prevention of myopia is achieved. By means of binocular fusion, the eye muscle exercises were conducted and resulted in not only the far point further but also the near point closer. The skiascopic examination carried out at the same time of binocular fusion showed that the degrees of relaxed accommodation was 97.9% that of looking at an object in far distance. The above results indicated that the binocular fusion method had excellent effect on the prevention of myopia. This method is simple and feasible, conforms to the visual physiology, and thus can be widely adopted.

Prevalence and associated factors of myopia among high school students in Gondar town, northwest Ethiopia, 2016

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Belete GT

2016-12-01

Full Text Available Gizachew Tilahun Belete,1 Dereje Hayilu Anbesse,1 Adino Tesfahun Tsegaye,2 Mohammed Seid Hussen1 1Department of Optometry, 2Department of Biostatistics and Epidemiology, Institute of Public Health, College of Medicine and Health Science, University of Gondar, Gondar, Ethiopia Introduction: Myopia is an important cause of correctable visual impairment and preventable blindness worldwide. Prevalence rates are approximately 20%–35% among the older teenage population globally. It has a medical burden of pathologic complications such as maculopathy and glaucomatous optic neuropathy. High school students experience high-performance and study pressures in the preparation for the final national examination. As a result they are exposed to excessive near work and indoor activities. They are also ignored for regular screening. Objective: To determine the prevalence and associated factors of myopia among high school students in Gondar town, Ethiopia. Methods: An institution-based cross-sectional study was conducted on 498 high school students with systematic random sampling method from April 18 to April 29, 2016, in three full-cycle high schools (9th–12th grades. A standardized structured questionnaire, Snellen acuity chart, pinhole, retinoscope, trial case lenses, pen torch, and direct ophthalmoscope were used to collect data. Results: A total of 495 study participants were included, and they had a mean age of 17.48±1.59 years. The prevalence of myopia was 11.9% (95% confidence interval [CI]: 10.2, 17.9. Family history of myopia (adjusted odds ratio [AOR]=8.08 [95% CI: 4.30, 15.16], school being private (AOR=2.88 [95% CI: 1.02, 8.11], longer time spent for near work (AOR=2.89 [95% CI: 1.12, 7.43], longer time spent partaking in indoor activities (AOR=4.32 [95% CI: 1.69, 10.99], shorter near working distance (AOR=3.06 [95% CI: 1.33, 7.06], lack of outdoor sport activities (AOR=2.27 [95% CI: 1.05, 4.90], use of visual display units (AOR=2.81 [95% CI

CORRELATION OF FUNDUS CHANGES IN RELATION TO REFRACTIVE ERROR IN PATIENTS WITH MYOPIA- A CLINICAL PROSPECTIVE STUDY

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Balasubramanian M. Manickavelu

2018-01-01

Full Text Available BACKGROUND Retina is unique among the complex element of the central nervous system and the special senses. It may be readily viewed during life and it is sufficiently transparent, so that alterations within and adjacent to it may be observed in vivo. The peripheral retina owing to its thinness comparing to that of the central part, poorly-developed retinal cells, absence of large blood vessels, relatively insensitive to light, less resistance to traction, forms a seat for various lesions, which are potentially dangerous for the vision. It is in myopia that we meet the most frequent and the most obvious anomalies in the fundus changes, which bear some relation to the degree of myopia and appeal to be concerned with it either as a cause or effect or perhaps both. The aim of our study is to correlate fundus changes in relation to refractive error in patients with myopia. MATERIALS AND METHODS In our study, 100 cases of myopic (-6D:50 cases patients were selected. Detailed evaluation done. History of refractive error includes duration, age at which spectacles were worn for the first time. Time of last change of spectacles, family history of myopia, history of other symptoms like progressive loss of vision, defective vision related to day or night, sudden loss of vision, flashes and floaters. Anterior segment was examined followed by the recording of initial visual acuity and the best corrected visual acuity was noted. IOP was measured for all the cases using Schiotz tonometry. Axial length was measured in all the cases. Fundus examined with direct ophthalmoscope, indirect ophthalmoscope, 3 mirror and 90D lens. Bscan was done in few cases. The media, disc, vessels, macula and the surrounding retina were examined. The periphery was examined with indentation method. The various fundus features and pathological lesions in different degrees of myopia were noted. RESULTS Females were comparatively more affected. Highest incidence was seen in the younger

Instrument-induced spatial crosstalk deconvolution algorithm

Science.gov (United States)

Wright, Valerie G.; Evans, Nathan L., Jr.

1986-01-01

An algorithm has been developed which reduces the effects of (deconvolves) instrument-induced spatial crosstalk in satellite image data by several orders of magnitude where highly precise radiometry is required. The algorithm is based upon radiance transfer ratios which are defined as the fractional bilateral exchange of energy betwen pixels A and B.

Common variant in myocilin gene is associated with high myopia in isolated population of Korcula Island, Croatia.

LENUS (Irish Health Repository)

Vatavuk, Zoran

2012-01-31

AIM: To study the association between genetic variants in myocilin and collagen type I alpha 1 genes and high myopia in an isolated island population. METHODS: A total of 944 examinees from the genetic epidemiology study conducted on the island of Korcula, Croatia, were included in the study. We selected 2 short nucleotide polymorphisms (SNP) available in our genome-wide scan set of SNPs that were previously associated with high myopia and used them to replicate previous claims of possible association. RESULTS: Nineteen cases of high myopia, defined as the refraction of <\\/=-6.00 diopters, were identified and included in the analysis. We showed that rs2075555 in the COL1A1 gene was not associated with high myopia. In contrast, rs2421853 in the myocilin gene was significantly associated in both bivariate (P=0.006) and age- and sex-adjusted analysis (P=0.049). CONCLUSION: Myocilin seems to be a very strong candidate for explaining some of the pathophysiological pathways leading to the development of both glaucoma and high myopia. As our finding was obtained in a relatively under-powered sample, further research and replication of these results is needed.

[The relationship between accommodative accuracy at different near-work distances and early-onset myopia].

Science.gov (United States)

Yu, Q W; Zhang, P; Zhou, S B; Hu, Y; Ji, M X; Luo, Y C; You, H L; Yao, Z X

2016-07-01

To observe the accommodative accuracy of children with early-onset myopia at different near-work distances, and discuss the relationship between accommodative accuracy and early-onset myopia. This was a case-control study. Thirty-seven emmetropic children, 41 early-onset myopic children without correction, and 39 early-onset myopic children with spectacles, aged 7 to 13 years, were included. Measures of refractive errors and accommodative accuracy at four near-work distances, including 50 cm, 40 cm, 30 cm, and 20 cm, were made using the binocular fusion cross cylinder (FCC) of an automatic phoropter. Most candidates showed accommodative lags, including the children with emmetropia. The ratio of lags in all candidates at different near-work distances was 75.21% (50 cm), 87.18% (40 cm), 92.31% (30 cm), and 98.29% (20 cm), respectively. All accommodative accuracies became worse, and the accommodative lag ratio and values of FCC increased, along with the shortening of the distance. The difference in accommodative accuracy among groups was statistically significant at 30 cm (χ(2)=7.852, P= 0.020) and 20 cm (χ(2)=6.480, P=0.039). The values of FCC among groups were significantly different at 30 cm (F=3.626, P=0.030) and 20 cm (F=3.703, P=0.028), but not at 50 cm and 40 cm (P>0.05). In addition, the FCC values of 30 cm and 20 cm had a statistically significant difference between myopic children without correction [(1.25±0.44) D and (1.76±0.43) D] and emmetropic children [(0.95±0.52) D and (1.41±0.58) D] (P=0.012, 0.008). The correlation between diopters of myopia and accommodative accuracy at different nearwork distances was not statistically significant (P>0.05). However, the correlation between diopters of myopia and the accommodative lag value (FCC) at 20 cm was statistically significant (r=0.246, P=0.028). The closer the near-work distance is, the worse the accommodative accuracy is. This is more significant in early-onset myopia, especially myopia without

The Distinct Biometric Features of High Myopia Compared to Moderate Myopia.

Science.gov (United States)

Chung, Hye Jin; Park, Chan Kee

2016-12-01

To evaluate changes in biometric parameters in myopic eyes. 412 eyes of 412 young myopic patients underwent ophthalmic examinations including assessments of refractive error, axial length (AL), anterior chamber depth (ACD), and central corneal thickness (CCT). By using spectral domain optical coherence tomography (SD-OCT), peripapillary retinal nerve fiber layer (pRNFL) thickness was measured. Subjects were divided into two groups: a moderate-myope group (-6 diopters (D) or more) and a high-myope group (less than -6 D). The relationships among ocular biometric parameters including pRNFL thickness, AL, ACD, and CCT were calculated for each group. In the moderate-myopia group, the anterior chamber deepened as AL increased (Pearson's coefficient = 0.346, p biometric parameter in highly myopic eyes should consider these differences.

[Eyeball shape in children with emmetropia and myopia].

Science.gov (United States)

Dolzhich, G I; Shurygina, I P; Shapovalova, V M

1991-01-01

In order to determine the eyeball shape, the authors have carried out ultrasonic biometry of its three major parameters, the anteroposterior axis (APA), horizontal diameter (HD), and vertical diameter (VD), and estimated the ratios of these values (APA/HD and APA/VD) in children with emmetropia (234 eyes) and those with slight and medium-grave myopia (660 eyes), aged 7 to 14. The findings evidence a compressed ellipsoidal shape of the eyeball, presenting as a vertical oval, in all subjects with emmetropic refraction, whatever their age. In myopia the eyeball shape transforms, and all the eyeball sizes are increased, but the APA size is growing more rapidly than the rest sizes, and the eyeball acquires the ball shape with a trend to an elongated ellipsoidal shape. The mean APA length in 7-14-year-old children with emmetropia was up to 23 +/- 0.15 mm, whereas in those with the ball shape of the eyeball it was distended.

Total flight hours, irritated and burning eye and risk of mild myopia in civilian pilots in Indonesia

Directory of Open Access Journals (Sweden)

Pritha Maya Savitri

2016-07-01

Full Text Available Abstrak Latar belakang: Miopia merupakan kelainan refraksi yang paling sering terjadi di antara penerbang. Pada penerbang, koreksi  miopia yang tidak sesuai dapat mempengaruhi  orientasi ruang. Penelitian ini bertujuan mengidentifikasi faktor risiko yang mempengaruhi timbulnya miopia ringan pada penerbang sipil di Indonesia. Metode : penelitian ini menggunakan metode potong lintang dengan purposive sampling diantara pilot berusia 21-45 tahun yang sedang melaksanakan pemeriksaan ksehatan berkala di Balai Kesehatan Penerbangan pada tanggal 5-21 Mei 2014. Subyek mengisi kuesioner sedangkan data tajam penglihatan didapatkan dari rekam medik. Analisis data dengan regresi Cox menggunakan Stata 9. Batasan miopia ringan adalah subyek dengan penurunan tajam penglihatan dan menggunakan lensa koreksi -0,25 s/d -0,30. Hasil : persentase miopia ringan dalam penelitian ini sebesar 36%. Subyek dengan jam terbang total 1000 jam atau lebih memiliki 28% resiko lebih tinggi untuk mengalami miopia ringan [risiko relatif (Rra = 1,28%; 95% interval kepercayaan (CI = 1,00-1,64; P= 0,047]. Adanya riwayat orang tua miopia akan meningkatkan risiko miopia ringan 5 kali (RRa=5,32; P=0,000. Subyek yang mengalami gejala kesulitan fokus memiliki risiko 48% lebih tinggi untuk mengalami miopia ringan (RRa = 1,48; 95% CI = 1,19-1,85; P = 0,001.  Subyek dengan gejala berupa iritasi mata, berpasir,rasa terbakar memiliki risiko 54% lebih rendah untuk mengalami miopia ringan (RRa = 0,46 ; 95% CI = 0,26-0,83; P = 0,009. Simpulan : Jam terbang total, riwayat orang tua miopia, adanya gejala kelelahan visual kesulitan fokus dan huruf berkabut merupakan faktor risiko yang berpengaruh terhadap miopia ringan pada penerbang sipil di Indonesia. Kata kunci : miopia ringan, penerbang sipil, jam terbang total, Indonesia.   Abstract Background: Spatial orientation is the main problem to pilot that determined by visual, vestibuler and propioseptif.  Myopia is more prevalent refraction error

Evaluation and diffusion of excimer laser treatment of myopia in the United States and in the Netherlands

NARCIS (Netherlands)

Vondeling, H.; Rosendal, H.; Banta, D.

1995-01-01

Excimer laser photorefractive keratectomy (PRK) is an experimental treatment to correct myopia (short-sightedness) that is diffusing into use without convincing evidence of safety and efficacy. It has been claimed that PRK may render conventional methods of correcting myopia, such as wearing glasses

Investigation of junior school student myopia in high-altitude Tibetan areas in Qinghai Province

OpenAIRE

Xia Han; Hai-Ling Miao; Dan Huang

2014-01-01

AIM: To know the rate of students' myopia in junior school and factors affecting its occurrence in high altitude Tibetan areas in Qinghai, and provide basis for the prevention of myopia. METHODS: Totally 2 209 junior school students were extracted as respondent with stratified cluster sampling method. The gender, age, ethnicity, grade, eye behavior, physical activity and parental visual conditions were collected by self-made questionnaire, and the curvature of the cornea, anterior chamber dep...

Global variations and time trends in the prevalence of childhood myopia, a systematic review and quantitative meta-analysis: implications for aetiology and early prevention.

Science.gov (United States)

Rudnicka, Alicja R; Kapetanakis, Venediktos V; Wathern, Andrea K; Logan, Nicola S; Gilmartin, Bernard; Whincup, Peter H; Cook, Derek G; Owen, Christopher G

2016-07-01

The aim of this review was to quantify the global variation in childhood myopia prevalence over time taking account of demographic and study design factors. A systematic review identified population-based surveys with estimates of childhood myopia prevalence published by February 2015. Multilevel binomial logistic regression of log odds of myopia was used to examine the association with age, gender, urban versus rural setting and survey year, among populations of different ethnic origins, adjusting for study design factors. 143 published articles (42 countries, 374 349 subjects aged 1-18 years, 74 847 myopia cases) were included. Increase in myopia prevalence with age varied by ethnicity. East Asians showed the highest prevalence, reaching 69% (95% credible intervals (CrI) 61% to 77%) at 15 years of age (86% among Singaporean-Chinese). Blacks in Africa had the lowest prevalence; 5.5% at 15 years (95% CrI 3% to 9%). Time trends in myopia prevalence over the last decade were small in whites, increased by 23% in East Asians, with a weaker increase among South Asians. Children from urban environments have 2.6 times the odds of myopia compared with those from rural environments. In whites and East Asians sex differences emerge at about 9 years of age; by late adolescence girls are twice as likely as boys to be myopic. Marked ethnic differences in age-specific prevalence of myopia exist. Rapid increases in myopia prevalence over time, particularly in East Asians, combined with a universally higher risk of myopia in urban settings, suggest that environmental factors play an important role in myopia development, which may offer scope for prevention. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Is poor glycaemic control in diabetic patients a risk factor of myopia?

DEFF Research Database (Denmark)

Jacobsen, N.; Jensen, H.; Lund-Andersen, H.

2008-01-01

haemoglobin (HbA(1c)), insulin dosage and myopia in diabetic patients. Methods: All type 1 diabetic patients aged 16-26 years [mean age 22.0, standard deviation (SD) 2.9] attending the eye clinic at Steno Diabetes Center, Copenhagen, in 1995-1997 were included in the study (n = 393). The following data were...... collected from the medical records from baseline to 2005: age at diabetes onset, age at baseline, sex, weight, HbA(1c), insulin dosage, refractive error, visual acuity and ocular diabetes complications. Results: The prevalence of myopia [spherical equivalent (SE) 0.5 D] was 53.3% [95% confidence...

Relationship of lifestyle and body stature growth with the development of myopia and axial length elongation in Taiwanese elementary school children.

Science.gov (United States)

Huang, Chung-Ying; Hou, Chiun-Ho; Lin, Ken-Kuo; Lee, Jiahn-Shing; Yang, Meng-Ling

2014-08-01

The development of myopia and growth of the eye, occur at a time when body stature is increasing. To investigate the relationship of lifestyle and body growth with axial elongation and myopia development among schoolchildren aged 7 to 9 years. Prospective study. Children in elementary schools without serious eye disorders were invited to participate. We measured cycloplegic refraction, corneal curvature, intraocular pressure, axial length, body height, and weight. Questionnaires about the children's daily lifestyles, family members' myopia and parents' socio-demographic status were completed. The children were followed up every 6 months in a 3-year period. Bivariate correlations, simple and multiple regression. Eighty-eight children participated in this study. Forty-eight were myopic at the beginning of the study, and their myopia correlated with longer axial length and parental myopia (P = 0.015, 0.012). Sixty-five children (74%) completed the study, and the rates of change per year were -0.43 ± 0.58 (mean + standard deviation) diopters in spherical equivalence, 0.32 ± 0.25 mm in axial length (AL), 5.73 ± 2.71 cm in body height, and 3.84 ± 2.23 kg in weight. The axial length change was positively correlated with the height change (P influence on myopia development, and the environment factor as near work intensity was related to myopia progression.

Intraocular pressure monitoring by rebound tonometry in children with myopia.

Science.gov (United States)

Weng, Jenchieh; Tsai, I-Lun; Kuo, Li-Lin; Tsai, Ching-Yao; Woung, Lin-Chung; Hsiao, Ya-Chuan

2017-01-01

Topical atropine treatment is generally accepted to retard the progression of myopia, but it is associated with side effects such as photophobia and elevation of intraocular pressure (IOP). IOP measurements in children are challenging. The traditional applanation tonometry by direct contact with the cornea will require patient's cooperation. The rebound tonometer, using a dynamic electromechanical method for measuring IOP, shows good correlation with traditional tonometry. The purpose of this study is to evaluate the IOP of myopic children under atropine treatment using rebound tonometer and to compare the characteristics between rebound tonometry and applanation tonometry. This study is a prospective study measuring IOP by rebound tonometer in myopic children under regular low-dose atropine treatment. We recruited children with refraction error showing myopia over -0.5 D with 0.15%, 0.3%, or 0.5% atropine eye drops use every night or every other night for myopia control. Children with treatment duration of atropine tonometer (Tono-Pen XL, Reichert) and rebound tonometer (ICARE). The reliability of rebound tonometer was analyzed with percentage. Comparison of IOP between rebound tonometer and applanation tonometry was presented. The rebound tonometry was well tolerated by all participants and caused no complaints, discomfort, or adverse events. Totally 42 myopic eyes of 42 subjects were included in the study. The average age of these participants was 10 years old, range from 5 to 16. Median = 10 years old. The average IOP of the right eye by rebound tonometer was 17.4 ± 3 mmHg, and 17.1 ± 3 mmHg by applanation tonometry. Nearly 19%, 33%, and 24% of difference of IOP readings between rebound tonometer and Tono-Pen applanation are within 0 mmHg, 1 mmHg, and 1-2 mmHg, respectively. Rebound tonometry has good correlation with applanation tonometry and 76.1% of differences between two tonometers are <2 mmHg. The advantage of drop-free rebound tonometry has made it

Analysis of biological characteristics of corneal endothelium in old patients with high myopia

Directory of Open Access Journals (Sweden)

Ya-Qiong Chen

2014-11-01

Full Text Available AIM: To analyze quantitatively the biological characteristics of corneal endothelium in old patients of high myopia with non-contact automatic corneal endothelial microscope.METHODS:A total of 189 old patients(197 eyeswere divided into the high myopia group and the normal control group according to refractive diopter, in which the former 98 cases(103 eyes, the latter 91 cases(94 eyes. The hexagonal cell(6A, the coefficient of variation(CV, the average cell area(AVE, the average cell density(CDand the central corneal thickness(CCTwere measured by non-contact automatic corneal endothelium. SPSS 14.0 software was used to analyze their percentage. Z-test was used to compare the mean and Chi-square test was used to compare the rate in between. RESULTS: The average cell density in high myopia patients decreased, but there were 14 eyes >3 000/mm2, 11 eyes 2 and 78 eyes in the 2 000～3 000/mm2, there were each 0 eye, 3 eyes and 91 eyes respectively in the normal control group. There was statistically significant difference between high myopia group and control(χ2=19.11, PPP>0.05. CONCLUSION: There will provide a reference valuable for clinical surgeon. Because according to the changes of parameters and morphology of the corneal endothelial cells, we can understand the repair ability, to predict the consequence of the treatment, in order to determine the design and the choice of a surgical.

Spectral-domain optical coherence tomography of macula in myopia.

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Choovuthayakorn, Janejit; Laowong, Taksaorn; Watanachai, Nawat; Patikulsila, Direk; Chaikitmongkol, Voraporn

2016-06-01

The aim of this study is to determine the associations between regional macular thickness and gender, age, axial length, and degree of myopia in young and middle-aged healthy myopic eyes. One hundred and seventy-one subjects with -0.5 diopters of myopia or worse underwent prospective macular thickness measurement by Spectralis spectral-domain optical coherence tomography. Subjects' mean age was 32.40 ± 8.25 years (range 18 to 49 years), with 45 % being male. The mean degree of myopia was -4.57 ± 3.52 diopters, with a mean axial length of 25.09 ± 1.67 mm. Multivariate regression analysis demonstrated significantly thicker central (mean 9.13 µm thicker) and inner subfields (mean 8.55 µm thicker) in males (P values were <0.001 and 0.002, respectively). In addition, in both genders, for each millimeter of increased axial length, the central subfield thickness increased by 2.11 µm, the inner subfield decreased by 2.25 µm, and the outer subfield decreased by 3.62 µm (P values were 0.010, <0.001, and <0.001, respectively). Factors including gender and axial length affect baseline regional macular thickness in young and middle-age myopic subjects. The central subfield and inner subfield were affected by both gender and axial length, while the outer subfield was affected only by axial length. The macular thickness of myopic subjects with macular disease should be interpreted in light of these factors.

Disturbance induced by surface preparation on instrumented indentation test

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Li, Yugang; Kanouté, Pascale; François, Manuel

2015-01-01

Surface preparation, which may induce considerable sample disturbance, plays an important role in instrumented indentation test (IIT). In this study, the sample disturbance (mainly divided into residual stresses and plastic strain) induced by the surface preparation process of instrumented indentation test specimens were investigated with both experimental tests and numerical simulations. Grazing incidence X-ray diffractions (GIXRD) and uniaxial tensile tests were conducted for characterizing the residual stresses and high plastic strain in the top surface layers of a carefully mechanically polished indentation sample, which, in the present work, is made of commercially pure titanium. Instrumented indentation tests and the corresponding finite element simulations were performed as well. For comparison, a reference sample (carefully mechanically polished & electrolytically polished) which represents the raw material was prepared and tested. Results showed that a careful mechanical polishing procedure can effectively reduce the level of residual stresses induced by this process. However, the high plastic strain in the surface region imposed by the polishing process is significant. The induced plastic strain can affect a depth up to 5 µm, which is deeper than the maximum penetration depth h max (3 µm) used for the instrumented indentation tests. In the near surface layer (in the range of depth about 350 nm), the plastic strain levels are fairly high. In the very top layer, the plastic strain was even estimated to reach more than 60%. The simultaneous use of indentation tests and numerical simulations showed that the existence of high plastic strain in the surface region will make the load vs depth (P–h) curve shift upwards, the contact hardness (H) increase and the contact stiffness (S) decrease

Disturbance induced by surface preparation on instrumented indentation test

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Li, Yugang, E-mail: yugang.li@utt.fr [Université de Technologie de Troyes (UTT), ICD-LASMIS, UMR CNRS 6281, 12, rue Marie Curie-CS 42060, 10010 Troyes Cedex (France); Kanouté, Pascale, E-mail: pascale.kanoute@onera.fr [Université de Technologie de Troyes (UTT), ICD-LASMIS, UMR CNRS 6281, 12, rue Marie Curie-CS 42060, 10010 Troyes Cedex (France); The French Aerospace Lab (ONERA), DMSM/MCE, 29 avenue de la Division Leclerc-BP 72, F-92322 Chatillon Cedex (France); François, Manuel, E-mail: manuel.francois@utt.fr [Université de Technologie de Troyes (UTT), ICD-LASMIS, UMR CNRS 6281, 12, rue Marie Curie-CS 42060, 10010 Troyes Cedex (France)

2015-08-26

Surface preparation, which may induce considerable sample disturbance, plays an important role in instrumented indentation test (IIT). In this study, the sample disturbance (mainly divided into residual stresses and plastic strain) induced by the surface preparation process of instrumented indentation test specimens were investigated with both experimental tests and numerical simulations. Grazing incidence X-ray diffractions (GIXRD) and uniaxial tensile tests were conducted for characterizing the residual stresses and high plastic strain in the top surface layers of a carefully mechanically polished indentation sample, which, in the present work, is made of commercially pure titanium. Instrumented indentation tests and the corresponding finite element simulations were performed as well. For comparison, a reference sample (carefully mechanically polished & electrolytically polished) which represents the raw material was prepared and tested. Results showed that a careful mechanical polishing procedure can effectively reduce the level of residual stresses induced by this process. However, the high plastic strain in the surface region imposed by the polishing process is significant. The induced plastic strain can affect a depth up to 5 µm, which is deeper than the maximum penetration depth h{sub max} (3 µm) used for the instrumented indentation tests. In the near surface layer (in the range of depth about 350 nm), the plastic strain levels are fairly high. In the very top layer, the plastic strain was even estimated to reach more than 60%. The simultaneous use of indentation tests and numerical simulations showed that the existence of high plastic strain in the surface region will make the load vs depth (P–h) curve shift upwards, the contact hardness (H) increase and the contact stiffness (S) decrease.

Identifying Children at Risk of High Myopia Using Population Centile Curves of Refraction.

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Yanxian Chen

Full Text Available To construct reference centile curves of refraction based on population-based data as an age-specific severity scale to evaluate their efficacy as a tool for identifying children at risk of developing high myopia in a longitudinal study.Data of 4218 children aged 5-15 years from the Guangzhou Refractive Error Study in Children (RESC study, and 354 first-born twins from the Guangzhou Twin Eye Study (GTES with annual visit were included in the analysis. Reference centile curves for refraction were constructed using a quantile regression model based on the cycloplegic refraction data from the RESC. The risk of developing high myopia (spherical equivalent ≤ -6 diopters [D] was evaluated as a diagnostic test using the twin follow-up data.The centile curves suggested that the 3rd, 5th, and 10th percentile decreased from -0.25 D, 0.00 D and 0.25 D in 5 year-olds to -6.00 D, -5.65D and -4.63 D in 15 year-olds in the population-based data from RESC. In the GTES cohort, the 5th centile showed the most effective diagnostic value with a sensitivity of 92.9%, a specificity of 97.9% and a positive predictive value (PPV of 65.0% in predicting high myopia onset (≤-6.00D before the age of 15 years. The PPV was highest (87.5% in 3rd centile but with only 50.0% sensitivity. The Mathew's correlation coefficient of 5th centile in predicting myopia of -6.0D/-5.0D/-4.0D by age of 15 was 0.77/0.51/0.30 respectively.Reference centile curves provide an age-specific estimation on a severity scale of refractive error in school-aged children. Children located under lower percentiles at young age were more likely to have high myopia at 15 years or probably in adulthood.

Myopia Control with Orthokeratology Contact Lenses in Spain (MCOS: Study Design and General Baseline Characteristics

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Jacinto Santodomingo-Rubido

2009-01-01

Conclusion: To the authors’ knowledge, MCOS is the first prospective clinical trial to assess the safety and efficacy of orthokeratology contact lens wear to slow myopia progression vs. single-vision spectacle wear. The MCOS offers a number of notable features: prospective design; well-matched samples and high-resolution ocular biometry measures, which should collectively elucidate whether orthokeratology contact lens wear is a feasible and safe method for myopia-progression control.

An Ecologic Study of Trends in the Prevalence of Myopia in Chinese Adults in Singapore Born from the 1920s to 1980s.

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Sensaki, Sonoko; Sabanayagam, Charumathi; Verkicharla, Pavan K; Awodele, Adeola; Tan, Kok Hian; Chia, Audrey; Saw, Seang Mei

2017-06-01

This study aimed to investigate secular trends in the prevalence of myopia over 6 decades (from the 1920s to 1980s) in Chinese adults in Singapore. Parental myopia prevalence was estimated using a parent-completed questionnaire in paediatric cohorts that included: 1) The Singapore Cohort Of Risk factors for Myopia (SCORM), 2) The Strabismus, Amblyopia and Refractive Error in Singaporean Children (STARS), and 3) The Growing Up in Singapore Towards healthy Outcomes (GUSTO). Published estimates for myopia prevalence from 5 adult studies in Singapore were reviewed. Secular trends in the prevalence of myopia were correlated with changes in the education system. The prevalence of parental myopia in SCORM (n = 2943), STARS (n = 4938), and GUSTO (n = 1072) was 47.8%, 53.4%, and 73.4%, respectively; corresponding calendar years these parents might have started schooling were 1966, 1973, and 1983 (born in 1960, 1967, and 1977), respectively. Mean age of parents was 41.3, 40.1, and 33.4 years, respectively. Prevalence of myopia in adult studies in persons who started elementary school in 1928, 1934, 1938, 1939, 1942, 1948, 1952, 1958, 1962, 1972, 1982, and 1995 were 36.4%, 39.7%, 30.0%, 31.5%, 33.0%, 26.4%, 32.5%, 48.7%, 39.4%, 52.0%, 82.2%, and 85.9%, respectively. During the past few decades, the prevalence of myopia increased rapidly, especially in persons who started elementary school after the 1980s (born after 1970). The education system was expanded after Singapore's independence in 1965, and the new education system was introduced in 1978. These changes, together with increasing intensive schooling, may have contributed to the increase in myopia prevalence.

Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review.

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Xiong, Shuyu; Sankaridurg, Padmaja; Naduvilath, Thomas; Zang, Jiajie; Zou, Haidong; Zhu, Jianfeng; Lv, Minzhi; He, Xiangui; Xu, Xun

2017-09-01

Outdoor time is considered to reduce the risk of developing myopia. The purpose is to evaluate the evidence for association between time outdoors and (1) risk of onset of myopia (incident/prevalent myopia); (2) risk of a myopic shift in refractive error and c) risk of progression in myopes only. A systematic review followed by a meta-analysis and a dose-response analysis of relevant evidence from literature was conducted. PubMed, EMBASE and the Cochrane Library were searched for relevant papers. Of the 51 articles with relevant data, 25 were included in the meta-analysis and dose-response analysis. Twenty-three of the 25 articles involved children. Risk ratio (RR) for binary variables and weighted mean difference (WMD) for continuous variables were conducted. Mantel-Haenszel random-effects model was used to pool the data for meta-analysis. Statistical heterogeneity was assessed using the I 2 test with I 2  ≥ 50% considered to indicate high heterogeneity. Additionally, subgroup analyses (based on participant's age, prevalence of myopia and study type) and sensitivity analyses were conducted. A significant protective effect of outdoor time was found for incident myopia (clinical trials: risk ratio (RR) = 0.536, 95% confidence interval (CI) = 0.338 to 0.850; longitudinal cohort studies: RR = 0.574, 95% CI = 0.395 to 0.834) and prevalent myopia (cross-sectional studies: OR = 0.964, 95% CI = 0.945 to 0.982). With dose-response analysis, an inverse nonlinear relationship was found with increased time outdoors reducing the risk of incident myopia. Also, pooled results from clinical trials indicated that when outdoor time was used as an intervention, there was a reduced myopic shift of -0.30 D (in both myopes and nonmyopes) compared with the control group (WMD = -0.30, 95% CI = -0.18 to -0.41) after 3 years of follow-up. However, when only myopes were considered, dose-response analysis did not find a relationship between time outdoors and myopic

[Regularities of the refractive genesis of school myopia and criteria for its prediction].

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Onufriĭchuk, O N; Rozenblium, Iu Z

2007-01-01

The paper provides the data of a 2-year monitoring of ocular refraction in 327 consecutive 10-14-year-old schoolchildren (654 eyes) unrandomized under natural conditions and cycloplegia. The authors studied whether there was an association of refraction and its changes with absolute and relative accommodation, habitual accommodation tonicity, the length of the anteroposterior optic axis, and the presence of pseudomyopathy and astigmatism. Over 2 years, myopia occurred in 15.4% of the eyes, its degree increased from -0.88 (-1.37/-0.50) to -1.25 (-2.31/-0.62) diopters. Criteria for myopia prediction were identified. These included a relative accommodation reserve of less than 2.5 diopters, an anteroposterior optic axis length of more than 24.33 mm, a habitual accommodation tonicity of less than + 0.41 diopters, the presence of pseudomyopia (77.8% of cases), reversed astigmatism and underlying emmetropia. A mathematical model was constructed for prediction of myopia, the proportion of its correct prediction being 90.4%, which makes it possible to recommend for clinical application.

Association between parents' attitudes and behaviors toward children's visual care and myopia risk in school-aged children.

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Zhou, Shuang; Yang, Lihua; Lu, Benlin; Wang, Hexin; Xu, Ting; Du, Dandan; Wu, Shiqing; Li, Xiuxiu; Lu, Meixia

2017-12-01

The purpose of this survey was to determine the association of parents' attitudes and behaviors toward children's visual care with myopia risk in school-aged children.A total of 894 parents of school-aged children were investigated in primary and middle schools in the central and noncentral urban area in Wuhan through stratified cluster random sampling on July, 2015. We analyzed the association by the generalized linear mixed model.The results indicated that children with parents' high expectations of 1.5 or higher on their vision exhibited a decreased risk of myopia compared with 1.0 and 0.5 or lower (OR = 0.49, 95%CI = 0.36-0.67). Children whose parents only paid attention to their vision in junior and senior school and in primary school had an increased myopia risk than that in preschool (OR = 2.12, 95%CI = 1.01-4.45, and OR = 3.11, 95%CI = 1.28-7.58, respectively). Children whose parents ensured for their sufficient sleep had a decreased myopia risk (OR = 0.45, 95%CI = 0.24-0.85). Compared with children whose parents who never adjusted electronic devices' parameters, the odds ratio of sometimes was 0.49 (95%CI = 0.31-0.79), often 0.53 (95%CI = 0.33-0.85), and always 0.44 (95%CI = 0.26-0.75), respectively.Parents' attitudes and behaviors toward children's visual care are significantly associated with the myopia risk in school-aged children. Consequently, efforts should be made to educate parents on how they protect children's vision and reduce their risk of myopia. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

Myopia Glasses and Optical Power Estimation: An Easy Experiment

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Ribeiro, Jair Lúcio Prados

2015-01-01

Human eye optics is a common high school physics topic and students usually show a great interest during our presentation of this theme. In this article, we present an easy way to estimate a diverging lens' optical power from a simple experiment involving myopia eyeglasses and a smartphone flashlight.

Photorefractive keratectomy (PRK) versus laser-assisted in-situ keratomileusis (LASIK) for myopia.

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Shortt, A J; Allan, B D S

2006-04-19

Myopia (also known as short-sightedness or near-sightedness) is an ocular condition in which the refractive power of the eye is greater than is required, resulting in light from distant objects being focused in front of the retina instead of directly on it. The two most commonly used surgical techniques to permanently correct myopia are photorefractive keratectomy (PRK) and laser-assisted in-situ keratomileusis (LASIK). The aim of this review was to compare the effectiveness and safety of PRK and LASIK for correction of myopia. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2005, Issue 3), MEDLINE (1966 to September 2005), EMBASE (1980 to September 2005) and LILACs (1982 to 3 November 2005). We also searched the reference lists of the studies and the Science Citation Index. We included randomised controlled trials comparing PRK and LASIK for correction of any degree of myopia. We also included data on adverse events from prospective multicentre consecutive case series in the Food and Drugs Administration (FDA) trials database (http//www.fda.gov/cdrh/LASIK/lasers.htm). Two authors independently assessed trial quality and extracted data. Data were summarised using odds ratio and mean difference. Odds ratios were combined using a random-effects model after testing for heterogeneity. This review included six randomised controlled trials involving a total of 417 eyes, of which 201 were treated with PRK and 216 with LASIK. We found that although LASIK gives a faster visual recovery than PRK, the effectiveness of these two procedures is comparable. We found some evidence that LASIK may be less likely than PRK to result in loss of best spectacle-corrected visual acuity. LASIK gives a faster visual recovery than PRK but the effectiveness of these two procedures is comparable. Further trials using contemporary techniques are required to determine whether LASIK and PRK are equally safe.

[Remote results of high myopia surgical correction by tunnel keratoplasty ].

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Dushin, N V; Beliaev, V S; Gonchar, P A; Barashkov, V I; Kravchinina, V V; Frolov, M A

2000-01-01

Remote results evidence high refraction efficiency of tunnel keratoplasty, stable results being observed for up to 15 years. A total of 104 operations (58 patients) were analyzed for a period of observation of more than 10 years. The patients' ages varied from 17 to 52 years, there were 34 women and 24 men. The main advantage of interlamellar refraction meridional keratoplasty is easiness of operation. At present it is the operation of choice for dosed reduction of eye refraction aimed at correction of high myopia and astigmatism. The possibility of correcting residual myopia after keratotomy and repair of refraction abnormalities resultant from perforating keratoplasty is particularly interesting. The possibility of regulating the corrective effect in remote periods by replacing the implants also deserves attention. Hence, low traumatism, high efficiency, and stability of the refraction effect once more confirm our recommendation to use tunnel keratoplasty in clinical practice.

Photorefractive Keratectomy With Mitomycin-C for High Myopia: Three Year Follow-Up Results

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Hassan Hashemi

2017-02-01

Full Text Available Photorefractive keratectomy (PRK is a safe and effective surgical keratorefractive technique which is done with the application of mitomycin-C (MMC in cases of high myopia to prevent the formation of corneal haze This study was conducted to evaluate 3-year visual acuity and quality outcomes of PRK-MMC in high myopia. This before-after study was conducted on 20 individuals (40 eyes with myopia more than 6.0 diopter (D. Visual acuity and quality indices were evaluated before and three years after the procedure and their stability was examined between the 1st and 3rd years. At 3 years after surgery, mean uncorrected visual acuity was 0.03±0.06 in the logarithm of minimum angle of resolution (logMAR unit which showed a significant improvement when compared to baseline (P<0.001 and means best corrected visual acuity was 0.03±0.06 logMAR, which showed no significant difference (P=0.730. Manifest refraction spherical equivalent (MRSE at 3 years (-0.12±0.2D was significantly decreased when compared to baseline (P<0.001, but it did not change significantly after the 1st year and was stable (P=0.368. Mean coma and spherical aberration 3 years postoperatively were -0.54±0.26 µm and 0.46±0.19 µm, respectively, and neither parameter showed significant differences when compared to baseline (P<0.001. No significant change was found in mesopic contrast sensitivity. The long-term results of this study showed that PRK-MMC could be regarded an effective, safe, and stable procedure in patients with myopia more than 6.0 D.

Comparative characteristics of morphometric, biometric and biomechanical parameters of myopic eyes in children with different types of progressive myopia

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T. E. Tsybulskaya

2014-10-01

Full Text Available Aim. With the progression of myopic process in children the changes of morphometric, biometric and biomechanical parameters of eyeball are observed. In order to study these parameters in the axial and refractive myopia 32 patients (64 eyes with axial and 26 patients (46 eyes with refractive myopia have been examined. Methods and results. It has been established that in patients with axial and refractive progressive myopia in 56.4% of cases there is a decrease of peripapillary zone thickness of nerve fiber and decrease of ganglion cells layer thickness, an increase of corneal-compensated intraocular pressure by 1.3 times, and also the reduce of corneal hysteresis by 1.2 times. Conclusion. These changes do not depend on the degree of refraction and are associated with an increase in axial length of the eye and decrease in the biomechanical properties of the root-scleral capsule regardless the type of myopia.

The Optic Nerve Head in Primary Open-Angle Glaucoma Eyes With High Myopia: Characteristics and Association With Visual Field Defects.

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Chen, Li-Wei; Lan, Yu-Wen; Hsieh, Jui-Wen

2016-06-01

To evaluate the morphologic characteristics of optic neuropathy and its association with visual field (VF) defects in primary open-angle glaucoma (POAG) eyes with high myopia. In this cross-sectional study, we reviewed data from 375 Taiwanese patients (375 eyes) of POAG, ages 20 to 60 years. Optic disc photographs were used for planimetric measurements of morphologic variables. The myopic refraction was divided into high myopia (<-6.0 D) and nonhigh myopia (moderate myopia to hyperopia). The optic disc area was classified as moderate (1.59 to 2.85 mm), large, and small. Differences in characteristics between groups, correlations with the disc area, and factors associated with VF defects were determined. Of the 142 highly myopic eyes, 33 (23%) had a large disc, 26 (18%) had a small disc, and 55 (39%) had a tilted disc. Large discs had a higher cup-to-disc (C/D) area ratio and a higher tilt ratio; small discs had a smaller rim area and a lower tilt ratio (all P<0.05). Characteristics associated with high myopia included a smaller rim area, a higher C/D area ratio, and a lower tilt ratio (all P<0.001). In logistic regression, the refraction, the C/D area ratio, the rim area, and the tilt ratio (all P<0.05) were associated with VF defects. In Taiwanese individuals with POAG, our study found that tilted, large, or small discs were prevalent in highly myopic eyes. Of these characteristics, only the disc tilt and high myopia by itself were associated with the severity of glaucomatous optic neuropathy.

Longitudinal changes in corneal curvature and its relationship to axial length in the Correction of Myopia Evaluation Trial (COMET cohort

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Mitchell Scheiman

2016-01-01

Conclusions: Differences in average corneal curvature by age, gender, and ethnicity observed in early childhood remain consistent as myopia progresses and stabilizes. This study also demonstrates increases in the AL/CR ratio as myopia progresses and then stabilizes, supporting observations from previous cross-sectional data.

Pharmacology of Myopia and Potential Role for Intrinsic Retinal Circadian Rhythms

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Stone, Richard A.; Pardue, Machelle T.; Iuvone, P. Michael; Khurana, Tejvir S.

2013-01-01

; these rhythms shift in eyes developing experimental ametropia. Long-standing clinical ideas about myopia in particular have postulated a role for ambient lighting, although molecular or cellular mechanisms for these speculations have remained obscure. Experimental myopia induced by the wearing of a concave spectacle lens alters the retinal expression of a significant proportion of intrinsic circadian clock genes, as well as genes encoding a melatonin receptor and the photopigment melanopsin. Together this evidence suggests a hypothesis that the retinal clock and intrinsic retinal circadian rhythms may be fundamental to the mechanism(s) regulating refractive development, and that disruptions in circadian signals may produce refractive errors. Here we review the potential role of biological rhythms in refractive development. While much future research is needed, this hypothesis could unify many of the disparate clinical and laboratory observations addressing the pathogenesis of refractive errors. PMID:23313151

Efficacy of intravitreal Ranibizumab injection for choroidal neovascularization secondary to pathologic myopia

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Li-Hong Cui

2016-03-01

Full Text Available AIM:To observe the efficacy and safety of intravitreal Ranibizumab injection in patiens with choroidal neovascularization(CNVsecondary to pathologic myopia.METHODS:In this retrospective and comparative study,24 patients(25 eyeswith CNV secondary to pathologic myopia were enrolled. All patients were assessed by examinations of ETDRS visual acuity chart, preplaced-mirror ophthalmoscopy, fundus fluorescein angiography(FFA, indocyanine green angiography(ICGAand optical coherence tomography(OCT. Patiens received intravitreally injected ranibizumab 0.5mg(0.05mL. Treatments were repeated if the follow-up indicated that it was necessary. The follow-up periods were 4～10mo. Best corrected visual acuity(BCVA, central macular thickness(CMTand leakage of CNV before and after the treatment were compared. RESULTS:No local or systemic complications occurred in any patients during the treatment or follow-up. The average time of injection was 1.52. The mean BCVA was 23.93±12.46 letters before the therapy. In the last follow-up, the mean BCVA was 40.63±7.25 letters, improved by 14.27±9.36 letters and the difference was statically significant(t=5.74, Pt=3.96, PCONCLUSION:Intravitreal ranibizumab injection for CNV secondary to pathologic myopia is safe and effective, and this treatment can improve visual acuity, reduce retina edema and leakage of CNV.

Changes in acetylcholine release from the chick retina are not associated with myopia development

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Vessey, K.A.; Cotriall, C.L.; McBrien, N.A.

2002-01-01

Full text: The effectiveness of muscarinic receptor antagonists in inhibiting myopia progression in animal models and humans implicates cholinergic signalling in ocular growth regulation. Therefore to determine if changes in the release of acetylcholine from the retina are involved in myopia development, the efflux of acetylcholine from the in vitro retina of normal and myopic chick eyes was investigated. Chicks were monocularly deprived (MD) of pattern vision with translucent occluders for 2 or 7 days and refractive error of MD groups and age matched normals was monitored using retinoscopy (n=6 each group). 3 H-choline-Cl (1 Ci in 7μL) was injected into the vitreous of each eye under 2.5% halothane anaesthesia. After 1hr, the eyes were enucleated, under terminal anaesthesia (sodium pentobarbital, 120 mg/kg, im). Retinas were flat-mounted on acetate filter discs and superfused with oxygenated physiological saline solution (PSS) for 30min at 0.4mL/min. Five baseline fractions were collected (B1-B5), then three stimulated fractions were collected in the presence of PSS containing 50mM KCl (K1-K3) at 2min intervals. 3 H-acetylcholine ( 3 H-ACh) in each fraction was quantified by liquid scintillation counting. Significant amounts of myopia were induced in MD eyes after 2 (-5.1±0.8D) and 7 days (-18.8±2.4D) relative to control eyes (paired t-test p 3 H-ACh release was 146±15% above basal levels (K2/B1%) from retinas of normal animals. After 2 days MD, there was no significant difference between KCl-evoked release of 3 H-ACh from deprived eyes (147 39%) compared to control eyes (198±61%, paired t-test, p=0.27) or the eyes of normal animals (ANOVA, p>0.5). Similar results were obtained following 7 days MD. The results demonstrate that evoked acetylcholine release from the chick retina of myopic eyes is unaltered relative to control or normal eyes using an in vitro approach. Copyright (2002) Australian Neuroscience Society

Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia

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Wen Jun Jiang

2017-03-01

Full Text Available To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2–3 weeks which either underwent unilateral or bilateral lens-induced myopization (group 1 or which were primarily myopic at baseline (group 2 received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15 μg three times in intervals of 9 days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00 ng, respectively. In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1 ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.

Preliminary results of tracked photorefractive keratectomy (T-PRK) for mild to moderate myopia with the autonomous technologies excimer laser at Cedars-Sinai Medical Center

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Maguen, Ezra I.; Salz, James J.; Nesburn, Anthony B.

1997-05-01

Preliminary results of the correction of myopia up to -7.00 D by tracked photorefractive keratectomy (T-PRK) with a scanning and tracking excimer laser by Autonomous Technologies are discussed. 41 eyes participated (20 males). 28 eyes were evaluated one month postop. At epithelization day mean uncorrected vision was 20/45.3. At one month postop, 92.8 of eyes were 20/40 and 46.4% were 20/20. No eye was worse than 20/50. 75% of eyes were within +/- 0.5 D of emmetropia and 82% were within +/- 1.00 D of emmetropia. Eyes corrected for monovision were included. One eye lost 3 lines of best corrected vision, and had more than 1.00 D induced astigmatism due to a central corneal ulcer. Additional complications included symptomatic recurrent corneal erosions which were controlled with topical hypertonic saline. T-PRK appears to allow effective correction of low to moderate myopia. Further study will establish safety and efficacy of the procedure.

The influence of LED lighting on task accuracy: time of day, gender and myopia effects

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Rao, Feng; Chan, A. H. S.; Zhu, Xi-Fang

2017-07-01

In this research, task errors were obtained during performance of a marker location task in which the markers were shown on a computer screen under nine LED lighting conditions; three illuminances (100, 300 and 500 lx) and three color temperatures (3000, 4500 and 6500 K). A total of 47 students participated voluntarily in these tasks. The results showed that task errors in the morning were small and nearly constant across the nine lighting conditions. However in the afternoon, the task errors were significantly larger and varied across lighting conditions. The largest errors for the afternoon session occurred when the color temperature was 4500 K and illuminance 500 lx. There were significant differences between task errors in the morning and afternoon sessions. No significant difference between females and males was found. Task errors for high myopia students were significantly larger than for the low myopia students under the same lighting conditions. In summary, the influence of LED lighting on task accuracy during office hours was not gender dependent, but was time of day and myopia dependent.

Small Incision Lenticule Extraction (SMILE) vs. Femtosecond Laser in Situ Keratomileusis (FS-LASIK) for treatment of myopia.

OpenAIRE

Hansen, Rasmus Søgaard; Lyhne, Niels; Justesen, Birgitte; Grauslund, Jakob; Vestergaard, Anders Højslet

2014-01-01

Purpose: - 67 ord LASIK has been the dominating corneal refractive procedure for almost two decades, but the new flap-free SMILE procedure has shown promising results. The aim of this study was to evaluate and compare refractive predictability, uncorrected and corrected distance visual acuity (UDVA and CDVA), and safety at 1 day, 1 week and 3 months after SMILE and FS-LASIK for all degrees of myopia, but in particular high myopia. Setting: Department of Ophthalmology, Odense University Hospit...

Global variations and time trends in the prevalence of childhood myopia, a systematic review and quantitative meta-analysis:implications for aetiology and early prevention

OpenAIRE

Rudnicka, Alicja R.; Kapetanakis, Venediktos V.; Wathern, Andrea K.; Logan, Nicola S.; Gilmartin, Bernard; Whincup, Peter H.; Cook, Derek G.; Owen, Christopher G.

2016-01-01

The aim of this review was to quantify the global variation in childhood myopia prevalence over time taking account of demographic and study design factors. A systematic review identified population-based surveys with estimates of childhood myopia prevalence published by February 2015. Multilevel binomial logistic regression of log odds of myopia was used to examine the association with age, gender, urban versus rural setting and survey year, among populations of different ethnic origins, adj...

Small-incision lenticule extraction for moderate to high myopia

DEFF Research Database (Denmark)

Vestergaard, Anders Højslet; Ivarsen, Anders R; Asp, Sven

2012-01-01

Purpose: To present our initial clinical experience with ReLEx® smile for treatment of moderate to high myopia. Setting: Department of Ophthalmology, Aarhus University Hospital. Design: Prospective clinical study. Methods: In ReLEx smile an intrastromal lenticule is cut by a femtosecond laser and...... of ReLEx smile, ReLEx flex, and FS-LASIK....

Subjective results of excimer laser correction of myopia. Review

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V. N. Trubilin

2012-01-01

Full Text Available In review presents data of various authors regarding the subjective results excimer laser correction of myopia by LASIK. It was revealed that a group of patients with a high degree of dissatisfaction amounts to 4.6% of the total in all studies. High subjective results are confirmed by the positive dynamics of the «quality of life» of the patient.

Effect of myopia onset time for macula choroidal thickness

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Shi-Ming Wang

2016-03-01

Full Text Available AIM:To investigate the effect of onset time(Tfor macula choroidal thickness(CTin myopia patient. METHODS:A prospective cohort study was designed.One hundred and twenty-two myopia patients(244 eyes; 67 male and 55 female; aged 30～41 years, mean 35.1±4.6 years oldwho received preoperative examinations from March 2014 to April 2015 were recruited in this study. The patients were divided into three groups according to onset time(T:group A(T≤5a, group B(5aF=1.56,P>0.05,age(F=2.13,P>0.05,best corrected visual acuity(BCVA, F=1.41,P>0.05,corneal curvature(F=1.65,P>0.05and axial length(F=1.89,P>0.05among the three groups. The choroid in macular region was measured by enhanced depth imaging(EDIusing spectral-domain optical coherence tomography(SD-OCT. This study recorded the CT at subfoveal(SFCT, 1mm at temporal(T1mm, nasal(N1mm, superior(S1mmand inferior(I1mmto the fovea and 3mm temporal(T3mm, nasal(N3mm, superior(S3mmand inferior(I3mmto the fovea, respectively. The differences of CT at the same position among the three groups were analyzed.RESULTS:The mean SFCT for group A,B,C were 238.32±57.95μm, 230.58±67.21μm, 221.63±62.37μm respectively in this study. The CT was found no significant difference in different locations except N3mm(tA-B=4.34,P3mm(tB-C=7.61,P3mm(t=0.76,P>0.05between group A and C. Significant difference was found at N3mm(tA-B=4.31,t B-C=7.59,tA-C=12.18; PCONCLUSION:The choroidal thickness decreases as the myopia onset time is earlier, especially at nasal.

Accommodation, accommodative convergence, and response AC/A ratios before and at the onset of myopia in children.

Science.gov (United States)

Gwiazda, Jane; Thorn, Frank; Held, Richard

2005-04-01

The purpose of this study was to investigate accommodation, accommodative convergence, and AC/A ratios before and at the onset of myopia in children. Refractive error, accommodation, and phorias were measured annually over a period of 3 years in 80 6- to 18-year-old children (mean age at first visit = 11.1 years), including 26 who acquired myopia of at least -0.50 D and 54 who remained emmetropic (-0.25 to + 0.75 D). Refraction was measured by noncycloplegic distance retinoscopy. Concomitant measures of accommodation and phorias were taken for letter targets at 4.0 m and 0.33 m using the Canon R-1 open field-of-view autorefractor with an attached motorized Risley prism and Maddox rod. The accommodation and phoria measurements were used to calculate response AC/A ratios. Compared with children who remained emmetropic, those who became myopic had elevated response AC/A ratios at 1 and 2 years before the onset of myopia, in addition to at onset and 1 year later (t's = -2.97 to -4.04, p accommodation. Accommodative convergence was significantly greater in myopes only at onset. These findings suggest that the abnormal oculomotor factors found before the onset of myopia may contribute to myopigenesis by producing hyperopic retinal defocus when a child is engaged in near-viewing tasks.

What is the influence of parents' myopia on their children's myopic progression? A 22-year follow-up study.

Science.gov (United States)

Pärssinen, Olavi; Kauppinen, Markku

2016-09-01

To study the connection between parental myopia and their children's myopia from school age to adulthood. Two hundred and forty myopic schoolchildren (119 boys, 121 girls, mean age 10.9 years) with no previous spectacles for myopia were recruited to a 3-year treatment trial with different use of spectacles. Follow-ups were performed at mean ages of 13.9, 23.7 and 33.2 years for 238, 176 and 170 subjects respectively. Subjective refraction was calibrated to the spherical equivalent at corneal level (SEcor). Corneal refractive power (CR) and axial length (AL) were measured. Parental myopia was assessed with a questionnaire and the children assigned accordingly to one of three hereditary groups: both parents myopic H++, one myopic parent = H+- and no myopic parents = H-. At baseline, no significant gender differences in age or SEcor were found in the different hereditary groups. Among girls, CR was significantly higher in hereditary group H++ (45.20 ± 1.08 D) than in group H+- (44.19 ± 1.28 D; p = 0.006) or H- (43.84 ± 1.18 D; p parents were myopic and -3.19 ± 1.36 D if neither parent was myopic (p = 0.035), but no significant difference was observed in AL. The main difference between the hereditary groups was higher CR and myopic progression among females with myopic parents than non-myopic parents, but with no significant difference in AL with respect to parental myopia at study end. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Femtosecond laser-assisted LASIK versus PRK for high myopia: comparison of 18-month visual acuity and quality.

Science.gov (United States)

Hashemi, Hassan; Ghaffari, Reza; Miraftab, Mohammad; Asgari, Soheila

2017-08-01

To compare 18-month outcomes between femtosecond laser-assisted LASIK (femto-LASIK) and photorefractive keratectomy with mitomycin-C (PRK-MMC) for myopia of more than 7.0 D in terms of visual acuity and quality. In this comparative nonrandomized clinical trial, 60 eyes from 30 patients (30 eyes in each group) were enrolled. The two procedures were compared in terms of 18-month changes in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, ocular and corneal higher order aberrations (HOAs), and contrast sensitivity (CS). Mean myopia was -8.65 ± 1.51 and -8.04 ± 1.70 D (P = 0.149) and mean ablation depth was 109.37 ± 9.07 and 105.09 ± 12.59 µm (P = 0.138), in the femto-LASIK and PRK-MMC groups, respectively. Baseline parameters were not significantly different between the two groups (all P > 0.05). At 18 months postoperatively, 75 % in the femto-LASIK, versus 57.1 % in the PRK-MMC group, had 20/20 UDVA (P = 0.017). CDVA remained similarly unchanged in both groups (P = 0.616). No case had residual refractive error more than 1.0 D in the femto-LASIK group, while 33.5 % in the other group had more than 1.0 D residual error (P = 0.390). Changes in corneal HOA were not significantly different between the two groups (P = 0.260). Cases in the femto-LASIK group showed more increase in ocular HOA (P = 0.032) and coma (P = 0.083, power = 72 %). CS remained similarly unchanged in all spatial frequencies in both groups (all P > 0.05). Although femto-LASIK induces more HOA compared to PRK-MMC, considering outcomes in terms of 20/20 UDVA, residual refractive error, and CS stability, femto-LASIK provides more favorable results than PRK-MMC in high myopia.

Assessment of phacoaspiration techniques in clear lens extraction for correction of high myopia

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Mostafa A El-Helw

2010-03-01

Full Text Available Mostafa A El-Helw, Ahmed M EmarahDepartment of Ophthalmology, Cairo University, EgyptPurpose: To evaluate various phacoaspiration techniques in clear lens extraction for the incidence of intraoperative difficulties and complications.Patients and methods: This was a prospective study in which bilateral clear lens extraction was performed on 40 eyes of 20 patients, to correct high myopia. The patients were divided into 2 groups: group A underwent supracapsular phacoaspiration; group B were the contralateral eyes of the same patient. These patients were operated on with endocapsular phacoaspiration with the divide and conquer (D and C technique. Preoperative ocular examination data were recorded and tested for significance. Intraoperative difficulties and complications such as nucleus cracking, capsule rupture and vitreous loss, and repeated chamber collapse were recorded. Postoperative examination data were recorded.Results: Mean age was 35.65 ± 5.85 years. Mean follow-up time was 17.1 ± 8.56 months. In group A mean myopia was -17.3 ± 5.07 diopters; in group B myopia was -17.9 ± 4.20 diopters. Mean preoperative uncorrected visual acuity (UCVA was 0.04 ± 0.0167, while the mean postoperative UCVA was 0.435 ± 0.1442. There was a significant difference in pre and postoperative BCVA within both groups, but not between the two groups. In both groups endothelial cell count (ECC showed a significant difference between pre- and postoperative data; however, there was no statistically significant difference between both groups in postoperative ECC. The effective phacoaspiration time for group A was 4.6 ± 1.6 seconds, and for group B 9.90 ± 2.27 seconds (P < 0.005. No cases of capsule rupture occurred in group A, but 3 cases occurred in group B (15 % (not significant, P = 0.231. Nucleus cracking did not occur in group A, but in group B 13 cases occurred (65%. Chamber collapse occurred in 4 cases (20% in group A and 5 cases (25% in group B (not

Comparison of clear lens extraction and collamer lens implantation in high myopia

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Ahmed M Emarah

2010-05-01

Full Text Available Ahmed M Emarah, Mostafa A El-Helw, Hazem M YassinCairo University, Cairo, EgyptAim: To compare the outcomes of clear lens extraction and collamer lens implantation in high myopia.Patients and methods: Myopic patients younger than 40 years old with more than 12 diopters of myopia or who were not fit for laser-assisted in situ keratomileusis were included. Group 1 comprised patients undergoing clear lens extraction and Group 2 patients received the Visian implantable collamer lens. Outcome and complications were evaluated.Results: Postoperative best corrected visual acuity was -0.61 ± 0.18 in Group 1 and 0.79 ± 0.16 in Group 2. In Group 1, 71.4% achieved a postoperative uncorrected visual acuity better than the preoperative best corrected visual acuity, while only 51.8% patients achieved this in Group 2. Intraocular pressure decreased by 12.55% in Group 1, and increased by 15.11% in Group 2. Corneal endothelial cell density decreased by 4.47% in Group 1 and decreased by 5.67% in Group 2. Posterior capsule opacification occurred in Group 1. In Group 2, lens opacification occurred in 11.11%, significant pigment dispersion in 3.7%, and pupillary block glaucoma in 3.7%.Conclusion: Clear lens extraction presents less of a financial load up front, and less likelihood of the need for a secondary intervention in the future. Clear lens extraction is a more viable solution in developing countries with limited financial resources.Keywords: clear lens extraction, implantable collamer lens, myopia

Retinal peripheral changes after laser in situ keratomileusis in patients with high myopia.

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Suzuki, Cássia R; Farah, Michel E

2004-02-01

Retinal detachment has been reported after laser in situ keratomileusis (LASIK) in myopic eyes. This complication may be related to the risk from myopia before surgery or may be induced by LASIK surgery itself. We performed a study to evaluate retinal peripheral changes after LASIK in patients with high myopia and to correlate symptoms on presentation and vitreoretinal anatomic changes. The study was carried out at a university-affiliated hospital in São Paulo between November 1997 and February 1999. Patients scheduled to undergo LASIK were included if their spherical equivalent was greater than 6.00 dioptres. The exclusion criteria were previous retinal treatment and myopic macular degenerations. We performed binocular indirect ophthalmoscopy with scleral indentation and fundus biomicroscopy with Goldmann lens before LASIK and 1, 3 and 6 months after surgery. We examined 198 eyes preoperatively. Of the 198, 50 did not undergo LASIK surgery owing to refractive criteria, and 79 were lost to follow-up. We thus studied 69 eyes. The mean spherical equivalent preoperatively was -8.00 D (standard deviation 1.95 D). Twenty-four eyes had normal retinal periphery preoperatively; all 24 remained without alterations after LASIK. Forty-five eyes had peripheral alterations: 17 (24.6%) had cystic degeneration, 14 (20.3%) had lattice degeneration, 11 (15.9%) had white-without-pressure, 5 (7.2%) had cystic tufts, 3 (4.3%) had pavingstone degeneration, 2 (2.9%) had pigmentary alteration, 1 (1.4%) had holes with free operculum, and 1 (1.4%) had punctiform holes. The only alteration after surgery was almost punctiform holes around the previous cystic tuft 1 month after surgery in one patient. Retinal detachment did not develop in any of the eyes. In this group of patients it appears that LASIK did not lead to progressive peripheral retinal lesions in asymptomatic patients during the period studied.

Retinitis pigmentosa inversa with unilateral high myopia with fellow eye optic disc pitting.

Science.gov (United States)

Sheth, Saumil; Rush, Ryan; Narayanan, Raja

2011-01-01

To report a possible rare association of bilateral retinitis pigmentosa inversa (RPI) with unilateral high myopia with fellow eye optic disc pitting. A 55-year-old man with a history of reduced vision in the right eye since childhood presented with gradually decreasing vision in the left eye. On examination, a -23.00 diopter refractive error and diffuse chorioretinal atrophy consistent with pathologic myopia was found in the right eye. An optic disc pit with posterior pole pigmentary alterations thought to be consequent to a previous neurosensory detachment was found in the left eye. Though the retinal arteriolar attenuation seen in both eyes with an inconsistent history of night blindness since childhood pointed towards the possibility of a concurrently existing rod or rod-cone dystrophy, the posterior pole pigmentary alterations characteristic of RPI were clearly masked by the above pathologies. Optical coherence tomography demonstrated prominent foveal atrophy and an optic disc pit in the left eye. Electroretinography (ERG) demonstrated moderately attenuated amplitudes with prolonged implicit times of rod and cone responses bilaterally. The patient was diagnosed with bilateral RPI and anisometropic amblyopia in the right eye. This report documents a unique constellation of findings which include bilateral RPI and unilateral high myopia with an optic disc pit in the fellow eye. An ERG confirmation of a dystrophic etiology should be sought in suspicious cases, especially when findings are masked by the concurrent presence of other pathologies.

Reduced vision in highly myopic eyes without ocular pathology: the ZOC-BHVI high myopia study.

Science.gov (United States)

Jong, Monica; Sankaridurg, Padmaja; Li, Wayne; Resnikoff, Serge; Naidoo, Kovin; He, Mingguang

2018-01-01

The aim was to investigate the relationship of the magnitude of myopia with visual acuity in highly myopic eyes without ocular pathology. Twelve hundred and ninety-two highly myopic eyes (up to -6.00 DS both eyes, no astigmatic cut-off) with no ocular pathology from the ZOC-BHVI high myopia study in China, had cycloplegic refraction, followed by subjective refraction and visual acuities and axial length measurement. Two logistic regression models were undertaken to test the association of age, gender, refractive error, axial length and parental myopia with reduced vision. Mean group age was 19.0 ± 8.6 years; subjective spherical equivalent refractive error was -9.03 ± 2.73 D; objective spherical equivalent refractive error was -8.90 ± 2.60 D and axial length was 27.0 ± 1.3 mm. Using visual acuity, 82.4 per cent had normal vision, 16.0 per cent had mildly reduced vision, 1.2 per cent had moderately reduced vision, 0.3 per cent had severely reduced vision and no subjects were blind. The percentage with reduced vision increased with spherical equivalent to 74.5 per cent from -15.00 to -39.99 D, axial length to 67.7 per cent of eyes from 30.01 to 32.00 mm and age to 22.9 per cent of those 41 years and over. Spherical equivalent and axial length were significantly associated with reduced vision (p vision. Gender was significant for one model (p = 0.04). Mildly reduced vision is common in high myopia without ocular pathology and is strongly correlated with greater magnitudes of refractive error and axial length. Better understanding is required to minimise reduced vision in high myopes. © 2017 Optometry Australia.

Refractive errors in 3-6 year-old Chinese children: a very low prevalence of myopia?

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Weizhong Lan

Full Text Available PURPOSE: To examine the prevalence of refractive errors in children aged 3-6 years in China. METHODS: Children were recruited for a trial of a home-based amblyopia screening kit in Guangzhou preschools, during which cycloplegic refractions were measured in both eyes of 2480 children. Cycloplegic refraction (from 3 to 4 drops of 1% cyclopentolate to ensure abolition of the light reflex was measured by both autorefraction and retinoscopy. Refractive errors were defined as followed: myopia (at least -0.50 D in the worse eye, hyperopia (at least +2.00 D in the worse eye and astigmatism (at least 1.50 D in the worse eye. Different definitions, as specified in the text, were also used to facilitate comparison with other studies. RESULTS: The mean spherical equivalent refractive error was at least +1.22 D for all ages and both genders. The prevalence of myopia for any definition at any age was at most 2.5%, and lower in most cases. In contrast, the prevalence of hyperopia was generally over 20%, and declined slightly with age. The prevalence of astigmatism was between 6% and 11%. There was very little change in refractive error with age over this age range. CONCLUSIONS: Previous reports of less hyperopic mean spherical equivalent refractive error, and more myopia and less hyperopia in children of this age may be due to problems with achieving adequate cycloplegia in children with dark irises. Using up to 4 drops of 1% cyclopentolate may be necessary to accurately measure refractive error in paediatric studies of such children. Our results suggest that children from all ethnic groups may follow a similar pattern of early refractive development, with little myopia and a hyperopic mean spherical equivalent over +1.00 D up to the age of 5-6 years in most conditions.

Outcomes of small incision lenticule extraction (SMILE) in low myopia.

Science.gov (United States)

Reinstein, Dan Z; Carp, Glenn I; Archer, Timothy J; Gobbe, Marine

2014-12-01

To report the visual and refractive outcomes of small incision lenticule extraction for low myopia using the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). A retrospective analysis of 120 consecutive small incision lenticule extraction procedures was performed for low myopia. Inclusion criteria were preoperative spherical equivalent refraction up to -3.50 diopters (D), cylinder up to 1.50 D, and corrected distance visual acuity of 20/20 or better. Outcomes analysis was performed for all eyes with 1-year follow-up according to the Standard Graphs for Reporting Refractive Surgery, and also including mesopic contrast sensitivity. One-year data were available for 110 eyes (92%). Preoperatively, mean spherical equivalent refraction was -2.61 ± 0.54 D (range: -1.03 to -3.50 D) and mean cylinder was 0.55 ± 0.38 D (range: 0.00 to 1.50 D). Postoperatively, mean spherical equivalent refraction was -0.05 ± 0.36 D (range: -0.94 to +1.25 D) and mean cylinder was ± 0.50 D in 84% and ± 1.00 D in 99% of eyes. Uncorrected distance visual acuity was 20/20 or better in 96% of eyes and 20/25 or better in 100% of eyes. One line of corrected distance visual acuity was lost in 9%, but no eyes lost two or more lines. There was an initial overcorrection in mean spherical equivalent refraction on day 1 (+0.37 D) as expected, which regressed to +0.10 D at 1 month and -0.05 D at 3 months, after which stability was reached (mean spherical equivalent refraction was -0.05 D at 1 year). Contrast sensitivity at 1 year was slightly increased at 3, 6, 12, and 18 cycles per degree (P < .05). Small incision lenticule extraction for low myopia was found to be safe and effective with outcomes similar to those previously reported for LASIK. Copyright 2014, SLACK Incorporated.

Refractive surgery: Is the new small-incision lenticule extraction (SMILE) technique equal to or better than the standard flap-and-ablation (FS-LASIK) technique for treating high-degree myopia?

DEFF Research Database (Denmark)

Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

Field: Ophthalmology Introduction: Corneal laser surgery for myopia (nearsightedness) is one of the most performed surgical procedures today. FS-LASIK has been the dominating surgical technique for almost two decades, but a shift to the new less invasive SMILE technique might be underway. However...... the literature on SMILE is sparse, especially for high-degree myopia (six or more dioptres (D)). We hypothesize that the accuracy, efficacy, stability and safety after SMILE is equal to or better than FS-LASIK up to three months post-operatively for high-degree myopia. Methods: Retrospective study of 1214 eyes...... treated with SMILE or FS-LASIK for high-degree myopia from 2011-2013 at the Department of Ophthalmology, Odense University Hospital, Denmark. Inclusion criteria: Best spectacle-corrected visual acuity (BSCVA) of 20/25 or better on Snellen chart, and no other ocular condition than high-degree myopia...

Functional outcomes and patient satisfaction after laser in situ keratomileusis for correction of myopia.

NARCIS (Netherlands)

Tahzib, N.G.; Bootsma, S.J.; Eggink, F.A.G.J.; Nabar, V.A.; Nuijts, R.M.

2005-01-01

PURPOSE: To determine subjective patient satisfaction and self-perceived quality of vision after laser in situ keratomileusis (LASIK) to correct myopia and myopic astigmatism. SETTING: Department of Ophthalmology, Academic Hospital Maastricht, Maastricht, The Netherlands. METHODS: A validated

Alcohol expectancies longitudinally predict drinking and the alcohol myopia effects of relief, self-inflation, and excess.

Science.gov (United States)

Lac, Andrew; Brack, Nathaniel

2018-02-01

Alcohol myopia theory posits that alcohol consumption attenuates information processing capacity, and that expectancy beliefs together with intake level are responsible for experiences in myopic effects (relief, self-inflation, and excess). Adults (N=413) averaging 36.39 (SD=13.02) years of age completed the Comprehensive Effects of Alcohol questionnaire at baseline, followed by alcohol use measures (frequency and quantity) and the Alcohol Myopia Scale one month later. Three structural equation models based on differing construct manifestations of alcohol expectancies served to longitudinally forecast alcohol use and myopia. In Model 1, overall expectancy predicted greater alcohol use and higher levels of all three myopic effects. In Model 2, specifying separate positive and negative expectancy factors, positive but not negative expectancy predicted greater use. Furthermore, positive expectancy and use explained higher myopic relief and higher self-inflation, whereas positive expectancy, negative expectancy, and use explained higher myopic excess. In Model 3, the seven specific expectancy subscales (sociability, tension reduction, liquid courage, sexuality, cognitive and behavioral impairment, risk and aggression, and self-perception) were simultaneously specified as predictors. Tension reduction expectancy, sexuality expectancy, and use contributed to higher myopic relief; sexuality expectancy and use explained higher myopic self-inflation; and risk and aggression expectancy and use accounted for higher myopic excess. Across all three predictive models, the total variance explained ranged from 12 to 19% for alcohol use, 50 to 51% for relief, 29 to 34% for self-inflation, and 32 to 35% for excess. Findings support that the type of alcohol myopia experienced is a concurrent function of self-fulfilling alcohol prophecies and drinking levels. The interpreted measurement manifestation of expectancy yielded different prevention implications. Copyright © 2017 Elsevier

Single-step transepithelial ASLA (SCHWIND) with mitomycin-C for the correction of high myopia: long term follow-up.

Science.gov (United States)

Aslanides, Ioannis M; Georgoudis, Panagiotis N; Selimis, Vasilis D; Mukherjee, Achyut N

2015-01-01

We wanted to compare the outcomes of single-step modified transepithelial photorefractive keratectomy (tPRK) termed a SCHWIND all surface laser ablation (ASLA) versus conventional alcohol-assisted photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK) for the correction of higher myopia of 6.00 diopters (D) or more, in an area with high risk of haze due to high intensity of sunlight. We used a prospective interventional cohort with matched retrospective control groups. Patients with >6 D myopia and 0.05). Mean logMAR (logarithm of the minimum angle of resolution) uncorrected distance visual acuity at 12 months was 0.00 (SD: 0.05), 0.06 (SD: 0.1), and 0.05 (SD: 0.09) in the ASLA, PRK, and LASIK groups, with significantly better vision in the tPRK group versus LASIK (P=0.01) and PRK (P=0.01) groups. ASLA (SCHWIND) tPRK with mitomycin C for high myopia demonstrates comparable refractive outcomes to LASIK and PRK, with relatively favorable visual acuity outcomes. There was no increased incidence of haze in the ASLA group.

Outdoor activity and myopia progression in 4-year follow-up of Chinese primary school children: The Beijing Children Eye Study.

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Yin Guo

Full Text Available To investigate factors associated with ocular axial elongation and myopia progression during a 4-year follow-up in primary school children in Beijing.This school-based study included 382 grade-1 children at baseline in 2011 (age:6.3±0.4 years with 305 (79.8% returning for the follow-up examination in 2015. At baseline and in yearly follow-up examinations, the children underwent a comprehensive eye examination including auto-refractometry, ocular biometry with measurement of axial length, and fundus photography. The parents underwent a standardized interview.During the study period, the mean axial length elongated by 1.15±0.56mm in boys and 1.10±0.63mm in girls. At baseline and at the end of follow-up, axial length was significantly (P<0.001 longer in boys, with no difference (P = 0.50 between genders in axial elongation. In multivariate analysis, greater axial elongation was associated (regression coefficient r2:0.15 with less time spent outdoors (P = 0.004; standardized coefficient beta: -0.22, more time spent indoors with studying (P = 0.02; beta: 0.18 and paternal myopia (P = 0.03; beta: 0.16. Larger increases in the axial length/anterior corneal curvature (AL/CC ratio were associated (r2:0.09 with less time spent outdoors (PP = 0.003; beta: -0.22 and maternal myopia (PP = 0.02; beta: 0.18.Myopic axial elongation during a 4-year follow-up was associated with shorter time spent outdoors and longer time spent indoors studying and with parental myopia. Other factors such as level of paternal education, family income, gender and region of habitation were significantly associated with axial elongation and with myopia progression only in univariate analysis.

INTACS before or after laser in situ keratomileusis: correction of thin corneas with moderately high myopia.

Science.gov (United States)

Ito, Mitsutoshi; Arai, Hiroyuki; Fukumoto, Teruki; Toda, Ikuko; Tsubota, Kazuo

2004-01-01

Intrastromal corneal ring segments (INTACS Micro-Thin Prescription Inserts by Addition Technologies, Fremont, Calif) were inserted as a combined surgery with laser in situ keratomileusis (LASIK) in six eyes with thin corneas to correct moderately high myopia. INTACS were implanted before LASIK (INTACS-LASIK) in three eyes and after LASIK (LASIK-INTACS) in three eyes. Mean preoperative manifest spherical equivalent refraction was -7.88 diopters. Mean follow-up was 306 days. No intraoperative complications occurred. The LASIK-INTACS eyes were slightly more overcorrected than the INTACS-LASIK eyes because of the enhanced performance of INTACS in the thinned corneal tissue. Induced astigmatism by INTACS per se was less in the LASIK-INTACS eyes than in the INTACS-LASIK eyes. At last examination, uncorrected visual acuity was better than 20/25 in all eyes. Best spectacle-corrected visual acuity was within 1 line of the preoperative value in all eyes. Both methods resulted in significant improvement in visual acuity and refraction. Based on our limited experience, however, LASIK followed by INTACS is preferred for reasons of safety, convenience, and lower induced cylinder.

Choroidal thickness and myopia in relation to physical activity - the CHAMPS Eye Study

DEFF Research Database (Denmark)

Lundberg, Kristian; Vestergaard, Anders Højslet; Jacobsen, Nina

2018-01-01

PURPOSE: To describe the relationship between choroidal thickness (CT) and myopia in relation to physical activity (PA) in a population-based child cohort. METHODS: In a prospective study of 307 children from the CHAMPS Study Denmark, we used objective data from GT3X accelerometer worn at four...

Photorefractive Keratectomy (PRK) is Safe and Effective for Patients with Myopia and Thin Corneas.

Science.gov (United States)

Naderi, Mostafa; Ghadamgahi, Saeed; Jadidi, Khosrow

2016-01-01

The aim of this study was to evaluate the long-term safety and efficacy of photorefractive keratectomy (PRK) for patients with myopia and thin corneas. In this retrospective case series, we included 74 eyes of 38 patients with myopia and central corneal thickness (CCT) PRK and had a mean postoperative follow-up period of four years. The following factors were evaluated: CCT, refraction, uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), ablation depth, safety and efficacy indices (i.e., the ratio of the mean postoperative BCVA to the mean preoperative BCVA, and the ratio of the mean postoperative UCVA to mean preoperative the BCVA, respectively), and evidence of corneal ectasia (based on Orbscan topography images).The patients were aged 20 - 46 years (mean ±SD age, 28.18± 6.82 years). The mean ± SD pre- and postoperative CCTwas485.92 ± 9.27 µm and 434.84 ± 20.48 µm, respectively. The mean ± SD pre- and postoperative myopia was -2.77 D ± 1.51 and -0.24 ± 0.39 D, respectively, and the mean ± SD pre- and postoperative astigmatism was -0.82 D ± 0.99 and -0.37 ± 0.37 D, respectively. The mean pre- and postoperative BCVA and postoperative UCVA was 0.011 ± 0.03 Logarithm of the Minimum Angle of Resolution (log MAR), 0.003 ± 0.01 log MAR, and 0.054 ± 0.09 log MAR, respectively. The mean ± SD ablation depth, safety index and efficacy index was 54.34 ± 16.28 µm, 0.02 ± 0.12, and 0.11 ± 0.50, respectively. Regarding the postoperative corneal clarity, 72 eyes (97.3%) had a clear cornea (grade 0) and the remaining two eyes of one patient (2.70%) had a trace haze (grade 1). There was no evidence of corneal ectasia on any of the Orbscan topography images. Thus, among patients with myopia and thin corneas (PRK seems to be acceptable in terms of both safety and efficacy 4 years after surgery, based on the stability of postoperative refraction, visual acuity, and topographic outcomes, and outcomes based on the safety and efficacy indexes.

Epithelium-on photorefractive intrastromal cross-linking (PiXL for reduction of low myopia

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Lim WK

2017-06-01

Full Text Available Wee Kiak Lim,1,2 Zhi Da Soh,1 Harold Kah Yen Choi,1 Julian Thiam Siew Theng1,3 1Eagle Eye Centre, Mount Alvernia Hospital, 2Department of Ophthalmology, Tan Tock Seng Hospital, 3Department of Ophthalmology, Khoo Teck Puat Hospital, Singapore Purpose: To report the 9–12-month outcomes of a novel procedure for reduction of low myopia through epithelium-on photorefractive intrastromal cross-linking (PiXL with customized control of topographic distribution of ultraviolet (UV-fluence. Method: Myopic patients with normal (non-ectatic corneas underwent the PiXL procedure for reduction of low myopia. PiXL treatments were delivered through selective application of UVA light based on the refractive error of each patient. Clinical evaluation included safety (corrected distance visual acuity, endothelial cell count, central corneal thickness, anterior ocular health and efficacy (uncorrected distance visual acuity, manifest refraction, K-mean examinations. In addition, a patient satisfaction survey was conducted at 9 months post-procedure to evaluate patients’ subjective experience with the procedure. Results: Fourteen myopic eyes (mean manifest refraction spherical equivalent –1.62±0.6D; range –0.75 to –2.65D of 8 subjects (mean age 30 years old; range 24–51 years old were enrolled in the study. At 12 months post-procedure, a mean manifest refraction spherical equivalent reduction of 0.72±0.43D (P<0.001 was observed, with a corresponding gain in uncorrected visual acuity of 0.25 logMAR and mean K-mean flattening of 0.47±0.46D. All patients achieved best corrected visual acuity of 20/20 or better from 1 month onward. There were no cases of ocular infection or secondary changes to the crystalline lens and retina due to UV exposure, while transient corneal haze subsided gradually. Conclusion: The epithelium-on PiXL procedure was safe and effective in reducing myopic refractive error in this study with up to 12 months follow-up. Early results of

Myopia, spectacle wear, and risk of bicycle accidents among rural Chinese secondary school students: the Xichang Pediatric Refractive Error Study report no. 7.

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Zhang, Mingzhi; Congdon, Nathan; Li, Liping; Song, Yue; Choi, Kai; Wang, Yunfei; Zhou, Zhongxia; Liu, Xiaojian; Sharma, Abhishek; Chen, Weihong; Lam, Dennis S C

2009-06-01

To study the effect of myopia and spectacle wear on bicycle-related injuries in rural Chinese students. Myopia is common among Chinese students but few studies have examined its effect on daily activities. Data on visual acuity, refractive error, current spectacle wear, and history of bicycle use and accidents during the past 3 years were sought from 1891 students undergoing eye examinations in rural Guangdong province. Refractive and accident data were available for 1539 participants (81.3%), among whom the mean age was 14.6 years, 52.5% were girls, 26.8% wore glasses, and 12.9% had myopia of less than -4 diopters in both eyes. More than 90% relied on bicycles to get to school daily. A total of 2931 accidents were reported by 423 participants, with 68 requiring medical attention. Male sex (odds ratio, 1.55; P accident, but habitual visual acuity and myopia were unassociated with the crash risk, after adjusting for age, sex, time spent riding, and risky riding behaviors. These results may be consistent with data on motor vehicle accidents implicating peripheral vision (potentially compromised by spectacle wear) more strongly than central visual acuity in mediating crash risk.

Implantable collamer lens and femtosecond laser for myopia: comparison using an adaptive optics visual simulator

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Cari Pérez-Vives

2014-04-01

Full Text Available Purpose: To compare optical and visual quality of implantable collamer lens (ICL implantation and femtosecond laser in situ keratomileusis (F-LASIK for myopia. Methods: The CRX1 adaptive optics visual simulator (Imagine Eyes, Orsay, France was used to simulate the wavefront aberration pattern after the two surgical procedures for -3-diopter (D and -6-D myopia. Visual acuity at different contrasts and contrast sensitivities at 10, 20, and 25 cycles/degree (cpd were measured for 3-mm and 5-mm pupils. The modulation transfer function (MTF and point spread function (PSF were calculated for 5-mm pupils. Results: F-LASIK MTF was worse than ICL MTF, which was close to diffraction-limited MTF. ICL cases showed less spread out of PSF than F-LASIK cases. ICL cases showed better visual acuity values than F-LASIK cases for all pupils, contrasts, and myopic treatments (p0.05. For -6-D myopia, however, statistically significant differences in contrast sensitivities were found for both pupils for all evaluated spatial frequencies (p<0.05. Contrast sensitivities were better after ICL implantation than after F-LASIK. Conclusions: ICL implantation and F-LASIK provide good optical and visual quality, although the former provides better outcomes of MTF, PSF, visual acuity, and contrast sensitivity, especially for cases with large refractive errors and pupil sizes. These outcomes are related to the F-LASIK producing larger high-order aberrations.

Myopia prevention and therapy. The role of pharmaceutical agents. Japanese studies.

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Hosaka, A

1988-01-01

In order to normalize the condition of pseudomyopia, the following can be summarized: One percent cyclopentolate was effective in 63%, and 0.4% tropicamide was effective in 59% of the cases. With a value of 68% after labetalol eye drops there were no significant differences in efficacy between this drug and the above cycloplegics. In subjects treated only with placebo, 4 out of 16 eyes, i.e. 25% were relieved. A significant difference (P less than 0.01) was found between the results with the above 3 drugs and placebo. On the other hand, the efficacy of 0.25% timolol (effect in 28%) and chemical X (effect in 37%) were not significantly different from the effect of placebo, though the results with chemical X encourage further trials. It can be postulated that by releasing an abnormal tension cycloplegics reduce the myopic condition. Regarding the hypotensive action of beta-adrenergic blockers on intraocular pressure, it presumably depends mainly on inhibition of secretion in the ciliary body. The fact that labetalol appeared effective, and timolol not, in treatment trials of slight myopia might imply that the mechanism behind an effect of labetalol on slight myopia is not merely a beta-adrenergic blocking action.

The Correction of Myopia Evaluation Trial: lessons from the study design.

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Hyman, L; Gwiazda, J

2004-01-01

The Correction of Myopia Evaluation Trial (COMET), a multicentre clinical trial based in 4 schools of optometry in the United States, evaluated the effect of progressive addition lenses versus single vision lenses on myopia progression in an ethnically diverse group of 469 myopic children aged 6 to 11 years. Completion of the clinical trial phase of the study provides an opportunity to evaluate aspects of the study design that contribute to its success. This article describes aspects of the study design that were influential in ensuring the smooth conduct of COMET. These include a dedicated team of investigators, an organisational structure with strong leadership and an independent Co-ordinating Centre, regular communication among investigators, flexible and creative approaches to recruitment and retention, sensitivity to concerns for child safety and child participation, and methods for enhancing and monitoring data reliability. The experience with COMET has provided a number of valuable lessons for all aspects of the study design that should benefit the development and implementation of future clinical trials, particularly those done in similar populations of children. The use of a carefully designed protocol using standard methods by dedicated members of the study team is essential in ensuring achievement of the study aims.

Comparison of laser epithelial keratomileusis and photorefractive keratectomy for the correction of myopia:a meta-analysis

Institute of Scientific and Technical Information of China (English)

CUI Min; CHEN Xiao-ming; L(U) Peng

2008-01-01

Background It is unclear whether a laser epithelial keratomileusis (LASEK) has any significant advantage over a photorefractive keratectomy (PRK) for correcting myopia.We undertook this meta-analysis of randomized controlled trials to examine possible differences in efficacy,accuracy,safety and side-effects between two methods,LASEK and PRK,for correcting myopia.Methods A systematic literature retrieval was conducted in the PubMed,EMBASE,Chinese Bio-medicine Database,and Cochrane Controlled Trials Register to identify potentially relevant randomized controlled trials.The statistical analysis was performed using a RevMan 4.2 software.The results included efficacy outcomes (proportion of eyes with uncorrected visual acuity (UCVA)≥ 20/20 at 1 month and 12 months post-treatment),accuracy outcomes (proportion of eyes within ±0.50 diopters (D) of target refraction at 1 month and 12 months post-treatment),safety outcomes (loss of ≥2 lines of best spectacle-corrected visual acuity (BSCVA) at ≥ 6 months post-treatment),mean pain scores on day 1 post-treatment,and mean corneal haze scores at 6 and 12 months post-treatment.Results Seven articles describing a total of 604 eyes with myopia from 0 to -9.0 D were identified in this meta-analysis.The combined results showed that the efficacy and accuracy outcomes between the two groups at 1 month and 12 months post-treatment were comparable.No patient lost ≥ 2 lines of BSCVA at ≥ 6 months post-treatment in four relevant trials.Compared with PRK,LASEK did not relieve discomfort on day 1 post-treatment or reduce corneal haze intensity at 6 and 12 months post-treatment.Conclusions According to the available data,LASEK does not appear to have any advantage over PRK for correcting myopia from 0 to -9.0 D.This meta-analysis focuses mainly on the comparison of the early,mid-term and mid-long term results of the two methods.Additional studies to compare the long-term (＞one year) results should be considered.

Efficacy and safety of orthokeratology to control myopia in Asia children: A Meta-analysis

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Zuo-Jie Zhang

2018-02-01

Full Text Available AIM: To assess the efficacy and safety of orthokeratology for reducing the progression of myopia in Asia children. METHODS: Seven databases, including the Cochrane Library, Medline, EMbase, CBM, CNKI, VIP, and WanFang Data, were searched. The published languages were limited to English and Chinese. The risk bias tool provided by Cochrance cooperation and methodological index for non-randomized studies(MINORSscale were used to assess the risk bias of included studies(randomized controlled trials and controlled trials. The published biases of included studies were assessed with funnel plot. Meta-analysis was performed with Review Manager 5.3. RESULTS: Seven eligible studies, including 478 children, were included, 250 cases in ortho-k group, 228 cases in control group. The Meta-analysis indicated that change in axial length of ortho-k group was significantly less than the control group \\〖WMD=-0.31, 95%CI(-0.35, -0.26, PCONCLUSION: The overall findings suggested that orthokeratology might slow the progression of myopia in children of Asia.

Vitrectomy with internal limiting membrane peeling for macular hole in high myopia eyes

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Chun-Mei Deng

2015-08-01

Full Text Available AIM: To compare the clinical effects between pars plana vitrectomy(PPVand PPV with internal limiting membrane peeling(ILMPfor macular hole in high myopia eyes. METHODS:The clinical data of 33 high myopia with macular hole patients(36 eyeswith or without retinal detachment caused by macular hole were retrospectively analyzed. The patients were divided into two groups according to different operation methods: 15 eyes in groupⅠhad undergone PPV; 21 eyes in groupⅡhad undergone PPV with ILMPP peeling. According to different conditions of patients,different auxiliary methods were accepted, such as silicone oil tamponade, C3F8 tamponade, photocoagulation, condensation, etc. The follow-up period was 3～12mo. Best corrected visual acuity(BCVA, macular hole closure rate and retinal reattachment rate were continuous checked after operation. Then we evaluated the outcome in the two groups by statistical analysis.RESULTS: The postoperative mean BCVA increased by 0.167 in group Ⅰand 0.456 in group Ⅱ than preoperative, the difference was significant(t=2.46,6.753; P=0.027,0.000. And the difference of BCVA improvement was significant between those two groups(t=-2.943, P=0.006. The macular hole closed in 7 eyes(46.67%in group Ⅰ,and 18 eyes(85.71%in group Ⅱ; The difference was significant between those two groups(χ2=6.287,P=0.025.Retinal reattachment was found in 11 eyes(91.67%in group Ⅰ and 19 eyes(94.73%in group Ⅱ. The difference was not significant between the two groups(χ2=0.856, P=0.418. CONCLUSION: PPV with ILMPP peeling for macular hole in high myopia eyes can obviously improve closure of macular hole and postoperative visual acuity. But the difference of retinal reattachment rate was not significant between peeling and unpeeling of ILMP.

Seven year follow-up after advanced surface ablation with excimer laser for treatment of myopia: Long-term outcomes of cooling PRK and LASEK.

OpenAIRE

Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob; Vestergaard, Anders Højslet

2014-01-01

Purpose: To evaluate and compare refractive predictability, uncorrected and corrected distance visual acuity (UDVA and CDVA), corneal haze, corneal densitometry and patient satisfaction up to 7 years after Photorefractive Keratectomy with cooling (cPRK) and Laser-Assisted Sub-epithelial Keratectomy (LASEK) for all degrees of myopia, but in particular high myopia. Setting: Department of Ophthalmology, Odense University Hospital, Odense, Denmark. Methods: Retrospective follow-up study of eyes t...

Prevalence of lattice degeneration and its relation to axial length in severe myopia.

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Celorio, J M; Pruett, R C

1991-01-15

We studied 436 eyes of 218 patients with myopia of -6.00 diopters or more in both eyes. Of 218 patients, 72 (33.0%) had lattice degeneration of the retina. Among these 72 patients, lattice lesions were uniocular in 39 (54.2%) and binocular in 33 (45.8%). Of 105 males, 33 (31.4%) had lattice degeneration; of 113 females, 39 (34.5%) had lattice degeneration. Contrary to previously published data, we found an inverse relationship between axial length and the prevalence of lattice degeneration in severely myopic eyes. The greatest prevalence of lattice degeneration (63 of 154 eyes, 40.9%) was found in eyes with an axial length of 26.0 to 26.9 mm (-6.00 to -8.70 diopters), and the least prevalence of lattice degeneration (five of 71 eyes, 7.0%) was found in eyes with an axial length of 32.0 mm (-24.00 diopters) or greater. This may explain the observation that retinal detachment after cataract surgery has been noted more commonly among patients with moderate than severe myopia.

Correlation between central corneal thickness and myopia in Taiwan

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Yi-Chun Chen

2014-01-01

Full Text Available The aim of the study was to explore the correlation between central corneal thickness (CCT and the degree of myopia in Taiwanese adults. A total of 528 individuals were enrolled to undergo myopic laser refractive surgery from January 2004 to December 2006. Preoperative CCT was measured using the Orbscan corneal topography system and refractive status was determined by cycloplegic spherical equivalent. The relationship between CCT and refractive error was investigated by interindividual and intraindividual analyses. Participants had a mean age of 34.8 ± 7.3 years, and 79.9% were female. The mean refractive error was −7.27 ± 2.96 diopters and the mean CCT measurement was 560 ± 35 μm. CCT revealed that there was no association with age. However, CCT was significantly (p = 0.012 less in females than in males. The CCT also showed no significant association with refractive error (p = 0.49. Among the 67 participants with myopic anisometropia, the mean difference between both eyes was 3.09 ± 1.06 diopters. There was no association between the intereye CCT difference and refractive error (p = 0.57. The results remained the same after adjusting for age and sex. In conclusion, there was no correlation between CCT and the degree of myopia among adults in Taiwan. These data might contribute to the ongoing discussion about the role of CCT in the higher incidence of development and progression of glaucoma in myopic individuals.

Association mapping of the high-grade myopia MYP3 locus reveals novel candidates UHRF1BP1L, PTPRR, and PPFIA2

DEFF Research Database (Denmark)

Hawthorne, Felicia; Feng, Sheng; Metlapally, Ravikanth

2013-01-01

PURPOSE: Myopia, or nearsightedness, is a common ocular genetic disease for which over 20 candidate genomic loci have been identified. The high-grade myopia locus, MYP3, has been reported on chromosome 12q21-23 by four independent linkage studies. METHODS: We performed a genetic association study...... statistically significant SNPs rs4764971, also found by qualitative testing (P = 3.1 × 10(-6)); rs7134216, in the 3' untranslated region (UTR) of DEPDC4 (P = 5.4 × 10(-7)); and rs17306116, an intronic SNP within PPFIA2 (P Independently conducted whole genome expression array analyses identified...... protein tyrosine phosphatase genes PTPRR and PPFIA2, which are in the same gene family, as differentially expressed in normal rapidly growing fetal relative to normal adult ocular tissue (confirmed by RT-qPCR). CONCLUSIONS: In an independent high-grade myopia cohort, an intronic SNP in UHRF1BP1L, rs...

Complications of laser in situ keratomileusis (LASIK) for correction of myopia and their management

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Lotfy, A A

2002-07-01

Complication of Laser in situ keratomileusis (Lasik) For correction of myopia and their management. Lasik has many many complications that the study discussed and also their management. Complications include; bleeding, infection, corneal haze and scarring, lost or displaced flap, corneal complications, over and under correction, and regression of refraction.

Complications of laser in situ keratomileusis (LASIK) for correction of myopia and their management

International Nuclear Information System (INIS)

Lotfy, A. A.

2002-01-01

Complication of Laser in situ keratomileusis (Lasik) For correction of myopia and their management. Lasik has many many complications that the study discussed and also their management. Complications include; bleeding, infection, corneal haze and scarring, lost or displaced flap, corneal complications, over and under correction, and regression of refraction

Association of vitamin D receptor gene start codon (Fok1 polymorphism with high myopia

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Sandhya Annamaneni

2011-01-01

Conclusion : The results suggest that VDR gene might not be playing a direct role in the development of myopia, but might contribute indirectly to the risk conferred by mechanical stress factors or growth/development related factors through its role in calcium homeostasis and regulation of ciliary muscle function.

Effect of outdoor activity on myopia onset and progression in school-aged children in northeast china: the sujiatun eye care study

OpenAIRE

Jin, Ju-Xiang; Hua, Wen-Juan; Jiang, Xuan; Wu, Xiao-Yan; Yang, Ji-Wen; Gao, Guo-Peng; Fang, Yun; Pei, Chen-Lu; Wang, Song; Zhang, Jie-Zheng; Tao, Li-Ming; Tao, Fang-Biao

2015-01-01

Background Due to its high prevalence and associated sight-threatening pathologies, myopia has emerged as a major health issue in East Asia. The purpose was to test the impact on myopia development of a school-based intervention program aimed at increasing the time student spent outdoors. Methods A total of 3051 students of two primary (grades 1-5, aged 6-11) and two junior high schools (grades 7-8, aged 12-14) in both urban and rural Northeast China were enrolled. The intervention group (n?=...

Comparison of the visual results after SMILE and femtosecond laser-assisted LASIK for myopia.

Science.gov (United States)

Lin, Fangyu; Xu, Yesheng; Yang, Yabo

2014-04-01

To perform a comparative clinical analysis of the safety, efficacy, and predictability of two surgical procedures (ie, small incision lenticule extraction [SMILE] and femtosecond laser-assisted LASIK [FS-LASIK]) to correct myopia. Sixty eyes of 31 patients with a mean spherical equivalent of -5.13 ± 1.75 diopters underwent myopia correction with the SMILE procedure. Fifty-one eyes of 27 patients with a mean spherical equivalent of -5.58 ± 2.41 diopters were treated with the FS-LASIK procedure. Postoperative uncorrected and corrected distance visual acuity, manifest refraction, and higher-order aberrations were analyzed statistically at 1 and 3 months postoperatively. No statistically significant differences were found at 1 and 3 months in parameters that included the percentage of eyes with an uncorrected distance visual acuity of 20/20 or better (P = .556, .920) and mean spherical equivalent refraction (P = .055, .335). At 1 month, 4 SMILE-treated eyes and 1 FS-LASIK-treated eye lost one or more line of visual acuity (P = .214, chi-square test). At 3 months, 2 SMILE-treated eyes lost one or more line of visual acuity, whereas all FS-LASIK-treated eyes had an unchanged or corrected distance visual acuity. Higher-order aberrations and spherical aberration were significantly lower in the SMILE group than the FS-LASIK group at 1 (P = .007, .000) and 3 (P = .006, .000) months of follow-up. SMILE and FS-LASIK are safe, effective, and predictable surgical procedures to treat myopia. SMILE has a lower induction rate of higher-order aberrations and spherical aberration than the FS-LASIK procedure. Copyright 2014, SLACK Incorporated.

Seven year follow-up after advanced surface ablation with excimer laser for treatment of myopia: Long-term outcomes of cooling PRK and LASEK

DEFF Research Database (Denmark)

Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

Purpose: To evaluate and compare refractive predictability, uncorrected and corrected distance visual acuity (UDVA and CDVA), corneal haze, corneal densitometry and patient satisfaction up to 7 years after Photorefractive Keratectomy with cooling (cPRK) and Laser-Assisted Sub-epithelial Keratectomy...... (LASEK) for all degrees of myopia, but in particular high myopia. Setting: Department of Ophthalmology, Odense University Hospital, Odense, Denmark. Methods: Retrospective follow-up study of eyes treated with cPRK or LASEK for all degrees of myopia from 2007 to 2009 at the Department of Ophthalmology...... laser with eye-tracker (Carl Zeiss Meditec AG, Jena, Germany) was used for photoablation in both procedures. Optical zone size ranged from 5.50 to 6.00 mm in both procedures, and maximum attempted spherical correction was -8.50 D. cPRK was performed as a standard PRK procedure, but with immediately...

A Questionnaire-based Long-term Follow-up of Photorefractive Keratectomy for Low to High Myopia

DEFF Research Database (Denmark)

Vestergaard, Anders; Hjortdal, Jesper; Ivarsen, Anders

and patient reported visual disturbances up to 19 years after treatment of myopia with excimer laser photorefractive keratectomy (PRK). Setting: Department of Ophthalmology, Odense University Hospital, Denmark. Methods: Retrospective questionnaire-based study. In 2011, questionnaires were sent to a cohort...... of the first patients treated with PRK in Denmark. Patients had been treated at Odense University Hospital, Denmark, in the period 1992 to 1998. Before surgery, all patients had had stable myopia for one year and no other ocular diseases or conditions. The same surgeon had performed all surgical procedures...... in quality of life, mean score was 7.3 ± 2.5 and 89% felt an improvement in quality of life after PRK. Thirty-nine percent had problems or many problems with backlight glare, and 48% with nighttime glare. Eleven percent had problems or many problems with halos around light sources in daylight and 40...

Myopia, contact lens use and self-esteem.

Science.gov (United States)

Dias, Lynette; Manny, Ruth E; Weissberg, Erik; Fern, Karen D

2013-09-01

To evaluate whether contact lens (CL) use was associated with self-esteem in myopic children originally enrolled in the Correction of Myopia Evaluation Trial (COMET), that after 5 years continued as an observational study of myopia progression with CL use permitted. Usable data at the 6-year visit, one year after CL use was allowed (n = 423/469, age 12-17 years), included questions on CL use, refractive error measurements and self-reported self-esteem in several areas (scholastic/athletic competence, physical appearance, social acceptance, behavioural conduct and global self-worth). Self-esteem, scored from 1 (low) to 4 (high), was measured by the Self-Perception Profile for Children in participants under 14 years or the Self-Perception Profile for Adolescents, in those 14 years and older. Multiple regression analyses were used to evaluate associations between self-esteem and relevant factors identified by univariate analyses (e.g., CL use, gender, ethnicity), while adjusting for baseline self-esteem prior to CL use. Mean (±S.D.) self-esteem scores at the 6-year visit (mean age = 15.3 ± 1.3 years; mean refractive error = -4.6 ± 1.5 D) ranged from 2.74 (± 0.76) on athletic competence to 3.33 (± 0.53) on global self-worth. CL wearers (n = 224) compared to eyeglass wearers (n = 199) were more likely to be female (p self-esteem or CL use. COMET participants who chose to wear CLs after 5 years of eyeglass use had higher self-esteem compared to those who remained in glasses both preceding and following CL use. This suggests that self-esteem may influence the decision to wear CLs and that CLs in turn are associated with higher self-esteem in individuals most likely to wear them. © 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Impact of varying the definition of myopia on estimates of prevalence and associations with risk factors: time for an approach that serves research, practice and policy.

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Cumberland, Phillippa M; Bountziouka, Vasiliki; Rahi, Jugnoo S

2018-02-03

Refractive error is an increasing global public health concern that requires robust and reliable research to identify modifiable risk factors and provide accurate estimates of population burden. We investigated the impact of reclassification of individuals when using different threshold values of spherical equivalent (SE) to define myopia, on estimates of frequency, distribution and associations with risk factors, to inform current international initiatives to standardise definitions. A random sample of 1985 individuals from the 1958 British birth cohort, at age 44, had autorefraction and self-reported on educational attainment and social class.Refraction status assigned in three different models using SE: (A) moderate to high myopia -3 diopters (D) or more extreme (≤-3.00D), (B) hypermetropia +1.00D or more extreme (≥+1.00D) and (C) mild myopia using three different thresholds: -1.00D, -0.75D or -0.50D, hence reciprocal changes in definition of emmetropia. Frequency estimates and associations with risk factors altered significantly as the threshold value for myopia moved towards SE 0.0D: prevalence of mild myopia increased from 28% to 47%, the association with highest educational attainment attenuated and with higher social class strengthened, with changes in risk ratios of approximately 20%. Even small changes in the threshold definition of myopia (±0.25D) can significantly affect the conclusions of epidemiological studies, creating both false-positive and false-negative associations for specific risk factors. An international classification for refractive error, empirically evidenced and cognisant of the question(s) being addressed and the population(s) being studied, is needed to serve better translational research, practice and policy. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Prevalence and characteristics of peripheral retinal degeneration in Chinese adults with high myopia: a cross-sectional prevalence survey.

Science.gov (United States)

Lam, Dennis S C; Fan, Dorothy S P; Chan, Wai-Man; Tam, Barbara S M; Kwok, Alvin K H; Leung, Alfred T S; Parsons, Hugh

2005-04-01

The purpose of this study was to study the prevalence of peripheral retinal findings in adult Chinese patients with high myopia (refraction degeneration (51.2%), followed by lattice degeneration in 12.2% and retinal holes in 7.5% of eyes. A positive correlation was noted between axial length and the lesions of pigmentary degeneration and pavingstone degeneration. The prevalence of retinal holes was 6.4% and 30.0% in eyes with axial length of or = 30 mm, respectively (chi-squared test, p = 0.006). A high prevalence of peripheral retinal degenerations was found in adult Chinese high myopes. The presence of retinal holes was positively correlated with very high myopia of an axial length of > or = 30 mm.

Mutations in zebrafish lrp2 result in adult-onset ocular pathogenesis that models myopia and other risk factors for glaucoma.

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Kerry N Veth

2011-02-01

Full Text Available The glaucomas comprise a genetically complex group of retinal neuropathies that typically occur late in life and are characterized by progressive pathology of the optic nerve head and degeneration of retinal ganglion cells. In addition to age and family history, other significant risk factors for glaucoma include elevated intraocular pressure (IOP and myopia. The complexity of glaucoma has made it difficult to model in animals, but also challenging to identify responsible genes. We have used zebrafish to identify a genetically complex, recessive mutant that shows risk factors for glaucoma including adult onset severe myopia, elevated IOP, and progressive retinal ganglion cell pathology. Positional cloning and analysis of a non-complementing allele indicated that non-sense mutations in low density lipoprotein receptor-related protein 2 (lrp2 underlie the mutant phenotype. Lrp2, previously named Megalin, functions as an endocytic receptor for a wide-variety of bioactive molecules including Sonic hedgehog, bone morphogenic protein 4, retinol-binding protein, vitamin D-binding protein, and apolipoprotein E, among others. Detailed phenotype analyses indicated that as lrp2 mutant fish age, many individuals--but not all--develop high IOP and severe myopia with obviously enlarged eye globes. This results in retinal stretch and prolonged stress to retinal ganglion cells, which ultimately show signs of pathogenesis. Our studies implicate altered Lrp2-mediated homeostasis as important for myopia and other risk factors for glaucoma in humans and establish a new genetic model for further study of phenotypes associated with this disease.

Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci

NARCIS (Netherlands)

C.L. Simpson (Claire); R. Wojciechowski (Robert); K. Oexle (Konrad); D. Murgia (Daniela); L. Portas (Laura); X. Li (X.); J.M.V. Virginie (J.M. Verhoeven); V. Vitart (Veronique); M. Schache (Maria); S. Mohsen Hosseini; P.G. Hysi (Pirro); L.J. Raffel (Leslie); M.F. Cotch (Mary Frances); E.Y. Chew (Emily); B.E.K. Klein (Barbara); R. Klein (Ronald); T.Y. Wong (Tien Yin); C.M. van Duijn (Cornelia); P. Mitchell (Paul); S-M. Saw (Seang-Mei); M. Fossarello (Maurizio); J.J. Wang (Jie Jin); O. Polasek (Ozren); H. Campbell (Harry); I. Rudan (Igor); B.A. Oostra (Ben); A.G. Uitterlinden (André); A. Hofman (Albert); F. Rivadeneira Ramirez (Fernando); N. Amin (Najaf); L.C. Karssen (Lennart); J.R. Vingerling (Hans); A. Döring (Angela); T. Bettecken (Thomas); G. Bencic (Goran); C. Gieger (Christian); H.E. Wichmann (Heinz Erich); J.F. Wilson (James F); C. Venturini (Cristina); B. Fleck (Brian); P. Cumberland (Phillippa); J.S. Rahi (Jugnoo); C.J. Hammond (Christopher); C. Hayward (Caroline); A. Wright (Alan); A.D. Paterson (Andrew); P.N. Baird (Paul); C.C.W. Klaver (Caroline); J.I. Rotter (Jerome I.); M. Pirastu (Mario); T. Meitinger (Thomas); J.E. Bailey-Wilson (Joan E.); D.E. Stambolian (Dwight)

2014-01-01

textabstractRefractive error (RE) is a complex, multifactorial disorder characterized by a mismatch between the optical power of the eye and its axial length that causes object images to be focused off the retina. The two major subtypes of RE are myopia (nearsightedness) and hyperopia

Epigenetic regulation of αA-crystallin in high myopia-induced dark nuclear cataract.

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Xiang-Jia Zhu

Full Text Available PURPOSE: To assess the etiology of early-onset dark nucleus in high-myopic patients and its relationship with the epigenetic regulation of αA-crystallin (CRYAA. METHODS: We reviewed clinical data from patients who underwent cataract surgery at our center in 2012. Lens epithelial samples were collected during capsulorhexis, whereas young lens epithelium was donated. Cataract type and severity were graded according to the Lens Opacity Classification System III (LOCS III. DNA methylation was analyzed by pyrosequencing the CpG islands of the CRYAA promoter in the following groups: Age-Related Cataract (ARC Nuclear Color (NC 2-3; High-Myopic Cataract (HMC NC2-3; ARC NC5-6; HMC NC5-6; and in young lenses graded NC1. We analyzed CRYAA expression by real-time polymerase chain reaction (PCR, reverse transcription PCR, and immunohistochemistry. RESULTS: The odds ratio of dark nucleus in high-myopic patients was 5.16 (95% confidence interval: 3.98-6.69; p<0.001. CpG islands in lens epithelial CRYAA promoter in the HMC NC5-6 Group exhibited the highest methylation of all the groups, but no statistically significant differences were evident between the HMC NC2-3 and ARC NC2-3 Groups. Likewise, CRYAA mRNA and protein levels in the HMC NC5-6 Group were significantly lower than the ARC NC5-6 Group and high-myopic controls. CONCLUSIONS: High myopia is a risk factor for dark nucleus. Downregulation of CRYAA via the hypermethylation of CpG islands in its promoter could underlie the earlier onset of dark nucleus in high-myopic patients.

A retrospective comparison of efficacy and safety of 680 consecutive lasik treatments for high myopia performed with two generations of flying-spot excimer lasers.

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Gazieva, Lola; Beer, Mette Hjuler; Nielsen, Kim; Hjortdal, Jesper

2011-12-01

To compare the visual refractive outcome and complication of laser in situ keratomileusis (LASIK) carried out with a Carl Zeiss-Meditec MEL-70 Excimer laser and a MEL-80 laser for treatment of high myopia. Journal records of 680 consecutive eyes that underwent LASIK with a Schwind Supratome microkeratome and a MEL-70 Excimer laser (Group A), or a Moria M2 microkeratome and a MEL-80 Excimer laser (Group B) were reviewed. Manifest refraction, uncorrected and best spectacle-corrected visual acuity (BSCVA), corneal topography and central corneal thickness (CCT) were recorded before and 3 months after treatment. Pre- and postoperative complications, visual and refractive outcome and frequency of retreatments were registered. Mean preoperative spherical equivalent refraction was -8.52 dioptres (-5.50- -18 dioptres), and the mean attempted laser correction was -8.02 dioptres (-5.50- -11 dioptres). Three months after LASIK, the average treatment error (difference between achieved and attempted correction) was 1.20 (SD=1.19) dioptres of under correction in Group A and 0.52 (SD=1.00) dioptres in Group B. Four eyes lost more than two lines of BSCVA (0.6%). In 110 eyes (16%), a re-LASIK procedure was performed to reduce remaining myopia after the primary procedure. Laser in situ keratomileusis treatment for high myopia can effectively reduce high degrees of myopia. Under correction was observed in both treatment groups but Group B has a slightly better predictability. Significant loss of BSCVA occurs infrequently after LASIK for even considerable grades of myopia (0.6% in each group). © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.

Clinical research on high myopia treatments using AMARIS trans-epithelial PRK

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Wu-Qiang Shan

2015-12-01

Full Text Available AIM:To evaluate the efficiency and safety of high myopia treatments using AMARIS trans-epithelial photorefractive keratectomy(PRK.METHODS:One hundred and thirty six eyes in 68 patients with high myopic were treated using Amaris trans-epithelial PRK during December 2012～December 2013. Post-operative pain, haze, visual acuity, refraction and intraocular pressure(IOPwere analyzed during 12mo follow-up post-operatively.RESULTS:One hundred and eight eyes in 54 patients felt no discomfort at all, while 28 eyes in 14 patients reported dry eye, slight pain and foreign body sensation. UCVA between the two groups showed statistically different at 3, 6mo and 1a(t=2.04, P=0.047. UCVA at 3mo was the best compared with those at other time pionts, and became stable at 6mo. UCVA of all patients were above 0.8 at 12mo,and had no difference with that before operations(t=1.508, P=0.1670. Haze were hardly seen, and most of them were between grade 0～1. The patients' satisfaction was over 85% according to the survey about night vision, dry eye and asthenopia.CONCLUSION:Because of the great advantages of no-touch, fast recovery and less side effects, trans-epithelial PRK has great efficiency, safety and satisfaction. It now is the most ideal method of surface ablation for high myopia treatments.

Long-term Results of Small-incision Lenticule Extraction in High Myopia

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Yusuf Yıldırım

2016-10-01

Full Text Available Objectives: To evaluate two-year results of small-incision lenticule extraction (SMILE for correction of high myopia. Materials and Methods: Forty-five eyes of 35 patients with mean spherical equivalent (SE of -7.10±0.95 D who underwent routine SMILE by a single surgeon and were followed for at least 2 years were analyzed by retrospective chart review. SMILE was performed with a Visumax femtosecond laser (Carl Zeiss Meditec, Jena, Germany. Follow-up intervals were at 1, 6, 12, and 24 months after surgery. Uncorrected and best corrected distance visual acuity (CDVA, corneal wavefront measurements, and all complications were recorded. Results: After 2 years, 86% of eyes with plano target had an uncorrected distant visual acuity (VA of 20/20 or better. Two percent of eyes lost 1 line of CDVA, while 32% gained 1 line. The mean SE after 2 years was -0.30±0.50 D. Corneal total high-order aberrations (HOA increased from 0.43 to 0.92 μm at postoperative 12 months. There were metallic foreign bodies at the corneal interface in 1 eye of 1 patient which caused no decrease in VA. Conclusion: SMILE for high myopia seems safe and effective in light of two-year follow-up results. The procedure caused a moderate increase in HOA.

MMP-2 participates in the sclera of guinea pig with form-deprivation myopia via IGF-1/STAT3 pathway.

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Liu, Y-X; Sun, Y

2018-05-01

To investigate the expression changes of MMP-2 (matrix metalloproteinases-2) mediated by IGF-1 (insulin-like growth factors-1) STAT3 (signal transducer and activator of transcription 3) pathway in the sclera of the form-deprivation myopia guinea pigs. Twenty-four three-week-old guinea pigs were randomly divided into 4 groups: group A (Control), B, C and D. Guinea pigs in group A were sacrificed after 21 days without any special treatment. Guinea pigs in group B were sacrificed 7 days after receiving stitch in the right eye. Guinea pigs in group C were sacrificed 14 days after receiving stitch in the right eye. Guinea pigs in group D were sacrificed 21 days after receiving stitch in the right eye. Eyeball refraction and axial length of guinea pigs were measured before sacrifice. Eyeballs of guinea pigs were enucleated after sacrifice. The expressions of IGF-1, STAT3 and MMP-2 in scleral tissue were detected by Western blot. Axial length extension and myopia appeared in the right eye of guinea pigs in group B. The expressions of IGF-1, STAT3 and MMP-2 in the sclera significantly increased after 7 days of occlusion compared with that in control group A (pIGF-1, STAT3 and MMP-2 in sclera significantly increased compared with that in group A (pIGF-1, STAT3 and MMP-2 in scleral significantly upregulated 21 days after occlusion (pIGF-1 in sclera were positively correlated (r = 0.962, pIGF-1, STAT3 and MMP-2 in the sclera and myopia of guinea pigs. The expressions of IGF-1, STAT3 and MMP-2 increased progressively over the time of deprivation. Additionally, overexpression of MMP-2 mediated by IGF-1/STAT3 pathway in sclera might promote the formation of myopia.

Short-term outcomes of small-incision lenticule extraction (SMILE) for low, medium, and high myopia.

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Fernández, Joaquín; Valero, Almudena; Martínez, Javier; Piñero, David P; Rodríguez-Vallejo, Manuel

2017-03-10

To determine the safety, efficacy, and predictability of small-incision lenticule extraction at 6-month follow-up, depending on the level of the myopic refractive error. The surgeries were performed by a surgeon new to this technique. Seventy-one subjects with a mean age of 31.86 ± 5.57 years were included in this retrospective observational study. Subjects were divided into 3 groups depending on the preoperative spherical equivalent (SE): low group from -1.00 D to -3.00 D, medium from -3.25 D to -5.00 D, and high from -5.25 D to -7.00 D. Manifest refraction, corrected distance visual acuity (CDVA), and uncorrected distance visual acuity (UDVA) were measured before surgery and at 6 months after the treatment. In total, 1.4% of the eyes lost 1 line of CDVA after the procedure, whereas 95.8% remained unchanged and 2.8% gained 1 line. A significant undercorrection (p = 0.031) was found in the high myopia group (median -0.50 D), whereas the low and medium groups remained near to emmetropia. In terms of efficacy, no statistically significant intergroup differences for postoperative UDVA (p = 0.282) were found. The vector analysis also showed undercorrection of the preoperative cylinder, even though the standard deviations decreased from 0.9 D in the x axis and 0.7 D in the y axis to 0.24 D and 0.27 D, respectively. Small-incision lenticule extraction might be a safe, effective, and predictable procedure even for inexperienced surgeons. No differences in efficacy were found among myopia levels even though undercorrections were found for SE and cylinder in high myopia.

Femtosecond laser based small incision lenticule extraction for moderate and high myopia

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Hjortdal, Jesper Østergaard; Asp, Sven; Ivarsen, Anders

Femtosecond laser based small incision lenticule extraction for moderate and high myopia. Jesper Hjortdal, Sven Asp, Anders Ivarsen, Anders Vestergaard Department of Ophthalmology, Aarhus University Hospital, Denmark Purpose: ReLEx® smile is a new keratorefractive procedure whereby a stromal lent....... Refractive predictability, safety and patient satisfaction at 3 months seems equal to ReLEx flex and FS-LASIK. Optimizing laser energy settings and surgeon experience is important to minimize initial inferior results....

Laser-assisted in-situ keratomileusis (LASIK) versus photorefractive keratectomy (PRK) for myopia.

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Shortt, Alex J; Allan, Bruce D S; Evans, Jennifer R

2013-01-31

Myopia (also known as short-sightedness or near-sightedness) is an ocular condition in which the refractive power of the eye is greater than is required, resulting in light from distant objects being focused in front of the retina instead of directly on it. The two most commonly used surgical techniques to permanently correct myopia are photorefractive keratectomy (PRK) and laser-assisted in-situ keratomileusis (LASIK). To compare the effectiveness and safety of LASIK and PRK for correction of myopia by examining post-treatment uncorrected visual acuity, refractive outcome, loss of best spectacle-corrected visual acuity, pain scores, flap complications in LASIK, subepithelial haze, adverse events, quality of life indices and higher order aberrations. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 11), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to November 2012), EMBASE (January 1980 to November 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to November 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 15 November 2012. We also searched the reference lists of the studies and the Science Citation Index. We included randomised controlled trials comparing LASIK and PRK for the correction of any degree of myopia. Two authors independently assessed trial quality and extracted data. We summarised data using the odds ratio and mean difference. We combined odds ratios using a random-effects model after testing for heterogeneity. We included 13 trials (1135 participants, 1923 eyes

Effects of Foveal Ablation on Emmetropization and Form-Deprivation Myopia

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Smith, Earl L.; Ramamirtham, Ramkumar; Qiao-Grider, Ying; Hung, Li-Fang; Huang, Juan; Kee, Chea-su; Coats, David; Paysse, Evelyn

2009-01-01

Purpose Because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea dominate refractive development. To test this assumption, the authors determined whether an intact fovea was essential for either normal emmetropization or the vision-induced myopic errors produced by form deprivation. Methods In 13 rhesus monkeys at 3 weeks of age, the fovea and most of the perifovea in one eye were ablated by laser photocoagulation. Five of these animals were subsequently allowed unrestricted vision. For the other eight monkeys with foveal ablations, a diffuser lens was secured in front of the treated eyes to produce form deprivation. Refractive development was assessed along the pupillary axis by retinoscopy, keratometry, and A-scan ultrasonography. Control data were obtained from 21 normal monkeys and three infants reared with plano lenses in front of both eyes. Results Foveal ablations had no apparent effect on emmetropization. Refractive errors for both eyes of the treated infants allowed unrestricted vision were within the control range throughout the observation period, and there were no systematic interocular differences in refractive error or axial length. In addition, foveal ablation did not prevent form deprivation myopia; six of the eight infants that experienced monocular form deprivation developed myopic axial anisometropias outside the control range. Conclusions Visual signals from the fovea are not essential for normal refractive development or the vision-induced alterations in ocular growth produced by form deprivation. Conversely, the peripheral retina, in isolation, can regulate emmetropizing responses and produce anomalous refractive errors in response to abnormal visual experience. These results indicate that peripheral vision should be considered when assessing the effects of visual experience on refractive development. PMID:17724167

Phacoemulsificatıon in eyes wıth cataract and high myopia

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Servet Cetinkaya

2015-10-01

Full Text Available ABSTRACTPurpose:To evaluate the outcomes and complications following phacoemulsification surgery in eyes with cataract and high myopia.Methods:We retrospectively evaluated the data of 43 eyes of 28 consecutive patients (12 males, 16 females with cataract and high myopia who had undergone phacoemulsification and intraocular lens (IOL implantation. The mean [± standard deviation (range] age of the patients was 59.20 ± 11.08 (39-77 years.Results:The frequency of nuclear cataract was significantly higher than that of other cataract types (P=0.003. The mean axial length was 28.97 ± 1.99 (26-33 mm and the mean IOL power was 5.09 ± 4.78 (-3.0 to +14.0 diopters (D. The mean preoperative spherical equivalent (SE was -16.48 ± 5.23 (-8.00 to -25.00 D and the mean postoperative SE was -1.46 ± 0.93 (0.00 to -3.00 D (P=0.00. The mean preoperative best-corrected visual acuity (BCVA was 0.91 ± 0.37 (0.30 to -1.50 logMAR and the mean postoperative BCVA was 0.29 ± 0.25 (0.00-1.00 logMAR (P=0.00. Twenty-two eyes (51.2% achieved the target postoperative refraction (±1.0 D. The eyes were divided into 3 groups according to the axial length. The mean biometric error was significantly higher in the group with the greatest axial length than in the other groups (P=0.007. Preoperative argon laser photocoagulation was performed in 7 eyes (16% on account of retinal tears, retinal holes, or lattice degeneration. Postoperatively, retinal tears developed in 2 eyes (4% and were treated with photocoagulation. One eye (2% developed retinal detachment postoperatively, with the patient consequently referred for retinal surgery. Postoperatively, posterior capsule opacities developed in 11 eyes (25%, with all cases treated by laser capsulotomy.Conclusions:Good postoperative outcomes following phacoemulsification surgery were observed in patients with cataract and high myopia. However, clinicians should be aware of the risk of postoperative retinal tears and rhegmatogenous

Phacoemulsificatıon in eyes wıth cataract and high myopia.

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Cetinkaya, Servet; Acir, Nursen Oncel; Cetinkaya, Yasemin Fatma; Dadaci, Zeynep; Yener, Halil İbrahim; Saglam, Faik

2015-01-01

To evaluate the outcomes and complications following phacoemulsification surgery in eyes with cataract and high myopia. We retrospectively evaluated the data of 43 eyes of 28 consecutive patients (12 males, 16 females) with cataract and high myopia who had undergone phacoemulsification and intraocular lens (IOL) implantation. The mean [± standard deviation (range)] age of the patients was 59.20 ± 11.08 (39-77) years. The frequency of nuclear cataract was significantly higher than that of other cataract types (P=0.003). The mean axial length was 28.97 ± 1.99 (26-33) mm and the mean IOL power was 5.09 ± 4.78 (-3.0 to +14.0) diopters (D). The mean preoperative spherical equivalent (SE) was -16.48 ± 5.23 (-8.00 to -25.00) D and the mean postoperative SE was -1.46 ± 0.93 (0.00 to -3.00) D (P=0.00). The mean preoperative best-corrected visual acuity (BCVA) was 0.91 ± 0.37 (0.30 to -1.50) logMAR and the mean postoperative BCVA was 0.29 ± 0.25 (0.00-1.00) logMAR (P=0.00). Twenty-two eyes (51.2%) achieved the target postoperative refraction (±1.0 D). The eyes were divided into 3 groups according to the axial length. The mean biometric error was significantly higher in the group with the greatest axial length than in the other groups (P=0.007). Preoperative argon laser photocoagulation was performed in 7 eyes (16%) on account of retinal tears, retinal holes, or lattice degeneration. Postoperatively, retinal tears developed in 2 eyes (4%) and were treated with photocoagulation. One eye (2%) developed retinal detachment postoperatively, with the patient consequently referred for retinal surgery. Postoperatively, posterior capsule opacities developed in 11 eyes (25%), with all cases treated by laser capsulotomy. Good postoperative outcomes following phacoemulsification surgery were observed in patients with cataract and high myopia. However, clinicians should be aware of the risk of postoperative retinal tears and rhegmatogenous retinal detachment. Preoperative

Clinical and theoretical results of intraocular lens power calculation for cataract surgery after photorefractive keratectomy for myopia.

NARCIS (Netherlands)

Odenthal, M.T.; Eggink, C.A.; Melles, G.R.J.; Pameyer, J.H.; Geerards, A.J.; Beekhuis, W.H.

2002-01-01

OBJECTIVES: To describe the refractive results of cataract surgery after photorefractive keratectomy (PRK) for patients with myopia, and to find a more accurate method to predict intraocular lens (IOL) power in these cases. DESIGN: Nonrandomized, retrospective clinical study. PATIENTS AND METHODS:

Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia

DEFF Research Database (Denmark)

Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

2015-01-01

Purpose: To evaluate and compare long-term outcomes ofafter photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia. Methods: Retrospective single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK...... or LASEK, using a high-frequency flying-spot excimer laser with eye-tracker (MEL80; Carl Zeiss, Jena, Germany). One eye of each patient was randomly chosen for analysis. Re-treated eyes were excluded. Results: Forty-six cPRK patients and 35 LASEK patients were included. Spherical equivalent averaged -7.......69 ± 1.47 diopters (D) in cPRK eyes and -7.98 ± 2.06 D in LASEK eyes (P=0.31) before surgery. Average follow-up time was 4.6 years in cPRK patients and 6.0 years in LASEK patients (PPRK eyes and 1 LASEK eye (P=0.46) had lost 2 lines of corrected distance visual acuity...

Visual quality analysis of femtosecond LASIK and iris location guided mechanical SBK for high myopia

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Hong-Su Jiang

2015-07-01

Full Text Available AIM: To make a analysis of visual quality of iris location guided femtosecond laser assisted in situ keratomi(LASIKand iris location guided mechanical sub-bowman keratomileusis(SBKfor high myopia treatment. METHODS:Femtosecond LASIK(study groupwas performed in 102 eyes of 51 patients with high myopia and 70 eyes of 35 patients were received mechanical SBK(control groupfrom January to October 2013. The spherical refraction of all the patients was from -6.00～-9.50D. Best corrected visual acuity(BCVAof the patients was ≥1.0. Uncorrected visual acuity(UCVA, BCVA, thickness of cornea flap, contrast sensitivity function(CSFand senior ocular aberration were examined in these patients and follow-up was 1a. RESULTS: At 1a after surgery 94.1% UCVA in study group reached ≥1.0 and there was 94.3% in control group. There was no significant difference between two groups(P>0.05. Residual refraction of study group was -0.08±0.10 D and control group was -0.10±0.07 D. There was no significant difference of residual refraction between two groups(P>0.05. C12, C8 of senior ocular aberration and RMSH in study group was less than control group, amplification: 0.1642±0.0519 and 0.2229±0.0382(t=8.077, Pt=0.556, P>0.05. C8 was 0.0950±0.069 and 0.1858±0.095(t=7.261, Pt=12.801, PP>0.05.CONCLUSION: Femtosecond LASIK and mechanical SBK is effective for high myopia. Compared to mechanical SBK, femtosecond LASIK shows more advantages in the senior ocular aberration and visual quality. The cornea flap is more regular from central to peripheral area with femtosecond laser.

Features of cerebral vascular reactivity in patients with different clinical course of a high degree of myopia

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G. V. Shkrebets

2014-07-01

Full Text Available Purpose: to examine the state rate parameters of cerebral and ocular vessels in patients with glaucoma combined with myopia of high degree.Methods: the study involved 3 groups of patients aged 16-32 years: 1st — 30 patients (60 eyes — with a stationary myopia of 6.5 to 9.0 D and normal intraocular pressure (IOP; 2nd — 23 patients (46 eyes — with a high degree of progressive myopia and glaucoma with normalized intraocular pressure during instillation Azopt included 2 subgroups: subgroup A — 14 patients (28 eyes — with ischemic variant of glaucoma; subgroup B — 9 patients (18 eyes — with dyscirculatory variant of glaucoma; 3rd group (control — 10 somatically healthy individuals of similar age. Following a standard ophthalmic examination techniques, as well as color Doppler mapping of the main arteries of the brain and the eyeball on the unit Acuson 128 HR/10 (USA and hypocapnic (with O2 and hypercapnic (CO2 probe.Results: In subgroup 2A patients showed significant (p <0.05 decrease in Vs in the central retinal artery and short posterior cili- ary arteries respectively 38.0% and 32.8% and increase the resistance index (RI of vessels in 21.8% and 22.6%, increase Vs in the middle cerebral artery (MCA at 11.5% and RI by 11.8% compared to the patients the third and first groups, with а hypocapnic test Vs in the MCA decreased by 35.4%, and increased with hypercapnic test for 23.0%; of the subgroup B in central retinal vein to 33.9% and 19.6%, lower Vs and RI in the vertebral artery (VA by 20,0% and 9,1% respectively, with a hypercapnic test Vs in the MCA increased by 32.2%, and decreased during hypocapnic sample at 26.0%.Conclusion: the predominance of the ability of MCA to vasoconstriction combined with reduced blood flow in central retinal artery and short posterior ciliary arteries and cause ischemica variant of glaucoma, slowing blood flow in the vertebrobasilar basin combined with a reduction of venous outflow of the of the

Small Incision Lenticule Extraction (SMILE) vs. Femtosecond Laser in Situ Keratomileusis (FS-LASIK) for treatment of myopia

DEFF Research Database (Denmark)

Hansen, Rasmus Søgaard; Lyhne, Niels; Justesen, Birgitte

Purpose: - 67 ord LASIK has been the dominating corneal refractive procedure for almost two decades, but the new flap-free SMILE procedure has shown promising results. The aim of this study was to evaluate and compare refractive predictability, uncorrected and corrected distance visual acuity (UDVA...... and CDVA), and safety at 1 day, 1 week and 3 months after SMILE and FS-LASIK for all degrees of myopia, but in particular high myopia. Setting: Department of Ophthalmology, Odense University Hospital, Odense, Denmark Methods: - 157 ord Retrospective study of results after SMILE and FS-LASIK for all degrees...... having undergone re-treatment. The SMILE treatments and FS-LASIK flaps were performed with a VisuMax® femtosecond laser (Carl Zeiss-Meditec, Jena, Germany). The FS-LASIK photoablation was performed with a MEL-80 flying-spot excimer laser with eye-tracker (Carl Zeiss-Meditec, Jena, Germany). In SMILE...

The rat with oxygen-induced retinopathy is myopic with low retinal dopamine.

Science.gov (United States)

Zhang, Nan; Favazza, Tara L; Baglieri, Anna Maria; Benador, Ilan Y; Noonan, Emily R; Fulton, Anne B; Hansen, Ronald M; Iuvone, P Michael; Akula, James D

2013-12-19

Dopamine (DA) is a neurotransmitter implicated both in modulating neural retinal signals and in eye growth. Therefore, it may participate in the pathogenesis of the most common clinical sequelae of retinopathy of prematurity (ROP), visual dysfunction and myopia. Paradoxically, in ROP myopia the eye is usually small. The eye of the rat with oxygen-induced retinopathy (OIR) is characterized by retinal dysfunction and short axial length. There have been several investigations of the early maturation of DA in rat retina, but little at older ages, and not in the OIR rat. Therefore, DA, retinal function, and refractive state were investigated in the OIR rat. In one set of rats, the development of dopaminergic (DAergic) networks was evaluated in retinal cross-sections from rats aged 14 to 120 days using antibodies against tyrosine hydroxylase (TH, the rate-limiting enzyme in the biosynthesis of DA). In another set of rats, retinoscopy was used to evaluate spherical equivalent (SE), electoretinography (ERG) was used to evaluate retinal function, and high-pressure liquid chromatography (HPLC) was used to evaluate retinal contents of DA, its precursor levodopamine (DOPA), and its primary metabolite 3,4-dihydroxyphenylacetic acid (DOPAC). The normally rapid postnatal ramification of DAergic neurons was disrupted in OIR rats. Retinoscopy revealed that OIR rats were relatively myopic. In the same eyes, ERG confirmed retinal dysfunction in OIR. HPLC of those eyes' retinae confirmed low DA. Regression analysis indicated that DA metabolism (evaluated by the ratio of DOPAC to DA) was an important additional predictor of myopia beyond OIR. The OIR rat is the first known animal model of myopia in which the eye is smaller than normal. Dopamine may modulate, or fail to modulate, neural activity in the OIR eye, and thus contribute to this peculiar myopia.

Long term results of Epi-LASIK and LASEK for myopia.

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Yuksel, Nilay; Bilgihan, Kamil; Hondur, Ahmet M; Yildiz, Burcin; Yuksel, Erdem

2014-06-01

To evaluate the long term clinical and confocal results of mechanical (Epi-LASIK) versus alcohol-assisted laser epithelial keratomileusis (LASEK) for correction of myopia. Gazi University Medical School, Department of Ophthalmology, Ankara, Turkey. Retrospective study. Twenty-two eyes treated with LASEK and twenty eyes treated with Epi-LASIK were evaluated with a mean follow-up duration of 45 months. Mechanical separation of the epithelium was performed with Lasitome epithelial separator, and alcohol-assisted separation with 25s application of 18% alcohol. Laser ablation was performed with the ESIRIS laser. All patients were examined daily until epithelial closure; at 1, 3, 6, and 12 months; and every year subsequently. Main outcome measures were uncorrected visual acuity (UCVA), manifest refraction, haze, and gray scale value in confocal microscopy, efficacy and safety indexes. Preoperative myopic spherical equivalent refraction was -4.65 ± 1.74 D in the LASEK and -3.87 ± 1.30 D in the Epi-LASIK-treated eyes (p=0.36). Of both LASEK and Epi-LASIK-treated eyes, 95% achieved 20/25 or better final UCVA. The grade of haze and mean gray scale value in confocal microscopy were similar in LASEK and Epi-LASIK-treated eyes at all postoperative periods. The efficacy index was 0.94 in LASEK group and 0.96 in Epi-LASIK group (p=0.44). The safety index was 1.01 in LASEK group and 1.02 in Epi-LASIK group (p=0.42). Both LASEK and Epi-LASIK offer safe and effective correction of myopia in the long term. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Contralateral eye comparison on changes in visual field following laser in situ keratomileusis vs photorefractive keratectomy for myopia: a randomized clinical trial.

Science.gov (United States)

Mostafaei, A; Sedgipour, M R; Sadeghi-Bazargani, H

2009-12-01

Study purpose was to compare the changes of Visual Field (VF) during laser in situ Keratomileusis (LASIK) VS photorefractive keratectomy (PRK). This randomized, double blind, study involved 54 eyes of 27 Myopia patients who underwent LASIK or PRK procedures for contralateral eyes in each patient. Using Humphrey 30-2 SITA standard, the Mean Defect (MD) and Pattern Standard Deviation (PSD) were evaluated preoperatively and three months after surgery. At the same examination optical zone size, papillary and corneal diameters were also evaluated. There was no clinically significant difference in PSD and MD measurements between treated eyes with LASIK or PRK in any zone pre and postoperatively. VF may not be affected by corneal changes induced by LASIK or PRK three months after surgery.

Laser-assisted subepithelial keratectomy (LASEK) versus photorefractive keratectomy (PRK) for correction of myopia.

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Li, Shi-Ming; Zhan, Siyan; Li, Si-Yuan; Peng, Xiao-Xia; Hu, Jing; Law, Hua Andrew; Wang, Ning-Li

2016-02-22

Myopia (near-sightedness or short-sightedness) is a condition in which the refractive power of the eye is greater than required. The most frequent complaint of people with myopia is blurred distance vision, which can be eliminated by conventional optical aids such as spectacles or contact lenses, or by refractive surgery procedures such as photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). PRK uses laser to remove the corneal stroma. Similar to PRK, LASEK first creates an epithelial flap and then replaces it after ablating the corneal stroma. The relative benefits and harms of LASEK and PRK, as shown in different trials, warrant a systematic review. The objective of this review is to compare LASEK versus PRK for correction of myopia by evaluating their efficacy and safety in terms of postoperative uncorrected visual acuity, residual refractive error, and associated complications. We searched CENTRAL (which contains the Cochrane Eyes and Vision group Trials Register) (2015 Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to December 2015), EMBASE (January 1980 to December 2015), Latin American and Caribbean Health Sciences (LILACS) (January 1982 to December 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 15 December 2015. We used the Science Citation Index and searched the reference lists of the included trials to identify relevant trials for this review. We included in this review randomized controlled trials (RCTs) comparing LASEK versus PRK for correction of myopia. Trial participants were 18 years of age or older and had no co

CONTRIBUTION OF A CHOLINERGIC REFLEX MECHANISM TO ALLERGEN-INDUCED BRONCHIAL HYPERREACTIVITY IN PERMANENTLY INSTRUMENTED, UNRESTRAINED GUINEA-PIGS

NARCIS (Netherlands)

SANTING, RE; PASMAN, Y; OLYMULDER, CG; ROFFEL, AF; MEURS, H; ZAAGSMA, J

1 In conscious, permanently instrumented, unrestrained, ovalbumin-sensitized guinea-pigs the development of allergen-induced bronchial hyperreactivity to histamine- and methacholine-inhalation was investigated after the early as well as after the late asthmatic response. 2 The allergen-induced

Clinical study on photorefractive keratectomy for high myopia with mitomycin C

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Hao-Jiang Yang

2013-06-01

Full Text Available AIM: To evaluate the efficacy, safety and stability of photorefractive keratectomy(PRKfor high myopia with 0.2g/L mitomycin C(MMC. METHODS: Totally 109 patients(201 eyesafter PRK were treated with intraoperative application of 0.2g/L MMC for 20 seconds. The recovery of cornea epithelium after surgery was regularly observed. The uncorrected visual acuity(UCVA, corrected distance visual acuity(CDVA, refraction, haze, complications and endothelial cell counts 1 month, 3, 6, 12 months after PRK were compared. RESULTS:The time of corneal epithelium recovery was 3.68±0.35 days. All eyes had a significant increase in UCVA. 12 months after surgery, 189 eyes(94%achieved UCVA better than 1.0 and 153 eyes(76%had a spherical equivalent(SEwithin±0.5D. 7 eyes(3%lost one line of CDVA. No one lost 2 or more lines of CDVA. Ninety-six percent eyes changed within±0.5D when comparing 3 month and 12 month. Postoperative endothelial cell density and coefficient of variability(CVdid not show a significant difference from preoperative measurements(P1=0.71; P2=0.83. Haze of grade 1 occurred in 12 eyes(6%and haze between grade 0.5 and 1 existed in 189 eyes(94%at 12 months. No eye developed haze over grade 2. No toxic effect and complications of MMC were found after surgery. CONCLUSION: PRK with intraoperative application of MMC for 20 seconds appears to be a safe and effective method for correction of high myopia.

Single-step transepithelial ASLA (SCHWIND with mitomycin-C for the correction of high myopia: long term follow-up

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Aslanides IM

2014-12-01

Full Text Available Ioannis M Aslanides, Panagiotis N Georgoudis, Vasilis D Selimis, Achyut N Mukherjee Emmetropia Mediterranean Eye Institute, Heraklion, Crete, Greece Purpose: We wanted to compare the outcomes of single-step modified transepithelial photorefractive keratectomy (tPRK termed a SCHWIND all surface laser ablation (ASLA versus conventional alcohol-assisted photorefractive keratectomy (PRK and laser-assisted in situ keratomileusis (LASIK for the correction of higher myopia of 6.00 diopters (D or more, in an area with high risk of haze due to high intensity of sunlight.Methods: We used a prospective interventional cohort with matched retrospective control groups. Patients with >6 D myopia and <3.5 D of astigmatism were included. All treatments were performed with the SCHWIND Amaris system using aspheric ablation profiles. Mitomycin C was used in all PRK and ASLA cases. Outcomes were postoperative refraction, visual acuity, stability, and complications. The follow-up period was up to 12 months.Results: In total, 101 eyes were included after exclusions. Mean preoperative spherical equivalent refraction was −7.9 D, −8.2 D, and −7.4 D in the ASLA (n=41, PRK (n=29, and LASIK (n=31 groups. Mean postoperative spherical equivalent at 12 months postoperatively was −0.1 (standard deviation [SD]: 0.34, −0.2 (SD: 0.59, and −0.08 (SD: 0.36 in the ASLA, PRK, and LASIK groups, with 91.4%, 85.7%, and 83.9% within 0.5 D of target, respectively. Refractive outcomes and regression at 12 months did not vary among groups (P>0.05. Mean logMAR (logarithm of the minimum angle of resolution uncorrected distance visual acuity at 12 months was 0.00 (SD: 0.05, 0.06 (SD: 0.1, and 0.05 (SD: 0.09 in the ASLA, PRK, and LASIK groups, with significantly better vision in the tPRK group versus LASIK (P=0.01 and PRK (P=0.01 groups.Conclusion: ASLA (SCHWIND tPRK with mitomycin C for high myopia demonstrates comparable refractive outcomes to LASIK and PRK, with relatively

Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia.

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Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob; Grønbech, Keea Treu; Vestergaard, Anders Højslet

2015-07-01

We aimed to evaluate and compare outcomes after photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia. This was a retrospective, single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK or LASEK, using a high-frequency flying-spot excimer laser with eye-tracker (MEL80; Carl Zeiss, Jena, Germany). One eye of each patient was randomly chosen for analysis. Re-treated eyes were excluded. Forty-six cPRK patients and 35 LASEK patients were included. Spherical equivalent averaged -7.69 ± 1.47 diopters (D) in cPRK eyes and -7.98 ± 2.06 D in LASEK eyes (p = 0.31) before surgery. The average follow-up time was 4.6 years in cPRK patients and 6.0 years in LASEK patients (p < 0.05). At final follow-up, no cPRK eyes and one LASEK eye (p = 0.46) had lost two lines of corrected distance visual acuity (CDVA). No eyes had significant haze at final follow-up, although trace haze was found in four cPRK eyes and six LASEK eyes (p = 0.44). However, at 6 weeks after surgery, zero cPRK eyes and nine LASEK eyes (p < 0.05) had significant haze. At final follow-up, 63 % of cPRK eyes and 35 % of LASEK eyes (p = 0.17) were within ±1.0 D of intended refraction. Finally, 100 % of cPRK patients and 92 % of LASEK patients (p = 0.87) were satisfied or very satisfied with the surgery at final follow-up. cPRK and LASEK seemed safe and with high patient satisfaction 4 to 7 years after surgery for high myopia. However, cPRK was more effective than LASEK in reducing initial significant corneal haze.

Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia

NARCIS (Netherlands)

Verhoeven, Virginie J. M.; Hysi, Pirro G.; Wojciechowski, Robert; Fan, Qiao; Guggenheim, Jeremy A.; Höhn, René; Macgregor, Stuart; Hewitt, Alex W.; Nag, Abhishek; Cheng, Ching-Yu; Yonova-Doing, Ekaterina; Zhou, Xin; Ikram, M. Kamran; Buitendijk, Gabriëlle H. S.; McMahon, George; Kemp, John P.; Pourcain, Beate St; Simpson, Claire L.; Mäkelä, Kari-Matti; Lehtimäki, Terho; Kähönen, Mika; Paterson, Andrew D.; Hosseini, S. Mohsen; Wong, Hoi Suen; Xu, Liang; Jonas, Jost B.; Pärssinen, Olavi; Wedenoja, Juho; Yip, Shea Ping; Ho, Daniel W. H.; Pang, Chi Pui; Chen, Li Jia; Burdon, Kathryn P.; Craig, Jamie E.; Klein, Barbara E. K.; Klein, Ronald; Haller, Toomas; Metspalu, Andres; Khor, Chiea-Chuen; Tai, E.-Shyong; Aung, Tin; Vithana, Eranga; Tay, Wan-Ting; Barathi, Veluchamy A.; Chen, Peng; Li, Ruoying; Liao, Jiemin; Zheng, Yingfeng; Bergen, Arthur A. B.; Chen, Wei

2013-01-01

Refractive error is the most common eye disorder worldwide and is a prominent cause of blindness. Myopia affects over 30% of Western populations and up to 80% of Asians. The CREAM consortium conducted genome-wide meta-analyses, including 37,382 individuals from 27 studies of European ancestry and

Ten years after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for moderate to high myopia (control-matched study).

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Alió, J L; Ortiz, D; Muftuoglu, O; Garcia, M J

2009-10-01

To compare the long-term outcomes of photorefractive keratectomy (PRK) and laser in situ keratomilesis (LASIK) for myopia between -6 and -10 D. A retrospective, control-matched study including 68 eyes, 34 which underwent PRK and 34 LASIK, with myopia between -6 and -10 D, operated using the VISX 20/20 excimer laser, was performed. Optical zones of 5.5 to 6 mm were used. All PRK-treated eyes were matched with LASIK-treated eyes of the same age, spherical equivalent within +/-1.25 D, sphere within +/-1.5 D and cylinder within +/-2.5 D. All patients were evaluated 3 months, 1 year, 2 years, 5 years and 10 years after surgery. The main outcomes measures were refractive predictability and stability, safety, efficacy and re-treatment rate. At 10 years, 20 (71%) and 23 (88%) were within +/-1.00 D after PRK and LASIK respectively. The re-treatment rate was 35% and 18% respectively. No eye lost more than two lines of BSCVA in both groups. The efficacy was 0.90 for PRK and 0.95 for LASIK. Both PRK and LASIK were safe for moderate myopia. LASIK demonstrated slightly better efficacy, predictability, and less rate of re-treatment after 10 years. The technical improvements should be taken into account when comparing these results with those obtained more recently.

Instrumentation

Energy Technology Data Exchange (ETDEWEB)

Decreton, M

2001-04-01

SCK-CEN's research and development programme on instrumentation involves the assessment and the development of sensitive measurement systems used within a radiation environment. Particular emphasis is on the assessment of optical fibre components and their adaptability to radiation environments. The evaluation of ageing processes of instrumentation in fission plants, the development of specific data evaluation strategies to compensate for ageing induced degradation of sensors and cable performance form part of these activities. In 2000, particular emphasis was on in-core reactor instrumentation applied to fusion, accelerator driven and water-cooled fission reactors. This involved the development of high performance instrumentation for irradiation experiments in the BR2 reactor in support of new instrumentation needs for MYRRHA, and for diagnostic systems for the ITER reactor.

Instrumentation

International Nuclear Information System (INIS)

Decreton, M.

2001-01-01

SCK-CEN's research and development programme on instrumentation involves the assessment and the development of sensitive measurement systems used within a radiation environment. Particular emphasis is on the assessment of optical fibre components and their adaptability to radiation environments. The evaluation of ageing processes of instrumentation in fission plants, the development of specific data evaluation strategies to compensate for ageing induced degradation of sensors and cable performance form part of these activities. In 2000, particular emphasis was on in-core reactor instrumentation applied to fusion, accelerator driven and water-cooled fission reactors. This involved the development of high performance instrumentation for irradiation experiments in the BR2 reactor in support of new instrumentation needs for MYRRHA, and for diagnostic systems for the ITER reactor

Refractive Outcomes, Contrast Sensitivity, HOAs, and Patient Satisfaction in Moderate Myopia: Wavefront-Optimized Versus Tissue-Saving PRK.

Science.gov (United States)

Nassiri, Nader; Sheibani, Kourosh; Azimi, Abbas; Khosravi, Farinaz Mahmoodi; Heravian, Javad; Yekta, Abasali; Moghaddam, Hadi Ostadi; Nassiri, Saman; Yasseri, Mehdi; Nassiri, Nariman

2015-10-01

To compare refractive outcomes, contrast sensitivity, higher-order aberrations (HOAs), and patient satisfaction after photorefractive keratectomy for correction of moderate myopia with two methods: tissue saving versus wavefront optimized. In this prospective, comparative study, 152 eyes (80 patients) with moderate myopia with and without astigmatism were randomly divided into two groups: the tissue-saving group (Technolas 217z Zyoptix laser; Bausch & Lomb, Rochester, NY) (76 eyes of 39 patients) or the wavefront-optimized group (WaveLight Allegretto Wave Eye-Q laser; Alcon Laboratories, Inc., Fort Worth, TX) (76 eyes of 41 patients). Preoperative and 3-month postoperative refractive outcomes, contrast sensitivity, HOAs, and patient satisfaction were compared between the two groups. The mean spherical equivalent was -4.50 ± 1.02 diopters. No statistically significant differences were detected between the groups in terms of uncorrected and corrected distance visual acuity and spherical equivalent preoperatively and 3 months postoperatively. No statistically significant differences were seen in the amount of preoperative to postoperative contrast sensitivity changes between the two groups in photopic and mesopic conditions. HOAs and Q factor increased in both groups postoperatively (P = .001), with the tissue-saving method causing more increases in HOAs (P = .007) and Q factor (P = .039). Patient satisfaction was comparable between both groups. Both platforms were effective in correcting moderate myopia with or without astigmatism. No difference in refractive outcome, contrast sensitivity changes, and patient satisfaction between the groups was observed. Postoperatively, the tissue-saving method caused a higher increase in HOAs and Q factor compared to the wavefront-optimized method, which could be due to larger optical zone sizes in the tissue-saving group. Copyright 2015, SLACK Incorporated.

ANALYSIS OF THE RESULTS OF PRESBYOPIA CORRECTION WITH APPLICATION OF A BI-ASPHERIC MULTIFOCAL PROFILE ON THE CORNEA BY THE PRK FOR PATIENTS WITH MYOPIA AND HYPEROPIA

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E. N. Eskina

2017-01-01

Full Text Available Purpose. To compare the efficacy, safety and predictability of presbyopia correction by the PRK with application of a bi-aspheric multifocal profile on the cornea with PresbyMax software for patients with hyperopia and myopia.Patients and methods: There were 2 patients group of 25 people each (50 eyes. They were operated with PRK method with application of a multifocal biaspheric profile for simultaneous correction of ametropia and presbyopia. Group I — patients with myopia and presbyopia. Group II — patients with hypermetropia and presbyopia.Results. In the group 1 year post operation binocular DUCVA was 0,93±0,19, NUCVA — 0,86±0,14, IUCVA — 0,67±0,11. Only two eyes (4 % lost DBCVA on the 1–2 lines. Target refraction of a dominant eye — emmetropia was 72 % of patients, 28 % observed myopia of –0,75 D. Target refraction of a nondominant eye was –0,75, 68 % had this result, 28 % had deviation –0,50 D of the target refraction, and 4 % — 1,00 D. In group 2 a year post operation binocular DUCVA was 0,96±0,16, NUCVA — 0,77±0,19, IUCVA — 0,64±0,15. Only two eyes (4 % lost DBCVA on the 1–2 lines. Target refraction of a dominant eye — emmetropia was 72 % of patients, 28 % observed myopia of –0,75 D. Target refraction of a nondominant eye was –0,75, 68 % had this result, 32 % had deviation to –0,75 D of the target refraction.Conclusions. PRK with application of a bi-aspheric multifocal profile on the cornea using PresbyMAX software and µ-monovision is effective for correction myopia and hypermetropia. Simultaneous correction of ametropia and presbyopia by the PRK method with the application of the multifocal biospheric profile to the cornea with the formation of a slight anisometropia (the concept of µ-monovision with the PresbyMax software is an effective, safe and predictable method of surgical intervention, both in myopia and hypermetropia.

Unexpected Genetic Cause in Two Female Siblings with High Myopia and Reduced Visual Acuity

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M. N. Preising

2018-01-01

Full Text Available In daily life, myopia is a frequent cause of reduced visual acuity (VA due to missing or incomplete optical correction. While the genetic cause of high myopia itself is not well understood, a significant number of cases are secondary to hereditary malfunctions or degenerations of the retina. The mechanism by which this occurs remains yet unclear. Two female siblings, 4 y and 2 y, respectively, from a consanguineous Pakistani family were referred to our department for reduced VA and strabismus. Both girls were highly myopic and hence were further examined using standard clinical tests and electroretinography (ERG. The latter confirmed confounded electrical coupling of photoreceptors and bipolar cells. Further inquiry and testing confirmed a similar condition for the father including impaired night vision, reduced VA, photophobia, and an equally characteristic ERG. Findings in the mother were unremarkable. Subsequent genetic analysis of autosomal recessive and X-linked genes for congenital stationary night blindness (CSNB revealed a novel homozygous splice site mutation in CACNA1F in the two girls transmitted from both the father and the mother. While in males the above clinical constellation is a frequent finding, this report, to the authors’ knowledge, is the first demonstrating biallelic mutations at the CACNA1F locus in females.

Orthokeratologic Lens Applications in the Correction of Low to Moderate Myopia

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Emine Kalkan Akçay

2013-12-01

Full Text Available Purpose: To evaluate the efficacy and safety of orthokeratology in patients with low and medium myopia. Material and Method: Twenty six eyes of 6 male and 7 female patients were evaluated prospectively. The mean spherical equivalent was -3.87±1.35 D (-7 - -2.25 in 26 eyes. Individual semi-rigid, gas-permeable night Gelflex lenses (Australia were performed based on keratometry values, ambient pupil, mesopic pupil, and autorefractometry values providing best-corrected visual acuity (BCVA. In all cases, uncorrected and best-corrected visual acuity, refraction, keratometry, corneal topography, slit lamp and intraocular pressure measurements were evaluated on first day, at first week, and at first, third and sixth months. Results: While the mean uncorrected visual acuity (UCVA before orthokeratology (Ortho-K was 1.08±0.24 (0.4-1.3 logMAR, first week after Ortho-K, it was 0.24±0.27 (0-1 logMAR. The BCVA was 0.01±0.07 (0-0.4 logMAR prior and first week after Ortho-K. First week after Ortho-K, it was 0.22 logMAR at right and 1 logMAR at left. While the average UCVA of our cases at first month was 0.11±0.19 (0-0.8 logMAR, the average BCVA at first month was 0.018±0.08 (0-0.4 logMAR. No ophthalmological complications were noted. Discussion: Ortho-K is a safe and effective method for correction of low and moderate myopia in patients who do not prefer surgery and do not wish to wear glasses or contact lenses during the day. (Turk J Ophthalmol 2013; 43: 317-20

LabVIEW-based control software for para-hydrogen induced polarization instrumentation.

Science.gov (United States)

Agraz, Jose; Grunfeld, Alexander; Li, Debiao; Cunningham, Karl; Willey, Cindy; Pozos, Robert; Wagner, Shawn

2014-04-01

The elucidation of cell metabolic mechanisms is the modern underpinning of the diagnosis, treatment, and in some cases the prevention of disease. Para-Hydrogen induced polarization (PHIP) enhances magnetic resonance imaging (MRI) signals over 10,000 fold, allowing for the MRI of cell metabolic mechanisms. This signal enhancement is the result of hyperpolarizing endogenous substances used as contrast agents during imaging. PHIP instrumentation hyperpolarizes Carbon-13 ((13)C) based substances using a process requiring control of a number of factors: chemical reaction timing, gas flow, monitoring of a static magnetic field (Bo), radio frequency (RF) irradiation timing, reaction temperature, and gas pressures. Current PHIP instruments manually control the hyperpolarization process resulting in the lack of the precise control of factors listed above, resulting in non-reproducible results. We discuss the design and implementation of a LabVIEW based computer program that automatically and precisely controls the delivery and manipulation of gases and samples, monitoring gas pressures, environmental temperature, and RF sample irradiation. We show that the automated control over the hyperpolarization process results in the hyperpolarization of hydroxyethylpropionate. The implementation of this software provides the fast prototyping of PHIP instrumentation for the evaluation of a myriad of (13)C based endogenous contrast agents used in molecular imaging.

LabVIEW-based control software for para-hydrogen induced polarization instrumentation

International Nuclear Information System (INIS)

Agraz, Jose; Grunfeld, Alexander; Li, Debiao; Cunningham, Karl; Willey, Cindy; Pozos, Robert; Wagner, Shawn

2014-01-01

The elucidation of cell metabolic mechanisms is the modern underpinning of the diagnosis, treatment, and in some cases the prevention of disease. Para-Hydrogen induced polarization (PHIP) enhances magnetic resonance imaging (MRI) signals over 10 000 fold, allowing for the MRI of cell metabolic mechanisms. This signal enhancement is the result of hyperpolarizing endogenous substances used as contrast agents during imaging. PHIP instrumentation hyperpolarizes Carbon-13 ( 13 C) based substances using a process requiring control of a number of factors: chemical reaction timing, gas flow, monitoring of a static magnetic field (B o ), radio frequency (RF) irradiation timing, reaction temperature, and gas pressures. Current PHIP instruments manually control the hyperpolarization process resulting in the lack of the precise control of factors listed above, resulting in non-reproducible results. We discuss the design and implementation of a LabVIEW based computer program that automatically and precisely controls the delivery and manipulation of gases and samples, monitoring gas pressures, environmental temperature, and RF sample irradiation. We show that the automated control over the hyperpolarization process results in the hyperpolarization of hydroxyethylpropionate. The implementation of this software provides the fast prototyping of PHIP instrumentation for the evaluation of a myriad of 13 C based endogenous contrast agents used in molecular imaging

Z-LASIK and Trans-PRK for correction of high-grade myopia: safety, efficacy, predictability and clinical outcomes.

Science.gov (United States)

Gershoni, Assaf; Mimouni, Michael; Livny, Eitan; Bahar, Irit

2018-03-12

The aim of the study was to examine the outcomes of transepithelial photorefractive keratectomy (Trans-PRK) and Femtosecond Laser-assisted in situ keratomileusis (Z-LASIK) for the correction of high myopia. A retrospective cohort study design was used. The study group included 792 eyes with high-grade myopia (- 6.0 diopters or higher) or high-grade myopia with astigmatism that were treated with Z-LASIK or Trans-PRK in 2013 through 2014 in an optical outpatient clinic of a large private medical service. The Trans-PRK group comprised of 674 eyes with a spherical equivalent (SE) of - 7.87 ± 1.46 and the Z-LASIK group comprised of 118 eyes with a SE of - 7.19 ± 0.81 (P PRK group was - 0.06 and - 0.02 in the Z-LASIK group (P = 0.545). Efficacy index values were 0.92 in the Trans-PRK group and 0.95 in the Z-LASIK group (P = 0.083), and corresponding safety index values were 0.95 and 0.97 (P = 0.056). An UCVA of 20/40 or better was achieved in 94.20% of eyes in the Trans-PRK group, and 98.31% in the Z-LASIK group (P = 0.063). The majority of eyes in both the Trans-PRK and Z-LASIK groups were within ± 0.5D of attempted correction: 59.35 and 64.71%, respectively (P = 0.271). Both Trans-PRK and Z-LASIK demonstrated excellent efficacy, safety and predictability profiles, with results comparable and in some cases superior to the current literature. Results of Z-LASIK were slightly better than those of Trans-PRK, though the preoperative SE of the latter was higher.

Femtosecond-Assisted LASIK Versus PRK: Comparison of 6-Month Visual Acuity and Quality Outcome for High Myopia.

Science.gov (United States)

Hashemi, Hassan; Miraftab, Mohammad; Ghaffari, Reza; Asgari, Soheila

2016-11-01

To compare the results of femtosecond-assisted laser in situ keratomileusis (femto-LASIK) and photorefractive keratectomy with mitomycin C (PRK-MMC) for the correction of myopia more than 7.0 diopters (D). In this comparative nonrandomized trial, 60 eyes (30 eyes in each group) were enrolled. Patients were tested for uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, ocular and corneal aberrations, and contrast sensitivity (CS) before surgery and at 3 and 6 months postoperatively. Mean preoperative myopia was -8.65±1.51 and -8.04±1.70 D in the femto-LASIK and PRK-MMC groups, respectively (P=0.149). Intergroup differences in baseline indices were not statistically significant. At 6 months after surgery, UDVA showed an improving trend, but it was better in the femto-LASIK group (P=0.026). CDVA in the two groups remained similarly unchanged (P=0.170). For the femto-LASIK and PRK-MMC groups, the safety indices were 1.01±0.05 and 1.01±0.14 (P=0.949), respectively, and the efficacy indices were 0.99±0.07 and 0.93±0.22 (P=0.192), respectively. Comparing CS, only CS18 showed a significantly greater decrease in the femto-LASIK group compared with the PRK-MMC group (P=0.016). Intergroup differences were not statistically significant in other spatial frequencies. Changes in the ocular and corneal higher order aberrations were not statistically different between the two groups except ocular coma, which increased in the femto-LASIK group (P=0.041). Femto-LASIK improves UDVA better than PRK-MMC in high myopia. However, because of increased coma, the quality of vision is reduced. In other words, visual acuity outcome is better with femto-LASIK and visual quality outcome is better with PRK-MMC.

[Peripheral refraction and retinal contour in children with myopia by results of refractometry and partial coherence interferometry].

Science.gov (United States)

Tarutta, E P; Milash, S V; Tarasova, N A; Romanova, L I; Markosian, G A; Epishina, M V

2014-01-01

To determine the posterior pole contour of the eye based on the relative peripheral refractive error and relative eye length. A parallel study was performed, which enrolled 38 children (76 eyes) with myopia from -1.25 to -10.82 diopters. The patients underwent peripheral refraction assessment with WR-5100K Binocular Auto Refractometer ("Grand Seiko", Japan) and partial coherence tomography with IOLMaster ("Carl Zeiss", Germany) for the relative eye length in areas located 15 and 30 degrees nasal and temporal from the central fovea along the horizontal meridian. In general, refractometry and interferometry showed high coincidence of defocus signs and values for the areas located 15 and 30 degrees nasal as well as 15 degrees temporal from the fovea. However, in 41% of patients defocus signs determined by the two methods mismatched in one or more areas. Most of the mismatch cases were mild myopia. We suppose that such a mismatch is caused by optical peculiarities of the anterior eye segment that have an impact on refractometry results.

The Charles F. Prentice Award Lecture 2010: A Case for Peripheral Optical Treatment Strategies for Myopia

Science.gov (United States)

Smith, Earl L.

2011-01-01

It is well established that refractive development is regulated by visual feedback. However, most optical treatment strategies designed to reduce myopia progression have not produced the desired results, primarily because some of our assumptions concerning the operating characteristics of the vision-dependent mechanisms that regulate refractive development have been incorrect. In particular, because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea determine the effects of vision on refractive development. However, experiments in laboratory animals demonstrate that ocular growth and emmetropization are mediated by local retinal mechanisms and that foveal vision is not essential for many vision-dependent aspects of refractive development. On the other hand, the peripheral retina, in isolation, can effectively regulate emmetropization and mediate many of the effects of vision on the eye’s refractive status. Moreover, when there are conflicting visual signals between the fovea and the periphery, peripheral vision can dominate refractive development. The overall pattern of results suggests that optical treatment strategies for myopia that take into account the effects of peripheral vision are likely to be more successful than strategies that effectively manipulate only central vision. PMID:21747306

Expression of Wnt/β-Catenin Signaling Pathway and Its Regulatory Role in Type I Collagen with TGF-β1 in Scleral Fibroblasts from an Experimentally Induced Myopia Guinea Pig Model

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Min Li

2016-01-01

Full Text Available Background. To investigate Wnt/β-catenin signaling pathway expression and its regulation of type I collagen by TGF-β1 in scleral fibroblasts from form-deprivation myopia (FDM guinea pig model. Methods. Wnt isoforms were examined using genome microarrays. Scleral fibroblasts from FDM group and self-control (SC group were cultured. Wnt isoforms, β-catenin, TGF-β1, and type I collagen expression levels were examined in the two groups with or without DKK-1 or TGF-β1 neutralizing antibody. Results. For genome microarrays, the expression of Wnt3 in FDM group was significantly greater as confirmed in retinal and scleral tissue. The expression of Wnt3 and β-catenin significantly increased in FDM group and decreased significantly with DKK-1. TGF-β1 expression level decreased significantly in FDM group and increased significantly with DKK-1. Along with morphological misalignment inside and outside cells, the amount of type I collagen decreased in FDM group. Furthermore, type I collagen increased and became regular in DKK-1 intervention group, whereas it decreased and rearranged more disorder in TGF-β1 neutralizing antibody intervention group. Conclusions. The activation of Wnt3/β-catenin signaling pathway was demonstrated in primary scleral fibroblasts in FDM. This pathway further reduced the expression of type I collagen by TGF-β1, which ultimately played a role in scleral remodeling during myopia development.

Laser-assisted subepithelial keratectomy (LASEK) versus laser-assisted in-situ keratomileusis (LASIK) for correcting myopia.

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Kuryan, Jocelyn; Cheema, Anjum; Chuck, Roy S

2017-02-15

Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia can be treated with spectacles, contact lenses, or refractive surgery. Options for refractive surgery include laser-assisted subepithelial keratectomy (LASEK) and laser-assisted in-situ keratomileusis (LASIK). Both procedures utilize a laser to shape the corneal tissue (front of the eye) to correct refractive error, and both create flaps before laser treatment of corneal stromal tissue. Whereas the flap in LASEK is more superficial and epithelial, in LASIK it is thicker and also includes some anterior stromal tissue. LASEK is considered a surface ablation procedure, much like its predecessor, photorefractive keratectomy (PRK). LASEK was developed as an alternative to PRK to address the issue of pain associated with epithelial debridement used for PRK. Assessing the relative benefits and risks/side effects of LASEK and LASIK warrants a systematic review. To assess the effects of LASEK versus LASIK for correcting myopia. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register (2016, Issue 10); MEDLINE Ovid (1946 to 24 October 2016); Embase.com (1947 to 24 October 2016); PubMed (1948 to 24 October 2016); LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 24 October 2016); the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), last searched 20 June 2014; ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 October 2016; and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 October 2016. We did not use any date or language restrictions in the electronic searches for trials. We considered only randomized controlled trials (RCTs) for the purposes of this review. Eligible RCTs were those in which myopic participants were

An angle-supported foldable phakic intraocular lens for correction of myopia: A five-year follow-up.

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Alió, J L; Plaza-Puche, A B; Cavas, F; Yébana Rubio, P; Sala, E

2017-01-01

To evaluate the efficacy and safety of an angle-supported foldable phakic intraocular lens (pIOL) for the correction of moderate to high myopia after 5 years follow-up. Prospective and retrospective, observational, longitudinal, non-randomised consecutive series of cases conducted on a total of 100 eyes of 67 patients with moderate to high myopia implanted with an Acrysof Cachet pIOL (Alcon Laboratories Inc.) with the aim of minimising the refractive error. The ages ranged between 18 to 60years. Uncorrected distance visual acuity (UDVA), manifest refraction, corrected distance visual acuity (CDVA), endothelial cells density, pIOL position, intraocular pressure, and complications were recorded preoperatively and during the 5 year follow-up. Five years after implantation, the mean manifest spherical equivalent refraction reduced significantly from -11.62±3.35 dioptres (D) to -0.33±0.85D. UDVA was 20/20 or better in 5 of 25 cases (20%), and 20/40 or better in 22 cases (88%). CDVA was 20/20 or better in 17 cases (68%), and 20/32 or better in 23 cases (92%) of eyes. The residual refractive error was within ±0.50D of emmetropia in 12 cases (48%), and within ±1.00D in 19 cases (76%). Mean endothelial cell loss at 5 years was 11.8% central, and 13.7% peripheral. Mean endothelium-pIOL distance was 2.11±0.18mm, and mean pIOL-crystalline distance was 0.88±0.20mm. This angle supported pIOL provided a favourable refractive correction and predictability, as well as acceptable safety in patients with moderate to high myopia. Although endothelial cell density decreased over 5years, the results are within the range reported in previous studies with other pIOLs. Copyright © 2016 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.

Research results of application of reflexo-therapy in correction of myopia

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Agasarov L.G.

2011-09-01

Full Text Available Objective: To develop the optimum scheme of acupuncture, aimed at improving the functional status of the visual analyzer in patients with myopia. Materials. Treatment was conducted in the main group by reflexology courses in 10 procedures and basic therapy in the control group, only basic therapy. The examination included the classic ophthal-mologic research methods, ultrasound and Doppler echoofthalmografy with color mapping of blood vessels — the ophthalmic artery (OA, central retinal artery (CRA and posterior long ciliary arteries (ZDTSA, the study of visual efficiency and visual assessment of the subjective expression of asthenopia. The results of these studies were subjected to statistical analysis using the method of variation statistics with the computation of the arithmetic mean (M, the average error of the arithmetic mean (m and the level of significance (p. Differences between mean values were considered significant if the probability of errors on the distribution of Student»s less than 0,05. The result showed a pronounced effect method of acupuncture on the clinical features, hemodynamic and ergonomic eye, the severity of visual fatigue and general condition of patients. Conclusion. The use of corporal-auricular acupuncture technique in patients with myopia allowed to increase the visual acuity without correction in 1,6 times, visual acuity with correction in 1,2 times, lower rates of subjective and objective refraction in an average of 29.8 and 32.4%, increase rates of accommodation of more than 1,5 times, to increase blood flow velocity characteristics in the GA by an average of 9.7, the CAC at 33.4 and ZDTSA by 27,5%. All this is possible to reduce the severity of subjective indicators of asthenopia in 58% of cases and to increase visual efficiency by 11,3%

Laser-induced emission, fluorescence and Raman hybrid setup: A versatile instrument to analyze materials from cultural heritage

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Syvilay, D.; Bai, X. S.; Wilkie-Chancellier, N.; Texier, A.; Martinez, L.; Serfaty, S.; Detalle, V.

2018-02-01

The aim of this research project was the development of a hybrid system in laboratory coupling together three analytical techniques, namely laser-induced breakdown spectroscopy (LIBS), laser-induced fluorescence (LIF) and Raman spectroscopy in a single instrument. The rationale for combining these three spectroscopies was to identify a material (molecular and elemental analysis) without any preliminary preparation, regardless of its organic or inorganic nature, on the surface and in depth, without any surrounding light interference thanks to time resolution. Such instrumentation would allow characterizing different materials from cultural heritage. A complete study on LIBS-LIF-Raman hybrid was carried out, from its conception to instrumental achievement, in order to elaborate a strategy of analysis according to the material and to be able to address conservation issues. From an instrumental point of view, condensing the three spectroscopies was achieved by using a single laser for excitation and two spectrometers (time-integrated and not time-integrated) for light collection. A parabolic mirror was used as collecting system, while three excitation sources directed through this optical system ensured the examination of a similar probe area. Two categories of materials were chosen to test the hybrid instrumentation on cultural heritage applications (copper corrosion products and wall paintings). Some examples are reported to illustrate the wealth of information provided by the hybrid, thus demonstrating its great potential to be used for cultural heritage issues. Finally, several considerations are outlined aimed at further improving the hybrid.

Single-Step Transepithelial PRK vs Alcohol-Assisted PRK in Myopia and Compound Myopic Astigmatism Correction

OpenAIRE

Kaluzny, Bartlomiej J.; Cieslinska, Iwona; Mosquera, Samuel A.; Verma, Shwetabh

2016-01-01

Abstract Transepithelial photorefractive keratectomy (tPRK), where both the epithelium and stroma are removed in a single-step, is a relatively new procedure of laser refractive error correction. This study compares the 3-month results of myopia and compound myopic astigmatism correction by tPRK or conventional alcohol-assisted PRK (aaPRK). This prospective, nonrandomized, case?control study recruited 148 consecutive patients; 93 underwent tPRK (173 eyes) and 55 aaPRK (103 eyes). Refractive r...

Laser subepithelial keratomileusis for myopia of -6 to -10 diopters with astigmatism with the MEL60 laser.

Science.gov (United States)

Bilgihan, Kamil; Hondur, Ahmet; Hasanreisoglu, Berati

2004-01-01

To evaluate the efficacy, predictability, and safety of laser subepithelial keratomileusis (LASEK) for treatment of high myopia with astigmatism. LASEK was performed in 61 eyes of 36 consecutive patients with myopic spherical equivalent refraction of -6.00 to -10.00 D using the Aesculap-Meditec MEL60 excimer laser. Data were collected prospectively with a follow-up of 6 to 17 months. Main outcome measures recorded were UCVA, BSCVA, residual refractive error, corneal haze, and complications. Ninety-six percent of eyes achieved 20/40 or better UCVA at 1 month. At 12 months, 64% of eyes achieved 20/20 and 92% achieved 20/40 or better UCVA. Two eyes lost 2 lines of BSCVA at 6 or 12 months. Accuracy of correction was +/- 0.50 D from emmetropia in 82% of eyes, and +/- 1.00 D in 90% at 12 months. No eye showed more than grade 1 haze. Grade 1 haze was observed in three eyes at 12 months. One patient had mild postoperative keratitis, which was successfully treated. LASEK with the Aesculap-Meditec MEL60 excimer laser appeared to be safe, effective, and highly predictable in treating high myopia.

EVALUATION OF PATCHY ATROPHY SECONDARY TO HIGH MYOPIA BY SEMIAUTOMATED SOFTWARE FOR FUNDUS AUTOFLUORESCENCE ANALYSIS.

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Miere, Alexandra; Capuano, Vittorio; Serra, Rita; Jung, Camille; Souied, Eric; Querques, Giuseppe

2017-05-31

To evaluate the progression of patchy atrophy in high myopia using semiautomated software for fundus autofluorescence (FAF) analysis. The medical records and multimodal imaging of 21 consecutive highly myopic patients with macular chorioretinal patchy atrophy (PA) were retrospectively analyzed. All patients underwent repeated fundus autofluorescence and spectral domain optical coherence tomography over at least 12 months. Color fundus photography was also performed in a subset of patients. Total atrophy area was measured on FAF images using Region Finder semiautomated software embedded in Spectralis (Heidelberg Engineering, Heidelberg, Germany) at baseline and during follow-up visits. Region Finder was compared with manually measured PA on FAF images. Twenty-two eyes of 21 patients (14 women, 7 men; mean age 62.8 + 13.0 years, range 32-84 years) were included. Mean PA area using Region Finder was 2.77 ± 2.91 SD mm at baseline, 3.12 ± 2.68 mm at Month 6, 3.43 ± 2.68 mm at Month 12, and 3.73 ± 2.74 mm at Month 18 (overall P autofluorescence analysis by Region Finder semiautomated software provides accurate measurements of lesion area and allows us to quantify the progression of PA in high myopia. In our series, PA enlarged significantly over at least 12 months, and its progression seemed to be related to the lesion size at baseline.

Corneal Epithelial Remodeling and Its Effect on Corneal Asphericity after Transepithelial Photorefractive Keratectomy for Myopia

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Jie Hou

2016-01-01

Full Text Available Purpose. To evaluate the changes in epithelial thickness profile following transepithelial photorefractive keratectomy (T-PRK for myopia and to investigate the effect of epithelial remodeling on corneal asphericity. Methods. Forty-four patients (44 right eyes who underwent T-PRK were retrospectively evaluated. Epithelial thickness was measured using spectral-domain optical coherence tomography at different corneal zones (central, 2 mm; paracentral, 2–5 mm; and mid-peripheral, 5-6 mm preoperatively and at 1 week and 1, 3, and 6 months postoperatively. The correlation between the changes in corneal epithelial thickness (ΔCET and postoperative Q-value changes (ΔQ was analyzed 6 months postoperatively. Results. Epithelial thickness at 6 months showed a negative meniscus-like lenticular pattern with less central thickening, which increased progressively toward the mid-periphery (3.69±4.2, 5.19±3.8, and 6.23±3.9 μm at the center, paracenter, and mid-periphery, resp., P<0.01. A significant positive relationship was observed between epithelial thickening and ΔQ 6 months postoperatively (r=0.438, 0.580, and 0.504, resp., P<0.01. Conclusions. Significant epithelial thickening was observed after T-PRK and showed a lenticular change with more thickening mid-peripherally, resulting in increased oblateness postoperatively. Epithelial remodeling may modify the epithelial thickness profile after surface ablation refractive surgery for myopia.

[Electrostimulation and magnetic therapy in the treatment of accommodation cramp and in the prevention of progressive myopia in children and adolescents].

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Riabtseva, A A; Gerasimenko, M Iu; Savina, M M; Filatova, E V

2002-01-01

The paper presents a procedure and results of use of electrostimulation, magnetic therapy, and electrophoresis during treatment for accommodation cramp and in the prevention of myopia in children and adolescents. Data that characterize the dynamics and stability of achieved results are given.

An improved Peltier effect-based instrument for critical temperature threshold measurement in cold- and heat-induced urticaria.

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Magerl, M; Abajian, M; Krause, K; Altrichter, S; Siebenhaar, F; Church, M K

2015-10-01

Cold- and heat-induced urticaria are chronic physical urticaria conditions in which wheals, angioedema or both are evoked by skin exposure to cold and heat respectively. The diagnostic work up of both conditions should include skin provocation tests and accurate determination of critical temperature thresholds (CTT) for producing symptoms in order to be able to predict the potential risk that each individual patient faces and how this may be ameliorated by therapy. To develop and validate TempTest(®) 4, a simple and relatively inexpensive instrument for the accurate determination of CTT which may be used in clinical practice. TempTest(®) 4 has a single 2 mm wide 350 mm U-shaped Peltier element generating a temperature gradient from 4 °C to 44 °C along its length. Using a clear plastic guide placed over the skin after provocation, CTT values may be determined with an accuracy of ±1 °C. Here, TempTest(®) 4 was compared with its much more expensive predecessor, TempTest(®) 3, in inducing wheals in 30 cold urticaria patients. Both TempTest(®) 4 and TempTest(®) 3 induced wheals in all 30 patients between 8 ° and 28 °C. There was a highly significant (P < 0.0001) correlation between the instruments in the CTT values in individual patients. The TempTest(®) 4 is a simple, easy to use, licensed, commercially available and affordable instrument for the determination of CTTs in both cold- and heat-induced urticaria. © 2014 European Academy of Dermatology and Venereology.

Improvement of uncorrected visual acuity (UCVA and contrast sensitivity (UCCS with perceptual learning and transcranial random noise stimulation (tRNS in individuals with mild myopia

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Rebecca eCamilleri

2014-10-01

Full Text Available Perceptual learning has been shown to produce an improvement of visual acuity (VA and contrast sensitivity (CS both in subjects with amblyopia and refractive defects such as myopia or presbyopia. Transcranial random noise stimulation (tRNS has proven to be efficacious in accelerating neural plasticity and boosting perceptual learning in healthy participants. In this study we investigated whether a short behavioural training regime using a contrast detection task combined with online tRNS was as effective in improving visual functions in participants with mild myopia compared to a two-month behavioural training regime without tRNS (Camilleri et al., 2014. After two weeks of perceptual training in combination with tRNS, participants showed an improvement of 0.15 LogMAR in uncorrected VA (UCVA that was comparable with that obtained after eight weeks of training with no tRNS, and an improvement in uncorrected CS (UCCS at various spatial frequencies (whereas no UCCS improvement was seen after eight weeks of training with no tRNS. On the other hand, a control group that trained for two weeks without stimulation did not show any significant UCVA or UCCS improvement. These results suggest that the combination of behavioural and neuromodulatory techniques can be fast and efficacious in improving sight in individuals with mild myopia.

Comparison of ReLEx SMILE and PRK in terms of visual and refractive outcomes for the correction of low myopia.

Science.gov (United States)

Ganesh, Sri; Brar, Sheetal; Patel, Utsav

2018-06-01

To compare the objective and subjective quality of vision after femtosecond laser-assisted small incision lenticule extraction (SMILE) and photorefractive keratectomy (PRK) for low myopia. One hundred and twenty eyes from 60 patients (34 females, 26 males) undergoing bilateral correction of low myopia (≤-4 D SE) with either ReLEx SMILE or PRK were included. Visual acuity, contrast sensitivity and higher-order aberrations were recorded preoperatively and compared postoperatively. A quality of vision questionnaire was scored and analyzed 3 months postoperatively. At 3 months, the SMILE group had significantly better uncorrected and corrected distant visual acuity (CDVA), compared to PRK group (p = 0.01). Post-op spherical equivalent (SE) was comparable in both groups (SMILE = -0.15 ± 0.19 D, PRK = -0.14 ± 0.23 D, p = 0.72). However, SE predictability was better in SMILE group with 97% eyes within ±0.05 D compared to 93% eyes in the PRK group. Total higher-order aberrations (HOAs) were significantly higher in PRK compared to the SMILE group (p = 0.022). The SMILE group demonstrated slightly better contrast sensitivity, which was significant at spatial frequency of 12 cpd (p = 0.03). Four eyes in the PRK group had loss of CDVA by one line due to mild haze. Both SMILE and PRK were effective procedures for correction of low myopia. However, SMILE offered superior quality of vision and patient satisfaction due to better postoperative comfort and lower induction of aberrations at 3 months.

Refractive lenticule extraction (ReLEx through a small incision (SMILE for correction of myopia and myopic astigmatism: current perspectives

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Ağca A

2016-10-01

Full Text Available Alper Ağca,1 Ahmet Demirok,2 Yusuf Yıldırım,1 Ali Demircan,1 Dilek Yaşa,1 Ceren Yeşilkaya,1 İrfan Perente,1 Muhittin Taşkapılı1 1Beyoğlu Eye Research and Training Hospital, 2Department of Ophthalmology, Istanbul Medeniyet University, Istanbul, Turkey Abstract: Small-incision lenticule extraction (SMILE is an alternative to laser-assisted in situ keratomileusis (LASIK and photorefractive keratectomy (PRK for the correction of myopia and myopic astigmatism. SMILE can be performed for the treatment of myopia ≤-12 D and astigmatism ≤5 D. The technology is currently only available in the VisuMax femtosecond laser platform. It offers several advantages over LASIK and PRK; however, hyperopia treatment, topography-guided treatment, and cyclotorsion control are not available in the current platform. The working principles, potential advantages, and disadvantages are discussed in this review. Keywords: SMILE, small-incision lenticule extraction, femtosecond laser, laser in situ keratomileusis, corneal biomechanics

[Transcultural adaptation of an instrument to evaluate hearing handicap in workers with noise-induced hearing loss].

Science.gov (United States)

Holanda, Wanessa Tenório Gonçalves; de Lima, Maria Luiza Carvalho; Figueiroa, José Natal

2011-01-01

The noise-induced hearing loss (NIHL) is a chronic and irreversible disease resulting of the exposure to noise in high levels at work. Even in the beginning, this hearing loss can damage in many degrees the worker's quality of life. Before this study, there wasn't an instrument, in Portuguese, to evaluate the psychosocial disadvantages of workers with NIHL. The aim of this research was to make a transcultural adaptation of an especific instrument to evaluate the hearing handicap from the original language to Portuguese, and check the reliability and legitimacy. The selected instrument passed by a process of semantic equivalence that was conducted in five stages: translation, back translation, critical appraisal of the versions, pre-test and a final review by a multi-professional group to develop a consensual version of the instrument for current use in Brazil. The instrument called "Inabilities Scale and Hearing Handicap" had, in general, acceptable psychometric measures, considering the little size of the sample and the fact that workers' hearing loss weren't too significant. Therefore, the Portuguese version of this instrument needs to be further tested in a representative sample of Brazilian workers with NIHL to ratify its utility in order to evaluate hearing handicap in this population.

Harvard ER-2 OH laser-induced fluorescence instrument

Science.gov (United States)

Wennberg, Paul O.; Anderson, James G.

1994-01-01

The Harvard ER-2 OH instrument is scheduled to be integrated into the NASA ER-2 high altitude aircraft ozone payload in August 1992. Design and fabrication is presently underway. This experiment is a descendant of a balloon borne instrument designed and built in the mid-1980s. The ER-2 instrument is being designed to measure OH and HO2 as part of the NASA ozone payload for the investigation of processes controlling the concentration of stratospheric ozone. Although not specifically designed to do so, it is hoped that valid measurements of OH and HO2 can be made in the remote free troposphere with this instrument.

Evaluation of the effectiveness of laser in situ keratomileusis and photorefractive keratectomy for myopia : A meta-analysis

OpenAIRE

Yang, Xin-Jun; Yan, Hong-Tao; Nakahori, Yutaka

2003-01-01

Objective: To evaluate the effectiveness of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for correcting myopia. Methods : Study selection, data extraction, and quality assessment were performed by two of authors independently. Summary odds ratios and 95% confidence intervals were calculated by DerSimonian amp Laird random-effects model and Mantel-Haenszel (fixed-effects) model. All calculations were based on an intention-to-treat and per protocol analysis. Result...

Large scale international replication and meta-analysis study confirms association of the 15q14 locus with myopia. The CREAM consortium

NARCIS (Netherlands)

V.J.M. Verhoeven (Virginie); P.G. Hysi (Pirro); S-M. Saw (Seang-Mei); V. Vitart (Veronique); A. Mirshahi (Alireza); J. Guggenheim (Jean); M.F. Cotch (Mary Frances); K. Yamashiro (Kenji); P.N. Baird (Paul); D.A. Mackey (David); R. Wojciechowski (Robert); M.K. Ikram (Kamran); A.W. Hewit (Alex); P. Duggal (Priya); S. Janmahasatian (Sarayut); C.C. Khor; Q. Fan (Qiao); X. Zhou (Xinying); T.L. Young (Terri); E.S. Tai (Shyong); L.-K. Goh; Y.J. Li (Yi); T. Aung (Tin); E.N. Vithana (Eranga); Y.Y. Teo (Yik Ying); W.-T. Tay; X. Sim (Xueling); I. Rudan (Igor); C. Hayward (Caroline); A.F. Wright (Alan); O. Polasek (Ozren); H. Campbell (Harry); J.F. Wilson (James); B. Fleck (Brian); I. Nakata (Isao); N. Yoshimura; R. Yamada (Ryo); F. Matsuda (Fumihiko); K. Ohno-Matsui (Kyoko); A. Nag (Abhishek); G. Mcmahon (George); B. St Pourcain (Beate); Y. Lu (Yi); J.S. Rahi (Jugnoo); P. Cumberland (Phillippa); S. Bhattacharya (Shoumo); C.L. Simpson (Claire); L.D. Atwood (Larry); X. Li (Xiaohui); L.J. Raffel (Leslie); D. Murgia (Daniela); L. Portas (Laura); D.D.G. Despriet (Dominique); L.M.E. van Koolwijk (Leonieke); C. Wolfram (Christian); K.J. Lackner (Karl); A. Tönjes (Anke); R. Mägi (Reedik); T. Lehtimäki (Terho); M. Kähönen (Mika); T. Esko (Tõnu); A. Metspalu (Andres); T. Rantanen (Taina); O. Pärssinen (Olavi); B.E.K. Klein (Barbara); T. Meitinger (Thomas); T.D. Spector (Timothy); B.A. Oostra (Ben); G.D. Smith; P.T.V.M. de Jong (Paulus); A. Hofman (Albert); N. Amin (Najaf); L.C. Karssen (Lennart); F. Rivadeneira Ramirez (Fernando); J.R. Vingerling (Hans); G. Eiriksdottir (Gudny); V. Gudnason (Vilmundur); A. Döring (Angela); T. Bettecken (Thomas); A.G. Uitterlinden (André); C. Williams (Cathy); T. Zeller (Tanja); R. Castagne (Raphaële); K. Oexle (Konrad); C.M. van Duijn (Cornelia); S.K. Iyengar (Sudha); P. Mitchell (Paul); J.J. Wang (Jie Jin); R. Höhn (René); A.F.H. Pfeiffer (Andreas); J.E. Bailey-Wilson (Joan); D.E. Stambolian (Dwight); T.Y. Wong (Tien Yin); C.J. Hammond (Christopher); C.C.W. Klaver (Caroline)

2012-01-01

textabstractMyopia is a complex genetic disorder and a common cause of visual impairment among working age adults. Genome-wide association studies have identified susceptibility loci on chromosomes 15q14 and 15q25 in Caucasian populations of European ancestry. Here, we present a confirmation and

Relative size of the eye and orbit: an evolutionary and craniofacial constraint model for examining the etiology and disparate incidence of juvenile-onset myopia in humans.

Science.gov (United States)

Masters, Michael P

2012-05-01

The principal aim of this research is to provide a new model for investigating myopia in humans, and contribute to an understanding of the degree to which modern variation and evolutionary change in orbital and overall craniofacial morphology may help explain the common eye form association with this condition. Recent research into long and short-term evolution of the human orbit reveals a number of changes in this feature, and particularly since the Upper Paleolithic. These include a reduction in orbital depth, a decrease in anterior projection of the upper and lower orbital margins, and most notably, a reduction in orbital volume since the Holocene in East Asia. Reduced orbital volume in this geographic region could exacerbate an existing trend in recent hominin evolution toward larger eyes in smaller orbits, and may help explain the unusually high frequency of myopia in East Asian populations. The objective of the current study is to test a null hypothesis of no relationship between a ratio of orbit to eye volume and spherical equivalent refractive error (SER) in a sample of Chinese adults, and examine how relative size of the eye within the orbit relates to SER between the sexes and across the sample population. Analysis of the orbit, eye, and SER reveals a strong relationship between relative size of the eye within the orbit and the severity of myopic refractive error. An orbit/eye ratio of 3 for females and 3.5 for males (or an eye that occupies approximately 34% and 29% of the orbit, respectively), designates a clear threshold at which myopia develops, and becomes progressively worse as the eye continues to occupy a greater proportion of the orbital cavity. These results indicate that relative size of the eye within the orbit is an important factor in the development of myopia, and suggests that individuals with large eyes in small orbits lack space for adequate development of ocular tissues, leading to compression and distortion of the lithesome globe

Large scale international replication and meta-analysis study confirms association of the 15q14 locus with myopia. The CREAM consortium

NARCIS (Netherlands)

Verhoeven, Virginie J. M.; Hysi, Pirro G.; Saw, Seang-Mei; Vitart, Veronique; Mirshahi, Alireza; Guggenheim, Jeremy A.; Cotch, Mary Frances; Yamashiro, Kenji; Baird, Paul N.; Mackey, David A.; Wojciechowski, Robert; Ikram, M. Kamran; Hewitt, Alex W.; Duggal, Priya; Janmahasatian, Sarayut; Khor, Chiea-Chuen; Fan, Qiao; Zhou, Xin; Young, Terri L.; Tai, E.-Shyong; Goh, Liang-Kee; Li, Yi-Ju; Aung, Tin; Vithana, Eranga; teo, Yik-Ying; Tay, Wanting; Sim, Xueling; Rudan, Igor; Hayward, Caroline; Wright, Alan F.; Polasek, Ozren; Campbell, Harry; Wilson, James F.; Fleck, Brian W.; Nakata, Isao; Yoshimura, Nagahisa; Yamada, Ryo; Matsuda, Fumihiko; Ohno-Matsui, Kyoko; Nag, Abhishek; McMahon, George; St Pourcain, Beate; Lu, Yi; Rahi, Jugnoo S.; Cumberland, Phillippa M.; Bhattacharya, Shomi; Simpson, Claire L.; Atwood, Larry D.; Li, Xiaohui; Raffel, Leslie J.; Murgia, Federico; Portas, Laura; Despriet, Dominiek D. G.; van Koolwijk, Leonieke M. E.; Wolfram, Christian; Lackner, Karl J.; Tönjes, Anke; Mägi, Reedik; Lehtimäki, Terho; Kähönen, Mika; Esko, Tõnu; Metspalu, Andres; Rantanen, Taina; Pärssinen, Olavi; Klein, Barbara E.; Meitinger, Thomas; Spector, Timothy D.; Oostra, Ben A.; Smith, Albert V.; de Jong, Paulus T. V. M.; Hofman, Albert; Amin, Najaf; Karssen, Lennart C.; Rivadeneira, Fernando; Vingerling, Johannes R.; Eiríksdóttir, Guðný; Gudnason, Vilmundur; Döring, Angela; Bettecken, Thomas; Uitterlinden, André G.; Williams, Cathy; Zeller, Tanja; Castagné, Raphaële; Oexle, Konrad; van Duijn, Cornelia M.; Iyengar, Sudha K.; Mitchell, Paul; Wang, Jie Jin; Höhn, René; Pfeiffer, Norbert; Bailey-Wilson, Joan E.; Stambolian, Dwight; Wong, Tien-Yin; Hammond, Christopher J.; Klaver, Caroline C. W.

2012-01-01

Myopia is a complex genetic disorder and a common cause of visual impairment among working age adults. Genome-wide association studies have identified susceptibility loci on chromosomes 15q14 and 15q25 in Caucasian populations of European ancestry. Here, we present a confirmation and meta-analysis

Krypton yellow laser for the treatment of macular hole in high myopia without retinal detachment.

Science.gov (United States)

Cai, Ji-Ping; Cheng, Jin-Wei; Ma, Xiao-Ye; Li, Yu-Zhen; Li, You; Wei, Rui-Li

2008-12-01

To evaluate the prophylactic effect of krypton yellow laser for the treatment of macular holes in high myopic eyes in order to reduce the risk of retinal detachment. Twenty-seven eyes of 27 patients with high myopia and macular holes were randomly assigned to two groups. Fifteen patients (group A, 15 eyes) were subject to laser photocoagulation around the hole margin along with an oral placebo (vitamin B1), while 12 patients (group B, 12 eyes) were only given the oral placebo (vitamin B1). The incident rate of retinal detachment due to macular hole and the mean best-corrected visual acuity of the two groups before and after treatment were measured. The data were statistically tested by X2 test and Student's t test. The incident rates of retina1 detachment in group A and group B were 20%(3/15) and 58.3%(7/12), respectively (X2=4.201, P0.05). The mean BCVA of group B on the initial examination was 24/200, while the mean BCVA at the final follow-up was 30/200 (P>0.05). No significant difference in initial visual acuity (P>0.05) or final visual acuity (P>0.05) was found between the two groups. Krypton yellow laser photocoagulation could reduce the incidence of retinal detachment due to a macular hole in high myopia with acceptable functional results in this study.

LASIK for myopia and astigmatism using the SCHWIND AMARIS excimer laser: an international multicenter trial.

Science.gov (United States)

Arbelaez, Maria Clara; Aslanides, Ioannis M; Barraquer, Carmen; Carones, Francesco; Feuermannova, Alena; Neuhann, Tobias; Rozsival, Pavel

2010-02-01

To assess the efficacy, predictability, and safety of LASIK for the surgical correction of low to moderate myopia with astigmatism using the SCHWIND AMARIS excimer laser. Six international study sites enrolled 358 eyes with a manifest refraction spherical equivalent (MRSE) from -0.50 to -7.38 diopters (D) (mean sphere: -3.13+/-1.58 D) with up to -5.00 D of astigmatism (mean: -0.69+/-0.67 D). All eyes underwent treatment with the nonwavefront-guided aspheric algorithm of the SCHWIND AMARIS excimer laser. All eyes were targeted for emmetropia. Refractive outcomes and corneal higher order aberrations were analyzed pre- and postoperatively. Visual quality was assessed using photopic and mesopic contrast sensitivity. Six-month postoperative outcomes are reported. At 6 months postoperative, the MRSE for all eyes was -0.21+/-0.20 D, and 96% (343/358) of eyes had MRSE within +/-0.50 D. Uncorrected visual acuity was 20/20 or better in 98% (351/358) of eyes, and no eyes lost 2 or more lines of best spectacle-corrected visual acuity. The total corneal higher order aberrations root-mean-square increased by 0.09 microm, spherical aberration increased by 0.08 microm, and coma increased by 0.04 microm postoperatively. Photopic and mesopic contrast sensitivity did not change 6 months postoperatively. Treatment of myopia with astigmatism using the SCHWIND AMARIS excimer laser is safe, efficacious, predictable, and maintains visual quality.

Central corneal thickness, intraocular pressure, and degree of myopia in an adult myopic population aged 20 to 40 years in southeast Spain: determination and relationships

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Manuel Garcia-Medina

2011-02-01

Full Text Available Manuel Garcia-Medina1, Jose Javier Garcia-Medina2,3, Pablo Garrido-Fernandez1, Jose Galvan-Espinosa1, Jesus Martin-Molina1, Carlos Garcia-Maturana4, Sergio Perez-Pardo1, Maria Dolores Pinazo-Duran3 1Department of Ophthalmology, Torrecardenas Hospital, Almeria, Spain; 2Department of Ophthalmology, Huercal Overa Hospital, Almeria, Spain; 3Ophthalmology Research Unit “Santiago Grisolia”, University Hospital Doctor Peset, Valencia, Spain; 4University of Sevilla, SpainObjective: To determine the values of, and study the relationships among, central corneal thickness (CCT, intraocular pressure (IOP, and degree of myopia (DM in an adult myopic population aged 20 to 40 years in Almeria (southeast Spain. To our knowledge this is first study of this kind in this region.Methods: An observational, descriptive, cross-sectional study was done in which a sample of 310 myopic patients (620 eyes aged 20 to 40 years was selected by gender- and age-stratified sampling, which was proportionally fixed to the size of the population strata for which a 20% prevalence of myopia, 5% epsilon, and a 95% confidence interval were hypothesized. We studied IOP, CCT, and DM and their relationships by calculating the mean, standard deviation, 95% confidence interval for the mean, median, Fisher’s asymmetry coefficient, range (maximum, minimum, and the Brown-Forsythe’s robust test for each variable (IOP, CCT, and DM.Results: In the adult myopic population of Almeria aged 20 to 40 years (mean of 29.8, the mean overall CCT was 550.12 µm. The corneas of men were thicker than those of women (P = 0.014. CCT was stable as no significant differences were seen in the 20- to 40-year-old subjects’ CCT values. The mean overall IOP was 13.60 mmHg. Men had a higher IOP than women (P = 0.002. Subjects over 30 years (13.83 had a higher IOP than those under 30 (13.38 (P = 0.04. The mean overall DM was -4.18 diopters. Men had less myopia than women (P < 0.001. Myopia was stable in the

A pilot study: LASEK with the Triple-A profile of a MEL 90 for mild and moderate myopia.

Science.gov (United States)

Chen, Yingjun; Yang, Dong; Han, Tian; Xu, Haipeng; Li, Meiyan; Zhou, Xingtao

2017-06-23

To investigate the visual and refractive outcomes in patients with mild to moderate myopia after laser-assisted subepithelial keratectomy (LASEK) using the 500 Hz pulse rate of the Triple-A profile. Thirty-six eyes of 20 patients (mean age, 27.5 ± 4.6 years) were included in this prospective, consecutive study. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal topography, and corneal aberrations were measured preoperatively and 1 day, 1 week, 1, 3 and 6 months post-operation. At 1 week after surgery, UDVA was better than or equal to 20/25 in all eyes. At postoperative 6 months, the efficacy and safety index was 1.05 ± 0.13 and 1.12 ± 0.15, respectively; all eyes had a UDVA of 20/20 or better, and no eyes showed a loss in CDVA; 100% of the eyes were within ±1.00 D of the attempted spherical equivalent (SE) correction. The postoperative results indicate that using the Triple-A ablation profile of the MEL 90 excimer laser with a 500 Hz pulse rate is a safe, efficient, and predictable method to correct mild to moderate myopia.

Evaluation of the effectiveness of laser in situ keratomileusis and photorefractive keratectomy for myopia: a meta-analysis.

Science.gov (United States)

Yang, Xin-Jun; Yan, Hong-Tao; Nakahori, Yutaka

2003-08-01

To evaluate the effectiveness of laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) for correcting myopia. Study selection, data extraction, and quality assessment were performed by two of authors independently. Summary odds ratios and 95% confidence intervals were calculated by DerSimonian & Laird random-effects model and Mantel-Haenszel (fixed-effects) model. All calculations were based on an intention-to-treat and per protocol analysis. Five hundred and eighty eyes (476 patients) from 5 randomized controlled trials were included in this study. At > or = 6 months follow-up, by random-effects model, the pooled odds ratios (OR, for LASIK vs. PRK) of postoperative uncorrected visual acuity (UCVA) of 20/20 or better for all trials were 1.31 (95% CI=0.77-2.22) by per protocol analysis and 1.18 (95% CI=0.74-1.88) by intention-to-treat analysis. In the refractive outcome, the pooled OR of the postoperative spherical equivalent refraction within +/-0.5 diopter (D) of emmetropia did not show any statistical significance, for which the OR were 0.75 (95% CI=0.48-1.18) by per protocol analysis and 0.70 (95% CI=0.47-1.04) by intention-to-treat analysis. LASIK and PRK were found to be similarly effective for the correction of myopia from -1.5 to -15.0 D in a greater than 6 month follow-up.

A Laser-Induced Fluorescence Instrument for Aircraft Measurements of Sulfur Dioxide in the Upper Troposphere and Lower Stratosphere

Science.gov (United States)

Rollins, Andrew W.; Thornberry, Troy D.; Ciciora, Steven J.; McLaughlin, Richard J.; Watts, Laurel A.; Hanisco, Thomas F.; Baumann, Esther; Giorgetta, Fabrizio R.; Bui, Thaopaul V.; Fahey, David W.

2016-01-01

This work describes the development and testing of a new instrument for in situ measurements of sulfur dioxide (SO2) on airborne platforms in the upper troposphere and lower stratosphere (UTLS). The instrument is based on the laser-induced fluorescence technique and uses the fifth harmonic of a tunable fiber-amplified semiconductor diode laser system at 1084.5 nm to excite SO2 at 216.9 nm. Sensitivity and background checks are achieved in flight by additions of SO2 calibration gas and zero air, respectively. Aircraft demonstration was performed during the NASA Volcano Plume Investigation Readiness and Gas-Phase and Aerosol Sulfur (VIRGAS) experiment, which was a series of flights using the NASA WB-57F during October 2015 based at Ellington Field and Harlingen, Texas. During these flights, the instrument successfully measured SO2 in the UTLS at background (non-volcanic) conditions with a precision of 2 ppt at 10 s and an overall uncertainty determined primarily by instrument drifts of +/- (16% + 0.9 ppt).

Choroidal thinning in high myopia measured by optical coherence tomography

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Ikuno Y

2013-05-01

Full Text Available Yasushi Ikuno, Satoko Fujimoto, Yukari Jo, Tomoko Asai, Kohji NishidaDepartment of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, JapanPurpose: To investigate the rate of choroidal thinning in highly myopic eyes.Patients and methods: A retrospective observational study of 37 eyes of 26 subjects (nine males and 17 females, mean age 39.6 ± 7.7 years with high myopia but no pathologies who had undergone spectral domain optical coherence tomography and repeated the test 1 year later (1 ± 0.25 year at Osaka University Hospital, Osaka, Japan. Patients older than 50 years with visual acuity worse than 20/40 or with whitish chorioretinal atrophy involving the macula were excluded. Two masked raters measured the choroidal thicknesses (CTs at the foveda, 3 mm superiorly, inferiorly, temporally, and nasally on the images and averaged the values. The second examination was about 365 days after the baseline examination. The CT reduction per year (CTRPY was defined as (CT 1 year after - baseline CT/days between the two examinations × 365. The retinal thicknesses were also investigated.Results: The CTRPY at the fovea was −1.0 ± 22.0 µm (range –50.2 to 98.5 at the fovea, –6.5 ± 24.3 µm (range −65.8 to 90.2 temporally, –0.5 ± 22.3 µm (range –27.1 to 82.5 nasally, –9.7 ± 21.7 µm (range –40.1 to 60.1 superiorly, and –1.4 ± 25.5 µm (range –85.6 to 75.2 inferiorly. There were no significant differences in the CTRPY at each location (P = 0.34. The CT decreased significantly (P < 0.05 only superiorly. The superior CTRPY was negatively correlated with the axial length (P < 0.05. The retinal thickness at the fovea did not change. Stepwise analysis for CTRPY selected axial length (P = 0.04, R2 = 0.13 and age (P = 0.08, R2 = 0.21 as relevant factors.Conclusions: The highly myopic choroid might gradually thin and be affected by many factors. Location and axial length are key factors to regulate the rate of choroidal

Choroidal thickness and myopia in relation to physical activity during childhood

DEFF Research Database (Denmark)

Lundberg, Kristian; Jacobsen, Nina; Vestergaard, Anders Højslet

Purpose: Decreasing physical activity (PA) has been suggested to be a driving force behind the rapid increase of myopia worldwide. The possible protective effects of PA might be through increased blood flow and subsequent change in thickness of the choroid. The purpose of this study......, L, M and V PA (2.31 µm/% (p=0.22), -3.99 µm/% (p=0.15), -5.43 µm/% (p=0.57) and -0.53 µm/% (p=0.95), respectively). Conclusions: We found no association between physical activity and the choroidal thickness, axial length or refractive error. However, the choroid was thinner in myopic eyes......±59 µm (3 mm zone), respectively. All CT measurements were thinner in myopic eyes (psex-adjusted linear regression there were no associations between PA and SE, AL or any CT measurements. There was no association between accumulated PA and the overall CT for SED...

Decision-making and addiction (part II): myopia for the future or hypersensitivity to reward?

Science.gov (United States)

Bechara, Antoine; Dolan, Sara; Hindes, Andrea

2002-01-01

On a decision-making instrument known as the "gambling task" (GT), a subgroup of substance dependent individuals (SDI) opted for choices that yield high immediate gains in spite of higher future losses. This resembles the behavior of patients with ventromedial (VM) prefrontal cortex lesions. In this study, we addressed the possibility that hypersensitivity to reward may account for the "myopia" for the future in this subgroup of SDI. We used a variant version of the GT, in which the good decks yielded high immediate punishment but higher delayed reward. The bad decks yielded low immediate punishment and lower delayed reward. We measured the skin conductance response (SCR) of subjects after receiving reward (reward SCR) and during their pondering from which deck to choose (anticipatory SCR). A subgroup of SDI who was not impaired on the original GT performed normally on the variant GT. The subgroup of SDI who was impaired on the original GT showed two levels of performance on the variant GT. One subgroup (36% of the sample) performed poorly on the variant GT, and showed similar behavioral and physiological impairments to VM patients. The other subgroup of SDI (64% of the sample) performed normally on the variant task, but had abnormally large physiological responses to reward, i.e. large SCR after receiving reward (reward SCR) and large SCR in anticipation of outcomes that yield large reward. Thus, the combined cognitive and physiological approach of assessing decision-making characterizes three sub-populations of SDI. One sub-population is without impairments that can be detected by any measure of the GT paradigm. Another sub-population is similar to VM patients in that they are insensitive to the future, both positive and negative. A third sub-population is hypersensitive to reward, so that the presence or the prospect of receiving, reward dominates their behavior.

Clinical observation of transepithelial photorefractive keratectomy for myopia

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Xiao-Ning Yang

2013-10-01

Full Text Available AIM: To assess the effectiveness and safety of transepithelial photorefractive keratectomy(TransPRKusing the AMARIS laser platform. METHODS: Eighty myopic cases(156 eyeswith or without astigmatism were treated by TransPRK. In all eyes, treatments were planned with Custom Ablation Manager Software and ablations performed with the SCHWIND AMARIS system. Clinical outcomes of visual acuity, manifest refraction, intraocular pressure, and corneal topography were observed and analyzed. The follow-up period was one year.RESULTS: All patients completed the 1-year follow-up. After one-year follow-up, 47 cases(92 eyes, 58.8%achieved an uncorrected distance visual acuity(UDVA≥1.0. Twenty cases(40 eyes, 25%was 0.8 and 13 cases(24 eyes, 16.3%was 0.6. Sixty-three cases(121 eyes, 78.8%were close to or above best corrected visual acuity(BCVA. Seventeen cases(34 eyes, 21.2%were slightly lower than BCVA 1 row or two. Nine cases(18 eyes, 11.3%got dry eye postoperatively. 16 cases(32 eyes, 20%complain of glare and poor night vision. CONCLUSION: The results show that TransPRK for myopia with or without astigmatism is safe and effective. The postoperative visual outcomes are stable.

Therapeutic efficiency of sodium hyaluronate eye drops on dry eye in juvenile with myopia wearing rigid gas permeable contact lens

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Bin Zhang

2016-03-01

Full Text Available AIM:To investigate the therapeutic efficiency of preservative-free sodium hyaluronate eye drops on dry eye in juvenile myopia wearing rigid gas permeable contact lens(RGP.METHODS:Ninety cases with dry eye related to wearing RGP in juvenile with myopia from January to May 2015 were selected. The patients aged 12.75±4.15 years old,with diopter of -3.50±1.50D as spherical equivalent and received normalized RGP. They were divided into 3 groups randomly,each group of 30 cases(60 eyes:group A used rewetting drops,1 drop each time,4 times per day; group B used preservative-free sodium hyaluronate eye drops(1g/L,1 drop each time,4 times per day; group C used rewetting drops at first, then sodium hyaluronate eye drops was used 15 minutes later.All cases had been detected and evaluated by subjective symptoms of dry eye,Schirmer I test(SⅠt,break-up time(BUTand corneal fluorescent staining,at pre-therapy and 1, 2, 4wk of post-therapy.RESULTS:The subjective symptoms of dry eye,corneal fluorescent staining and BUT of three groups had been obviously improved at 1wk after therapies than those before therapies(PP>0.05.Every index of the three groups measured at 2 and 4wk after treatments had no significant differences compared to those measured at 1wk(P>0.05.There was no significant difference on subjective symptoms,SⅠt and BUT between group A and B(P>0.05,except on corneal fluorescent staining, on which group B was superior to group A and on which the difference was significant(PPPCONCLUSION:Preservative-free sodium hyaluronate eye drops(1g/Lcan stabilize the tear film and promote the repair of corneal epithelial defects and significantly improve dry eye symptoms and signs in juvenile myopia wearing RGP,so it has certain clinical application value.

The study of the effectiveness and safety of vitamin-mineral complex «Focus Forte» for myopia treatment

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E. Yu. Egorova

2012-01-01

Full Text Available Purpose: the estimation of the results of a randomized study of the effectiveness of vitamin-mineral complex «Focus Forte» at myopia.Methods: this study included 60 young patients (in age from 16 to18 years, university students, full-time education in the context of complex treatment within 2 months. Patients were randomized to receive the preparation (n=30 or into the control group (standard therapy, n=30. On the day «0» and the day «60» over 80 parameters of vision were measured using a special software package.Results: the comparisons of the studied parameters of vision on the day of «60» shown statistically significant differences in electrosen- sibility (O. R. 4.6, 95% C. I. 1.4-16, p=0,03, spatial contrast sensitivity (O. R. 9.0, 95% C. I. 1.5-17, p<0,006 and luminance sensitivity (O. R. 5.6, 95% DI 1.7-19; p=0,003 as well as a significant reduction of clinical symptoms of zinc deficiency and hypovitaminosеs A, C, E, B2 (p<0,001.Conclusion: «Focus Forte» helps to improve visual function among the students with myopia, helping to compensate for deficiency of vitamins and micronutrients, which is required for the physiological support of the molecular processes of vision.

The study of the effectiveness and safety of vitamin-mineral complex «Focus Forte» for myopia treatment

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E. Yu. Egorova

2014-07-01

Full Text Available Purpose: the estimation of the results of a randomized study of the effectiveness of vitamin-mineral complex «Focus Forte» at myopia.Methods: this study included 60 young patients (in age from 16 to18 years, university students, full-time education in the context of complex treatment within 2 months. Patients were randomized to receive the preparation (n=30 or into the control group (standard therapy, n=30. On the day «0» and the day «60» over 80 parameters of vision were measured using a special software package.Results: the comparisons of the studied parameters of vision on the day of «60» shown statistically significant differences in electrosen- sibility (O. R. 4.6, 95% C. I. 1.4-16, p=0,03, spatial contrast sensitivity (O. R. 9.0, 95% C. I. 1.5-17, p<0,006 and luminance sensitivity (O. R. 5.6, 95% DI 1.7-19; p=0,003 as well as a significant reduction of clinical symptoms of zinc deficiency and hypovitaminosеs A, C, E, B2 (p<0,001.Conclusion: «Focus Forte» helps to improve visual function among the students with myopia, helping to compensate for deficiency of vitamins and micronutrients, which is required for the physiological support of the molecular processes of vision.

Clinical outcomes of small incision lenticule extraction versus femtosecond laser-assisted LASIK for myopia: a Meta-analysis

Science.gov (United States)

Yan, Huan; Gong, Li-Yan; Huang, Wei; Peng, Yan-Li

2017-01-01

AIM To evaluate the possible differences in visual quality between small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK) for myopia. METHODS A Meta-analysis was performed. Patients were from previously reported comparative studies treated with SMILE versus FS-LASIK. The PubMed, EMBASE, Cochrane, Web of Science and Chinese databases (i.e. WANFANG and CNKI) were searched in Nov. of 2016 using RevMan 5.1 version software. The differences in visual acuity, aberration and biomechanical effects within six months postoperatively were showed. Twenty-seven studies including 4223 eyes were included. RESULTS No significant differences were observed between SMILE and FS-LASIK in terms of the proportion of eyes that lost one or more lines of corrected distance visual acuity after surgery (P=0.14), the proportion of eyes achieving an uncorrected distance visual acuity of 20/20 or better (P=0.43), the final refractive spherical equivalent (P=0.89), the refractive spherical equivalent within ±1.00 diopter of the target values (P=0.80), vertical coma (P=0.45) and horizontal coma (P=0.06). Compared with the FS-LASIK group, total higher-order aberration (PLASIK are comparable in efficacy, safety and predictability for correcting myopia. However, the aberration in the SMILE group is superior to that in the FS-LASIK group, and the loss of biomechanical effects may occur less frequently after SMILE than after FS-LASIK. PMID:28944205

Corneal endothelial cell density after femtosecond thin-flap LASIK and PRK for myopia: a contralateral eye study.

Science.gov (United States)

Smith, Ryan T; Waring, George O; Durrie, Daniel S; Stahl, Jason E; Thomas, Priscilla

2009-12-01

To compare the effect of femtosecond thinflap LASIK and photorefractive keratectomy (PRK) on postoperative endothelial cell density. In a prospective, randomized, contralateral, single-center clinical trial, 25 patients (mean age: 30+/-5 years [range: 21 to 38 years]) underwent PRK in one eye and thin-flap LASIK in the fellow eye for the correction of myopia using a wavefront-guided platform. The central corneal endothelial cell density was measured using the NIDEK Confoscan 4 preoperatively, and at 1 and 3 months postoperatively. Changes in endothelial cell density were analyzed over time between the two refractive techniques. In PRK, the average preoperative endothelial cell density was 3011+/-329 cells/mm(2), which decreased to 2951+/-327 cells/mm(2) at 1 month (P=.5736) and 2982+/-365 cells/mm(2) at 3 months (P=.6513). In thinflap LASIK, the average preoperative endothelial cell density was 2995+/-325 cells/mm(2), which decreased to 2977+/-358 cells/mm(2) at 1 month (P=.5756) and 2931+/-369 cells/mm(2) at 3 months (P=.4106). No statistically significant difference was found between the two groups at 1 (P=.7404) or 3 (P=.3208) months postoperatively. No statistically significant change was noted in endothelial cell density following either PRK or thin-flap LASIK for the treatment of myopia. Furthermore, no statistically significant difference was found between the two groups out to 3 months postoperatively, indicating that thin-flap LASIK is as safe as PRK with regards to endothelial health.

Riboflavin and ultraviolet A irradiation for the prevention of progressive myopia in a guinea pig model.

Science.gov (United States)

Li, Xiaoxia; Wu, Miaoqin; Zhang, Luyi; Liu, Hui; Zhang, Lan; He, Jinjing

2017-12-01

In this study, we evaluated the effect of oral administration of riboflavin combined with whole-body ultraviolet A (UVA) irradiation on the biochemical and biomechanical properties of sclera in a guinea pig model to control the progression of myopia. Experimental groups were administered 0.1% riboflavin solution with or without vitamin C by gavage from 3 days before myopic modeling and during the modeling process. Guinea pigs underwent 30 min of whole-body UVA irradiation after each gavage for 2 weeks. For control groups, guinea pigs were administered vitamin C and underwent either whole-body UVA irradiation without 0.1% riboflavin solution or whole-body fluorescent lamp irradiation with or without 0.1% riboflavin solution. Resultantly, myopia models were established with an increased axial length and myopic diopter. Compared with myopic eyes in the control groups, the net increase in axial length, diopter and strain assessment decreased significantly, and the net decrease in sclera thickness, ultimate load, and stress assessment decreased significantly in experimental groups. MMP-2 expression showed a lower net increase, while TIMP-2 expression showed a lower net decrease. In addition, hyperplasia of scleral fibroblasts was more active in myopic eyes of experimental groups. Overall, our results showed that oral administration of riboflavin with whole-body UVA irradiation could increase the strength and stiffness of sclera by altering the biochemical and biomechanical properties, and decreases in axial elongation and myopic diopter are greater in the guinea pig myopic model. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

The Rat With Oxygen-Induced Retinopathy Is Myopic With Low Retinal Dopamine

OpenAIRE

Zhang, Nan; Favazza, Tara L.; Baglieri, Anna Maria; Benador, Ilan Y.; Noonan, Emily R.; Fulton, Anne B.; Hansen, Ronald M.; Iuvone, P. Michael; Akula, James D.

2013-01-01

The rat model of retinopathy of prematurity (the 'ROP rat') is found to be the first known animal model of myopia in which the eye is smaller than normal. Data suggests that reduced retinal dopamine metabolism may contribute to the peculiar myopia of ROP.

Femtosecond (FS) laser vision correction procedure for moderate to high myopia

DEFF Research Database (Denmark)

Vestergaard, Anders Højslet; Ivarsen, Anders; Asp, Sven

2013-01-01

Purpose:  To present our initial clinical experience with ReLEx(®) flex (ReLEx) for moderate to high myopia. We compare efficacy, safety and corneal higher-order aberrations after ReLEx with femtosecond laser in situ keratomileusis (FS-LASIK). Methods:  Prospective study of ReLEx compared...... with a retrospective study of FS-LASIK. ReLEx is a new keratorefractive procedure, where a stromal lenticule is cut by a femtosecond laser and manually extracted. Forty patients were treated with ReLEx on both eyes. A comparable group of 41 FS-LASIK patients were retrospectively identified. Visual acuity, spherical...... equivalent (SE) and corneal tomography were measured before and 3 months after surgery. Results:  Preoperative SE averaged -7.50 ± 1.16 D (ReLEx) and -7.32 ± 1.09 D (FS-LASIK). For all eyes, mean corrected distance visual acuity remained unchanged in both groups. For eyes with emmetropia as target refraction...

Assessment of visual function based on IOL-Master comparing with traditional ultrasonic biometry for intraocular lens calculation in high myopia patients

Directory of Open Access Journals (Sweden)

Lu Zhang

2013-10-01

Full Text Available AIM: To evaluate the clinical feasibility of using a new optical coherence interferometry(IOL-Master, comparing with traditional ultrasonic biometry and manual keratometry in the accuracy and characteristics for intraocular lens calculation of high myopia.METHODS: The measurement of axial length was performed in 60 eyes(30 eyes for each groupwith senile cataract of high myopia(≥-6.00Dusing IOL-Master and ultrasonic biometry. The measurement of corneal power(Kwas also performed in the patient using IOL-Master and manual keratometry preoperatively. Phacoemulsification and foldable lens implantation were done on the patients. IOL power calculation was carried out according to the SRK/T formula on the basis of the group-related data. Best corrected visual acuity, refraction, contrast sensitivity and wave front aberration root mean square(RMSwere re-tested after 3 months postoperatively.RESULTS: Significant difference between the two methods in axial length measurement which was 29.81±1.53mm by ultrasound and 29.63±1.81mm by IOL-Master(P=0.001. And in corneal power measurement which was 43.22±1.67K by manual keratometry and 44.27±1.39K by IOL-Master(P=0.006. There was a significant difference between the two groups(P=0.001. 63.0% vs 31.2% had a mean absolute refractive error(MAREwithin ±0.50 diopter for the IOL-Master and A-scan groups, respectively(χ2=3.1, Pth order aberration, 4th order spherical aberration and total high order aberration in the IOL-Master group were lower than those in the A-scan group at 6mm pupil diameter 3 months later. CONCLUSION: IOL-Master is a non-contact, accurate, safe and reliable tool for calculating IOL power and it is more accurate on the design of the IOL in the cataract surgery on the high myopia patients.

Development of prototype induced-fission-based Pu accountancy instrument for safeguards applications.

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Seo, Hee; Lee, Seung Kyu; An, Su Jung; Park, Se-Hwan; Ku, Jeong-Hoe; Menlove, Howard O; Rael, Carlos D; LaFleur, Adrienne M; Browne, Michael C

2016-09-01

Prototype safeguards instrument for nuclear material accountancy (NMA) of uranium/transuranic (U/TRU) products that could be produced in a future advanced PWR fuel processing facility has been developed and characterized. This is a new, hybrid neutron measurement system based on fast neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) methods. The FNEM method is sensitive to the induced fission rate by fast neutrons, while the PNAR method is sensitive to the induced fission rate by thermal neutrons in the sample to be measured. The induced fission rate is proportional to the total amount of fissile material, especially plutonium (Pu), in the U/TRU product; hence, the Pu amount can be calibrated as a function of the induced fission rate, which can be measured using either the FNEM or PNAR method. In the present study, the prototype system was built using six (3)He tubes, and its performance was evaluated for various detector parameters including high-voltage (HV) plateau, efficiency profiles, dead time, and stability. The system's capability to measure the difference in the average neutron energy for the FNEM signature also was evaluated, using AmLi, PuBe, (252)Cf, as well as four Pu-oxide sources each with a different impurity (Al, F, Mg, and B) and producing (α,n) neutrons with different average energies. Future work will measure the hybrid signature (i.e., FNEM×PNAR) for a Pu source with an external interrogating neutron source after enlarging the cavity size of the prototype system to accommodate a large-size Pu source (~600g Pu). Copyright © 2016 Elsevier Ltd. All rights reserved.

Axial Myopia and its Influence on Diabetic Retinopathy

International Nuclear Information System (INIS)

Tayyab, H.; Haider, M. A.; Bukhari, S. A. H.

2014-01-01

Objective: To evaluate the correlation between axial myopia and diabetic retinopathy. Study Design: Cross-sectional study. Place and Duration of Study: Eye Department of Postgraduate Medical Institute, Lahore General Hospital, from August 2012 to February 2013. Methodology: A total of 258 participants suffering from type-2 diabetic retinopathy were included. Axial length was measured by two optometrists using contact type ultrasound biometer. Colored retinal photographs, red free retinal photographs and Fundus Fluorescein Angiography (FFA) were performed on all patients using standard fundus camera. All fundus photographs and angiograms were independently reviewed and graded by two qualified vitreoretinal fellows. Results: Out of 258 patients, 163 were males (63.2%) and 95 (36.8%) were females. Average age of patients was 56.30 +- 7.57 years. Average axial length of right and left eyes were 23.16 mm and 23.15 mm respectively. There was statistically significant negative correlation between axial length and severity of diabetic retinopathy in the right eye, (Spearman correlation = -0.511, p = 0.0001) as well as the left eye (Spearman correlation = -0.522, p = 0.0001). Conclusion: There is a protective influence of longer axial length of globe on the stage and severity of diabetic retinopathy. This study may help in modifying the screening protocol for diabetic retinopathy amongst patients of differing axial lengths. (author)

Single-Step Transepithelial PRK vs Alcohol-Assisted PRK in Myopia and Compound Myopic Astigmatism Correction.

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Kaluzny, Bartlomiej J; Cieslinska, Iwona; Mosquera, Samuel A; Verma, Shwetabh

2016-02-01

Transepithelial photorefractive keratectomy (tPRK), where both the epithelium and stroma are removed in a single-step, is a relatively new procedure of laser refractive error correction. This study compares the 3-month results of myopia and compound myopic astigmatism correction by tPRK or conventional alcohol-assisted PRK (aaPRK).This prospective, nonrandomized, case-control study recruited 148 consecutive patients; 93 underwent tPRK (173 eyes) and 55 aaPRK (103 eyes). Refractive results, predictability, safety, and efficacy were evaluated during the 3-month follow-up. The main outcome measures were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and mean refractive spherical equivalent (MRSE).Mean preoperative MRSE was -4.30 ± 1.72 D and -4.33 ± 1.96 D, respectively (P = 0.87). The 3-month follow-up rate was 82.1% in the tPRK group (n = 145) and 86.4% in aaPRK group (n = 90), P = 0.81. Postoperative UDVA was 20/20 or better in 97% and 94% of eyes, respectively (P = 0.45). In the tPRK and aaPRK groups, respectively, 13% and 21% of eyes lost 1 line of CDVA, and 30% and 31% gained 1 or 2 lines (P = 0.48). Mean postoperative MRSE was -0.14 ± 0.26 D in the tPRK group and -0.12 ± 0.20 D in the aaPRK group (P = 0.9). The correlation between attempted versus achieved MRSE was equally high in both groups.Single-step transepithelial PRK and conventional PRK provide very similar results 3 months postoperatively. These procedures are predictable, effective, and safe for correction of myopia and compound myopic astigmatism.

A LabVIEW-Based Virtual Instrument System for Laser-Induced Fluorescence Spectroscopy.

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Wu, Qijun; Wang, Lufei; Zu, Lily

2011-01-01

We report the design and operation of a Virtual Instrument (VI) system based on LabVIEW 2009 for laser-induced fluorescence experiments. This system achieves synchronous control of equipment and acquisition of real-time fluorescence data communicating with a single computer via GPIB, USB, RS232, and parallel ports. The reported VI system can also accomplish data display, saving, and analysis, and printing the results. The VI system performs sequences of operations automatically, and this system has been successfully applied to obtain the excitation and dispersion spectra of α-methylnaphthalene. The reported VI system opens up new possibilities for researchers and increases the efficiency and precision of experiments. The design and operation of the VI system are described in detail in this paper, and the advantages that this system can provide are highlighted.

Study of krypton laser-induced choroidal neovascularization in a Guinea pig model of high anisometropia.

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Wang, Jianghui; Jiang, Wei; Kang, Zefeng; Liang, Lina; Liu, Xiaoman; Tian, Nannan; Zhang, Qing

2012-06-01

To investigate the association between high anisometropia and the area of choroidal neovascularization (CNV) induced by krypton laser in guinea pigs and better understand the pathogenesis and prevention of myopic CNV. Nine 3-week old male guinea pigs with anisometropia >6.00D were randomly assigned to three groups according to examination date after laser photocoagulation (7d, 14d and 28d). All animals underwent refraction. The eye with higher myopia was used as the experimental eye, and the other as the control eye. All eyes received repeated multi-wavelength krypton laser photocoagulation treatments (wavelength: 532nm; laser power: 400mW; spot diameter: 50μm; exposure time: 0.1s). Fundus photography and indocyanine green angiography (ICGA) were performed. Afterwards, the animals were sacrificed immediately, and the eyes were enucleated and processed for histopathologic examination and flat mounts. CNV appeared at 7d after laser treatment. The area of CNV peaked at 14d, and decrease in area and the presence of scarring was noted at 28 d. CNV was present in 66.7% of eyes by ICGA at 14 d. CNV could be observed under light microscopy at all three time points. At 14d, flat mount showed the neovascular plexus around the lesion. Semi-quantitative analysis revealed that the area of CNV in treated eyes was greater than that of control eyes. Since the mechanism of CNV in this study resembles that of CNV in pathological myopia, this model can be used to investigate the etiology, pathogenesis and treatment of CNV in pathological myopia.

Effects of Constant Flickering Light on Refractive Status, 5-HT and 5-HT2A Receptor in Guinea Pigs.

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Li, Bing; Luo, Xiumei; Li, Tao; Zheng, Changyue; Ji, Shunmei; Ma, Yuanyuan; Zhang, Shuangshuang; Zhou, Xiaodong

2016-01-01

To investigate the effects of constant flickering light on refractive development, the role of serotonin (i.e.5-hydroxytryptamine, 5-HT)and 5-HT2A receptor in myopia induced by flickering light in guinea pigs. Forty-five guinea pigs were randomly divided into three groups: control, form deprivation myopia (FDM) and flickering light induced myopia (FLM) groups(n = 15 for each group). The right eyes of the FDM group were covered with semitransparent hemispherical plastic shells serving as eye diffusers. Guinea pigs in FLM group were raised with illumination of a duty cycle of 50% at a flash frequency of 0.5Hz. The refractive status, axial length (AL), corneal radius of curvature(CRC) were measured by streak retinoscope, A-scan ultrasonography and keratometer, respectively. Ultramicroscopy images were taken by electron microscopy. The concentrations of 5-HTin the retina, vitreous body and retinal pigment epithelium (RPE) were assessed by high performance liquid chromatography, the retinal 5-HT2A receptor expression was evaluated by immunohistofluorescence and western blot. The refraction of FDM and FLM eyes became myopic from some time point (the 4th week and the 6th week, respectively) in the course of the experiment, which was indicated by significantly decreased refraction and longer AL when compared with the controls (plight could cause progressive myopia in guinea pigs. 5-HT and 5-HT2A receptor increased both in form deprivation myopia and flickering light induced myopia, indicating that 5-HT possibly involved in myopic development via binding to5-HT2A receptor.

Refractive outcomes of an advanced aspherically optimized profile for myopia corrections by LASIK: a retrospective comparison with the standard aspherically optimized profile

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Meyer B

2015-02-01

Full Text Available Bertram Meyer,1 Georg Sluyterman van Langeweyde,2 Matthias Wottke2 1Augencentrum Köln, Cologne, Germany; 2Carl Zeiss Meditec AG, Jena, Germany Purpose: A retrospective comparison of refractive outcomes of a new, aspherically optimized profile with an enhanced energy correction feature (Triple-A and the conventionally used aspherically optimized profile (ASA, or aberration smart ablation for correction of low-to-high myopia.Setting: Augen-OP-Centrum, Cologne, GermanyDesign: Retrospective nonrandomized comparative studyMethods: A central database at the Augen-OP-Centrum was used to gather retrospective data for low-to-high myopia (up to -10 D. One hundred and seven eyes (56 patients were treated with the ASA profile, and 79 eyes (46 patients were treated with the Triple-A profile. Postoperative outcomes were evaluated at 1 month, 3 months, 6 months, and 1 year follow-up time points.Results: The Triple-A profile showed better predictability indicated by a significantly lower standard deviation of residuals (0.32–0.34 vs 0.36–0.44, Triple-A vs ASA in the 6-month to 1-year period. The Triple-A group had better stability across all time intervals and achieved better postoperative astigmatism improvements with significantly lower scatter. This group achieved better safety at 1 year, with 100% of eyes showing no change or gain in Snellen lines, compared with 97% in the ASA group. A better safety index was observed for the Triple-A group at later time points. The Triple-A group had a better efficacy index and a higher percentage of eyes with an uncorrected Snellen visual acuity of 20/20 or greater at all investigated follow-up time points.Conclusion: The new aspherically optimized Triple-A profile can safely and effectively correct low-to-high myopia. It has demonstrated superiority over the ASA profile in most refractive outcomes. Keywords: Triple-A, wavefront measurements, corneal aberrations, corneal asphericity, ablation profile

Computer simulation of photorefractive keratectomy for the correction of myopia and hyperopia

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Pinault, Pascal; 'Huillier, J. P.

1996-01-01

Photorefractive keratectomy (PRK) performed by means of the 193 nm excimer laser has stimulated considerable interest in the ophthalmic community because this new procedure has the potential to correct myopia, hyperopia, and astigmatism. The use of a laser beam to remove a controlled amount of tissue from the cornea implies that both the energy density of the laser beam and the target removed rate are accurately known. In addition, the required tissue ablation profile to achieve refractive correction must be predicted by optical calculations. This paper investigates: (1) Optical computations based on raytracing model to determine what anterior profile of cornea is needed postoperatively for ametropia. (2) Maximal depth of the removed corneal tissue against the ablation zone treated. And (3) the thickness of ablated corneal lenticule at any distance from the optical axis. Relationships between these data are well fitted by polynomial regressive curves in order to be useful as an algorithm in the computer-controlled delivery of the ArF laser beam.

The application of online transcranial random noise stimulation and perceptual learning in the improvement of visual functions in mild myopia.

Science.gov (United States)

Camilleri, Rebecca; Pavan, Andrea; Campana, Gianluca

2016-08-01

It has recently been demonstrated how perceptual learning, that is an improvement in a sensory/perceptual task upon practice, can be boosted by concurrent high-frequency transcranial random noise stimulation (tRNS). It has also been shown that perceptual learning can generalize and produce an improvement of visual functions in participants with mild refractive defects. By using three different groups of participants (single-blind study), we tested the efficacy of a short training (8 sessions) using a single Gabor contrast-detection task with concurrent hf-tRNS in comparison with the same training with sham stimulation or hf-tRNS with no concurrent training, in improving visual acuity (VA) and contrast sensitivity (CS) of individuals with uncorrected mild myopia. A short training with a contrast detection task is able to improve VA and CS only if coupled with hf-tRNS, whereas no effect on VA and marginal effects on CS are seen with the sole administration of hf-tRNS. Our results support the idea that, by boosting the rate of perceptual learning via the modulation of neuronal plasticity, hf-tRNS can be successfully used to reduce the duration of the perceptual training and/or to increase its efficacy in producing perceptual learning and generalization to improved VA and CS in individuals with uncorrected mild myopia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterisation of an inlet pre-injector laser-induced fluorescence instrument for the measurement of atmospheric hydroxyl radicals

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Novelli, A.; Hens, K.; Tatum Ernest, C.; Kubistin, D.; Regelin, E.; Elste, T.; Plass-Dülmer, C.; Martinez, M.; Lelieveld, J.; Harder, H.

2014-10-01

Atmospheric measurements of hydroxyl radicals (OH) are challenging due to a high reactivity and consequently low concentration. The importance of OH as an atmospheric oxidant has motivated a sustained effort leading to the development of a number of highly sensitive analytical techniques. Recent work has indicated that the laser-induced fluorescence of the OH molecules method based on the fluorescence assay by gas expansion technique (LIF-FAGE) for the measurement of atmospheric OH in some environments may be influenced by artificial OH generated within the instrument, and a chemical method to remove this interference was implemented in a LIF-FAGE system by Mao et al. (2012). While it is not clear whether other LIF-FAGE instruments suffer from the same interference, we have applied this method to our LIF-FAGE HORUS (Hydroxyl Radical Measurement Unit based on fluorescence Spectroscopy) system, and developed and deployed an inlet pre-injector (IPI) to determine the chemical zero level in the instrument via scavenging the ambient OH radical. We describe and characterise this technique in addition to its application at field sites in forested locations in Finland, Spain and Germany. Ambient measurements show that OH generated within the HORUS instrument is a non-negligible fraction of the total OH signal, which can comprise 30 to 80% during daytime and 60 to 100% during the night. The contribution of the background OH varied greatly between measurement sites and was likely related to the type and concentration of volatile organic compounds (VOCs) present at each particular location. Two inter-comparisons in contrasting environments between the HORUS instrument and two different chemical ionisation mass spectrometers (CIMS) are described to demonstrate the efficacy of IPI and the necessity of the chemical zeroing method for our LIF-FAGE instrument in such environments.

Cognitive-analytical therapy for a patient with functional neurological symptom disorder-conversion disorder (psychogenic myopia: A case study

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Hamid Nasiri

2015-01-01

Full Text Available Functional neurological symptom disorder commonly presents with symptoms and defects of sensory and motor functions. Therefore, it is often mistaken for a medical condition. It is well known that functional neurological symptom disorder more often caused by psychological factors. There are three main approaches namely analytical, cognitive and biological to manage conversion disorder. Any of such approaches can be applied through short-term treatment programs. In this case, study a 12-year-old boy with the diagnosed functional neurological symptom disorder (psychogenic myopia was put under a cognitive-analytical treatment. The outcome of this treatment modality was proved successful.

Cognitive-analytical therapy for a patient with functional neurological symptom disorder-conversion disorder (psychogenic myopia): A case study.

Science.gov (United States)

Nasiri, Hamid; Ebrahimi, Amrollah; Zahed, Arash; Arab, Mostafa; Samouei, Rahele

2015-05-01

Functional neurological symptom disorder commonly presents with symptoms and defects of sensory and motor functions. Therefore, it is often mistaken for a medical condition. It is well known that functional neurological symptom disorder more often caused by psychological factors. There are three main approaches namely analytical, cognitive and biological to manage conversion disorder. Any of such approaches can be applied through short-term treatment programs. In this case, study a 12-year-old boy with the diagnosed functional neurological symptom disorder (psychogenic myopia) was put under a cognitive-analytical treatment. The outcome of this treatment modality was proved successful.

The Development and Deployment of a Ground-Based, Laser-Induced Fluorescence Instrument for the In Situ Detection of Iodine Monoxide Radicals

Science.gov (United States)

Thurlow, M. E.; Co, D. T.; O'Brien, A. S.; Hannun, R. A.; Lapson, L. B.; Hanisco, T. F.; Anderson, J. G.

2014-01-01

High abundances of iodine monoxide (IO) are known to exist and to participate in local photochemistry of the marine boundary layer. Of particular interest are the roles IO plays in the formation of new particles in coastal marine environments and in depletion episodes of ozone and mercury in the Arctic polar spring. This paper describes a ground-based instrument that measures IO at mixing ratios less than one part in 1012. The IO radical is measured by detecting laser-induced fluorescence at wavelengths longer that 500 nm. Tunable visible light is used to pump the A23/2 (v = 2) ? X23/2 (v = 0) transition of IO near 445 nm. The laser light is produced by a solid-state, Nd:YAG-pumped Ti:Sapphire laser at 5 kHz repetition rate. The laser-induced fluorescence instrument performs reliably with very high signal-to-noise ratios (>10) achieved in short integration times (<1 min). The observations from a validation deployment to the Shoals Marine Lab on Appledore Island, ME are presented and are broadly consistent with in situ observations from European Coastal Sites. Mixing ratios ranged from the instrumental detection limit (<1 pptv) to 10 pptv. These data represent the first in situ point measurements of IO in North America.

Mineralogy and Astrobiology Detection Using Laser Remote Sensing Instrument

Science.gov (United States)

Abedin, M. Nurul; Bradley, Arthur T.; Sharma, Shiv K.; Misra, Anupam K.; Lucey, Paul G.; Mckay, Chistopher P.; Ismail, Syed; Sandford, Stephen P.

2015-01-01

A multispectral instrument based on Raman, laser-induced fluorescence (LIF), laser-induced breakdown spectroscopy (LIBS), and a lidar system provides high-fidelity scientific investigations, scientific input, and science operation constraints in the context of planetary field campaigns with the Jupiter Europa Robotic Lander and Mars Sample Return mission opportunities. This instrument conducts scientific investigations analogous to investigations anticipated for missions to Mars and Jupiter's icy moons. This combined multispectral instrument is capable of performing Raman and fluorescence spectroscopy out to a >100 m target distance from the rover system and provides single-wavelength atmospheric profiling over long ranges (>20 km). In this article, we will reveal integrated remote Raman, LIF, and lidar technologies for use in robotic and lander-based planetary remote sensing applications. Discussions are focused on recently developed Raman, LIF, and lidar systems in addition to emphasizing surface water ice, surface and subsurface minerals, organics, biogenic, biomarker identification, atmospheric aerosols and clouds distributions, i.e., near-field atmospheric thin layers detection for next robotic-lander based instruments to measure all the above-mentioned parameters. OCIS codes: (120.0280) Remote sensing and sensors; (130.0250) Optoelectronics; (280.3640) Lidar; (300.2530) Fluorescence, laser-induced; (300.6450) Spectroscopy, Raman; (300.6365) Spectroscopy, laser induced breakdown

Development of Real-Time Coal Monitoring Instrument

Energy Technology Data Exchange (ETDEWEB)

Rajan Gurjar, Ph.D.

2010-06-17

Relying on coal for energy requires optimizing the extraction of heat content from various blends of coal fuel and reducing harmful constituents and byproducts. Having a real-time measurement instrument provides relevant information about toxic constituents released in the atmosphere from burning coal and optimizes the performance of a power plant. A few commercial instruments exist and have been in operation for more than a decade. However, most of these instruments are based on radioactive sources and are bulky, expensive and time-consuming. The proposed instrument is based on the Laser Induced Breakdown Spectroscopy (LIBS). The advantage of LIBS is that it is a standoff instrument, does not require sample preparation and provides precise information about sample constituents.

The development and deployment of a ground-based, laser-induced fluorescence instrument for the in situ detection of iodine monoxide radicals

Energy Technology Data Exchange (ETDEWEB)

Thurlow, M. E., E-mail: thurlow@huarp.harvard.edu; Hannun, R. A.; Lapson, L. B.; Anderson, J. G. [Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138 (United States); Co, D. T. [Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138 (United States); Argonne-Northwestern Solar Energy Research Center and Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113 (United States); O' Brien, A. S. [Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138 (United States); Department of Civil and Environmental Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Hanisco, T. F. [Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138 (United States); NASA Goddard Space Flight Center, Code 614, Greenbelt, Maryland 20771 (United States)

2014-04-15

High abundances of iodine monoxide (IO) are known to exist and to participate in local photochemistry of the marine boundary layer. Of particular interest are the roles IO plays in the formation of new particles in coastal marine environments and in depletion episodes of ozone and mercury in the Arctic polar spring. This paper describes a ground-based instrument that measures IO at mixing ratios less than one part in 10{sup 12}. The IO radical is measured by detecting laser-induced fluorescence at wavelengths longer that 500 nm. Tunable visible light is used to pump the A{sup 2}Π{sub 3/2} (v{sup ′} = 2) ← X{sup 2}Π{sub 3/2} (v{sup ″} = 0) transition of IO near 445 nm. The laser light is produced by a solid-state, Nd:YAG-pumped Ti:Sapphire laser at 5 kHz repetition rate. The laser-induced fluorescence instrument performs reliably with very high signal-to-noise ratios (>10) achieved in short integration times (<1 min). The observations from a validation deployment to the Shoals Marine Lab on Appledore Island, ME are presented and are broadly consistent with in situ observations from European Coastal Sites. Mixing ratios ranged from the instrumental detection limit (<1 pptv) to 10 pptv. These data represent the first in situ point measurements of IO in North America.

The development and deployment of a ground-based, laser-induced fluorescence instrument for the in situ detection of iodine monoxide radicals

International Nuclear Information System (INIS)

Thurlow, M. E.; Hannun, R. A.; Lapson, L. B.; Anderson, J. G.; Co, D. T.; O'Brien, A. S.; Hanisco, T. F.

2014-01-01

High abundances of iodine monoxide (IO) are known to exist and to participate in local photochemistry of the marine boundary layer. Of particular interest are the roles IO plays in the formation of new particles in coastal marine environments and in depletion episodes of ozone and mercury in the Arctic polar spring. This paper describes a ground-based instrument that measures IO at mixing ratios less than one part in 10 12 . The IO radical is measured by detecting laser-induced fluorescence at wavelengths longer that 500 nm. Tunable visible light is used to pump the A 2 Π 3/2 (v ′ = 2) ← X 2 Π 3/2 (v ″ = 0) transition of IO near 445 nm. The laser light is produced by a solid-state, Nd:YAG-pumped Ti:Sapphire laser at 5 kHz repetition rate. The laser-induced fluorescence instrument performs reliably with very high signal-to-noise ratios (>10) achieved in short integration times (<1 min). The observations from a validation deployment to the Shoals Marine Lab on Appledore Island, ME are presented and are broadly consistent with in situ observations from European Coastal Sites. Mixing ratios ranged from the instrumental detection limit (<1 pptv) to 10 pptv. These data represent the first in situ point measurements of IO in North America

Dry Eye Disease following Refractive Surgery: A 12-Month Follow-Up of SMILE versus FS-LASIK in High Myopia

Science.gov (United States)

Wang, Bingjie; Chu, Renyuan; Dai, Jinhui; Qu, Xiaomei; Zhou, Hao

2015-01-01

Purpose. To compare dry eye disease following SMILE versus FS-LASIK. Design. Prospective, nonrandomised, observational study. Patients. 90 patients undergoing refractive surgery for myopia were included. 47 eyes underwent SMILE and 43 eyes underwent FS-LASIK. Methods. Evaluation of dry eye disease was conducted preoperatively and at 1, 3, 6, and 12 months postoperatively, using the Salisbury Eye Evaluation Questionnaire (SEEQ) and TBUT. Results. TBUT reduced following SMILE at 1 and 3 months (p dry eye disease than FS-LASIK at 6 months postoperatively but demonstrates similar degrees of dry eye disease at 12 months. PMID:26649190

Alteraciones del polo posterior en la miopía degenerativa Alterations of the posterior pole in degenerative myopia patients

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Suzel Ivón Lapido Polanco

2012-12-01

Full Text Available La miopía degenerativa constituye una de las causas fundamentales de pérdida de la visión. Esto está relacionado con las alteraciones del polo posterior, que afectan la retina neurosensorial, el epitelio pigmentario de la retina y las capas más internas de la coroides. Su curso lento y progresivo demanda una exploración integral, con seguimiento en el tiempo y constituye un reto para el oftalmólogo. Se realizó una revisión de artículos publicados e indexados en la base de datos de PubMed que se refirieran a las características clínicas del fondo de ojo en pacientes con miopía degenerativa, para describir las principales alteraciones del polo posterior del globo ocular en esta entidad. Se encontró entre las lesiones típicas de la alta miopía, al estafiloma posterior como un signo patognomónico de la enfermedad, asociado a la atrofia coriorretiniana en parches o difusa, así como las estrías de laca y las hemorragias maculares secundarias a ellas o provenientes de membranas neovasculares coroideas. La tomografía de coherencia óptica ha permitido un diagnóstico más preciso de otras lesiones maculares como la foveosquisis, el agujero macular y, más recientemente, la mácula en domo. Los cambios degenerativos del polo posterior parecen guardar relación unos con otros pero la patogenia no ha sido bien esclarecida a pesar de los avances tecnológicos.Degenerative myopia is one of the main causes of visual impairment. This is related to disorders in the posterior pole, affecting the neurosensorial retina, the retinal pigmented epithelium and the inner choroidal layers. The slow and progressive course of this condition demands comprehensive assessment and long follow-up, which is a challenging task for ophthalmologists. A review of the articles indexed in PubMed regarding the clinical characteristics of the fundus in patients with degenerative myopia was made to describe the main disorders of the posterior pole of the eyeball

Long term results of no-alcohol laser epithelial keratomileusis and photorefractive keratectomy for myopia

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Leopoldo Spadea

2015-06-01

Full Text Available RESULTS: Twenty-one eyes and 22 eyes completed follow-up of 60mo in LASEK and PRK group respectively. Manifest refraction at 60mo follow-up was -0.01 and 0.26 in LASEK and PRK group respectively. In the LASEK group mean UDVA and mean CDVA after 60mo were 20/22 and 20/20 respectively (P>0.01. In the PRK group mean UDVA and mean CDVA at 60mo follow-up were 20/20 and 20/20 after 60mo (P>0.01. The efficacy indexes were 0.87 and 0.95, and the safety indexes were 1.25 and 1.4 respectively for LASEK group and PRK group.CONCLUSION:Both standard PRK and no-alcohol LASEK offer safe and effective correction of low-moderate myopia in the long term without any statistically significant difference between the two groups.

Long -term effects of optical defocus on eye growth and refractogenesis.

Science.gov (United States)

Tarutta, Elena; Khodzhabekyan, Narine; Filinova, Oksana; Milash, Sergei; Kruzhkova, Galina

The aim of this paper was to study the effect of binocular and alternating monocular myopic constant defocus prescribed in spectacle format on myopia onset and progression in children. 129 children aged 5–12 years were divided into 4 groups: 48 children aged 5–8 years (1st group) with emmetropia and risk factors of myopia development were prescribed the continuous wearing of plus lenses to induce myopia of 1.0 D. 46 children aged 7–11 years (2nd group) with low myopia from −0.75 to −2.25 D were prescribed 2 pairs of spectacles for alternating continuous wearing. One eye was corrected for distance to obtain residual myopia in spectacles of about 0.50 D, and the fellow eye was corrected to obtain residual or induced myopia of about 1.50 D. The children changed spectacles every day. Control data were obtained from 15 children aged 6–9 years (1st control group) with pseudomyopia with no correction administered, and 20 low myopic children aged 7–12 years (2nd control group) wearing conventional spectacle correction. Autorefractometry before and after cycloplegia and ultrasound biometry were performed. A hyperopic shift caused by thinning of the crystalline lens and deepening of the anterior chamber in all patients of the 1st group was observed after 1 month and persisted over the follow -up period. Horizontal diameter (HD) increased more than 3 times as much as the axial length (AL). No cases of myopia onset were observed during the 9 -year follow -up period. 36 (81.8%) children of the 2nd group had stable refraction over the 4 year follow up, an insignificant increase in the AL and a significant increase in the HD were revealed. A 3-year follow -up revealed an increase in cycloplegic refraction in both control groups; the AL increased significantly, while the HD showed an insignificant increase. Permanent low myopic defocus of the image in binocular spectacle format inhibits eye growth and refraction shift to myopia in children with low hyperopia

[Laser in situ keratomyleusis (LASIK) for correction of myopia and hypermetropia--our one year experience].

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Vukosavljević, Miroslav; Milivojević, Milorad; Resan, Mirko; Cerović, Vesna

2009-12-01

Laser in situ keratamileusis (LASIK) is the most commonly used refractive surgical method worldwide. The aim of this study was to examine the effectiveness and safety of LASIK in the correction of myopia and hyperopia. The study included myopic and hyperopic eyes with preoperative best corrected visual acuity (BCVA) = 1 (20/20), of the total number of 322 divided into 2 groups--1) myopic eyes (n = 241) which were divided into 4 subgroups according to the myopia strength: a) or = -7 D (n = 24); 2) hyperopic eyes (n = 81) which were divided into 3 subgroups according to the hyperopia strength: a) or = +4 D (n = 25). Myopic and hyperopic eyes with preoperative BCVA ambliopia) were excluded from the study, as well as eyes with astigmatism > 1.5 D. To assess the effectiveness of LASIK we examined the percentage of eyes in the mentioned subgroups, which derived uncorrected visual acuity (UCVA) 6 month after the intervention to the following: a) UCVA = 1 (20/20) and b) UCVA > or = 0.5 (20/40). To assess the safety of LASIK we examined the frequency of intraoperative and postoperative complications. A prospective study was performed in a 6-months follow-up period. RESULTS. Refractive spherical equivalent (RSE) of myopic eyes was in the range from -0.75 D to -12 D. In the first subgroup preoperative mean value of RSE with standard deviation (mean RSE +/- SD) was -1.39 +/- 0.36 D, and 6 months after the LASIK 100% of the eyes had UCVA = 20/20. In the second subgroup preoperative mean RSE +/- SD was -2.85 +/- 0.50 D, and 6 months after LASIK 93% of the eyes had UCVA = 20/20, but 100% of the eyes had UCVA > or = 20/40. In the third subgroup preoperative mean RSE +/- SD was -5.03 +/- 0.75 D, and 6 months after the LASIK 90% of the eyes had UCVA = 20/20, but 100% of the eyes had UCVA > or = 20/40. In the fourth subgroup preoperative mean RSE +/- SD was -7.68 +/- 1.03 D, and 6 months after the LASIK 96% of the eyes had UCVA = 20/20, but 100% of eyes had UCVA > or = 20

Gyrate atrophy of choroid and retina with myopia, cataract and systemic proximal myopathy: A rare case report from rural India

Directory of Open Access Journals (Sweden)

Surekha Bangal

2012-12-01

Full Text Available AbstractGyrate atrophy is a rare metabolic disease with autosomal recessive inheritance pattern characterised by hyperornithinemia and typical ocular findings. This report presents a 17-year-old intellectually challenged girl consulting for a progressive fall of visual acuity with night blindness. Fundus examination showed patches of chorioretinal atrophy with typical scalloped borders and peri vascular pigmentation in the equatorial region. Fundus fluroscein angiography revealed characteristic staining pattern. Other ocular associations included myopia and posterior sub capsular cataract. Progressive systemic proximal myopathy was one of the associated features. Dietary supplementation of vitamin B6 was advised.

Characterisation of an inlet pre-injector laser induced fluorescence instrument for the measurement of ambient hydroxyl radicals

Science.gov (United States)

Novelli, A.; Hens, K.; Tatum Ernest, C.; Kubistin, D.; Regelin, E.; Elste, T.; Plass-Dülmer, C.; Martinez, M.; Lelieveld, J.; Harder, H.

2014-01-01

Ambient measurements of hydroxyl radicals (OH) are challenging due to a high reactivity and consequently low concentration. The importance of OH as an atmospheric oxidant has resulted in a sustained effort leading to the development of a number of analytical techniques. Recent work has indicated that the laser-induced fluorescence of the OH molecules method based on the fluorescence assay by gas expansion technique (LIF-FAGE) for the measurement of atmospheric OH in some environments may be influenced by artificial OH generated within the instrument, and a chemical method to remove this interference was implemented in a LIF-FAGE system by Mao et al. (2012). We have applied this method to our LIF-FAGE HORUS (HydrOxyl Radical Measurement Unit based on fluorescence Spectroscopy) system, and developed and deployed an inlet pre-injector (IPI) to determine the chemical zero level in the instrument via scavenging the ambient OH radical. We describe and characterise this technique in addition to its application at field sites in forested locations in Finland, Spain, and Germany. Ambient measurements show that OH generated within the HORUS instrument is a non-negligible fraction of the total OH signal, which can comprise 30% to 80% during the day and 60% to 100% during the night. The contribution of the background OH varied greatly between measurement sites and was likely related to the type and concentration of volatile organic compounds (VOCs) present at each particular location. Two inter-comparisons in contrasting environments between the HORUS instrument and two different chemical ionisation mass spectrometers (CIMS) are described to demonstrate the efficacy of the inlet-pre-injector and the necessity of the chemical zeroing method in such environments.

Conceptual Design and Analysis of Service Oriented Architecture (SOA) for Command and Control of Space Assets

Science.gov (United States)

2010-12-01

organizational inertia (26) play a role here: o Distorted Perception  Myopia – According to organizational theory, the simplest source of induced myopia is... reality . Also complicating the presentation of these functions as services are the associated stringent performance requirements. These services...Reference Architecture Factsheet. GMSEC Home. [Online] March 2004. http://gmsec.gsfc.nasa.gov/factSheets/GMSECarch.ppt. 16. Virtual Mission Operations

Comparison of photorefractive keratectomy and laser in situ keratomileusis for myopia of -6 D or less using the Nidek EC-5000 laser.

Science.gov (United States)

Fernández, A P; Jaramillo, J; Jaramillo, M

2000-01-01

We compared the efficacy, predictability, and safety of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for the surgical correction of low and moderate myopia. A retrospective study was performed to evaluate uncorrected and spectacle-corrected visual acuity, and manifest refraction 1 year after PRK or LASIK. All procedures were done using an automatic microkeratome (Chiron Ophthalmic) and the Nidek EC-5000 excimer laser. PRK was performed in 75 eyes of 45 patients and LASIK in 133 eyes of 77 patients. Mean age for PRK patients was 32.8 years (range, 18 to 52 yr) and LASIK patients was 29.6 years (range, 18 to 49 yr). Mean preoperative spherical equivalent refraction for PRK patients was -3.28 D (range, -1.00 to -6.00 D) and LASIK, -3.86 D (range, -1.00 to -6.00 D). One year after surgery, mean spherical equivalent refraction for Group 1 (baseline, -1.00 to -3.00 D) PRK eyes was -0.18 +/- 0.61 D (range, -1.50 to +0.75 D) and for LASIK eyes, -0.08 +/- 0.61 D (range, -1.50 to +1.62 D), with no statistically significant difference. For Group 2 eyes (baseline, -3.25 to -6.00 D), mean spherical equivalent refraction for PRK eyes was -0.44 +/- 0.87 D (range, -2.00 to +2.12 D) and for LASIK eyes, -0.09 +/- 0.83 D (range, -1.50 to +1.75 D), with no statistically significant difference. The antilogarithm of the mean UCVA (antilogUCVA) in Group 1 for PRK was 0.79 +/- 0.21 (20/25) and for LASIK was 0.87 +/- 0.19 (20/23), with no statistically significant difference. The antilogUCVA in Group 2 for PRK eyes was 0.70 +/- 0.24 (20/28) and for LASIK eyes was 0.83 +/- 0.18 (20/24), with a statistically significant difference (0.7 vs. 0.83, P 20/40 in Group 1 for PRK was 91.5% (38 eyes) and for LASIK was 95% (50 eyes) (no statistically significant difference), and in Group 2 for PRK eyes, it was 82% (27 eyes) and 97.5% (78 eyes) for LASIK (statistically significant difference, P PRK and LASIK with the Nidek EC-5000 excimer laser are effective and safe for

Axial length and cone density as assessed with adaptive optics in myopia

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Supriya Dabir

2015-01-01

Full Text Available Aim: To assess the variations in cone mosaic in myopia and its correlation with axial length (AL. Subjects and Methods: Twenty-five healthy myopic volunteers underwent assessment of photoreceptors using adaptive optics retinal camera at 2° and 3° from the foveal center in four quadrants superior, inferior, temporal and nasal. Data was analyzed using SPSS version 17 (IBM. Multivariable regression analysis was conducted to study the relation between cone density and AL, quadrant around the fovea and eccentricity from the fovea. Results: The mean cone density was significantly lower as the eccentricity increased from 2° from the fovea to 3° (18,560 ± 5455-16,404 ± 4494/mm 2 respectively. There was also a statistically significant difference between four quadrants around the fovea. The correlation of cone density and spacing with AL showed that there was a significant inverse relation of AL with the cone density. Conclusion: In myopic patients with good visual acuity cone density around the fovea depends on the quadrant, distance from the fovea as well as the AL. The strength of the relation of AL with cone density depends on the quadrant and distance.

Microbiologic study of soft contact lenses after laser subepithelial keratectomy for myopia.

Science.gov (United States)

Hondur, Ahmet; Bilgihan, Kamil; Cirak, Meltem Yalinay; Dogan, Ozgur; Erdinc, Alper; Hasanreisoglu, Berati

2008-01-01

To evaluate the extent and agents of bacterial contamination of bandage disposable soft contact lenses after laser subepithelial keratectomy (LASEK) and to correlate the findings with clinical data. Disposable soft contact lenses were collected from 52 eyes of 26 consecutive patients treated with LASEK for myopia. The patients were treated with a fixed combination of tobramycin and diclofenac until epithelial closure. The lenses were removed on the fourth or fifth postoperative day with sterile forceps and immediately placed in sterile tubes containing culture media brain-heart infusion broth. The lenses were evaluated for microbial colonization. Of the 52 contact lenses analyzed, six (11.5%) had positive cultures. However, no clinical finding of infection was noted. Isolated microorganisms were coagulase-negative staphylococci (two lenses), Stenotrophomonas maltophilia (two lenses), Acinetobacter species (one lens), and Aeromonas hydrophila (one lens). Except for one case, the microorganisms were sensitive to the administered antibiotic. The risk of infectious keratitis after LASEK seems to be low. Except for staphylococci, the isolated microorganisms have not been previously reported to colonize the ocular surface or cause keratitis after refractive surgery. These findings may suggest a changing trend of potentially infectious agents after surface ablation.

Caracterización clínico-epidemiológica de la miopía en la población infantil de un municipio de Venezuela Clinical-epidemiological characterization of myopia in children from a Venezuelan municipality

Directory of Open Access Journals (Sweden)

Ceilan Carballo Wong

2011-06-01

affections, the early detection and the appropriate treatment of these defects during childhood prevent future affection of visual health with a high cost in quality of life. The objective of present research was to describe the clinical-epidemiological behavior of myopia in children aged 5-15 from the Rafael Urdaneta municipality of Miranda state, Venezuela during the second trimester of 2008. METHODS. A cross-sectional, descriptive and observational study was conducted. The variables analyzed included age, sex, skin color and clinical-epidemiological features of refractive defect: degree, signs, symptoms, associated ocular diseases, family background of myopia and family and personal pathological backgrounds of systemic and ocular diseases. The universe and sample included patients aged between 5 -15 diagnosed with myopia applying inclusion criteria (sample of 104 patients. The data analysis and processing was by descriptive statistical techniques. RESULTS. There was predominance of myopia among 10 and 15 years old (57,7% in both sexes, although in the female one it was slightly more frequent among the cases (58,7%, as well as among the half-castes (54,8%. The mild myopia was the commonest defect (61,5% and the visual decrease from a distance and the palpebral cleavage were the more represented sign and symptom (100% and 91.3% of patients, respectively. The 47,1% of myopic persons had the background of family myopia and the bronchial asthma was the more significant systemic background. CONCLUSIONS. The mild myopia was the commonest defect found in study population whose frequency increasing with age and in presence of risk factors.

Vibration test report on the instrumented capsule for fuel irradiation test

Energy Technology Data Exchange (ETDEWEB)

Ryu, Jeong Soo; Yoon, D. B.; Wu, J. S.; Oh, J. M.; Park, S. J.; Cho, M. S.; Kim, B. G.; Kang, Y. W

2003-01-01

The fluid-induced vibration level of instrumented capsule, which was manufactured for fuel irradiation test at the reactor core of HANARO, was investigated. For this purpose, the instrumented capsule was loaded at the OR site of the HANARO design verification test facility that could simulate identical flow condition as the HANARO core. Then, vibration signals of the instrumented capsule subjected to various flow conditions were measured by using vibration sensors. In time domain analysis, maximum amplitudes and RMS values of the measured acceleration and displacement signals were obtained. By using frequency domain analysis, frequency components of the fluid-induced vibration were analyzed. In addition, natural frequencies of the instrumented capsule were obtained by performing modal test. The frequency analysis results showed that the natural frequency components near 7.5Hz and 17.5Hz were dominant in the fluid-induced vibration signal. The maximum amplitude of the accelerations was measured as 12.04m/s{sup 2} that is within the allowable vibrational limit(18.99m/s{sup 2})of the reactor structure. Also, the maximum displacement amplitude was calculated as 0.191mm. Since these vibration levels are remarkably low, excessive vibration is not expected when the irradiation test of the instrumented capsule is performed at the HANARO core.

Green-synthetized silver nanoparticles for Nanoparticle-Enhanced Laser Induced Breakdown Spectroscopy (NELIBS) using a mobile instrument

Science.gov (United States)

Poggialini, F.; Campanella, B.; Giannarelli, S.; Grifoni, E.; Legnaioli, S.; Lorenzetti, G.; Pagnotta, S.; Safi, A.; Palleschi, V.

2018-03-01

When compared to other analytical techniques, LIBS shows relatively low precision and, generally, high Limits of Detection (LODs). Until recently, the attempts in improving the LIBS performances have been based on the use of more stable/powerful lasers, high sensitivity detectors or controlled environmental parameters. This can hinder the competitiveness of LIBS by increasing the instrumental setup cost and the difficulty of operation. Sample treatment has proved to be a viable and simple way to increase the LIBS signal; in particular, the Nanoparticle-Enhanced Laser Induced Breakdown Spectroscopy (NELIBS) methodology uses a deposition of metal nanoparticles on the sample to greatly increase the emission of the LIBS plasma. In this work, we used a simple, fast, "green" and low-cost method to synthetize silver nanoparticles by using coffee extract as reducing agents for a silver nitrate solution. This allowed us to obtain nanoparticles of about 25 nm in diameter. We then explored the application of such nanoparticles to the NELIBS analysis of metallic samples with a mobile LIBS instrument. By adjusting the laser parameters and optimizing the sample preparation procedure, we obtained a NELIBS signal that is 4 times the LIBS one. This showed the potential of green-synthetized nanoparticle for NELIBS applications and suggests the possibility of an in-situ application of the technique.

High Myopia Caused by a Mutation in LEPREL1, Encoding Prolyl 3-Hydroxylase 2

Science.gov (United States)

Mordechai, Shikma; Gradstein, Libe; Pasanen, Annika; Ofir, Rivka; El Amour, Khalil; Levy, Jaime; Belfair, Nadav; Lifshitz, Tova; Joshua, Sara; Narkis, Ginat; Elbedour, Khalil; Myllyharju, Johanna; Birk, Ohad S.

2011-01-01

Autosomal-recessive high-grade axial myopia was diagnosed in Bedouin Israeli consanguineous kindred. Some affected individuals also had variable expressivity of early-onset cataracts, peripheral vitreo-retinal degeneration, and secondary sight loss due to severe retinal detachments. Through genome-wide linkage analysis, the disease-associated gene was mapped to ∼1.7 Mb on chromosome 3q28 (the maximum LOD score was 11.5 at θ = 0 for marker D3S1314). Sequencing of the entire coding regions and intron-exon boundaries of the six genes within the defined locus identified a single mutation (c.1523G>T) in exon 10 of LEPREL1, encoding prolyl 3-hydroxylase 2 (P3H2), a 2-oxoglutarate-dependent dioxygenase that hydroxylates collagens. The mutation affects a glycine that is conserved within P3H isozymes. Analysis of wild-type and p.Gly508Val (c.1523G>T) mutant recombinant P3H2 polypeptides expressed in insect cells showed that the mutation led to complete inactivation of P3H2. PMID:21885030

Early rhegmatogenous retinal detachment following laser in situ keratomileusis for high myopia.

Science.gov (United States)

Farah, M E; Höfling-Lima, A L; Nascimento, E

2000-01-01

Four eyes had early rhegmatogenous retinal detachment within 3 months of laser in situ keratomileusis (LASIK) for correction of high myopia using the microkeratome, Clear Corneal Molder. In two eyes, retinal detachment resulted from horseshoe tears, one occurring in an otherwise normal region of the retina and the other at the margin of an area of lattice degeneration detected during preoperative examination. The first eye was treated with retinopexy using a 287 encircling scleral exoplant, drainage of subretinal fluid, and laser photocoagulation by indirect ophthalmoscopy. The other eye was treated with pneumatic retinopexy and cryotherapy. In the other eyes, retinal detachment was the result of giant tears with no evidence of prior retinal degeneration. These eyes were treated with pars plana vitrectomy, fluid-gas exchange with 15% perfluoropropane (C3F8), endolaser photocoagulation, and a 42 encircling scleral exoplant. After treatment, the first two eyes achieved spectacle-corrected visual acuity of 20/40. In the last two eyes, final spectacle-corrected visual acuity was 20/400 in one eye and light perception in the other. Although no cause-effect relationship between LASIK and retinal detachment can be stated, these cases suggest that LASIK may be associated with retinal detachment, particularly in highly myopic eyes. Further studies are necessary to determine high-risk patient characteristics.

Uncorrected and Corrected Distance Visual Acuity, Predictability, Efficacy, and Safety after Femtosecond Laser in Situ Keratomileusis (FS-LASIK) and Refractive Lenticule extraction (ReLEx) for Moderate and High Myopia

DEFF Research Database (Denmark)

Vestergaard, Anders; Justesen, Birgitte Larsen; Melsen, Charlotte

Title: Uncorrected and Corrected Distance Visual Acuity, Predictability, Efficacy, and Safety after Femtosecond Laser in Situ Keratomileusis (FS-LASIK) and Refractive Lenticule extraction (ReLEx) for Moderate and High Myopia. Vestergaard A., Justesen B., Melsen C., Lyhne N., Department of Ophthal......Title: Uncorrected and Corrected Distance Visual Acuity, Predictability, Efficacy, and Safety after Femtosecond Laser in Situ Keratomileusis (FS-LASIK) and Refractive Lenticule extraction (ReLEx) for Moderate and High Myopia. Vestergaard A., Justesen B., Melsen C., Lyhne N., Department...... predictability, efficacy and safety after femtosecond LASIK (FS-LASIK) with ReLEx. Setting: Department of Ophthalmology, Odense University Hospital, Denmark. Methods: Retrospective study of results after FS-LASIK and ReLEx (including ReLEx flex, ReLEx pseudo-smile, and ReLEx smile). In total, 228 eyes were...... treated with FS-LASIK and 83 eyes with ReLEx, at the Department of Ophthalmology, Odense University Hospital in the period of April to November 2011. Only otherwise healthy myopic eyes with up to 3.00 D of astigmatism and with CDVA ≤ 0.30 (logMAR) before surgery were included in this study. FS-LASIK flaps...

Consistent comparison of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided LASIK for myopia by EX500 excimer laser.

Science.gov (United States)

Sun, Ming-Shen; Zhang, Li; Guo, Ning; Song, Yan-Zheng; Zhang, Feng-Ju

2018-01-01

To evaluate and compare the uniformity of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided ablation of laser in situ keratomileusis (LASIK) by EX500 excimer laser for myopia. Totally 145 cases (290 consecutive eyes )with myopia received LASIK with a target of emmetropia. The ablation for 86 cases (172 eyes) was guided manually based on Oculyzer topography (study group), while the ablation for 59 cases (118 eyes) was guided automatically by Topolyzer Vario topography (control group). Measurement of adjustment values included data respectively in horizontal and vertical direction of cornea. Horizontally, synclastic adjustment between manually actual values (dx manu ) and Oculyzer topography guided data (dx ocu ) accounts 35.5% in study group, with mean dx manu /dx ocu of 0.78±0.48; while in control group, synclastic adjustment between automatically actual values (dx auto ) and Oculyzer topography data (dx ocu ) accounts 54.2%, with mean dx auto /dx ocu of 0.79±0.66. Vertically, synclastic adjustment between dy manu and dy ocu accounts 55.2% in study group, with mean dy manu /dy ocu of 0.61±0.42; while in control group, synclastic adjustment between dy auto and dy ocu accounts 66.1%, with mean dy auto /dy ocu of 0.66±0.65. There was no statistically significant difference in ratio of actual values/Oculyzer topography guided data in horizontal and vertical direction between two groups ( P =0.951, 0.621). There is high consistency in angle Kappa adjustment guided manually by Oculyzer and guided automatically by Topolyzer Vario topography during corneal refractive surgery by WaveLight EX500 excimer laser.

Matched optical quality comparison of 3-year results of PRK–MMC and phakic IOL implantation in the correction of high myopia

Science.gov (United States)

Miraftab, M; Hashemi, H; Asgari, S

2015-01-01

Aims To compare 3-year results of PRK–MMC and phakic intraocular lens (PIOL) implantation in patients with >8.0 diopters (D) of myopia. Methods This study was conducted as a non-randomized clinical trial on 23 eyes treated with PIOL (Artiflex; group A) and 23 eyes treated with PRK–MMC (group B). This report compares 3-year treatment results in these two groups. Results At 3 years after surgery, uncorrected visual acuity was 0.02±0.06 LogMAR in group A and 0.04±0.07 LogMAR in group B (P=0.639). Mean best corrected visual acuity in group A (0.004±0.02) was better than group B (0.03±0.07 LogMAR) (P=0.035). Mean manifest refraction spherical equivalent was −0.16±0.21 and −0.09±0.20D (P=0.190), respectively. Mesopic contrast sensitivity (CS) in the spatial frequency of three cycle/degree (CS3) significantly decreased in both groups, but the reduction was significantly higher in group B (P=0.024). CS6 decreased significantly only in group B (P=0.019). Changes in CS12 and CS18 showed no significant inter-group difference. In group A, the increase in C6 trefoil (0.16±0.18 μm, P=0.003) and reduction in spherical aberration (SA; 0.16±0.08 μm, PPRK–MMC for treating patients with >8.0D myopia. However, for patients with an inadequate aqueous depth, PRK–MMC can be an acceptable treatment option with a potential for decreased quality of vision. PMID:25976638

Matched optical quality comparison of 3-year results of PRK-MMC and phakic IOL implantation in the correction of high myopia.

Science.gov (United States)

Miraftab, M; Hashemi, H; Asgari, S

2015-07-01

To compare 3-year results of PRK-MMC and phakic intraocular lens (PIOL) implantation in patients with >8.0 diopters (D) of myopia. This study was conducted as a non-randomized clinical trial on 23 eyes treated with PIOL (Artiflex; group A) and 23 eyes treated with PRK-MMC (group B). This report compares 3-year treatment results in these two groups. At 3 years after surgery, uncorrected visual acuity was 0.02±0.06 LogMAR in group A and 0.04±0.07 LogMAR in group B (P=0.639). Mean best corrected visual acuity in group A (0.004±0.02) was better than group B (0.03±0.07 LogMAR) (P=0.035). Mean manifest refraction spherical equivalent was -0.16±0.21 and -0.09±0.20D (P=0.190), respectively. Mesopic contrast sensitivity (CS) in the spatial frequency of three cycle/degree (CS3) significantly decreased in both groups, but the reduction was significantly higher in group B (P=0.024). CS6 decreased significantly only in group B (P=0.019). Changes in CS12 and CS18 showed no significant inter-group difference. In group A, the increase in C6 trefoil (0.16±0.18 μm, P=0.003) and reduction in spherical aberration (SA; 0.16±0.08 μm, PPRK-MMC for treating patients with >8.0D myopia. However, for patients with an inadequate aqueous depth, PRK-MMC can be an acceptable treatment option with a potential for decreased quality of vision.

Optical 'dampening' of the refractive error to axial length ratio: implications for outcome measures in myopia control studies.

Science.gov (United States)

Cruickshank, Fiona E; Logan, Nicola S

2018-05-01

To gauge the extent to which differences in the refractive error axial length relationship predicted by geometrical optics are observed in actual refractive/biometric data. This study is a retrospective analysis of existing data. Right eye refractive error [RX] and axial length [AXL] data were collected on 343 6-to-7-year-old children [mean 7.18 years (S.D. 0.35)], 294 12-to-13-year-old children [mean 13.12 years (S.D. 0.32)] and 123 young adults aged 18-to-25-years [mean 20.56 years (S.D. 1.91)]. Distance RX was measured with the Shin-Nippon NVision-K 5001 infrared open-field autorefractor. Child participants were cyclopleged prior to data collection (1% Cyclopentolate Hydrochloride). Myopia was defined as a mean spherical equivalent [MSE] ≤-0.50 D. Axial length was measured using the Zeiss IOLMaster 500. Optical modelling was based on ray tracing and manipulation of parameters of a Gullstrand reduced model eye. There was a myopic shift in mean MSE with age (6-7 years +0.87 D, 12-13 years -0.06 D and 18-25 years -1.41 D), associated with an increase in mean AXL (6-7 years 22.70 mm, 12-13 years 23.49 mm and 18-25 years 23.98 mm). There was a significant negative correlation between MSE and AXL for all age groups (all p theory predicts that there will be a reduction in the RX: AXL ratio with longer eyes. The participant data although adhering to this theory show a reduced effect, with eyes with longer axial lengths having a lower refractive error to axial length ratio than predicted by model eye calculations. We propose that in myopia control intervention studies when comparing efficacy, consideration should be given to the dampening effect seen with a longer eye. © 2018 The Authors. Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.

Two-years results of small-incision lenticule extraction and wavefront-guided laser in situ keratomileusis for Myopia.

Science.gov (United States)

Kobashi, Hidenaga; Kamiya, Kazutaka; Igarashi, Akihito; Takahashi, Masahide; Shimizu, Kimiya

2018-03-01

To compare the 2-years visual and refractive outcomes between small-incision lenticule extraction (SMILE) and wavefront-guided laser in situ keratomileusis (LASIK) in eyes with myopia and myopic astigmatism. Our retrospective case-control study examined 30 eyes of 30 patients with the manifest refraction spherical equivalent (MRSE) of -3.71 ± 1.83 dioptres (D) who underwent SMILE and 30 eyes of 30 patients with MRSE of -3.81 ± 1.40 D who underwent wavefront-guided LASIK. We assessed the 2-years clinical outcomes. Logarithm of the minimal angle of resolution (LogMAR)-corrected distance visual acuity (CDVA) was -0.23 ± 0.07 in the SMILE group and -0.24 ± 0.07 in the wavefront-guided LASIK group 2 years postoperatively (p = 0.82). Logarithm of the minimal angle of resolution-uncorrected distance visual acuity (UDVA) was -0.18 ± 0.09 and -0.15 ± 0.11 (p = 0.30, respectively). In the SMILE and wavefront-guided LASIK groups 2 years postoperatively, 100% and 73% of eyes, respectively, were within 0.5 D of the prompted MRSE correction (p = 0.005). Changes in the MRSE of -0.10 ± 0.30 D and -0.23 ± 0.51 D occurred from 3 months to 2 years (p = 0.40, respectively). We found a significant correlation between myopic regression and the changes in the keratometric readings from 3 months to 2 years after wavefront-guided LASIK (r = -0.48, p = 0.002), but not after SMILE (r = -0.004, p = 0.90). Small-incision lenticule extraction offers better refractive outcomes than wavefront-guided LASIK during a 2-years follow-up for the correction of myopia and myopic astigmatism. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Instrumentation Cables Test Plan

Energy Technology Data Exchange (ETDEWEB)

Muna, Alice Baca [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); LaFleur, Chris Bensdotter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2016-10-01

A fire at a nuclear power plant (NPP) has the potential to damage structures, systems, and components important to safety, if not promptly detected and suppressed. At Browns Ferry Nuclear Power Plant on March 22, 1975, a fire in the reactor building damaged electrical power and control systems. Damage to instrumentation cables impeded the function of both normal and standby reactor coolant systems, and degraded the operators’ plant monitoring capability. This event resulted in additional NRC involvement with utilities to ensure that NPPs are properly protected from fire as intended by the NRC principle design criteria (i.e., general design criteria 3, Fire Protection). Current guidance and methods for both deterministic and performance based approaches typically make conservative (bounding) assumptions regarding the fire-induced failure modes of instrumentation cables and those failure modes effects on component and system response. Numerous fire testing programs have been conducted in the past to evaluate the failure modes and effects of electrical cables exposed to severe thermal conditions. However, that testing has primarily focused on control circuits with only a limited number of tests performed on instrumentation circuits. In 2001, the Nuclear Energy Institute (NEI) and the Electric Power Research Institute (EPRI) conducted a series of cable fire tests designed to address specific aspects of the cable failure and circuit fault issues of concern1. The NRC was invited to observe and participate in that program. The NRC sponsored Sandia National Laboratories to support this participation, whom among other things, added a 4-20 mA instrumentation circuit and instrumentation cabling to six of the tests. Although limited, one insight drawn from those instrumentation circuits tests was that the failure characteristics appeared to depend on the cable insulation material. The results showed that for thermoset insulated cables, the instrument reading tended to drift

Evaluation of Biomechanical Changes in Myopia Patients with Unsatisfactory Corneas After Femto Second-Laser In Situ Keratomileusis (FS-LASIK) Concurrent with Accelerated Corneal Collagen Cross-Linking Using Corvis-ST: Two-Year Follow-Up Results.

Science.gov (United States)

Xu, Weiwei; Tao, Ye; Wang, Liqiang; Huang, Yifei

2017-07-27

BACKGROUND Some myopia patients with unsatisfactory corneas consider corneal refractive surgery for different reasons. Accelerated corneal collagen crosslinking (ACXL) is an effective method to enhance the resistance of the cornea. The present investigation was designed to evaluate the changes of biomechanical properties in patients with myopia and thin corneas after femtosecond-laser in situ keratomileusis (FS-LASIK) concurrent with ACXL. MATERIAL AND METHODS A prospective study was designed. A total of 22 eyes of 11 myopia astigmatism patients with unsatisfactory corneas were enrolled. The patients were assigned to femtosecond-laser in situ keratomileusis concurrent with accelerated corneal collagen crosslinking (FS-LASIK-ACXL). The follow-up duration was 24 months. Manifest refraction, uncorrected (UDVA), and corrected distance visual acuity (CDVA), ultra-high-speed camera (Corvis-ST), corneal topography, anterior segment OCT (AS-OCT), Pentacam, and endothelial cell density (ECD) were examined before and after the operation. The corneal biomechanical and refractive data was analyzed using SAS9.3. Data were analyzed through normal distribution test and variance of analysis. The difference was considered as statistically significant when pLASIK-ACXL operation. The values of first applanation length (A1L), the second applanation length (A2L), the first applanation velocity (A1V), the second applanation velocity (A2V), deformation amplitude (DA), highest concavity peak distance (PD), and radius of curvature at the time of highest concavity (HCR) did not show significant difference after the operation. CONCLUSIONS FS-LASIK-ACXL is an effective and safe surgery for improving visual acuity for myopic patients with thin corneas, and it does not increase the risk of iatrogenic keratectasia.

Laser in situ keratomyleusis (LASIK for correction of myopia and hypermetropia: Our one year experience

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Vukosavljević Miroslav

2009-01-01

Full Text Available Background/Aim. Laser in situ keratamileusis (LASIK is the most commonly used refractive surgical method worldwide. The aim of this study was to examine the effectiveness and safety of LASIK in the correction of myopia and hyperopia. Methods. The study included myopic and hyperopic eyes with preoperative best corrected visual acuity (BCVA = 1 (20/20, of the total number of 322 divided into 2 groups - 1 myopic eyes (n = 241 which were divided into 4 subgroups according to the myopia strength: a ≤ -1.75 D (n = 23, b from -2 to -3.75 D (n = 81, c from -4 to -6.75 D (n = 113, d ≥ -7 D (n = 24; 2 hyperopic eyes (n = 81 which were divided into 3 subgroups according to the hyperopia strength: a ≤ +1.75D (n = 10, b from +2 to +3.75 D (n = 46, c ≥ +4 D (n = 25. Myopic and hyperopic eyes with preoperative BCVA ≤ 0.9 (eyes with ambliopia were excluded from the study, as well as eyes with astigmatism > 1.5 D. To assess the effectiveness of LASIK we examined the percentage of eyes in the mentioned subgroups, which derived uncorrected visual acuity (UCVA 6 month after the intervention to the following: a UCVA = 1 (20/20 and b UCVA ≥ 0.5 (20/40. To assess the safety of LASIK we examined the frequency of intraoperative and postoperative complications. A prospective study was performed in a 6-months follow-up period. Results. Refractive spherical equivalent (RSE of myopic eyes was in the range from -0.75 D to -12 D. In the first subgroup preoperative mean value of RSE with standard deviation (mean RSE ± SD was -1.39 ± 0.36 D, and 6 months after the LASIK 100% of the eyes had UCVA = 20/20. In the second subgroup preoperative mean RSE ± SD was -2.85 ± 0.50 D, and 6 months after LASIK 93% of the eyes had UCVA = 20/20, but 100% of the eyes had UCVA ≥ 20/40. In the third subgroup preoperative mean RSE ± SD was -5.03 ± 0.75 D, and 6 months after the LASIK 90% of the eyes had UCVA = 20/20, but 100% of the eyes had UCVA ≥ 20/40. In the fourth

Drug treatment for high IOP at early stage after vitrectomy for macular hole caused by high myopia

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Yu-Juan Zhou

2015-12-01

Full Text Available AIM:To study the effect of only latanoprost eye drops or combined with other medicines on lowering intraocular pressure(IOPafter early pars plana vitrectomy(PPVfor macular hole without retinal detachment caused by high myopia.METHODS:One hundred and eighty-eight cases(205 eyessuffered from macular hole caused by high myopia without reinal detachment who underwent PPV combined with C3F8 tamponade were studied retrospectively and measured the IOP at 1wk after surgeries. The patients whose IOP was 22～29mmHg were named as group A. Then they were divided randomly into two subgroups, group A1(treated by carteolol eye dropsand subgroup A2(treated by latanoprost eye drops. The patients whose IOP was 30～39mmHg were named as group B. Then they were divided randomly into two subgroups, group B1(treated by both carteolol and brimonidine tartrate eye dropsand subgroup B2(treated by both latanoprost and carteolol eye drops. The patients whose IOP was ≥40mmHg were named as group C and they were all treated by rapid intravenous injection of 20% Mannitol. Meanwhile, they were divided randomly into two subgroups, group C1(treated by carteolol,brimonidine tartrate and brinzolamide eye drops and subgroup C2(treated by carteolol,brimonidine tartrate and latanoprost eye drops. Continuous observation lasted 3d. If IOP dropped to below 21 mmHg, we considered it valid. And then,compare the effectiveness, IOP reduction and the average effective duration. RESULTS:Eighty-nine eyes met the criteria of high IOP and IOP of 70 eyes(78.6%increased within 3d after operations. There were 31 eyes in group A including 14 eyes in group A1 and 17 eyes in group A2.The number of effective cases of the two groups was 5(35.7%and 13(76.5%respectively, the difference was statistically significant(χ2=5.24,P=0.03.The IOP reduction of the two groups were 4.21±1.22mmHg(24%, 8.76±3.03mmHg(29.6%, respectively, and the difference was statistically significant(t=5.73,Pt=2.85,P=0.012.There

Development of a fiber-coupled laser-induced breakdown spectroscopy instrument for analysis of underwater debris in a nuclear reactor core

International Nuclear Information System (INIS)

Saeki, Morihisa; Iwanade, Akio; Ohba, Hironori; Ito, Chikara; Wakaida, Ikuo; Thornton, Blair; Sakka, Tetsuo

2014-01-01

To inspect the post-accident nuclear core reactor of the TEPCO Fukushima Daiichi nuclear power plant (F1-NPP), a transportable fiber-coupled laser-induced breakdown spectroscopy (LIBS) instrument has been developed. The developed LIBS instrument was designed to analyze underwater samples in a high-radiation field by single-pulse breakdown with gas flow or double-pulse breakdown. To check the feasibility of the assembled fiber-coupled LIBS instrument for the analysis of debris material (mixture of the fuel core, fuel cladding, construction material and so on) in the F1-NPP, we investigated the influence of the radiation dose on the optical transmittance of the laser delivery fiber, compared data quality among various LIBS techniques for an underwater sample and studied the feasibility of the fiber-coupled LIBS system in an analysis of the underwater sample of the simulated debris in F1-NPP. In a feasible study conducted by using simulated debris, which was a mixture of CeO 2 (surrogate of UO 2 ), ZrO 2 and Fe, we selected atomic lines suitable for the analysis of materials, and prepared calibration curves for the component elements. The feasible study has guaranteed that the developed fiber-coupled LIBS system is applicable for analyzing the debris materials in the F1-NPP. (author)

Comparison of Bigbag and Rayner620H intraocular lens in cataract surgeries in high myopia patients

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Zhan-Jiang Liu

2016-01-01

Full Text Available AIM:To investigate the effects of Bigbag and Rayner620H intraocular lens in cataract surgeries in high myopia patients. METHODS:Seventy-seven patients(128 eyeswere treated by phacoemulsification combined with intraocular lens implantation from January 2014 to March 2015 in our hospital. Thirty-nine patients(65 eyeswere treated with Bigbag intraocular lens, 38 cases(63 eyeswere treated with Rayner620H. The best corrected visual acuity(BCVAdistribution, the actual refractive value, the difference between predictive refractive value and actual refractive value and complications were measured and recorded in the two groups at 1mo after surgeries. RESULTS:The difference between the two groups on BCVA are statistically significant(PWilcoxon rank sum test. The differences between predictive refractive value and actual refractive value of the two groups were statistically significant(PPCONCLUSION:The effect of Bigbag intraocular lens for patients with phacoemulsification and intraocular lens implantation is good, and it can reduce the risk of complications.

Proof-testing strategies induced by dangerous detected failures of safety-instrumented systems

International Nuclear Information System (INIS)

Liu, Yiliu; Rausand, Marvin

2016-01-01

Some dangerous failures of safety-instrumented systems (SISs) are detected almost immediately by diagnostic self-testing as dangerous detected (DD) failures, whereas other dangerous failures can only be detected by proof-testing, and are therefore called dangerous undetected (DU) failures. Some items may have a DU- and a DD-failure at the same time. After the repair of a DD-failure is completed, the maintenance team has two options: to perform an insert proof test for DU-failure or not. If an insert proof test is performed, it is necessary to decide whether the next scheduled proof test should be postponed or performed at the scheduled time. This paper analyzes the effects of different testing strategies on the safety performance of a single channel of a SIS. The safety performance is analyzed by Petri nets and by approximation formulas and the results obtained by the two approaches are compared. It is shown that insert testing improves the safety performance of the channel, but the feasibility and cost of the strategy may be a hindrance to recommend insert testing. - Highlights: • Identify the tests induced by detected failures. • Model the testing strategies following DD-failures. • Propose analytical formulas for effects of strategies. • Simulate and verify the proposed models.

Comparison of the efficacy of intravitreal ranibizumab for choroidal neovascularization due to pathological myopia with and without a dome-shaped macula.

Science.gov (United States)

Cai, Bincui; Yang, Jin; Li, Shuang; Wang, Linni; Chen, Lu; Li, Xiaorong; Li, Zhiqing

2017-12-01

Ranibizumab injection in the treatment of choroidal neovascularization (CNV) secondary to pathologic myopia (PM) with and without a dome-shaped macula (DSM).Prospective observational study.A total of 24 patients (24 eyes) with angiographic evidence of CNV secondary to PM were divided into 2 groups: eyes with a DSM and eyes without DSM. All patients received a baseline intravitreal ranibizumab injection. Additional injections were considered at each follow-up visit. Best-corrected visual acuity (BCVA) and optical coherence tomography were tested monthly through 12 months of follow-up. The mean changes in BCVA, central retinal thickness (CRT, including retinal and CNV thickness), and the number of injections were evaluated.There were no significant differences in visual outcomes between the groups over 12 months (P > .05). Patients with a DSM had a mean change in BCVA of +8.7 letters compared with +14.2 letters in patients without a DSM (P = .68). However, there were more patients without a DSM who gained at least 15 letters from baseline compared with patients with a DSM. By the end of the follow-up, there was no significant difference in the mean change in baseline CRT between patients with and without a DSM (-65.0 and -90.7, respectively, P = .42). The mean number of injections was 8.83 in the patients with DSM and 8.17 in the patients without a DSM (P > .05).For the pathological myopia patients who had CNV with a DSM, the DSM did not alter the effect of the ranibizumab treatment. There was no difference in the visual improvement, anatomic benefit and number of treatments between the 2 groups. Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. All rights reserved.

Visumax femtolasik versus Moria M2 microkeratome in mild to moderate myopia: efficacy, safety, predictability, aberrometric changes and flap thickness predictability.

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Torky, Magda A; Al Zafiri, Yousif A; Khattab, Abeer M; Farag, Rania K; Awad, Eman A

2017-07-17

This is an interventional prospective clinical study which was conducted to evaluate the efficacy, safety, predictability, ocular aberrations, and flap thickness predictability of Visumax femtosecond laser (FSL) compared to Moria M2 microkeratome (MK) in mild to moderate myopia. This study included 60 eyes who were divided into two groups. Thirty eyes in group (I) in which the flap was created with Visumax FSL, while in group II (30 eyes) the Moria M2 MK was used. Keratometric, refractive, and aberrometric measurements were compared preoperatively and 3 months postoperatively. The intraoperative subtraction pachymetry (the SP 100 Handy pachymeter (Tomey, Nagoya, Japan) was used for preoperative pachymetry and flap thickness measurement. No significant difference was found between the two groups in regards to postoperative manifest sphere, spherical equivalent, astigmatism, safety indices nor ocular aberrations. Twenty six eyes (86.6%) in group I and 23 eyes in group II (76.6%) were within ±0.5D of the intended correction and 23 eyes (76.6%) in group I and 15 eyes in group II (50%) were within ±0.25D of the intended correction. In group I, the mean postoperative actual flap thickness was 100.12 ± 16.1 μm (81 to 122 μm), while in group II, it was 104.6 ± 20.1 μm (62 to 155 μm). The difference was statistically significant (p = 0.001). Both Visumax and Moria M2 MK are safe and effective in treating myopia with no statistically significant difference in induction of ocular aberrations but with potential advantage for Visumax regarding predictability. More accurate flap thickness is achieved with Visumax femtolasik. This study was retrospectively registered on 19/6/2017. Trial registration number NCT03193411 , clinicalTrials.gov .

Instrument performance and simulation verification of the POLAR detector

Science.gov (United States)

Kole, M.; Li, Z. H.; Produit, N.; Tymieniecka, T.; Zhang, J.; Zwolinska, A.; Bao, T. W.; Bernasconi, T.; Cadoux, F.; Feng, M. Z.; Gauvin, N.; Hajdas, W.; Kong, S. W.; Li, H. C.; Li, L.; Liu, X.; Marcinkowski, R.; Orsi, S.; Pohl, M.; Rybka, D.; Sun, J. C.; Song, L. M.; Szabelski, J.; Wang, R. J.; Wang, Y. H.; Wen, X.; Wu, B. B.; Wu, X.; Xiao, H. L.; Xiong, S. L.; Zhang, L.; Zhang, L. Y.; Zhang, S. N.; Zhang, X. F.; Zhang, Y. J.; Zhao, Y.

2017-11-01

POLAR is a new satellite-born detector aiming to measure the polarization of an unprecedented number of Gamma-Ray Bursts in the 50-500 keV energy range. The instrument, launched on-board the Tiangong-2 Chinese Space lab on the 15th of September 2016, is designed to measure the polarization of the hard X-ray flux by measuring the distribution of the azimuthal scattering angles of the incoming photons. A detailed understanding of the polarimeter and specifically of the systematic effects induced by the instrument's non-uniformity are required for this purpose. In order to study the instrument's response to polarization, POLAR underwent a beam test at the European Synchrotron Radiation Facility in France. In this paper both the beam test and the instrument performance will be described. This is followed by an overview of the Monte Carlo simulation tools developed for the instrument. Finally a comparison of the measured and simulated instrument performance will be provided and the instrument response to polarization will be presented.

Vergence driven accommodation with simulated disparity in myopia and emmetropia.

Science.gov (United States)

Maiello, Guido; Kerber, Kristen L; Thorn, Frank; Bex, Peter J; Vera-Diaz, Fuensanta A

2018-01-01

The formation of focused and corresponding foveal images requires a close synergy between the accommodation and vergence systems. This linkage is usually decoupled in virtual reality systems and may be dysfunctional in people who are at risk of developing myopia. We study how refractive error affects vergence-accommodation interactions in stereoscopic displays. Vergence and accommodative responses were measured in 21 young healthy adults (n=9 myopes, 22-31 years) while subjects viewed naturalistic stimuli on a 3D display. In Step 1, vergence was driven behind the monitor using a blurred, non-accommodative, uncrossed disparity target. In Step 2, vergence and accommodation were driven back to the monitor plane using naturalistic images that contained structured depth and focus information from size, blur and/or disparity. In Step 1, both refractive groups converged towards the stereoscopic target depth plane, but the vergence-driven accommodative change was smaller in emmetropes than in myopes (F 1,19 =5.13, p=0.036). In Step 2, there was little effect of peripheral depth cues on accommodation or vergence in either refractive group. However, vergence responses were significantly slower (F 1,19 =4.55, p=0.046) and accommodation variability was higher (F 1,19 =12.9, p=0.0019) in myopes. Vergence and accommodation responses are disrupted in virtual reality displays in both refractive groups. Accommodation responses are less stable in myopes, perhaps due to a lower sensitivity to dioptric blur. Such inaccuracies of accommodation may cause long-term blur on the retina, which has been associated with a failure of emmetropization. Copyright © 2017 Elsevier Ltd. All rights reserved.

An in vitro comparison of apically extruded debris using three rotary nickel-titanium instruments

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Tamer Tasdemir

2010-09-01

Conclusion: According to this study, all instrumentation techniques apically extruded debris through the apical foramen. However, the BioRaCe instruments induced less extruded debris than the ProTaper Universal and Mtwo rotary systems.

Safety, efficacy, and predictability of laser in situ keratomileusis to correct myopia or myopic astigmatism with a 750 Hz scanning-spot laser system.

Science.gov (United States)

Tomita, Minoru; Watabe, Miyuki; Yukawa, Satoshi; Nakamura, Nobuo; Nakamura, Tadayuki; Magnago, Thomas

2014-02-01

To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) to correct myopia or myopic astigmatism using the Amaris 750S 750 Hz excimer laser. Private LASIK center, Tokyo, Japan. Case series. Patients with myopia or myopic astigmatism (spherical equivalent -0.50 to -11.63 diopters [D]), a corrected distance visual acuity (CDVA) of 20/20 or better, and an estimated residual bed thickness of 300 μm or more had LASIK using the aspheric aberration-free ablation profile of the 750 Hz scanning-spot laser and the Femto LDV Crystal Line femtosecond laser for flap creation. Study parameters included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, astigmatism, and higher-order aberrations (HOAs). The study included 1280 eyes (685 patients). At 3 months, 96.6% of eyes had a UDVA of 20/20 or better and 99.1% had 20/32 or better; 94.1% of eyes were within ± 0.50 D of the intended correction and 98.9% were within ± 1.00 D; 89.7% of eyes had no residual cylinder and 96.0% had a postoperative astigmatism of less than 0.50 D. All eyes had a postoperative CDVA of 20/20 or better. The HOAs increased postoperatively (PLaser in situ keratomileusis with the 750 Hz scanning-spot laser was safe, effective, and predictable. No specific clinical side effects that might be associated with a high repetition rate occurred. Mr. Magnago is an employee of Schwind eye-tech-solutions GmbH. No other author has a financial or proprietary interest in any material or method mentioned. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Aspheric photorefractive keratectomy for myopia and myopic astigmatism with the SCHWIND AMARIS laser: 2 years postoperative outcomes

Science.gov (United States)

Aslanides, Ioannis M.; Padroni, Sara; Arba-Mosquera, Samuel

2012-01-01

Purpose To evaluate mid-term refractive outcomes and higher order aberrations of aspheric PRK for low, moderate and high myopia and myopic astigmatism with the AMARIS excimer laser system (SCHWIND eye-tech-solutions GmbH, Kleinostheim, Germany). Methods This prospective longitudinal study evaluated 80 eyes of 40 subjects who underwent aspheric PRK. Manifest refractive spherical equivalent (MRSE) of up to −10.00 diopters (D) at the spectacle plane with cylinder up to 3.25 was treated. Refractive outcomes and corneal wavefront data (6 mm pupil to the 7th Zernike order) were evaluated out to 2 years postoperatively. Statistical significance was indicated by P  0.05, both cases). There was a statistical increase in postoperative coma (+0.12 μm) and spherical aberration (+0.14 μm) compared to preoperatively (P < 0.001, both cases). Conclusion Aspheric PRK provides excellent visual and refractive outcomes with induction in individual corneal aberrations but not overall corneal aberrations.

Pilot study of a novel classroom designed to prevent myopia by increasing children's exposure to outdoor light.

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Zhou, Zhongqiang; Chen, Tingting; Wang, Mengrui; Jin, Ling; Zhao, Yongyi; Chen, Shangji; Wang, Congyao; Zhang, Guoshan; Wang, Qilin; Deng, Qiaoming; Liu, Yubo; Morgan, Ian G; He, Mingguang; Liu, Yizhi; Congdon, Nathan

2017-01-01

We sought to assess light characteristics and user acceptability of a prototype Bright Classroom (BC), designed to prevent children's myopia by exposing them to light conditions resembling the outdoors. Conditions were measured throughout the school year in the glass-constructed BC, a traditional classroom (TC) and outdoors. Teachers and children completed user questionnaires, and children rated reading comfort at different light intensities. A total of 230 children (mean age 10.2 years, 57.4% boys) and 13 teachers (36.8 years, 15.4% men) completed questionnaires. The median (Inter Quartile Range) light intensity in the BC (2,540 [1,330-4,060] lux) was greater than the TC (477 [245-738] lux, P 500 [8,960-36,000] lux, P summer and on sunny days (>5,000 lux) was at the upper limit of children's comfort for reading. In summary, light intensity in the BC exceeds TC, and is at the practical upper limit for routine use. Children and teachers prefer the BC.

Laser-induced breakdown spectroscopy (LIBS), part II: review of instrumental and methodological approaches to material analysis and applications to different fields.

Science.gov (United States)

Hahn, David W; Omenetto, Nicoló

2012-04-01

The first part of this two-part review focused on the fundamental and diagnostics aspects of laser-induced plasmas, only touching briefly upon concepts such as sensitivity and detection limits and largely omitting any discussion of the vast panorama of the practical applications of the technique. Clearly a true LIBS community has emerged, which promises to quicken the pace of LIBS developments, applications, and implementations. With this second part, a more applied flavor is taken, and its intended goal is summarizing the current state-of-the-art of analytical LIBS, providing a contemporary snapshot of LIBS applications, and highlighting new directions in laser-induced breakdown spectroscopy, such as novel approaches, instrumental developments, and advanced use of chemometric tools. More specifically, we discuss instrumental and analytical approaches (e.g., double- and multi-pulse LIBS to improve the sensitivity), calibration-free approaches, hyphenated approaches in which techniques such as Raman and fluorescence are coupled with LIBS to increase sensitivity and information power, resonantly enhanced LIBS approaches, signal processing and optimization (e.g., signal-to-noise analysis), and finally applications. An attempt is made to provide an updated view of the role played by LIBS in the various fields, with emphasis on applications considered to be unique. We finally try to assess where LIBS is going as an analytical field, where in our opinion it should go, and what should still be done for consolidating the technique as a mature method of chemical analysis. © 2012 Society for Applied Spectroscopy

Risk Factors for Retreatment Following Myopic LASIK with Femtosecond Laser and Custom Ablation for the Treatment of Myopia.

Science.gov (United States)

Kruh, Jonathan N; Garrett, Kenneth A; Huntington, Brian; Robinson, Steve; Melki, Samir A

2017-01-01

To identify risks factors for retreatment post-laser in situ keratomeliusis (LASIK). A retrospective chart review from December 2008 to September 2012 identified 1,402 patients (2,581 eyes) that underwent LASIK treatment for myopia with the Intralase™ FS, STAR S4 IR™ Excimer Laser, and WaveScan WaveFront™ technology. In this group, 83 patients were retreated. All charts were reviewed for preoperative age, gender, initial manifest refraction spherical equivalent (MRSE), total astigmatism, and iris registration. Increased incidence rates of retreatment post-LASIK were preoperative age >40 years (p -3.0 D (p = 0.02), and astigmatism >1D (p = 0.001). Iris registration capture did not significantly reduce the retreatment rate (p = 0.12). Risk factors for retreatment included preoperative age >40 years, initial MRSE > -3.0 D, and astigmatism >1D. There was no difference in retreatment rate for patients based on gender or iris registration capture.

Vertical distribution of elements in non-polluted estuarine sediments determined by neutron induced prompt gamma-ray and instrumental neutron activation analyses

International Nuclear Information System (INIS)

Kuno, A.; Sampei, K.; Matsuo, M.; Sawahata, H.

1999-01-01

Neutron induced prompt gamma-ray analysis (PGA) and instrumental neutron activation analysis (INAA) have been applied to the sediments collected from the Yasaka River estuary in Oita Prefecture, Japan. The vertical distribution of 33 elements in the sediments has been determined and compared with that in more polluted estuarine sediments. While the S content increased with increasing depth because of a sulphide accumulation under reducing condition, the increase in sulphide-forming elements such as Ag, Cd, Co and Zn was not observed in the deeper section of the Yasaka River estuarine sediments. (author)

Results of Posterior Chamber Lens Implantation for Correction of Myopia

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Pınar Sorgun Evcili

2012-10-01

Full Text Available Pur po se: To evaluate the results of posterior chamber phakic intraocular lens implantation in myopic patients. Ma te ri al and Met hod: Posterior chamber phakic intraocular lens (STAAR ICL implantation was performed in 58 eyes of 33 patients with mean spherical equivalent of -13.12±5.31 diopters (D (-2.5 - -24.75 D between August 2007 and October 2010 at Dr. Lütfi Kırdar Kartal Training and Research Hospital, Second Eye Clinic. The mean age of the patients was 32.84 ± 9.95 years (18-55 years - 24 (72.7% were male and 9 (27.3% were female. The study was designed as prospective case series. The patients were evaluated regarding visual acuity, refraction, endothelial cell count, and complications in postoperative period. Re sults: The mean follow-up time was 21.5±4.9 (12-24 months months. The mean spherical equivalent was -1.29±1.53 D (-5.6 D - +2.60 D at the last postoperative follow-up visit. Visual acuity was better or equal to preoperative best-corrected value in 42 (72.4% of eyes at the last follow-up visit postoperatively. Mean spherical equivalent was regressed to -1.13±1.59D at 1-month and -1.39±1.53D at 24-month postoperative follow-up visit. Pupillary-block glaucoma in 1 eye (1.7%, anterior subcapsular opacification not affecting the vision in 4 eyes, and retinal detachment in 1 eye were detected at follow-up visits. Dis cus si on: ICL implantation was observed to be an effective and safe method for correction of myopia in two-year follow-up. As possible retinal complications may develop, the patients must be followed carefully during the preoperative and postoperative period. (Turk J Ophthalmol 2012; 42: 349-54

Alcohol myopia and sexual abdication among women: examining the moderating effect of child sexual abuse.

Science.gov (United States)

Staples, Jennifer M; George, William H; Stappenbeck, Cynthia A; Davis, Kelly Cue; Norris, Jeanette; Heiman, Julia R

2015-02-01

HIV and other STIs are major public health concerns for women, and risky sexual behaviors increase the risk of transmission. Risky sexual behaviors include sexual abdication, that is, willingness to let a partner decide how far to go sexually. Alcohol intoxication is a risk factor for risky sexual behavior, and the Inhibition Conflict Model of Alcohol Myopia may help explain this relationship. This model suggests that in order for intoxication to influence behavior there must be high conflict, meaning the strength of the instigatory cues and inhibitory cues are both high. Recent research indicates that the degree to which cues are experienced as high in instigation or inhibition is subject to individual difference factors. One individual difference factor associated with alcohol-related sexual risk taking is child sexual abuse (CSA) history. The current study examined the influence of acute alcohol intoxication, CSA, and inhibition conflict on sexual abdication with 131 women (mean age 25) randomized into a 2 (alcohol, control)×2 (high conflict, low conflict) experimental design. Regression analyses yielded a significant 3-way interaction, F (1,122)=8.15, R(2)=.14, psexual decision making among women with CSA. Copyright © 2014 Elsevier Ltd. All rights reserved.

Outside-the-box, but Inside-the-elevator: A Case of Leadership Myopia Reaching Media

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Miriam Costea

2013-05-01

Full Text Available Practitioners claim that successful leaders should be able to think out-of-the-box and “first break all the rules”. However, when it comes to organizational regulation inside some public institutions, more often than not the leaders replace the organizational creativity with an extreme exploitation of the existing rules. The “tendency to overinvest in exploitation” (Levinthal & March 1993 of the routines that proved successful in the past is well-known in the literature on organizational learning. In the present study, we examine a specific context in which a traditional rule meant to offer legitimacy to the public leaders was over-exploited up to the point when all national media reacted against the actions of the public institution. Thus, instead of obtaining more legitimacy, the leaders learned the hard way that the organizational rules should be assessed periodically and the obsolete ones be replaced/balanced with new rules, resulting from the exploratory dimension of organizational learning. We consider that an explanation for this specific case of leadership myopia may be found in a recently defined leadership style, ie, the spiritual leadership (Fry, 2003, situated in a case of over-exploiting an impermanent institutionalized rule (Schulz, 2003.

Preparation and characterization of a new set of IAEA reference air filters using instrumental neutron activation analysis, proton-induced X-ray emission and Rutherford backscattering

Czech Academy of Sciences Publication Activity Database

Kučera, Jan; Havránek, Vladimír; Krausová, Ivana

2009-01-01

Roč. 281, č. 1 (2009), s. 123-129 ISSN 0236-5731. [9th International Conference on Nuclear Analytical Methods in the Life Sciences. Lisbon, 07.09.2008-12.09.2008] Institutional research plan: CEZ:AV0Z10480505 Keywords : Reference air filters * instrumental neutron activation analysis * Proton induced X-ray emission Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.631, year: 2009

In-pile Instrumentation Development

International Nuclear Information System (INIS)

Vermeeren, L.

2005-01-01

Advanced irradiations in research reactors require the on-line monitoring of crucial parameters like neutron fluxes, gamma dose rates, central fuel rod temperatures, fission gas release pressures and small geometry changes. Our activities in this field aim at a detailed understanding of the sensor behaviour in the irradiation conditions in order to extract reliable real-time information. The objectives of work performed by SCK-CEN are to study of the on-line in-pile measurement of gamma and neutron fluxes in real time and to investigate parasitic radiation-induced signals in instrumentation cables

Inspector-instrument interface in portable NDA instrumentation

International Nuclear Information System (INIS)

Halbig, J.K.; Klosterbuer, S.F.

1981-01-01

Recent electronics technology advances make it possible to design sophisticated instruments in small packages for convenient field implementation. An inspector-instrument interface design that allows communication of procedures, responses, and results between the instrument and user is presented. This capability has been incorporated into new spent-fuel instrumentation and a battery-powered multichannel analyzer

Inspector-instrument interface in portable NDA instrumentation

International Nuclear Information System (INIS)

Halbig, J.K.; Klosterbuer, S.F.

1981-01-01

Recent electronics technology advances make it possible to design sophisticated instruments in small packages for convenient field implementation. This report describes an inspector-instrument interface design which allows communication of procedures, responses, and results between the instrument and user. The interface has been incorporated into new spent-fuel instrumentation and a battery-powered multichannel analyzer

The M. D. Anderson Symptom Inventory-Head and Neck Module, a Patient-Reported Outcome Instrument, Accurately Predicts the Severity of Radiation-Induced Mucositis

International Nuclear Information System (INIS)

Rosenthal, David I.; Mendoza, Tito R.; Chambers, Mark; Burkett, V. Shannon; Garden, Adam S.; Hessell, Amy C.; Lewin, Jan S.; Ang, K. Kian; Kies, Merrill S.; Gning, Ibrahima; Wang, Xin S.; Cleeland, Charles S.

2008-01-01

Purpose: To compare the M. D. Anderson Symptom Inventory-Head and Neck (MDASI-HN) module, a symptom burden instrument, with the Functional Assessment of Cancer Therapy-Head and Neck (FACT-HN) module, a quality-of-life instrument, for the assessment of mucositis in patients with head-and-neck cancer treated with radiotherapy and to identify the most distressing symptoms from the patient's perspective. Methods and Materials: Consecutive patients with head-and-neck cancer (n = 134) completed the MDASI-HN and FACT-HN before radiotherapy (time 1) and after 6 weeks of radiotherapy or chemoradiotherapy (time 2). The mean global and subscale scores for each instrument were compared with the objective mucositis scores determined from the National Cancer Institute Common Terminology Criteria for Adverse Events, version 3.0. Results: The global and subscale scores for each instrument showed highly significant changes from time 1 to time 2 and a significant correlation with the objective mucositis scores at time 2. Only the MDASI scores, however, were significant predictors of objective Common Terminology Criteria for Adverse Events mucositis scores on multivariate regression analysis (standardized regression coefficient, 0.355 for the global score and 0.310 for the head-and-neck cancer-specific score). Most of the moderate and severe symptoms associated with mucositis as identified on the MDASI-HN are not present on the FACT-HN. Conclusion: Both the MDASI-HN and FACT-HN modules can predict the mucositis scores. However, the MDASI-HN, a symptom burden instrument, was more closely associated with the severity of radiation-induced mucositis than the FACT-HN on multivariate regression analysis. This greater association was most likely related to the inclusion of a greater number of face-valid mucositis-related items in the MDASI-HN compared with the FACT-HN

Instrument to determine prestress remaining in a damaged bridge girder

Science.gov (United States)

Civjan, Scott A.; Jirsa, James O.; Carrasquillo, Ramon L.; Fowler, David W.

1998-03-01

An instrument has been developed to estimate stress levels in prestress strands in existing members. The prototype instrument applies a lateral load to an exposed prestressing strand and measures the resulting displacements. The instrument was calibrated for 0.5-inch (12.7 mm) diameter seven-wire strand with exposed lengths of 1.5 feet (0.46 m) to 3.75 feet (1.14 m). It was tested to determine its accuracy, precision, and usefulness in the field. Strand forces were consistently estimated to within ten percent of the actual load. The device was also utilized in the placement of strand splices and was found to be more reliable in checking induced strand tensions than the standard torque wrench method.

Refractive Development in the “ROP Rat”

Directory of Open Access Journals (Sweden)

Toco Y. P. Chui

2012-01-01

Full Text Available Although retinopathy of prematurity (ROP is clinically characterized by abnormal retinal vessels at the posterior pole of the eye, it is also commonly characterized by vascular abnormalities in the anterior segment, visual dysfunction which is based in retinal dysfunction, and, most commonly of all, arrested eye growth and high refractive error, particularly (and paradoxically myopia. The oxygen-induced retinopathy rat model of ROP presents neurovascular outcomes similar to the human disease, although it is not yet known if the “ROP rat” also models the small-eyed myopia characteristic of ROP. In this study, magnetic resonance images (MRIs of albino (Sprague-Dawley and pigmented (Long-Evans ROP rat eyes, and age- and strain-matched room-air-reared (RAR controls, were examined. The positions and curvatures of the various optical media were measured and the refractive state (℞ of each eye estimated based on a previously published model. Even in adulthood (postnatal day 50, Sprague-Dawley and Long-Evans ROP rats were significantly myopic compared to strain-matched controls. The myopia in the Long-Evans ROP rats was more severe than in the Sprague-Dawley ROP rats, which also had significantly shorter axial lengths. These data reveal the ROP rat to be a novel and potentially informative approach to investigating physiological mechanisms in myopia in general and the myopia peculiar to ROP in particular.

Modern Diagnostic Techniques for the Assessment of Ocular Blood Flow in Myopia: Current State of Knowledge.

Science.gov (United States)

Grudzińska, Ewa; Modrzejewska, Monika

2018-01-01

Myopia is the most common refractive error and the subject of interest of various studies assessing ocular blood flow. Increasing refractive error and axial elongation of the eye result in the stretching and thinning of the scleral, choroid, and retinal tissues and the decrease in retinal vessel diameter, disturbing ocular blood flow. Local and systemic factors known to change ocular blood flow include glaucoma, medications and fluctuations in intraocular pressure, and metabolic parameters. Techniques and tools assessing ocular blood flow include, among others, laser Doppler flowmetry (LDF), retinal function imager (RFI), laser speckle contrast imaging (LSCI), magnetic resonance imaging (MRI), optical coherence tomography angiography (OCTA), pulsatile ocular blood flowmeter (POBF), fundus pulsation amplitude (FPA), colour Doppler imaging (CDI), and Doppler optical coherence tomography (DOCT). Many researchers consistently reported lower blood flow parameters in myopic eyes regardless of the used diagnostic method. It is unclear whether this is a primary change that causes secondary thinning of ocular tissues or quite the opposite; that is, the mechanical stretching of the eye wall reduces its thickness and causes a secondary lower demand of tissues for oxygen. This paper presents a review of studies assessing ocular blood flow in myopes.

LARF: Instrumental Variable Estimation of Causal Effects through Local Average Response Functions

Directory of Open Access Journals (Sweden)

Weihua An

2016-07-01

Full Text Available LARF is an R package that provides instrumental variable estimation of treatment effects when both the endogenous treatment and its instrument (i.e., the treatment inducement are binary. The method (Abadie 2003 involves two steps. First, pseudo-weights are constructed from the probability of receiving the treatment inducement. By default LARF estimates the probability by a probit regression. It also provides semiparametric power series estimation of the probability and allows users to employ other external methods to estimate the probability. Second, the pseudo-weights are used to estimate the local average response function conditional on treatment and covariates. LARF provides both least squares and maximum likelihood estimates of the conditional treatment effects.

Instrumentation

International Nuclear Information System (INIS)

Prieur, G.; Nadi, M.; Hedjiedj, A.; Weber, S.

1995-01-01

This second chapter on instrumentation gives little general consideration on history and classification of instrumentation, and two specific states of the art. The first one concerns NMR (block diagram of instrumentation chain with details on the magnets, gradients, probes, reception unit). The first one concerns precision instrumentation (optical fiber gyro-meter and scanning electron microscope), and its data processing tools (programmability, VXI standard and its history). The chapter ends with future trends on smart sensors and Field Emission Displays. (D.L.). Refs., figs

The Comparison of Regional RNFL and Fundus Vasculature by OCTA in Chinese Myopia Population.

Science.gov (United States)

Li, Yuanjun; Miara, Hamza; Ouyang, Pingbo; Jiang, Bing

2018-01-01

To determine the correlations between peripapillary vessel density, retinal nerve fibre layer (RNFL) thickness, and myopic indices at retina quadrants with optical coherence tomography angiography (OCTA) in Chinese. Fifty-six subjects with a mean spherical equivalent (MSE) of -3.63 ± 0.29 D were included. Peripapillary RNFL thickness and retinal vessel density in four sectors (superior, nasal, inferior, and temporal quadrants) were determined by OCTA, and correlations of the main outcomes were analyzed. Negative correlations were found between the peripapillary RNFL thickness and axial length (AL) at superior ( r = -0.335, P = 0.001) and inferior ( r = -0.551, P < 0.001) quadrants. There was a significant positive correlation with spherical equivalent (SE) at the corresponding quadrants as well as at the nasal quadrant ( r = 0.339, P = 0.001; r = 0.379, P < 0.001; and r = 0.209, P = 0.039, resp.). Peripapillary retinal vessel density was also negatively correlated with AL at the nasal quadrant ( r = -0.392, P < 0.001), and only at the nasal quadrant, there was a positive correlation between the peripapillary vessel density and SE ( r = 0.319, P = 0.001). The degree of myopia and elongation of AL were negatively correlated with peripapillary RNFL thickness at superior and inferior quadrants and with peripapillary retinal vessel density at the nasal quadrant.

Instrument pre-development activities for FLEX

Science.gov (United States)

Pettinato, L.; Fossati, E.; Coppo, P. M.; Taiti, A.; Labate, D.; Capanni, A.; Taccola, M.; Bézy, J. L.; Francois, M.; Meynart, R.; Erdmann, L.; Triebel, P.

2017-09-01

The FLuorescence Imaging Spectrometer (FLORIS) is the payload of the FLuorescence Explorer Mission (FLEX) of the European Space Agency. The mission objective is to perform quantitative measurements of the solar induced vegetation fluorescence to monitor photosynthetic activity. FLORIS works in a push-broom configuration and it is designed to acquire data in the 500-780 nm spectral range, with a sampling of 0.1 nm in the oxygen bands (759-769 nm and 686- 697 nm) and 0.5-2.0 nm in the red edge, chlorophyll absorption and Photochemical Reflectance Index bands. FLEX will fly in formation with Sentinel-3 to benefit of the measurements made by the Sentinel-3 instruments OLCI and SLSTR, particularly for cloud screening, proper characterization of the atmospheric state and determination of the surface temperature. The instrument concept is based on a common telescope and two modified Offner spectrometers with reflective concave gratings both for the High Resolution (HR) and Low Resolution (LR) spectrometers. In the frame of the instrument pre-development Leonardo Company (I) has built and tested an elegant breadboard of the instrument consisting of the telescope and the HR spectrometer. The development of the LR spectrometer is in charge of OHB System AG (D) and is currently in the manufacturing phase. The main objectives of the activity are: anticipate the development of the instrument and provide early risk retirement of critical components, evaluate the system performances such as imaging quality parameters, straylight, ghost, polarization sensitivity and environmental influences, verify the adequacy of critical tests such as spectral characterization and straylight, define and optimize instrument alignment procedures. Following a brief overview of the FLEX mission, the paper will cover the design and the development of the optics breadboard with emphasis on the results obtained during the tests and the lessons learned for the flight unit.

Opto-mechanical design for transmission optics in cryogenic space instrumentation

Science.gov (United States)

Kroes, Gabby; Venema, Lars; Navarro, Ramón

2017-11-01

NOVA is involved in the development and realization of various optical astronomical instruments for groundbased as well as space telescopes, with a focus on nearand mid-infrared instrumentation. NOVA has developed a suite of scientific instruments with cryogenic optics for the ESO VLT and VLTI instruments: VISIR, MIDI, the SPIFFI 2Kcamera for SINFONI, X-shooter and MATISSE. Other projects include the cryogenic optics for MIRI for the James Webb Space Telescope and several E-ELT instruments. Mounting optics is always a compromise between firmly fixing the optics and preventing stresses within the optics. The fixing should ensure mechanical stability and thus accurate positioning in various gravity orientations, temperature ranges, during launch, transport or earthquake. On the other hand, the fixings can induce deformations and sometimes birefringence in the optics and thus cause optical errors. Even cracking or breaking of the optics is a risk, especially when using brittle infrared optical materials at the cryogenic temperatures required in instruments for infrared astronomy, where differential expansion of various materials amounts easily to several millimeters per meter. Special kinematic mounts are therefore needed to ensure both accurate positioning and low stress. This paper concentrates on the opto-mechanical design of optics mountings, especially for large transmission optics in cryogenic circumstances in space instruments. It describes the development of temperature-invariant ("a-thermal") kinematic designs, their implementation in ground based instrumentation and ways to make them suitable for space instruments.

Differentiation of Induced Pluripotent Stem Cells to Lentoid Bodies Expressing a Lens Cell-Specific Fluorescent Reporter.

Directory of Open Access Journals (Sweden)

Taruna Anand

Full Text Available Curative approaches for eye cataracts and other eye abnormalities, such as myopia and hyperopia currently suffer from a lack of appropriate models. Here, we present a new approach for in vitro growth of lentoid bodies from induced pluripotent stem (iPS cells as a tool for ophthalmological research. We generated a transgenic mouse line with lens-specific expression of a fluorescent reporter driven by the alphaA crystallin promoter. Fetal fibroblasts were isolated from transgenic fetuses, reprogrammed to iPS cells, and differentiated to lentoid bodies exploiting the specific fluorescence of the lens cell-specific reporter. The employment of cell type-specific reporters for establishing and optimizing differentiation in vitro seems to be an efficient and generally applicable approach for developing differentiation protocols for desired cell populations.

Heritability of myopia and ocular biometrics in Koreans: the healthy twin study.

Science.gov (United States)

Kim, Myung Hun; Zhao, Di; Kim, Woori; Lim, Dong-Hui; Song, Yun-Mi; Guallar, Eliseo; Cho, Juhee; Sung, Joohon; Chung, Eui-Sang; Chung, Tae-Young

2013-05-01

To estimate the heritabilities of myopia and ocular biometrics among different family types among a Korean population. We studied 1508 adults in the Healthy Twin Study. Spherical equivalent, axial length, anterior chamber depth, and corneal astigmatism were measured by refraction, corneal topography, and A-scan ultrasonography. To see the degree of resemblance among different types of family relationships, intraclass correlation coefficients (ICC) were calculated. Variance-component methods were applied to estimate the genetic contributions to eye phenotypes as heritability based on the maximum likelihood estimation. Narrow sense heritability was calculated as the proportion of the total phenotypic variance explained by additive genetic effects, and linear and nonlinear effects of age, sex, and interactions between age and sex were adjusted. A total of 240 monozygotic twin pairs, 45 dizygotic twin pairs, and 938 singleton adult family members who were first-degree relatives of twins in 345 families were included in the study. ICCs for spherical equivalent from monozygotic twins, pooled first-degree pairs, and spouse pairs were 0.83, 0.34, and 0.20, respectively. The ICCs of other ocular biometrics were also significantly higher in monozygotic twins compared with other relative pairs, with greater consistency and conformity. The estimated narrow sense heritability (95% confidence interval) was 0.78 (0.71-0.84) for spherical equivalent; 0.86 (0.82-0.90) for axial length; 0.83 (0.76-0.91) for anterior chamber depth; and 0.70 (0.63-0.77) for corneal astigmatism. The estimated heritability of spherical equivalent and ocular biometrics in the Korean population suggests the compelling evidence that all traits are highly heritable.

Changes in higher order aberrations after wavefront-guided PRK for correction of low to moderate myopia and myopic astigmatism: two-year follow-up.

Science.gov (United States)

Wigledowska-Promienska, D; Zawojska, I

2007-01-01

To assess efficacy, safety, and changes in higher order aberrations after wavefront-guided photorefractive keratectomy (PRK) in comparison with conventional PRK for low to moderate myopia with myopic astigmatism using a WASCA Workstation with the MEL 70 G-Scan excimer laser. A total of 126 myopic or myopic-astigmatic eyes of 112 patients were included in this retrospective study. Patients were divided into two groups: Group 1, the study group; and Group 2, the control group. Group 1 consisted of 78 eyes treated with wavefront-guided PRK. Group 2 consisted of 48 eyes treated with spherocylindrical conventional PRK. Two years postoperatively, in Group 1, 5% of eyes achieved an uncorrected visual acuity (UCVA) of 0.05; 69% achieved a UCVA of 0.00; 18% of eyes experienced enhanced visual acuity of -0.18 and 8% of -0.30. In Group 2, 8% of eyes achieved a UCVA of 0.1; 25% achieved a UCVA of 0.05; and 67% achieved a UCVA of 0.00 according to logMAR calculation method. Total higher-order root-mean square increased by a factor 1.18 for Group 1 and 1.6 for Group 2. There was a significant increase of coma by a factor 1.74 in Group 2 and spherical aberration by a factor 2.09 in Group 1 and 3.56 in Group 2. The data support the safety and effectiveness of the wavefront-guided PRK using a WASCA Workstation for correction of low to moderate refractive errors. This method reduced the number of higher order aberrations induced by excimer laser surgery and improved uncorrected and spectacle-corrected visual acuity when compared to conventional PRK.

Effect of rotary or manual instrumentation, with or without a calcium hydroxide/1% chlorhexidine intracanal dressing, on the healing of experimentally induced chronic periapical lesions.

Science.gov (United States)

De Rossi, Andiara; Silva, Léa A B; Leonardo, Mario R; Rocha, Lenaldo B; Rossi, Marcos A

2005-05-01

To evaluate the healing of experimentally induced chronic periapical lesions in dogs at 30, 75, and 120 days after root canal instrumentation with rotary NiTi files or manual K-files, with or without a calcium hydroxide/1% chlorhexidine paste intracanal dressing. The second, third, and fourth mandibular premolars and the second and third maxillary premolars of 5 dogs (12 to 18 months of age, weighing 8 to 15 kg) were selected for treatment (a total of 82 root canals). After pulp removal, the root canals were left exposed to the oral cavity for 7 days to allow microbial contamination, after which the root canals were sealed with ZOE cement until periapical lesions were confirmed with radiography. Group I and II teeth were instrumented with manual K-files using the crown-down technique. In group III and IV teeth, NiTi rotary files were used. The apical delta was perforated by using #20 to #30 K-files at the length of the tooth, thus creating a standardized apical opening. The apical stop was enlarged to size 70, with 2.5% sodium hypochlorite irrigation at each file change. Teeth in groups II and IV were dressed with calcium hydroxide (Ca(OH) 2 )/1% chlorhexidine (CHX) paste for 15 days before root filling. Group I and III teeth did not receive an intracanal dressing. The access openings of the teeth were permanently restored with silver amalgam condensed on a glass ionomer cement base. Pairs of standardized periapical radiographs were taken at the beginning of the treatment (0 days) and at 30, 75, and 120 days after filling. There was no significant difference in the rate of radiographic healing of the periapical lesions between manual and rotary instrumentation. Radiographs taken at 120 days showed that the treatment with Ca(OH) 2 /1% CHX paste resulted in a significant reduction in mean size of the periapical lesions in comparison to single-session treatment. These findings were also true for histologic observations. The findings support the hypothesis that

Radioisotope instruments

CERN Document Server

Cameron, J F; Silverleaf, D J

1971-01-01

International Series of Monographs in Nuclear Energy, Volume 107: Radioisotope Instruments, Part 1 focuses on the design and applications of instruments based on the radiation released by radioactive substances. The book first offers information on the physical basis of radioisotope instruments; technical and economic advantages of radioisotope instruments; and radiation hazard. The manuscript then discusses commercial radioisotope instruments, including radiation sources and detectors, computing and control units, and measuring heads. The text describes the applications of radioisotop

Instrument Remote Control via the Astronomical Instrument Markup Language

Science.gov (United States)

Sall, Ken; Ames, Troy; Warsaw, Craig; Koons, Lisa; Shafer, Richard

1998-01-01

The Instrument Remote Control (IRC) project ongoing at NASA's Goddard Space Flight Center's (GSFC) Information Systems Center (ISC) supports NASA's mission by defining an adaptive intranet-based framework that provides robust interactive and distributed control and monitoring of remote instruments. An astronomical IRC architecture that combines the platform-independent processing capabilities of Java with the power of Extensible Markup Language (XML) to express hierarchical data in an equally platform-independent, as well as human readable manner, has been developed. This architecture is implemented using a variety of XML support tools and Application Programming Interfaces (API) written in Java. IRC will enable trusted astronomers from around the world to easily access infrared instruments (e.g., telescopes, cameras, and spectrometers) located in remote, inhospitable environments, such as the South Pole, a high Chilean mountaintop, or an airborne observatory aboard a Boeing 747. Using IRC's frameworks, an astronomer or other scientist can easily define the type of onboard instrument, control the instrument remotely, and return monitoring data all through the intranet. The Astronomical Instrument Markup Language (AIML) is the first implementation of the more general Instrument Markup Language (IML). The key aspects of our approach to instrument description and control applies to many domains, from medical instruments to machine assembly lines. The concepts behind AIML apply equally well to the description and control of instruments in general. IRC enables us to apply our techniques to several instruments, preferably from different observatories.

Onboard calibration igneous targets for the Mars Science Laboratory Curiosity rover and the Chemistry Camera laser induced breakdown spectroscopy instrument

Energy Technology Data Exchange (ETDEWEB)

Fabre, C., E-mail: cecile.fabre@g2r.uhp-nancy.fr [G2R, Nancy Universite (France); Maurice, S.; Cousin, A. [IRAP, Toulouse (France); Wiens, R.C. [LANL, Los Alamos, NM (United States); Forni, O. [IRAP, Toulouse (France); Sautter, V. [MNHN, Paris (France); Guillaume, D. [GET, Toulouse (France)

2011-03-15

Accurate characterization of the Chemistry Camera (ChemCam) laser-induced breakdown spectroscopy (LIBS) on-board composition targets is of prime importance for the ChemCam instrument. The Mars Science Laboratory (MSL) science and operations teams expect ChemCam to provide the first compositional results at remote distances (1.5-7 m) during the in situ analyses of the Martian surface starting in 2012. Thus, establishing LIBS reference spectra from appropriate calibration standards must be undertaken diligently. Considering the global mineralogy of the Martian surface, and the possible landing sites, three specific compositions of igneous targets have been determined. Picritic, noritic, and shergottic glasses have been produced, along with a Macusanite natural glass. A sample of each target will fly on the MSL Curiosity rover deck, 1.56 m from the ChemCam instrument, and duplicates are available on the ground. Duplicates are considered to be identical, as the relative standard deviation (RSD) of the composition dispersion is around 8%. Electronic microprobe and laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) analyses give evidence that the chemical composition of the four silicate targets is very homogeneous at microscopic scales larger than the instrument spot size, with RSD < 5% for concentration variations > 0.1 wt.% using electronic microprobe, and < 10% for concentration variations > 0.01 wt.% using LA ICP-MS. The LIBS campaign on the igneous targets performed under flight-like Mars conditions establishes reference spectra for the entire mission. The LIBS spectra between 240 and 900 nm are extremely rich, hundreds of lines with high signal-to-noise, and a dynamical range sufficient to identify unambiguously major, minor and trace elements. For instance, a first LIBS calibration curve has been established for strontium from [Sr] = 284 ppm to [Sr] = 1480 ppm, showing the potential for the future calibrations for other major or minor

Onboard calibration igneous targets for the Mars Science Laboratory Curiosity rover and the Chemistry Camera laser induced breakdown spectroscopy instrument

International Nuclear Information System (INIS)

Fabre, C.; Maurice, S.; Cousin, A.; Wiens, R.C.; Forni, O.; Sautter, V.; Guillaume, D.

2011-01-01

Accurate characterization of the Chemistry Camera (ChemCam) laser-induced breakdown spectroscopy (LIBS) on-board composition targets is of prime importance for the ChemCam instrument. The Mars Science Laboratory (MSL) science and operations teams expect ChemCam to provide the first compositional results at remote distances (1.5-7 m) during the in situ analyses of the Martian surface starting in 2012. Thus, establishing LIBS reference spectra from appropriate calibration standards must be undertaken diligently. Considering the global mineralogy of the Martian surface, and the possible landing sites, three specific compositions of igneous targets have been determined. Picritic, noritic, and shergottic glasses have been produced, along with a Macusanite natural glass. A sample of each target will fly on the MSL Curiosity rover deck, 1.56 m from the ChemCam instrument, and duplicates are available on the ground. Duplicates are considered to be identical, as the relative standard deviation (RSD) of the composition dispersion is around 8%. Electronic microprobe and laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) analyses give evidence that the chemical composition of the four silicate targets is very homogeneous at microscopic scales larger than the instrument spot size, with RSD 0.1 wt.% using electronic microprobe, and 0.01 wt.% using LA ICP-MS. The LIBS campaign on the igneous targets performed under flight-like Mars conditions establishes reference spectra for the entire mission. The LIBS spectra between 240 and 900 nm are extremely rich, hundreds of lines with high signal-to-noise, and a dynamical range sufficient to identify unambiguously major, minor and trace elements. For instance, a first LIBS calibration curve has been established for strontium from [Sr] = 284 ppm to [Sr] = 1480 ppm, showing the potential for the future calibrations for other major or minor elements.

Corneal power, thickness, and stiffness: results of a prospective randomized controlled trial of PRK and LASIK for myopia.

Science.gov (United States)

Hjortdal, Jesper Ø; Møller-Pedersen, Torben; Ivarsen, Anders; Ehlers, Niels

2005-01-01

To compare the short-, medium-, and long-term changes in corneal optical power and corneal aberrations, central corneal thickness, and corneal "stiffness" assessed by pneumotonometry readings in patients having laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) for myopia. Department of Ophthalmology, Arhus University Hospital, Arhus, Denmark. One eye of each of 45 patients with myopia ranging from -6.00 to -8.00 diopters (D) (spherical equivalent spectacle refraction [SER]) was randomized to LASIK (n=25; mean SER -7.12 D +/- 0.57 [SD]) or PRK (n=20; mean SER -6.91 +/- 0.57 D). Data were collected prospectively before and 1, 3, 6, 12, and 36 months after surgery. Measurements included corneal topography (TMS-1, Tomey), corneal thickness (ultrasound pachymetry), and apparent intraocular pressure (IOP) (pneumotonometry). Retreatments were not performed during the first year, and retreated eyes were excluded from the 3-year follow-up. Changes in corneal power and aberrations, thickness, and apparent IOP were calculated in a pair-wise manner for 3 time periods: short term (preoperative to 1 month after surgery), medium term (1 to 12 months after surgery), and long term (1 to 3 years after surgery). In the short term, corneal power decreased equally in LASIK and PRK eyes. Spherical aberrations and coma-like aberrations increased equally, while corneal thickness decreased significantly less in LASIK eyes than in PRK eyes. The apparent IOP decreased more in LASIK eyes than in PRK eyes. In the medium term, corneal power increased significantly in both groups. Spherical aberrations decreased significantly in PRK eyes but not in LASIK eyes. From 1 to 12 months, corneal thickness increased more in PRK eyes than in LASIK eyes. During this period, the apparent IOP increased significantly in LASIK eyes. In the long term, corneal power and corneal aberrations did not change significantly in either group. Corneal thickness increased slightly but

The Comparison of Regional RNFL and Fundus Vasculature by OCTA in Chinese Myopia Population

Directory of Open Access Journals (Sweden)

Yuanjun Li

2018-01-01

Full Text Available Purpose. To determine the correlations between peripapillary vessel density, retinal nerve fibre layer (RNFL thickness, and myopic indices at retina quadrants with optical coherence tomography angiography (OCTA in Chinese. Methods. Fifty-six subjects with a mean spherical equivalent (MSE of −3.63 ± 0.29 D were included. Peripapillary RNFL thickness and retinal vessel density in four sectors (superior, nasal, inferior, and temporal quadrants were determined by OCTA, and correlations of the main outcomes were analyzed. Results. Negative correlations were found between the peripapillary RNFL thickness and axial length (AL at superior (r=−0.335, P=0.001 and inferior (r=−0.551, P<0.001 quadrants. There was a significant positive correlation with spherical equivalent (SE at the corresponding quadrants as well as at the nasal quadrant (r=0.339, P=0.001; r=0.379, P<0.001; and r=0.209, P=0.039, resp.. Peripapillary retinal vessel density was also negatively correlated with AL at the nasal quadrant (r=−0.392, P<0.001, and only at the nasal quadrant, there was a positive correlation between the peripapillary vessel density and SE (r=0.319, P=0.001. Conclusions. The degree of myopia and elongation of AL were negatively correlated with peripapillary RNFL thickness at superior and inferior quadrants and with peripapillary retinal vessel density at the nasal quadrant.

Differential dependence of Pavlovian incentive motivation and instrumental incentive learning processes on dopamine signaling

Science.gov (United States)

Wassum, Kate M.; Ostlund, Sean B.; Balleine, Bernard W.; Maidment, Nigel T.

2011-01-01

Here we attempted to clarify the role of dopamine signaling in reward seeking. In Experiment 1, we assessed the effects of the dopamine D1/D2 receptor antagonist flupenthixol (0.5 mg/kg i.p.) on Pavlovian incentive motivation and found that flupenthixol blocked the ability of a conditioned stimulus to enhance both goal approach and instrumental performance (Pavlovian-to-instrumental transfer). In Experiment 2 we assessed the effects of flupenthixol on reward palatability during post-training noncontingent re-exposure to the sucrose reward in either a control 3-h or novel 23-h food-deprived state. Flupenthixol, although effective in blocking the Pavlovian goal approach, was without effect on palatability or the increase in reward palatability induced by the upshift in motivational state. This noncontingent re-exposure provided an opportunity for instrumental incentive learning, the process by which rats encode the value of a reward for use in updating reward-seeking actions. Flupenthixol administered prior to the instrumental incentive learning opportunity did not affect the increase in subsequent off-drug reward-seeking actions induced by that experience. These data suggest that although dopamine signaling is necessary for Pavlovian incentive motivation, it is not necessary for changes in reward experience, or for the instrumental incentive learning process that translates this experience into the incentive value used to drive reward-seeking actions, and provide further evidence that Pavlovian and instrumental incentive learning processes are dissociable. PMID:21693635

Instrumentation

International Nuclear Information System (INIS)

Umminger, K.

2008-01-01

A proper measurement of the relevant single and two-phase flow parameters is the basis for the understanding of many complex thermal-hydraulic processes. Reliable instrumentation is therefore necessary for the interaction between analysis and experiment especially in the field of nuclear safety research where postulated accident scenarios have to be simulated in experimental facilities and predicted by complex computer code systems. The so-called conventional instrumentation for the measurement of e. g. pressures, temperatures, pressure differences and single phase flow velocities is still a solid basis for the investigation and interpretation of many phenomena and especially for the understanding of the overall system behavior. Measurement data from such instrumentation still serves in many cases as a database for thermal-hydraulic system codes. However some special instrumentation such as online concentration measurement for boric acid in the water phase or for non-condensibles in steam atmosphere as well as flow visualization techniques were further developed and successfully applied during the recent years. Concerning the modeling needs for advanced thermal-hydraulic codes, significant advances have been accomplished in the last few years in the local instrumentation technology for two-phase flow by the application of new sensor techniques, optical or beam methods and electronic technology. This paper will give insight into the current state of instrumentation technology for safety-related thermohydraulic experiments. Advantages and limitations of some measurement processes and systems will be indicated as well as trends and possibilities for further development. Aspects of instrumentation in operating reactors will also be mentioned.

The design of an instrumented rebar for assessment of corrosion in cracked reinforced concrete

DEFF Research Database (Denmark)

Pease, Bradley Justin; Geiker, Mette Rica; Stang, Henrik

2011-01-01

rebar with 17 electronically isolated corrosion sensors. Instrumented and standard rebars were cast into concrete beams and bending cracks were induced and held open using steel frames. Epoxy impregnation was used to assess and compare cracks in the concrete around the instrumented and standard rebar...... between the steel and concrete. Cracked beams with cast-in instrumented and standard rebars were ponded with a 10\\% chloride solution and the open circuit corrosion potential (OCP) of the 17 sensors was measured for up to 62 days. Measurements from the individual sensors indicate when and where active...

Small incision corneal refractive surgery using the small incision lenticule extraction (SMILE) procedure for the correction of myopia and myopic astigmatism: results of a 6 month prospective study.

Science.gov (United States)

Sekundo, Walter; Kunert, Kathleen S; Blum, Marcus

2011-03-01

This 6 month prospective multi-centre study evaluated the feasibility of performing myopic femtosecond lenticule extraction (FLEx) through a small incision using the small incision lenticule extraction (SMILE) procedure. Prospective, non-randomised clinical trial. PARTICIPANTS; Ninety-one eyes of 48 patients with myopia with and without astigmatism completed the final 6 month follow-up. The patients' mean age was 35.3 years. Their preoperative mean spherical equivalent (SE) was −4.75±1.56 D. A refractive lenticule of intrastromal corneal tissue was cut utilising a prototype of the Carl Zeiss Meditec AG VisuMax femtosecond laser system. Simultaneously two opposite small ‘pocket’ incisions were created by the laser system. Thereafter, the lenticule was manually dissected with a spatula and removed through one of incisions using modified McPherson forceps. Uncorrected visual acuity (UCVA) and best spectacle corrected visual acuity (BSCVA) after 6 months, objective and manifest refraction as well as slit-lamp examination, side effects and a questionnaire. Six months postoperatively the mean SE was −0.01 D±0.49 D. Most treated eyes (95.6%) were within ±1.0 D, and 80.2% were within ±0.5 D of intended correction. Of the eyes treated, 83.5% had an UCVA of 1.0 (20/20) or better, 53% remained unchanged, 32.3% gained one line, 3.3% gained two lines of BSCVA, 8.8% lost one line and 1.1% lost ≥2 lines of BSCVA. When answering a standardised questionnaire, 93.3% of patients were satisfied with the results obtained and would undergo the procedure again. SMILE is a promising new flapless minimally invasive refractive procedure to correct myopia.

Photorefractive keratectomy for correction of myopia: Our one-year experience

Directory of Open Access Journals (Sweden)

Resan Mirko

2012-01-01

Full Text Available Background/Aim. Photorefractive keratectomy (PRK, after laser in situ keratomileusis (LASIK, is commonly performed refractive surgical method worldwide. The aim of this study was to examine the effectiveness and safety of PRK in correction of various strengths of myopia and to assess how much corneal tissue is being removed with one diopter sphere (Dsph correction by using different optical zones (OZ. Methods. A prospective study with a follow-up period of 6 months included 55 patients of which 100 myopic eyes were treated by PRK method (one eye was included in 10 patients. Myopic eyes with a preoperative best corrected visual acuity (BCVA = 1.0 (20/20 were analysed. In order to assess the effectiveness of PRK operated myopic eyes were divided into four groups according to the dioptric power: 1≤ -1.75 Dsph (n = 26; 2 from -2 to -3.75 Dsph (n = 44; 3 from -4 to -6.75 Dsph (n = 23, and 4 ≥ -7 Dsph (n = 7. Myopic eyes with preoperative BCVA ≤ 0.9 (amblyopic eyes were excluded from the study, as well as eyes with astigmatism > -1.5 Dcyl. To assess the effectiveness of PRK we examined the percentage of eyes in the mentioned groups, which derived uncorrected visual acuity (UCVA 6 months after the intervention to the following: a UCVA = 1.0 (20/20 and b UCVA ≥ 0.5 (20/40. To assess the safety of PRK we examined the frequency of intraoperative and postoperative complications. To estimate how much corneal tissue was removed with one Dsph correction by using different OZ, we used preoperative and postoperative (after 6 months central pachymetry values expressed in μm and volume of cornea (central 7 mm expressed in mm³. In that sense, we used only the myopic eyes with clear preoperative spherical refraction. The total number of these eyes was 27, of which 16 eyes were treated using a 6.5 mm OZ and 11 eyes using a 7 mm OZ. Results. Refractive spherical equivalent (RSE for all eyes was in the range from -0.75 to -8.75 Dsph, and preoperative mean

Instrumental interaction

OpenAIRE

Luciani , Annie

2007-01-01

International audience; The expression instrumental interaction as been introduced by Claude Cadoz to identify a human-object interaction during which a human manipulates a physical object - an instrument - in order to perform a manual task. Classical examples of instrumental interaction are all the professional manual tasks: playing violin, cutting fabrics by hand, moulding a paste, etc.... Instrumental interaction differs from other types of interaction (called symbolic or iconic interactio...

Relationships between central and peripheral corneal thickness in different degrees of myopia.

Science.gov (United States)

Ortiz, Sara; Mena, Laura; Rio-San Cristobal, Ana; Martin, Raul

2014-01-01

To analyze the relationship between the central corneal thickness (CCT) and mid-peripheral corneal thickness (PCT) with the degree of myopia [axial length (AL) and spherical equivalent refractive error (SE)]. 175 right myopic eyes from 175 patients were divided according to the degree of SE: group #1 (n=76, 12.00 D). The CCT and PCT (3mm from the apex to the superior, inferior, nasal and temporal locations) were measured with the Orbscan-II. Relative peripheral index (RPI) was calculated by dividing the PCT by the CCT. The AL was measured with the IOL Master, and the SE was obtained with subjective refraction. AL was 25.18±1.16 mm, 26.59±1.26 mm and 29.45±2.58 mm and SE was -3.31±1.40 D, -8.32±1.64 D and -16.44±4.48 D for groups #1, #2 and #3, respectively. Non-statistically significant differences in central and peripheral corneal thickness were found between groups (P>0.05 ANOVA). Non-significant relationship was found between central and peripheral corneal thickness with the AL and SE in the three study groups and in the total sample (r0.05). The RPI values were similar between groups without significant difference between groups (P>0.05 ANOVA). Linear relationship was found between RPI superior location in group #2 (r=-0.23; P=0.04) and RPI nasal location in group #3 with the EE (r=0.41; P=0.03). There are no significant differences among low, moderate and extremely myopic eyes related to the CCT and PCT. Corneal thickness is very similar in myopic eyes with small differences that are not clinically relevant to myopic patient management. Copyright © 2012 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Visual outcomes after Epi-LASIK and PRK for low and moderate myopia.

Science.gov (United States)

Sia, Rose K; Coe, Charles D; Edwards, Jayson D; Ryan, Denise S; Bower, Kraig S

2012-01-01

To evaluate visual outcomes following epi-LASIK compared to photorefractive keratectomy (PRK). Of a total 294 patients aged ≥21 years, 145 (290 eyes) underwent epi-LASIK and 149 (298 eyes) underwent PRK for low to moderate myopia or myopic astigmatism. Epi-LASIK was performed with the Amadeus II epikeratome (Abbott Medical Optics) and PRK with the Amoils rotary epithelial brush (Innovative Excimer Solutions). All ablations were performed using the same excimer laser system. Outcome measures included intraoperative complications, corneal reepithelialization, postoperative pain, uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent (MRSE), corrected distance visual acuity (CDVA), corneal haze, and quality of vision. Mean preoperative MRSE was -2.97±1.19 diopters (D) for epi-LASIK versus -2.95±1.06 D for PRK. Complete reepithelialization was achieved by postoperative day 4 in 46.9% of epi-LASIK eyes versus 92.4% of PRK eyes, with superior UDVA at postoperative day 1 in the PRK group (P=.002). Using Fisher exact test, a significantly higher percentage of epi-LASIK eyes compared to PRK eyes achieved 20/15 or better at 1 month (25.8% vs 17.8%, P=.031), 3 months (62.3% vs 49.3%, P=.004), 6 months (77.1% vs 57.9%, Pvs 61.9%, P=.002). A change in MRSE >0.50 D occurred in 8.4% of epi-LASIK eyes within the 3- and 12-month interval versus 17.7% of PRK eyes (P=.04). No differences were noted between the two procedures in CDVA or clinically significant haze. Epi-LASIK showed superior refractive efficacy and stability but required more time for wound healing, resulting in inferior early visual outcomes and a tendency to overcorrect higher refractive errors compared to PRK. Both treatments were safe and comparable in terms of pain and haze formation. Copyright 2012, SLACK Incorporated.

Autosomal recessive retinitis pigmentosa with RP1 mutations is associated with myopia.

Science.gov (United States)

Chassine, Thomas; Bocquet, Béatrice; Daien, Vincent; Avila-Fernandez, Almudena; Ayuso, Carmen; Collin, Rob Wj; Corton, Marta; Hejtmancik, J Fielding; van den Born, L Ingeborgh; Klevering, B Jeroen; Riazuddin, S Amer; Sendon, Nathacha; Lacroux, Annie; Meunier, Isabelle; Hamel, Christian P

2015-10-01

To determine the refractive error in patients with autosomal recessive retinitis pigmentosa (arRP) caused by RP1 mutations and to compare it with that of other genetic subtypes of RP. Twenty-six individuals had arRP with RP1 mutations, 25 had autosomal dominant RP (adRP) with RP1 mutation, 8 and 33 had X-linked RP (xlRP) with RP2 and RPGR mutations, respectively, 198 and 93 had Usher syndrome and arRP without RP1 mutations, respectively. The median of the spherical equivalent (SE) and the IQR (Q25-Q75) was determined and multiple comparisons were performed. arRP patients with RP1 mutations had SE median at -4.0 dioptres (D) OD (Ocula Dextra); -3.88 D OS (Ocula Sinistra), whereas arRP patients without RP1 mutations (-0.50 D OD; -0.75 D OS) and Usher syndrome patients (-0.50 D OD; -0.38 D OS) were significantly less myopic (pUsher syndrome and adRP with RP1 mutation had a narrow IQR (-9.06 to -1.13 D), whereas arRP with RP1 mutations and xlRP with RP2 or RPGR mutations had a larger range (-9.06; -1.13 D). arRP patients with RP1 mutations have myopia not different from patients with xlRP with RP2 or RPGR mutations, while RP patients from other genetic subgroups were emmetropic or mildly myopic. We suggest that arRP patients with high myopic refractive error should be preferentially analysed for RP1 mutations. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Instrumentation development

International Nuclear Information System (INIS)

Ubbes, W.F.; Yow, J.L. Jr.

1988-01-01

Instrumentation is developed for the Civilian Radioactive Waste Management Program to meet several different (and sometimes conflicting) objectives. This paper addresses instrumentation development for data needs that are related either directly or indirectly to a repository site, but does not touch on instrumentation for work with waste forms or other materials. Consequently, this implies a relatively large scale for the measurements, and an in situ setting for instrument performance. In this context, instruments are needed for site characterization to define phenomena, develop models, and obtain parameter values, and for later design and performance confirmation testing in the constructed repository. The former set of applications is more immediate, and is driven by the needs of program design and performance assessment activities. A host of general technical and nontechnical issues have arisen to challenge instrumentation development. Instruments can be classed into geomechanical, geohydrologic, or other specialty categories, but these issues cut across artificial classifications. These issues are outlined. Despite this imposing list of issues, several case histories are cited to evaluate progress in the area

Instrumentation

International Nuclear Information System (INIS)

Decreton, M.

2002-01-01

SCK-CEN's R and D programme on instrumentation involves the development of advanced instrumentation systems for nuclear applications as well as the assessment of the performance of these instruments in a radiation environment. Particular emphasis is on the use of optical fibres as umbilincal links of a remote handling unit for use during maintanance of a fusion reacor, studies on the radiation hardening of plasma diagnostic systems; investigations on new instrumentation for the future MYRRHA accelerator driven system; space applications related to radiation-hardened lenses; the development of new approaches for dose, temperature and strain measurements; the assessment of radiation-hardened sensors and motors for remote handling tasks and studies of dose measurement systems including the use of optical fibres. Progress and achievements in these areas for 2001 are described

Instrumentation

Energy Technology Data Exchange (ETDEWEB)

Decreton, M

2002-04-01

SCK-CEN's R and D programme on instrumentation involves the development of advanced instrumentation systems for nuclear applications as well as the assessment of the performance of these instruments in a radiation environment. Particular emphasis is on the use of optical fibres as umbilincal links of a remote handling unit for use during maintanance of a fusion reacor, studies on the radiation hardening of plasma diagnostic systems; investigations on new instrumentation for the future MYRRHA accelerator driven system; space applications related to radiation-hardened lenses; the development of new approaches for dose, temperature and strain measurements; the assessment of radiation-hardened sensors and motors for remote handling tasks and studies of dose measurement systems including the use of optical fibres. Progress and achievements in these areas for 2001 are described.

Policy instruments for energy conservation: A multidimensional assessment

International Nuclear Information System (INIS)

Giraudet, Louis-Gaetan

2011-01-01

This thesis evaluates the effectiveness of various forms of taxes, subsidies and regulations implemented to correct for market failures that may prevent energy savings. It builds on various approaches, with gradual complexity. First, a standard micro-economic model is developed to compare the static performances of these instruments. Second, the representation of consumer behaviour is strengthened in a model of the residential energy demand for space heating in France, which allows to identify the dynamic mechanisms by which instruments can correct for the main market failures. Third, an empirical evaluation of 'white certificate' schemes - tradable energy saving obligations imposed on energy operators - is made from the comparison between the British, Italian and French experiences, taking into account national institutions. The following conclusions can be drawn from these various approaches: (i) energy taxes, by encouraging both energy efficiency investment and sufficiency behaviour, are particularly effective; (ii) energy efficiency regulations have a significant impact on the diffusion of efficient technologies; (iii) subsidies to energy efficiency induce a large rebound effect; (iv) depending on the institutional environment in which they operate, white certificate schemes combine different properties of these instruments. Applied to the French residential building sector, the most effective combination of these instruments does not allow to reach the energy saving target set by the Government. (author)

Vision though afocal instruments: generalized magnification and eye-instrument interaction

Science.gov (United States)

Harris, William F.; Evans, Tanya

2018-04-01

In Gaussian optics all observers experience the same magnification, the instrument's angular magnification, when viewing distant objects though a telescope or other afocal instruments. However, analysis in linear optics shows that this is not necessarily so in the presence of astigmatism. Because astigmatism may distort and rotate images it is appropriate to work with generalized angular magnification represented by a 2 × 2 matrix. An expression is derived for the generalized magnification for an arbitrary eye looking through an arbitrary afocal instrument. With afocal instruments containing astigmatic refracting elements not all eyes experience the same generalized magnification; there is interaction between eye and instrument. Eye-instrument interaction may change as the instrument is rotated about its longitudinal axis, there being no interaction in particular orientations. A simple numerical example is given. For sake of completeness, expressions for generalized magnification are also presented in the case of instruments that are not afocal and objects that are not distant.

Pre-flight calibration and initial data processing for the ChemCam laser-induced breakdown spectroscopy instrument on the Mars Science Laboratory rover

Science.gov (United States)

Wiens, R.C.; Maurice, S.; Lasue, J.; Forni, O.; Anderson, R.B.; Clegg, S.; Bender, S.; Blaney, D.; Barraclough, B.L.; Cousin, A.; DeFlores, L.; Delapp, D.; Dyar, M.D.; Fabre, C.; Gasnault, O.; Lanza, N.; Mazoyer, J.; Melikechi, N.; Meslin, P.-Y.; Newsom, H.; Ollila, A.; Perez, R.; Tokar, R.; Vaniman, D.

2013-01-01

The ChemCam instrument package on the Mars Science Laboratory rover, Curiosity, is the first planetary science instrument to employ laser-induced breakdown spectroscopy (LIBS) to determine the compositions of geological samples on another planet. Pre-processing of the spectra involves subtracting the ambient light background, removing noise, removing the electron continuum, calibrating for the wavelength, correcting for the variable distance to the target, and applying a wavelength-dependent correction for the instrument response. Further processing of the data uses multivariate and univariate comparisons with a LIBS spectral library developed prior to launch as well as comparisons with several on-board standards post-landing. The level-2 data products include semi-quantitative abundances derived from partial least squares regression. A LIBS spectral library was developed using 69 rock standards in the form of pressed powder disks, glasses, and ceramics to minimize heterogeneity on the scale of the observation (350–550 μm dia.). The standards covered typical compositional ranges of igneous materials and also included sulfates, carbonates, and phyllosilicates. The provenance and elemental and mineralogical compositions of these standards are described. Spectral characteristics of this data set are presented, including the size distribution and integrated irradiances of the plasmas, and a proxy for plasma temperature as a function of distance from the instrument. Two laboratory-based clones of ChemCam reside in Los Alamos and Toulouse for the purpose of adding new spectra to the database as the need arises. Sensitivity to differences in wavelength correlation to spectral channels and spectral resolution has been investigated, indicating that spectral registration needs to be within half a pixel and resolution needs to match within 1.5 to 2.6 pixels. Absolute errors are tabulated for derived compositions of each major element in each standard using PLS regression

PERIPHERAL AVASCULAR RETINA WITH DISK ANOMALY AND HIGH MYOPIA: A Novel Association in a Hereditary Isolated Ocular Disorder.

Science.gov (United States)

Habib, Ahmed M; Elkitkat, Rania S; Saleh, Mohamed I; Abd El-Salam, Mohammed M

2016-02-01

To describe a family pedigree with a previously undescribed association of autosomal dominantly inherited ocular abnormalities. Case series study performed on 15 family members. Examination included history taking, visual acuity, intraocular pressure, slit-lamp, gonioscopy, indirect ophthalmoscopy (10 members), fluorescein angiography (5 members), general examination and renal ultrasound (4 members), and hemoglobin electrophoresis for the proband and another member. Family pedigree revealed autosomal-dominant inheritance. Visual acuity ranged from 6/36 to no light perception. Examination revealed rubeosis in 7 eyes and atrophia bulbi in 11 eyes. Indirect ophthalmoscopy for 11 eyes revealed evidence of an ocular triad of peripheral avascular retina, disk anomaly (cavitary optic disk anomaly or disk dysplasia), and tessellated fundus of high myopia. The authors also observed new vessels elsewhere with or without extensive subretinal exudations in 6 eyes. All patients with any residual vision (up to perception of light) had nystagmus. Four affected members underwent general examination, renal ultrasound, and serum creatinine level (to exclude papillorenal syndrome), and all were normal. Hemoglobin electrophoresis (to exclude sickle cell retinopathy) revealed within normal values. To the authors' knowledge, the aforementioned ocular triad has not been previously described, in association, with an autosomal-dominant pattern of inheritance.

Changes in higher order aberrations after wavefront guided FS-LASIK for myopia combined with moderate to high astigmatism

Directory of Open Access Journals (Sweden)

Cang-Yu Guan

2018-02-01

Full Text Available AIM: To assess the changes in higher order aberrations after wavefront guided femtosecond laser assisted laser in situ keratomileusis(FS-LASIKfor moderate to high astigmatism. METHODS: Eighty-eight eyes of 50 myopia patients with moderate to high astigmatism were included in this prospective study. There were 51 eyes with moderate astigmatism(≥-1.50D and RESULTS: At the 3mo after operation, the mean UDVA of all eyes was above 20/20, better than before operation(PP=0.36and no eyes lost ≥2 lines of CDVA. Mean astigmstism of 85 eyes(97%was reduced below -1.00D, mean astigmatism of 70 eyes(80%was reduced below -0.50D(PPP=0.078, 0.065. The spherical aberration, secondary astigmatism and the HOA root mean square(RMSincreased from 0.19±0.06, 0.05±0.02 and 0.42±0.12, preoperatively to 0.32±0.17, 0.26±0.08 and 0.78±0.28(PCONCLUSION: Wavefront-guided FS-LASIK is a safe and effective option for the patients with moderate to high astigmstism although parts of HOAs increased.

Censored Quantile Instrumental Variable Estimates of the Price Elasticity of Expenditure on Medical Care.

Science.gov (United States)

Kowalski, Amanda

2016-01-02

Efforts to control medical care costs depend critically on how individuals respond to prices. I estimate the price elasticity of expenditure on medical care using a censored quantile instrumental variable (CQIV) estimator. CQIV allows estimates to vary across the conditional expenditure distribution, relaxes traditional censored model assumptions, and addresses endogeneity with an instrumental variable. My instrumental variable strategy uses a family member's injury to induce variation in an individual's own price. Across the conditional deciles of the expenditure distribution, I find elasticities that vary from -0.76 to -1.49, which are an order of magnitude larger than previous estimates.

A method for profiling biometric changes during disaccommodation.

Science.gov (United States)

Alderson, Alison; Davies, Leon N; Mallen, Edward A H; Sheppard, Amy L

2012-05-01

To demonstrate the application of low-coherence reflectometry to the study of biometric changes during disaccommodation responses in human eyes after cessation of a near task and to evaluate the effect of contact lenses on low-coherence reflectometry biometric measurements. Ocular biometric parameters of crystalline lens thickness (LT) and anterior chamber depth (ACD) were measured with the LenStar device during and immediately after a 5 D accommodative task in 10 participants. In a separate trial, accommodation responses were recorded with a Shin-Nippon WAM-5500 optometer in a subset of two participants. Biometric data were interleaved to form a profile of post-task anterior segment changes. In a further experiment, the effect of soft contact lenses on LenStar measurements was evaluated in 15 participants. In 10 adult participants, increased LT and reduced ACD was seen during the 5 D task. Post-task, during fixation of a 0 D target, a profile of the change in LT and ACD against time was observed. In the two participants with accommodation data (one a sufferer of nearwork-induced transient myopia and other a non-sufferer), the post-task changes in refraction compared favorably with the interleaved LenStar biometry data. The insertion of soft contact lenses did not have a significant effect on LenStar measures of ACD or LT (mean change: -0.007 mm, p = 0.265 and + 0.001 mm, p = 0.875, respectively). With the addition of a relatively simple stimulus modification, the LenStar instrument can be used to produce a profile of post-task changes in LT and ACD. The spatial and temporal resolution of the system is sufficient for the investigation of nearwork-induced transient myopia from a biometric viewpoint. LenStar measurements of ACD and LT remain valid after the fitting of soft contact lenses.

Pancreatitis Quality of Life Instrument: Development of a new instrument

Directory of Open Access Journals (Sweden)

Wahid Wassef

2014-02-01

Full Text Available Objectives: The goal of this project was to develop the first disease-specific instrument for the evaluation of quality of life in chronic pancreatitis. Methods: Focus groups and interview sessions were conducted, with chronic pancreatitis patients, to identify items felt to impact quality of life which were subsequently formatted into a paper-and-pencil instrument. This instrument was used to conduct an online survey by an expert panel of pancreatologists to evaluate its content validity. Finally, the modified instrument was presented to patients during precognitive testing interviews to evaluate its clarity and appropriateness. Results: In total, 10 patients were enrolled in the focus groups and interview sessions where they identified 50 items. Once redundant items were removed, the 40 remaining items were made into a paper-and-pencil instrument referred to as the Pancreatitis Quality of Life Instrument. Through the processes of content validation and precognitive testing, the number of items in the instrument was reduced to 24. Conclusions: This marks the development of the first disease-specific instrument to evaluate quality of life in chronic pancreatitis. It includes unique features not found in generic instruments (economic factors, stigma, and spiritual factors. Although this marks a giant step forward, psychometric evaluation is still needed prior to its clinical use.

Scleral Cross-Linking Using Riboflavin UVA Irradiation for the Prevention of Myopia Progression in a Guinea Pig Model: Blocked Axial Extension and Altered Scleral Microstructure.

Directory of Open Access Journals (Sweden)

Shuai Liu

Full Text Available To develop methods of collagen cross-linking (CXL in the sclera for the treatment of progressive myopia and to investigate the biomechanical and histological changes that occur in as a result.Twenty 14-day-old guinea pigs were divided into 3 groups: the cross-linking group (CL, n = 8, non cross-linking group (NCL, n = 8, and control group (n = 4. The scleras of the right eyes of the guinea pigs in the CL group were surgically exposed and riboflavin was dropped onto the irradiation zone for 20 seconds prior to ultraviolet-A (UVA irradiation. The same procedure was conducted on the NCL group but without UVA irradiation. No procedure was conducted on the control group. The right eyes of the guinea pigs in the CL and NCL groups were then fitted with -10.00DS optics for six weeks. Retinoscopy and the axial lengths (AXL were measured at baseline, and at the second, fourth and sixth weeks post-treatment in all three groups. All animal subjects were euthanized after the sixth week and then biomechanical and histopathological examinations of the scleras were conducted.The mean AXL of the NCL group was longer than both the control and CL groups at six weeks (P = 0.001. The mean refractive error in the NCL group was statistically significantly more negative than both the control and the CL groups at six weeks (P = 0.001. The scleral collagen fiber arrangements of the CL and control groups were denser and more regularly distributed than the NCL group. Ultimate stress of the sclera was lowest in the NCL group, followed by the CL then the control group (P<0.05. Ultimate strain (% of the sclera was lowest in the CL group followed by the NCL and then the control group (P<0.05.Our study demonstrates that scleral CXL using riboflavin UVA irradiation effectively prevents the progression of myopia by increasing scleral biomechanical strength in a guinea pig model.

The Characterization of Biosignatures in Caves Using an Instrument Suite

Science.gov (United States)

Uckert, Kyle; Chanover, Nancy J.; Getty, Stephanie; Voelz, David G.; Brinckerhoff, William B.; McMillan, Nancy; Xiao, Xifeng; Boston, Penelope J.; Li, Xiang; McAdam, Amy; Glenar, David A.; Chavez, Arriana

2017-12-01

The search for life and habitable environments on other Solar System bodies is a major motivator for planetary exploration. Due to the difficulty and significance of detecting extant or extinct extraterrestrial life in situ, several independent measurements from multiple instrument techniques will bolster the community's confidence in making any such claim. We demonstrate the detection of subsurface biosignatures using a suite of instrument techniques including IR reflectance spectroscopy, laser-induced breakdown spectroscopy, and scanning electron microscopy/energy dispersive X-ray spectroscopy. We focus our measurements on subterranean calcium carbonate field samples, whose biosignatures are analogous to those that might be expected on some high-interest astrobiology targets. In this work, we discuss the feasibility and advantages of using each of the aforementioned instrument techniques for the in situ search for biosignatures and present results on the autonomous characterization of biosignatures using multivariate statistical analysis techniques.

Detection of posterior vortex veins in eyes with pathologic myopia by ultra-widefield indocyanine green angiography.

Science.gov (United States)

Moriyama, Muka; Cao, Kejia; Ogata, Satoko; Ohno-Matsui, Kyoko

2017-09-01

To analyse the characteristics of posterior vortex veins detected in highly myopic eyes by wide-field indocyanine green angiography (ICGA). One hundred and fifty-eight consecutive patients (302 eyes) with high myopia (myopic refractive error >8.0 dioptres (D) or axial length ≥26.5 mm) were studied. Wide-field ICGA was performed with the Spectralis HRA module. Posterior vortex veins were found in 80 eyes (26%). The prevalence of posterior staphyloma was significantly higher in eyes in which posterior vortex vein was detected than in eyes without posterior vortex vein. The posterior vortex veins were classified into five types according to the site of exit from the eye; around the optic nerve in 28%, in the macular area in 17%, along the border of staphyloma in 6%, along the margin of macular atrophy or large peripapillary conus in 21%, and elsewhere in 28%. In one eye, two posterior vortex veins collected the choroidal venous blood from the entire fundus. Wide-field ICGA can analyse the characteristic features of choroidal blood outflow system through posterior vortex veins in highly myopic eyes. They may play an important role as routes of choroidal outflow in highly myopic eyes. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Comparison of the Early Clinical Outcomes between Combined Small-Incision Lenticule Extraction and Collagen Cross-Linking versus SMILE for Myopia.

Science.gov (United States)

Ng, Alex L K; Chan, Tommy C Y; Cheng, George P M; Jhanji, Vishal; Ye, Cong; Woo, Victor C P; Lai, Jimmy S M

2016-01-01

Background. To compare the early outcome of combined SMILE and collagen crosslinking (SMILE Xtra) with SMILE. Method. Prospective, comparative interventional study of 21 eyes receiving SMILE Xtra using a low energy protocol and 32 control eyes receiving SMILE only. The outcomes were compared at 1, 3, and 6 months postoperatively. Results. Both groups had myopia with spherical equivalent refraction (SEQ) > 4.00 D. The SMILE Xtra group had thinner preoperative central corneal thickness and residual stromal bed thickness (p line in corrected distance visual acuity. The safety index was 0.96 ± 0.06 and 1.00 ± 0.00 in SMILE Xtra and control, respectively (p SMILE Xtra and +0.03 ± 0.25 D for control (p = 0.021). The efficacy index was 0.88 ± 0.13 and 0.97 ± 0.06, respectively (p = 0.005). Conclusion. SMILE Xtra had good overall safety profile and predictability at 6 months. However, when compared with control, the safety index and efficacy index were statistically significantly lower in the early postoperative period.

Conduction cooled compact laser for chemcam instrument

Science.gov (United States)

Faure, B.; Saccoccio, M.; Maurice, S.; Durand, E.; Derycke, C.

2017-11-01

A new conduction cooled compact laser for Laser Induced Breakdown Spectroscopy (LIBS) on Mars is presented. The laser provides pulses with energy higher than 30mJ at 1μm of wavelength with a good spatial quality. Three development prototypes of this laser have been built and functional and environmental tests have been done. Then, the Qualification and Flight models have been developed and delivered. A spare model is now developed. This laser will be mounted on the ChemCam Instrument of the NASA mission MSL 2009. ChemCam Instrument is developed in collaboration between France (CESR and CNES) and USA (LANL). The goal of this Instrument is to study the chemical composition of Martian rocks. A laser source (subject of this presentation) emits a pulse which is focused by a telescope. It creates a luminous plasma on the rock; the light of this plasma is then analysed by three spectrometers to obtain information on the composition of the rock. The laser source is developed by the French company Thales Laser, with a technical support from CNES and CESR. This development is funded by CNES. The laser is compact, designed to work in burst mode. It doesn't require any active cooling.

Instrument performance evaluation

International Nuclear Information System (INIS)

Swinth, K.L.

1993-03-01

Deficiencies exist in both the performance and the quality of health physics instruments. Recognizing the implications of such deficiencies for the protection of workers and the public, in the early 1980s the DOE and the NRC encouraged the development of a performance standard and established a program to test a series of instruments against criteria in the standard. The purpose of the testing was to establish the practicality of the criteria in the standard, to determine the performance of a cross section of available instruments, and to establish a testing capability. Over 100 instruments were tested, resulting in a practical standard and an understanding of the deficiencies in available instruments. In parallel with the instrument testing, a value-impact study clearly established the benefits of implementing a formal testing program. An ad hoc committee also met several times to establish recommendations for the voluntary implementation of a testing program based on the studies and the performance standard. For several reasons, a formal program did not materialize. Ongoing tests and studies have supported the development of specific instruments and have helped specific clients understand the performance of their instruments. The purpose of this presentation is to trace the history of instrument testing to date and suggest the benefits of a centralized formal program

Dry Eye Disease following Refractive Surgery: A 12-Month Follow-Up of SMILE versus FS-LASIK in High Myopia

Directory of Open Access Journals (Sweden)

Bingjie Wang

2015-01-01

Full Text Available Purpose. To compare dry eye disease following SMILE versus FS-LASIK. Design. Prospective, nonrandomised, observational study. Patients. 90 patients undergoing refractive surgery for myopia were included. 47 eyes underwent SMILE and 43 eyes underwent FS-LASIK. Methods. Evaluation of dry eye disease was conducted preoperatively and at 1, 3, 6, and 12 months postoperatively, using the Salisbury Eye Evaluation Questionnaire (SEEQ and TBUT. Results. TBUT reduced following SMILE at 1 and 3 months (p<0.001 and at 1, 3, and 6 months following FS-LASIK (p<0.001. TBUT was greater following SMILE than FS-LASIK at 3, 6, and 12 months (p<0.001, p<0.001, and p=0.009, resp.. SEEQ scores increased (greater symptoms following SMILE at 1 month (p<0.001 and 3 months (p=0.003 and at 1, 3, and 6 months following FS-LASIK (p<0.001. SMILE produced lower SEEQ scores (fewer symptoms than FS-LASIK at 1, 3, and 6 months (p<0.001. Conclusion. SMILE produces less dry eye disease than FS-LASIK at 6 months postoperatively but demonstrates similar degrees of dry eye disease at 12 months.

Photodynamic monotherapy or combination treatment with intravitreal triamcinolone acetonide, bevacizumab or ranibizumab for choroidal neovascularization associated with pathological myopia

Directory of Open Access Journals (Sweden)

Pukhraj Rishi

2011-01-01

Full Text Available This retrospective, interventional case series analyses treatment outcomes in eyes with choroidal neovascularization (CNV secondary to pathological myopia, managed with photodynamic therapy, (PDT, (Group 1, N = 11, PDT and intravitreal triamcinolone acetonide (4 mg/0.1ml (Group 2, N = 3, PDT and intravitreal anti-vascular endothelial growth factor (anti-VEGF bevacizumab 1.25 mg/0.05 ml, ranibizumab 0.5 mg/0.05 ml and reduced-fluence PDT and intravitreal ranibizumab 0.5 mg/0.05 ml (Group 3, N=12. All the patients underwent PDT. Intravitreal injections were repeated as required. SPSS 14 software was used to evaluate the data. Wilcoxon signed ranks test was used to evaluate pre- and post-treatment vision. The Kruskal-Wallis test was used for comparison between the groups. All the groups were statistically comparable. All the eyes showed complete regression of CNV, with a minimum follow-up of six months. All groups had visual improvement; significantly in Group 3 ( p = 0.003. Combination PDT with anti-VEGF agents appeared to be efficacious in eyes with myopic CNV. However, a larger study with a longer follow-up is required to validate these results.

Avaliação das alterações fundoscópicas na miopia degenerativa Fundus changes evaluation in degenerative myopia

Directory of Open Access Journals (Sweden)

Oswaldo Ferreira Moura Brasil

2006-04-01

Full Text Available OBJETIVO: Avaliar a presença de alterações fundoscópicas em pacientes portadores de miopia degenerativa. MÉTODOS: Quarenta pacientes com erro refrativo de pelo menos -6,00 dioptrias foram selecionados para exame oftalmológico, complementado por retinografia do pólo posterior e ecobiometria. RESULTADOS: Foram estudados 57 olhos de 37 pacientes com erro refrativo de -6,25 a -28,50 dioptrias, com média de -14,05, e comprimento axial de 26,06 a 32,86 mm, com média de 28,01. Encontramos crescente temporal em 36,5% e circunferencial em 21% dos olhos. Vasos da coróide foram visualizados em 35% dos olhos. As alterações do pólo posterior foram as seguintes: estafiloma posterior em 10,5%, mancha de Fuchs em 3,5% e "lacquer cracks" em 1,5%. O exame da periferia retiniana evidenciou atrofia corio-retiniana tipo pavimentosa em 17,5%, branco sem pressão em 10,5%, degeneração "lattice" em 5%, ruptura retiniana em 3,5% e retinosquise em 1,5% dos olhos examinados. CONCLUSÕES: Alterações fundoscópicas que levam à baixa visual são freqüentes em pacientes com miopia degenerativa. O exame da periferia retiniana é muito importante nestes pacientes devido ao risco aumentado de descolamento de retina.PURPOSE: To evaluate the presence of fundus changes in degenerative myopia. METHODS: Forty patients with refractive error of at least -6.00 diopters were selected for ophthalmologic examination followed by posterior pole photograph and echobiometry. RESULTS: We studied 57 eyes of 37 patients with refractive error ranging from -6.25 to -28.50 diopters, with mean -14.05, and axial length ranging from 26.06 to 32.86 mm, with mean 28.01. We found a temporal crescent in 36.5% and a peripapillary one in 20% of the eyes. Choroidal vessels were seen in 35% of the eyes. Posterior pole changes were as follow: posterior staphyloma in 10.5%, Fuchs' spots in 3.5% and lacquer cracks in 1.5%. Peripheral retinal examination revealed paving stone chorioretinal

The OCO-3 Mission: Science Objectives and Instrument Performance

Science.gov (United States)

Eldering, A.; Basilio, R. R.; Bennett, M. W.

2017-12-01

The Orbiting Carbon Observatory 3 (OCO-3) will continue global CO2 and solar-induced chlorophyll fluorescence (SIF) using the flight spare instrument from OCO-2. The instrument is currently being tested, and will be packaged for installation on the International Space Station (ISS) (launch readiness in early 2018.) This talk will focus on the science objectives, updated simulations of the science data products, and the outcome of recent instrument performance tests. The low-inclination ISS orbit lets OCO-3 sample the tropics and sub-tropics across the full range of daylight hours with dense observations at northern and southern mid-latitudes (+/- 52º). The combination of these dense CO2 and SIF measurements provides continuity of data for global flux estimates as well as a unique opportunity to address key deficiencies in our understanding of the global carbon cycle. The instrument utilizes an agile, 2-axis pointing mechanism (PMA), providing the capability to look towards the bright reflection from the ocean and validation targets. The PMA also allows for a snapshot mapping mode to collect dense datasets over 100km by 100km areas. Measurements over urban centers could aid in making estimates of fossil fuel CO2 emissions. Similarly, the snapshot mapping mode can be used to sample regions of interest for the terrestrial carbon cycle. In addition, there is potential to utilize data from ISS instruments ECOSTRESS (ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station) and GEDI (Global Ecosystem Dynamics Investigation), which measure other key variables of the control of carbon uptake by plants, to complement OCO-3 data in science analysis. In 2017, the OCO-2 instrument was transformed into the ISS-ready OCO-3 payload. The transformed instrument was thoroughly tested and characterized. Key characteristics, such as instrument ILS, spectral resolution, and radiometric performance will be described. Analysis of direct sun measurements taken during testing

The effect of instrument alignment on peripheral refraction measurements by automated optometer.

Science.gov (United States)

Ehsaei, Asieh; Chisholm, Catharine M; Mallen, Edward A H; Pacey, Ian E

2011-07-01

Interest in peripheral refraction measurement has grown in recent years in response to the insight it may provide into myopia development. In light of the likely increase in the clinical use of open-field autorefractors for peripheral refraction measurements, the question of instrument alignment and its impact on the accuracy of refraction measurements is raised. The aim of this study was to investigate the accuracy and precision when an open-field device was moved away from alignment with the corneal reflex towards the pupil margins, and to determine the optimum alignment position for peripheral refraction measurements. Autorefractions were performed on the right eyes of 10 healthy participants using the Shin-Nippon NVision-K 5001 autorefractor. At least five measurements were taken with the subject fixating a distance target in the primary position of gaze, and then four peripheral fixation targets located along the horizontal meridian (10° and 20° eccentricities in the nasal and temporal retina). Measurements were taken at seven alignment positions across the pupil for each fixation angle. Refraction was recorded as the spherical and cylindrical power. The central objective refraction achieved under cycloplegia based on the autorefraction result for the whole sample, ranged between -5.62 D and +1.85 D for the value of sphere, with a maximum astigmatism of -1.00 D. Acceptable alignment position range varied with fixation angle but was -1.0 to +1.0 mm in width across the pupil. Peripheral refraction measurements centred on the entrance pupil were as reliable as those centred on the corneal reflex. Our data suggest that for peripheral refraction measurements, there is a range of acceptable positions and operators can be confident of the validity of results obtained if aligned half way between the pupil centre and corneal reflex. The alignment becomes more critical at greater eccentricities. Ophthalmic & Physiological Optics © 2011 The College of Optometrists.

Instrumentation

International Nuclear Information System (INIS)

Decreton, M.

2000-01-01

SCK-CEN's research and development programme on instrumentation aims at evaluating the potentials of new instrumentation technologies under the severe constraints of a nuclear application. It focuses on the tolerance of sensors to high radiation doses, including optical fibre sensors, and on the related intelligent data processing needed to cope with the nuclear constraints. Main achievements in these domains in 1999 are summarised

Pre-flight calibration and initial data processing for the ChemCam laser-induced breakdown spectroscopy instrument on the Mars Science Laboratory rover

Energy Technology Data Exchange (ETDEWEB)

Wiens, R.C., E-mail: rwiens@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Maurice, S.; Lasue, J.; Forni, O. [Institut de Recherche en Astrophysique et Planetologie, Toulouse (France); Anderson, R.B. [United States Geological Survey, Flagstaff, AZ (United States); Clegg, S. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Bender, S. [Planetary Science Institute, Tucson, AZ (United States); Blaney, D. [Jet Propulsion Laboratory, Pasadena, CA (United States); Barraclough, B.L. [Planetary Science Institute, Tucson, AZ (United States); Cousin, A. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Institut de Recherche en Astrophysique et Planetologie, Toulouse (France); Deflores, L. [Jet Propulsion Laboratory, Pasadena, CA (United States); Delapp, D. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Dyar, M.D. [Mount Holyoke College, South Hadley, MA (United States); Fabre, C. [Georessources, Nancy (France); Gasnault, O. [Institut de Recherche en Astrophysique et Planetologie, Toulouse (France); Lanza, N. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States); Mazoyer, J. [LESIA, Observatoire de Paris, Meudon (France); Melikechi, N. [Delaware State University, Dover, DE (United States); Meslin, P.-Y. [Institut de Recherche en Astrophysique et Planetologie, Toulouse (France); Newsom, H. [University of New Mexico, Albuquerque, NM (United States); and others

2013-04-01

The ChemCam instrument package on the Mars Science Laboratory rover, Curiosity, is the first planetary science instrument to employ laser-induced breakdown spectroscopy (LIBS) to determine the compositions of geological samples on another planet. Pre-processing of the spectra involves subtracting the ambient light background, removing noise, removing the electron continuum, calibrating for the wavelength, correcting for the variable distance to the target, and applying a wavelength-dependent correction for the instrument response. Further processing of the data uses multivariate and univariate comparisons with a LIBS spectral library developed prior to launch as well as comparisons with several on-board standards post-landing. The level-2 data products include semi-quantitative abundances derived from partial least squares regression. A LIBS spectral library was developed using 69 rock standards in the form of pressed powder disks, glasses, and ceramics to minimize heterogeneity on the scale of the observation (350–550 μm dia.). The standards covered typical compositional ranges of igneous materials and also included sulfates, carbonates, and phyllosilicates. The provenance and elemental and mineralogical compositions of these standards are described. Spectral characteristics of this data set are presented, including the size distribution and integrated irradiances of the plasmas, and a proxy for plasma temperature as a function of distance from the instrument. Two laboratory-based clones of ChemCam reside in Los Alamos and Toulouse for the purpose of adding new spectra to the database as the need arises. Sensitivity to differences in wavelength correlation to spectral channels and spectral resolution has been investigated, indicating that spectral registration needs to be within half a pixel and resolution needs to match within 1.5 to 2.6 pixels. Absolute errors are tabulated for derived compositions of each major element in each standard using PLS regression

Performing the Super Instrument

DEFF Research Database (Denmark)

Kallionpaa, Maria

2016-01-01

can empower performers by producing super instrument works that allow the concert instrument to become an ensemble controlled by a single player. The existing instrumental skills of the performer can be multiplied and the qualities of regular acoustic instruments extended or modified. Such a situation......The genre of contemporary classical music has seen significant innovation and research related to new super, hyper, and hybrid instruments, which opens up a vast palette of expressive potential. An increasing number of composers, performers, instrument designers, engineers, and computer programmers...... have become interested in different ways of “supersizing” acoustic instruments in order to open up previously-unheard instrumental sounds. Super instruments vary a great deal but each has a transformative effect on the identity and performance practice of the performing musician. Furthermore, composers...

Small Incision Lenticule Extraction (SMILE versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK for Myopia: A Systematic Review and Meta-Analysis.

Directory of Open Access Journals (Sweden)

Zeren Shen

Full Text Available The goal of this study was to compare small incision lenticule extraction (SMILE with femtosecond laser-assisted in situ keratomileusis (FS-LASIK for treating myopia.The CENTRAL, EMBASE, PubMed databases and a Chinese database (SinoMed were searched in May of 2016. Twelve studies with 1,076 eyes, which included three randomized controlled trials (RCTs and nine cohorts, met our inclusion criteria. The overall quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE working group framework. Data were extracted and analysed at three to six months postoperatively. Primary outcome measures included a loss of one or more lines of best spectacle corrected visual acuity (BSCVA, uncorrected visual acuity (UCVA of 20/20 or better, mean logMAR UCVA, postoperative mean spherical equivalent (SE and postoperative refraction within ±1.0 D of the target refraction. Secondary outcome measures included ocular surface disease index (OSDI, tear breakup time (TBUT and Schirmer's 1 test (S1T as dry eye parameters, along with corneal sensitivity.The overall quality of evidence was considered to be low to very low. Pooled results revealed no significant differences between the two groups with regard to a loss of one or more lines in the BSCVA (OR 1.71; 95% CI: 0.81, 3.63; P = 0.16, UCVA of 20/20 or better (OR 0.71; 95% CI: 0.44, 1.15; P = 0.16, logMAR UCVA (MD 0.00; 95% CI: -0.03, 0.04; P = 0.87, postoperative refractive SE (MD -0.00; 95% CI: -0.05, 0.05; P = 0.97 or postoperative refraction within ±1.0 D of the target refraction (OR 0.78; 95% CI: 0.22, 2.77; P = 0.70 within six months postoperatively. The pooled analysis also indicated that the FS-LASIK group suffered more severely from dry eye symptoms (OSDI; MD -6.68; 95% CI: -11.76, -2.00; P = 0.006 and lower corneal sensitivity (MD 12.40; 95% CI: 10.23, 14.56; P < 0.00001 at six months postoperatively.In conclusion, both FS-LASIK and SMILE are safe

Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted In Situ Keratomileusis (FS-LASIK) for Myopia: A Systematic Review and Meta-Analysis

Science.gov (United States)

Shen, Zeren; Shi, Keda; Yu, Yinhui; Yu, Xiaoning; Lin, Yuchen; Yao, Ke

2016-01-01

Purpose The goal of this study was to compare small incision lenticule extraction (SMILE) with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for treating myopia. Methods The CENTRAL, EMBASE, PubMed databases and a Chinese database (SinoMed) were searched in May of 2016. Twelve studies with 1,076 eyes, which included three randomized controlled trials (RCTs) and nine cohorts, met our inclusion criteria. The overall quality of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) working group framework. Data were extracted and analysed at three to six months postoperatively. Primary outcome measures included a loss of one or more lines of best spectacle corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA) of 20/20 or better, mean logMAR UCVA, postoperative mean spherical equivalent (SE) and postoperative refraction within ±1.0 D of the target refraction. Secondary outcome measures included ocular surface disease index (OSDI), tear breakup time (TBUT) and Schirmer’s 1 test (S1T) as dry eye parameters, along with corneal sensitivity. Results The overall quality of evidence was considered to be low to very low. Pooled results revealed no significant differences between the two groups with regard to a loss of one or more lines in the BSCVA (OR 1.71; 95% CI: 0.81, 3.63; P = 0.16), UCVA of 20/20 or better (OR 0.71; 95% CI: 0.44, 1.15; P = 0.16), logMAR UCVA (MD 0.00; 95% CI: -0.03, 0.04; P = 0.87), postoperative refractive SE (MD -0.00; 95% CI: -0.05, 0.05; P = 0.97) or postoperative refraction within ±1.0 D of the target refraction (OR 0.78; 95% CI: 0.22, 2.77; P = 0.70) within six months postoperatively. The pooled analysis also indicated that the FS-LASIK group suffered more severely from dry eye symptoms (OSDI; MD -6.68; 95% CI: -11.76, -2.00; P = 0.006) and lower corneal sensitivity (MD 12.40; 95% CI: 10.23, 14.56; P LASIK and SMILE are safe, effective and predictable surgical

The Hydraulic Test Procedure for Non-instrumented Irradiation Test Rig of Annular Fuel

Energy Technology Data Exchange (ETDEWEB)

Kim, Dae Ho; Lee, Kang Hee; Shin, Chang Hwan; Park, Chan Kook

2008-08-15

This report presents the procedure of pressure drop test, vibration test and endurance test for the non-instrumented rig using the irradiation test in HANARO of advanced PWR annular fuel which were designed and fabricated by KAERI. From the out-pile thermal hydraulic tests, confirm the flow rate at the 200 kPa pressure drop and measure the RMS displacement at this time. And the endurance test is confirmed the wear and the integrity of the non-instrumented rig at the 110% design flow rate. This out-pile test perform the Flow-Induced Vibration and Pressure Drop Experimental Tester(FIVPET) facility. The instruments in FIVPET facility was calibrated in KAERI and the pump and the thermocouple were certified by manufacturer.

Validation of a low field Rheo-NMR instrument and application to shear-induced migration of suspended non-colloidal particles in Couette flow

Science.gov (United States)

Colbourne, A. A.; Blythe, T. W.; Barua, R.; Lovett, S.; Mitchell, J.; Sederman, A. J.; Gladden, L. F.

2018-01-01

Nuclear magnetic resonance rheology (Rheo-NMR) is a valuable tool for studying the transport of suspended non-colloidal particles, important in many commercial processes. The Rheo-NMR imaging technique directly and quantitatively measures fluid displacement as a function of radial position. However, the high field magnets typically used in these experiments are unsuitable for the industrial environment and significantly hinder the measurement of shear stress. We introduce a low field Rheo-NMR instrument (1 H resonance frequency of 10.7MHz), which is portable and suitable as a process monitoring tool. This system is applied to the measurement of steady-state velocity profiles of a Newtonian carrier fluid suspending neutrally-buoyant non-colloidal particles at a range of concentrations. The large particle size (diameter > 200 μm) in the system studied requires a wide-gap Couette geometry and the local rheology was expected to be controlled by shear-induced particle migration. The low-field results are validated against high field Rheo-NMR measurements of consistent samples at matched shear rates. Additionally, it is demonstrated that existing models for particle migration fail to adequately describe the solid volume fractions measured in these systems, highlighting the need for improvement. The low field implementation of Rheo-NMR is complementary to shear stress rheology, such that the two techniques could be combined in a single instrument.

Clinical analysis of outpatients with ametropia in Hebeisheng Eye Hospital

Directory of Open Access Journals (Sweden)

Xiao Chen

2017-11-01

Full Text Available AIM: To perform a clinical analysis of 1 500 cases of outpatients with ametropia in Hebeisheng Eye Hospital, to provide a theoretical basis for diagnosis, treatment, and prevention of patients with ametropia.METHODS: Totally 1 500 cases(2 840 eyesof outpatient with ametropia were chosen as the research objects in Hebeisheng Eye Hospital from June 2013 to July 2014. All cases were treated with TOPCON RM-8800 computer optometry instrument for objective optometry, and used TOPCON phoropter for subjective optometry. The combination of the two instruments was taken to determine the diopter later. Diopter and axial distribution of the myopic astigmatism and hyperopic astigmatism were observed, age of astigmatic patient, distribution of astigmatism axis were observed as well. Meanwhile, a total of 150 cases were chosen randomly to measure their corneal curvature, anterior chamber depth, axial length and other static refractive index. All indexes were compared with those of the normal people subsequently, such as amplitude of accommodation, negative relative accommodation, positive relative accommodation, sensitivity of accommodation and other dynamic refractive index. RESULTS: Ametropia types of all patients were mainly simple myopia, simple myopia astigmatism, compound myopic astigmatism, simple hypermetropia, simple hyperopia astigmatism, compound hyperopic astigmatism and mixed astigmatism, the proportion were 38.99%, 3.27%, 23.94%, 4.68%, 1.34%, 13.52%, 15.25% respectively. There were 773 eyes with myopia astigmatism. The proportion of people with a myopia astigmatism diopter of above -0.25 to -0.50, -0.75 to -1.00, -1.25 to -1.50, above -1.75 were 31.05%, 38.55%, 16.56%, 13.84%. There were 421 eyes with hyperopia astigmatism, the proportion of people with hyperopia astigmatism diopter of 0.25-0.50, 0.75-1.00, 1.25- 1.50, >1.75 were 26.60%, 24.94%, 16.63%, 31.83%. Static refractive index of 150 patients(300 eyesshowed that corneal curvature was(41

Instrumentation

Energy Technology Data Exchange (ETDEWEB)

Decreton, M

2000-07-01

SCK-CEN's research and development programme on instrumentation aims at evaluating the potentials of new instrumentation technologies under the severe constraints of a nuclear application. It focuses on the tolerance of sensors to high radiation doses, including optical fibre sensors, and on the related intelligent data processing needed to cope with the nuclear constraints. Main achievements in these domains in 1999 are summarised.

VIRUS instrument enclosures

Science.gov (United States)

Prochaska, T.; Allen, R.; Mondrik, N.; Rheault, J. P.; Sauseda, M.; Boster, E.; James, M.; Rodriguez-Patino, M.; Torres, G.; Ham, J.; Cook, E.; Baker, D.; DePoy, Darren L.; Marshall, Jennifer L.; Hill, G. J.; Perry, D.; Savage, R. D.; Good, J. M.; Vattiat, Brian L.

2014-08-01

The Visible Integral-Field Replicable Unit Spectrograph (VIRUS) instrument will be installed at the Hobby-Eberly Telescope† in the near future. The instrument will be housed in two enclosures that are mounted adjacent to the telescope, via the VIRUS Support Structure (VSS). We have designed the enclosures to support and protect the instrument, to enable servicing of the instrument, and to cool the instrument appropriately while not adversely affecting the dome environment. The system uses simple HVAC air handling techniques in conjunction with thermoelectric and standard glycol heat exchangers to provide efficient heat removal. The enclosures also provide power and data transfer to and from each VIRUS unit, liquid nitrogen cooling to the detectors, and environmental monitoring of the instrument and dome environments. In this paper, we describe the design and fabrication of the VIRUS enclosures and their subsystems.

Health physics instrument manual

International Nuclear Information System (INIS)

Gupton, E.D.

1978-08-01

The purpose of this manual is to provide apprentice health physics surveyors and other operating groups not directly concerned with radiation detection instruments a working knowledge of the radiation detection and measuring instruments in use at the Laboratory. The characteristics and applications of the instruments are given. Portable instruments, stationary instruments, personnel monitoring instruments, sample counters, and miscellaneous instruments are described. Also, information sheets on calibration sources, procedures, and devices are included. Gamma sources, beta sources, alpha sources, neutron sources, special sources, a gamma calibration device for badge dosimeters, and a calibration device for ionization chambers are described

Optic disc and peripapillary retinal nerve fiber layer characteristics associated with glaucomatous optic disc in young myopia.

Science.gov (United States)

Lee, Jong Eun; Sung, Kyung Rim; Park, Ji Min; Yoon, Joo Young; Kang, Sung Yong; Park, Sung Bae; Koo, Hyung Jin

2017-03-01

To explore optic disc and peripapillary retinal nerve fiber layer (RNFL) features associated with glaucomatous optic disc (GOD) in young myopia. Presence of GOD, optic disc tilt, and disc torsion were determined using fundus photographs. If the measured disc tilt ratio was >1.3, the optic disc was classified as tilted. Optic disc torsion was defined as a >15° deviation in the long axis of the optic disc from the vertical meridian. The average and four quadrants RNFL thicknesses were assessed using spectral domain optical coherence tomography (SD-OCT). Logistic regression analyses were performed to identify factors associated with the presence of GOD. Nine hundred and sixty myopic subjects were recruited from four refractive surgery clinic databases. The mean age was 26.6 ± 5.7 years and spherical equivalent (SE) was -5.5 ± 2.5 diopters. Among 960 eyes, 26 (2.7%) received GOD group classification. Among 934 normal eyes, 290 (31.0%) had titled optic discs. Eighteen eyes (69.2%) in the GOD group had tilted optic discs. When compared to normal eyes, the GOD group had significantly higher tilt ratios (1.4 ± 0.2 vs. 1.2 ± 0.1, p Optic disc tilt was found in approximately one-third of young myopic eyes and was independently associated with the presence of GOD.

Efficacy of punctal occlusion in management of dry eyes after laser in situ keratomileusis for myopia.

Science.gov (United States)

Alfawaz, Abdullah M; Algehedan, Saeed; Jastaneiah, Sabah S; Al-Mansouri, Samir; Mousa, Ahmed; Al-Assiri, Abdullah

2014-03-01

To evaluate the effect of punctal plug use in preventing dry eye after laser in situ keratomileusis (LASIK). A randomized clinical trial at a tertiary eye care center, Riyadh, Saudi Arabia. Participants underwent LASIK for myopia in both eyes and a lower punctal occlusion in one eye only while the other eye served as control. Both eyes received the same postoperative medications except for lubricant duration (subject eye: four times per day for one week; control eye: four times per day for 6 months). Participants were evaluated at 1 week, 2, and 6 months after surgery for signs and symptoms of dry eye. The main outcome measures were visual acuity; ocular surface parameters; and Ocular Surface Disease Index questionnaire. Seventy-eight eyes of 39 patients were included in this study. The Ocular Surface Disease Index scores of eyes with punctal plugs were better at all follow-up visits, and the differences between both eyes were statistically significant (1 week, p eyes was higher in eyes with punctal plugs for all ocular surface parameters (Schirmer 1 test, 94.9%; tear breakup time, 77.8%; punctate epithelial keratitis score, 71.8%) compared to eyes without occlusion (Schirmer 1 test, 92.3%; tear breakup time, 58.3%; punctate epithelial keratitis score, 53.8%); however, such differences were not statistically significant. Punctal plug insertion after LASIK surgeries may minimize the need for frequent lubricant application and hence improve patient satisfaction.

Comparison of instrumental neutron activation analysis and instrumental charged-particle activation analysis for determining of Zn-68 abundance

International Nuclear Information System (INIS)

Rafii, H.; Mirzaei, M.; Aslani, G.R.; Kamali-Dehghan, M.; Rajamand, A-A.; Rahiminejad, A.; Mirzajani, N.; Sardari, D.; Shahabi, I.; Majidi, F.

2004-01-01

Gallium-67 has found important applications in nuclear medicine since last decades. The bombardment of enriched zinc-68 by proton beams in cyclotron is the most suitable method for the carrier-free production of this radionuclide. Any traces and isotopic impurities of the target cause serious radiological hazards because of their associated induced radioactivities. Trace analysis and Zn-68 content determination of the target material before any bombardment and chemical separation provide a valuable assessment of desired product. The elemental abundance evaluation of enriched isotopes is generally carried out by inductively coupled plasma-mass spectrometry method, ICP-Ms Instrumental neutron activation analysis and instrumental charged particle activation analysis. International neutron activation analysis and instrumental charged- particle activation analysis, looks be an alternative nuclear method for determining the abundance evaluation of enriched Zn-68 enrichment in two different samples has been studied by mean of international neutron activation analysis and instrumental charged- particle activation analysis . One sample was purchased from a French company, cortecnet, and the other was separated by an electromagnetic system in the Ions source department of our center, NRCAM. The neutron or proton irradiation was took place respectively in miniature neutron source reactor of Esfahan by flux of (1 to 5) 10 11 n/cm 2 .sec for 30 min and in Cyclon30 by 19 MeV proton beams of 100μA current for 12 min. The produced radioactivity was measured by HpGe detector for determination of trace impurities and evaluation of Zn-68 content in the samples. The result shows a good agreement with the reported ones by their producers and their low derivation of about ± indicates that the international neutron activation analysis and instrumental charged- particle activation analysis are relatively precise and rapid and each one can be used as a supplemental method for analyzing

Nuclear reactor instrumentation

International Nuclear Information System (INIS)

Duncombe, E.; McGonigal, G.

1975-01-01

A liquid metal cooled nuclear reactor is described which has an equal number of fuel sub-assemblies and sensing instruments. Each instrument senses temperature and rate of coolant flow of a coolant derived from a group of three sub-assemblies so that an abnormal value for one sub-assembly will be indicated on three instruments thereby providing for redundancy of up to two of the three instruments. The abnormal value may be a precurser to unstable boiling of coolant

In vivo confocal laser microscopy of morphologic changes after small incision lenticule extraction with accelerated cross-linking (SMILE Xtra) in patients with thin corneas and high myopia.

Science.gov (United States)

Zhou, Yugui; Liu, Manli; Zhang, Ting; Zheng, Hua; Sun, Yuan; Yang, Xiaonan; Weng, Shengbei; Lin, Haiqin; Liu, Quan

2018-01-01

To evaluate the microstructural modifications and safety of small incision lenticule extraction combined with accelerated cross-linking (SMILE Xtra) in high myopia and thin corneas by means of in vivo confocal microscopy (IVCM) and 3D-OCT after a 6-month follow-up. Forty-three eyes with high myopia and thin corneas were enrolled. All eyes underwent SMILE procedure. After the lenticule was extracted, 0.25% riboflavin was injected into the interface and allowed to diffuse for 60 s. The eye was irradiated with UVA radiation of 30 mW/cm 2 for 90 s through the cap. The total energy delivered was 2.7 J/cm 2 . Morphologic modifications of corneal architecture were evaluated prior to SMILE Xtra and 7 days, 1, 3, and 6 months after SMILE by in vivo confocal microscopy (IVCM) and 3D-OCT. The corneal epithelial cells showed slight damage until 3 months postoperatively. The subepithelial nerve plexus decreased but no absence within the treatment zone at the first week after treatment, recolonized at 3 months postoperatively, and had mostly recovered at the 6 months postoperative but remained less than its normal baseline state. Keratocytes were absent in the surgical interface area, and the presence of strong reflective particles and cicatricial reaction in the anterior stroma were observed during the entire 6-month examination period. Increased hyperreflectivity was observed from the cap side at a depth of 60 µm to stroma bed at a depth of 388 µm through 6 months. The depth of the demarcation line in 40 eyes (93.0%) was at a mean depth of 296.12 ± 47.86 μm (range, 211-388 μm). No particular change between preoperative and postoperative corneal endothelium was observed. Confocal microscopy showed increased hyperreflectivity in the SMILE Xtra eyes, and no changes in corneal endothelium. We confirmed the safety of the SMILE Xtra but recognize that larger and longer-term studies of SMILE Xtra are necessary.

Instrument validation project

International Nuclear Information System (INIS)

Reynolds, B.A.; Daymo, E.A.; Geeting, J.G.H.; Zhang, J.

1996-06-01

Westinghouse Hanford Company Project W-211 is responsible for providing the system capabilities to remove radioactive waste from ten double-shell tanks used to store radioactive wastes on the Hanford Site in Richland, Washington. The project is also responsible for measuring tank waste slurry properties prior to injection into pipeline systems, including the Replacement of Cross-Site Transfer System. This report summarizes studies of the appropriateness of the instrumentation specified for use in Project W-211. The instruments were evaluated in a test loop with simulated slurries that covered the range of properties specified in the functional design criteria. The results of the study indicate that the compact nature of the baseline Project W-211 loop does not result in reduced instrumental accuracy resulting from poor flow profile development. Of the baseline instrumentation, the Micromotion densimeter, the Moore Industries thermocouple, the Fischer and Porter magnetic flow meter, and the Red Valve Pressure transducer meet the desired instrumental accuracy. An alternate magnetic flow meter (Yokagawa) gave nearly identical results as the baseline fischer and Porter. The Micromotion flow meter did not meet the desired instrument accuracy but could potentially be calibrated so that it would meet the criteria. The Nametre on-line viscometer did not meet the desired instrumental accuracy and is not recommended as a quantitative instrument although it does provide qualitative information. The recommended minimum set of instrumentation necessary to ensure the slurry meets the Project W-058 acceptance criteria is the Micromotion mass flow meter and delta pressure cells

Astronomical Instruments in India

Science.gov (United States)

Sarma, Sreeramula Rajeswara

The earliest astronomical instruments used in India were the gnomon and the water clock. In the early seventh century, Brahmagupta described ten types of instruments, which were adopted by all subsequent writers with minor modifications. Contact with Islamic astronomy in the second millennium AD led to a radical change. Sanskrit texts began to lay emphasis on the importance of observational instruments. Exclusive texts on instruments were composed. Islamic instruments like the astrolabe were adopted and some new types of instruments were developed. Production and use of these traditional instruments continued, along with the cultivation of traditional astronomy, up to the end of the nineteenth century.

Detecting charging state of ultra-fine particles: instrumental development and ambient measurements

Directory of Open Access Journals (Sweden)

L. Laakso

2007-01-01

Full Text Available The importance of ion-induced nucleation in the lower atmosphere has been discussed for a long time. In this article we describe a new instrumental setup – Ion-DMPS – which can be used to detect contribution of ion-induced nucleation on atmospheric new particle formation events. The device measures positively and negatively charged particles with and without a bipolar charger. The ratio between "charger off" to "charger on" describes the charging state of aerosol particle population with respect to equilibrium. Values above one represent more charges than in an equilibrium (overcharged state, and values below unity stand for undercharged situation, when there is less charges in the particles than in the equilibrium. We performed several laboratory experiments to test the operation of the instrument. After the laboratory tests, we used the device to observe particle size distributions during atmospheric new particle formation in a boreal forest. We found that some of the events were clearly dominated by neutral nucleation but in some cases also ion-induced nucleation contributed to the new particle formation. We also found that negative and positive ions (charged particles behaved in a different manner, days with negative overcharging were more frequent than days with positive overcharging.

Well logging instrumental and methodological research

International Nuclear Information System (INIS)

Andrassy, L.; Barath, I.; Dorko, R.

1983-01-01

This part of the Annual Report of the Roland Eoetvoes Geophysical Institute (ELGI) of Hungary for 1982, summarizes the well logging instrumental and methodological researches of ELGI. The theoretical neutron diffusion fluxes for black and brown coals of Hungarian mines were calculated. A coal probe was developed and tested in boreholes using computerized data processing and interpretation. An X-ray radiometric method was used for the determination of Cu and Fe contents of minerals. Researches in the field of magnetic susceptibility and induced polarization logging are also summarized. A rapid analyzer for bauxite mining and a photorecorder for petroleum industry were developed by ELGI. (D.Gy.)

Instrumentation a reader

CERN Document Server

Pope, P

1990-01-01

This book contains a selection of papers and articles in instrumentation previously pub­ lished in technical periodicals and journals of learned societies. Our selection has been made to illustrate aspects of current practice and applications of instrumentation. The book does not attempt to be encyclopaedic in its coverage of the subject, but to provide some examples of general transduction techniques, of the sensing of particular measurands, of components of instrumentation systems and of instrumentation practice in two very different environments, the food industry and the nuclear power industry. We have made the selection particularly to provide papers appropriate to the study of the Open University course T292 Instrumentation. The papers have been chosen so that the book covers a wide spectrum of instrumentation techniques. Because of this, the book should be of value not only to students of instrumen­ tation, but also to practising engineers and scientists wishing to glean ideas from areas of instrumen...

Zyoptix wavefront-guided versus standard photorefractive keratectomy (PRK) in low and moderate myopia: randomized controlled 6-month study.

Science.gov (United States)

Mastropasqua, L; Toto, L; Zuppardi, E; Nubile, M; Carpineto, P; Di Nicola, M; Ballone, E

2006-01-01

efficacious for the correction of myopia and myopic astigmatism as PlanoScan PRK. Moreover this technique induces a smaller increase of third order coma aberration compared to standard PRK. The use of Zyoptix wavefront-guided PRK is particularly indicated in eyes with higher preoperative RMS values.

Comparison of dentinal damage induced by different nickel-titanium rotary instruments during canal preparation: An in vitro study.

Science.gov (United States)

Garg, Shiwani; Mahajan, Pardeep; Thaman, Deepa; Monga, Prashant

2015-01-01

To compare dentinal damage caused by hand and rotary nickel-titanium instruments using ProTaper, K3 Endo, and Easy RaCe systems after root canal preparation. One hundred and fifty freshly extracted mandibular premolars were randomly divided into five experimental groups of 30 teeth each and biomechanical preparation was done: Group 1 with unprepared teeth; Group 2 were prepared with hand files; Group 3 with ProTaper rotary instruments; Group 4 with K3 rotary; Group 5 with Easy RaCe rotary instruments. Then, roots were cut horizontally at 3, 6, and 9 mm from apex and were viewed under stereomicroscope. The presence of dentinal defects was noted. Groups were analyzed with the Chi-square test. Significant difference was seen between groups. No defects were found in unprepared roots and those prepared with hand files. ProTaper, K3 rotary, and Easy RaCe preparations resulted in dentinal defects in 23.3%, 10%, and 16.7% of teeth, respectively. More defects were shown in coronal and middle sections, and no defect was seen in apical third. The present study revealed that use of rotary instruments could result in an increased chance for dentinal defects as compared to hand instrumentation.

Radiation induced charge transfer inefficiencies in the Sentinel 4 instrument: modeling, performance, and correction

Science.gov (United States)

Irizar, J.; Gulde, S.; Skegg, M.; Levillain, Y.; Weber, H.

2017-09-01

Sentinel 4 is an imaging UVN (UV-VIS-NIR) dispersive spectrometer, developed by Airbus DS under an ESA contract in the frame of the joint EU/ESA COPERNICUS program. The instrument is introduced in a dedicated presentation in this conference.

Efectividad de los lentes fáquicos Artisan en la corrección de la alta miopía Effectiveness of Artisan phakic lenses in the correction of high myopia

Directory of Open Access Journals (Sweden)

Yanele Ruiz Rodríguez

2010-12-01

Full Text Available OBJETIVO: Determinar la efectividad de los lentes intraoculares fáquicos Artisan en la corrección de la alta miopía en el Instituto Cubano de Oftalmología "Ramón Pando Ferrer" en el período de enero del 2006 a enero del 2009. MÉTODOS: Se realizó un estudio prospectivo, descriptivo. El universo estuvo constituido por el total de ojos (120 a los cuales se les implantó estos lentes. RESULTADOS: Se encontró un componente esférico de 0,5, no astigmatismo inducido y una mejoría de la agudeza visual corregida de 0,9. No se presentaron complicaciones transoperatorias y entre las posoperatorias mediatas predominó la iritis o uveítis (3,4 % así como la atrofia iridiana (5 % entre las tardías. CONCLUSIONES: Los resultados refractivos fueron favorables. Predominaron los pacientes sin complicaciones.OBJECTIVE: To determine the effectiveness of Artisan phakic intraocular lenses in correcting high myopia at "Ramón Pando Ferrer" Cuban Institute of Ophthalmology in January 2006 to January 2009 period. METHODS: A prospective descriptive study was made in which the universe of study was 120 eyes implanted with this type of lenses. RESULTS: Spheral component of 0.5; the induced astigmatism was not found and the corrected visual acuity improvement was 0.9. There were no transoperative complications; the predominant postoperative mediate complications were iritis or uveitis (3.4 % and iridic atrophy (5 % prevailed in the late ones. CONCLUSIONS: The refractive results were favourable. The uncomplicated patients predominated.

A new LIF instrument for aircraft related and ground related masurements of OH and HO{sub 2} radicals in the troposphere; Ein neues LIF-Instrument fuer flugzeug- und bodengebundene Messungen von OH- und HO{sub 2}-Radikalen in der Troposphaere

Energy Technology Data Exchange (ETDEWEB)

Broch, Sebastian

2011-07-01

The author of the contribution under consideration describes the development and characterization of an instrument for the measurement of OH and HO{sub 2} radicals by means of laser-induced fluorescence (LIF). This instrument can be used from the lower troposphere to the lower stratosphere both on the ground and in aircraft applications. After describing the basics of the OH radical chemistry and the measurement principle of laser-induced fluorescence, a new instrument is presented. The LIF measuring cells needs long inlet pipes which lead to a modification of the verification of OH radicals. The effect of these modifications as well as the height dependence of the detection sensitivity for the OH radicals is examined. A model for the theoretical description of the altitude dependence of the detection sensitivity is described. The modification of the measuring cell influences the ozone-water interference in the LIF measurement system. Therefore, the author develops a model to describe the interference in the new system and evaluate this model by measurements. The applicability of this new instrument for ground and flight applications is analyzed in the range from 0 to 18 kilometers regarding sensitivity, detection limit and interference.

IOT Overview: IR Instruments

Science.gov (United States)

Mason, E.

In this instrument review chapter the calibration plans of ESO IR instruments are presented and briefly reviewed focusing, in particular, on the case of ISAAC, which has been the first IR instrument at VLT and whose calibration plan served as prototype for the coming instruments.

Troubleshooting in nuclear instruments

International Nuclear Information System (INIS)

1987-06-01

This report on troubleshooting of nuclear instruments is the product of several scientists and engineers, who are closely associated with nuclear instrumentation and with the IAEA activities in the field. The text covers the following topics: Preamplifiers, amplifiers, scalers, timers, ratemeters, multichannel analyzers, dedicated instruments, tools, instruments, accessories, components, skills, interfaces, power supplies, preventive maintenance, troubleshooting in systems, radiation detectors. The troubleshooting and repair of instruments is illustrated by some real examples

Visual disability, visual function, and myopia among rural chinese secondary school children: the Xichang Pediatric Refractive Error Study (X-PRES)--report 1.

Science.gov (United States)

Congdon, Nathan; Wang, Yunfei; Song, Yue; Choi, Kai; Zhang, Mingzhi; Zhou, Zhongxia; Xie, Zhenling; Li, Liping; Liu, Xueyu; Sharma, Abhishek; Wu, Bin; Lam, Dennis S C

2008-07-01

To evaluate visual acuity, visual function, and prevalence of refractive error among Chinese secondary-school children in a cross-sectional school-based study. Uncorrected, presenting, and best corrected visual acuity, cycloplegic autorefraction with refinement, and self-reported visual function were assessed in a random, cluster sample of rural secondary school students in Xichang, China. Among the 1892 subjects (97.3% of the consenting children, 84.7% of the total sample), mean age was 14.7 +/- 0.8 years, 51.2% were female, and 26.4% were wearing glasses. The proportion of children with uncorrected, presenting, and corrected visual disability (visual disability when tested without correction, 98.7% was due to refractive error, while only 53.8% (414/770) of these children had appropriate correction. The girls had significantly (P visual disability and myopia visual function (ANOVA trend test, P Visual disability in this population was common, highly correctable, and frequently uncorrected. The impact of refractive error on self-reported visual function was significant. Strategies and studies to understand and remove barriers to spectacle wear are needed.

Instrumentation

International Nuclear Information System (INIS)

Muehllehner, G.; Colsher, J.G.

1982-01-01

This chapter reviews the parameters which are important to positron-imaging instruments. It summarizes the options which various groups have explored in designing tomographs and the methods which have been developed to overcome some of the limitations inherent in the technique as well as in present instruments. The chapter is not presented as a defense of positron imaging versus single-photon or other imaging modality, neither does it contain a description of various existing instruments, but rather stresses their common properties and problems. Design parameters which are considered are resolution, sampling requirements, sensitivity, methods of eliminating scattered radiation, random coincidences and attenuation. The implementation of these parameters is considered, with special reference to sampling, choice of detector material, detector ring diameter and shielding and variations in point spread function. Quantitation problems discussed are normalization, and attenuation and random corrections. Present developments mentioned are noise reduction through time-of-flight-assisted tomography and signal to noise improvements through high intrinsic resolution. Extensive bibliography. (U.K.)

Decreased retinal capillary flow is not a mediator of the protective myopia-diabetic retinopathy relationship.

Science.gov (United States)

Man, Ryan Eyn Kidd; Sasongko, Muhammad Bayu; Xie, Jing; Best, William J; Noonan, Jonathan E; Lo, Tiffany Ching Shen; Wang, Jie Jin; Luu, Chi D; Lamoureux, Ecosse L

2014-09-30

The mechanisms supporting the protective relationship between a longer axial length (AL) and a decreased risk of diabetic retinopathy (DR) remain unclear. Previous studies have demonstrated reduced retinal blood flow in axial myopia, and it has been suggested that the compromised retinal capillaries in diabetes are less likely to leak and rupture as a result of this decreased flow. In this study, we therefore investigated if reduced retinal capillary flow (RCF) is a potential mechanism underpinning this protective relationship. Retinal capillary flow was assessed using the Heidelberg Retinal Flowmeter in 150 eyes of 85 patients with diabetes aged 18+ years from the Royal Victorian Eye and Ear Hospital and St. Vincent's Hospital (Melbourne), Australia. Axial length was measured using the Intraocular Lens Master. Diabetic retinopathy was graded from two-field retinal photographs into none, mild, moderate, and severe DR using the modified Airlie House classification system. A total of 74 out of 150 eyes (49.3%) had DR. A longer AL was associated with decreased odds of DR presence (per mm increase in AL, odds ratio [OR] 0.61, 95% confidence interval [CI] 0.41-0.91) and DR severity (OR: 0.65; 95% CI: 0.44-0.95). However, no association was found between AL and RCF (per mm increase in AL, regression coefficient [β] -1.80, 95% CI -13.50 to 9.50) or between RCF and DR (per unit increase in RCF, OR 1.00; 95% CI 0.99-1.00). Our finding suggests that diminished RCF may not be a major factor underlying the protective association between axial elongation and DR. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Problems with radiological surveillance instrumentation

International Nuclear Information System (INIS)

Swinth, K.L.; Tanner, J.E.; Fleming, D.M.

1984-09-01

Many radiological surveillance instruments are in use at DOE facilities throughout the country. These instruments are an essential part of all health physics programs, and poor instrument performance can increase program costs or compromise program effectiveness. Generic data from simple tests on newly purchased instruments shows that many instruments will not meet requirements due to manufacturing defects. In other cases, lack of consideration of instrument use has resulted in poor acceptance of instruments and poor reliability. The performance of instruments is highly variable for electronic and mechanical performance, radiation response, susceptibility to interferences and response to environmental factors. Poor instrument performance in these areas can lead to errors or poor accuracy in measurements

Problems with radiological surveillance instrumentation

International Nuclear Information System (INIS)

Swinth, K.L.; Tanner, J.E.; Fleming, D.M.

1985-01-01

Many radiological surveillance instruments are in use at DOE facilities throughout the country. These instruments are an essential part of all health physics programs, and poor instrument performance can increase program costs or compromise program effectiveness. Generic data from simple tests on newly purchased instruments shows that many instruments will not meet requirements due to manufacturing defects. In other cases, lack of consideration of instrument use has resulted in poor acceptance of instruments and poor reliability. The performance of instruments is highly variable for electronic and mechanical performance, radiation response, susceptibility to interferences and response to environmental factors. Poor instrument performance in these areas can lead to errors or poor accuracy in measurements

Choroidal thickness and biometric markers for the screening of lacquer cracks in patients with high myopia.

Directory of Open Access Journals (Sweden)

Nan-Kai Wang

Full Text Available OBJECTIVES: Validation of choroidal thickness and other biometrics measured by spectral domain optical coherence tomography (SD-OCT in predicting lacquer cracks formation in highly myopic eyes. METHODS: Patients with a refractive error worse than -8 diopters and moderate myopic maculopathy were recruited into two groups based on the presence or absence of lacquer cracks (36 eyes without and 33 eyes with lacquer cracks. Choroidal thickness, refractive error, and axial length were measured and subjected to receiver operating characteristic curve analysis to identify the optimal cutoff values at predicting lacquer crack formation. The width of the retinal pigment epithelium (RPE, RPE to the inner segment/outer segment line, RPE to the external limiting membrane were also measured and compared to the subfoveal choroidal thickness to assess their relationships as potential markers of lacquer crack formation. RESULTS: Lacquer crack is associated with decreased choroidal thickness, lower best-corrected visual acuity, longer axial length and higher refractive errors. Choroidal thickness has the strongest association with lacquer crack formation versus axial length and refractive error. In eyes with lacquer cracks, stellate lacquer cracks are associated with thinner choroidal thickness compared to eyes with linear lacquer cracks. Subfoveal choroidal thickness less than the width of the retinal pigment epithelium to the inner segment/outer segment line is also associated with lacquer crack formation (sensitivity 78.8%, specificity 88.3%, and accuracy 81.2%. CONCLUSIONS: This study suggests that choroidal thickness and other SD-OCT measurements could be employed clinically to predict the development and severity of lacquer cracks in patients with high myopia.

Comparison of corneal sensation between small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK for myopia.

Science.gov (United States)

Li, Meiyan; Zhou, Zimei; Shen, Yang; Knorz, Michael C; Gong, Lan; Zhou, Xingtao

2014-02-01

To compare the impact on corneal sensation after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (femto-LASIK) in patients with myopia. In this prospective, nonrandomized comparative study, 71 subjects were enrolled. Thirty-eight eyes of 38 patients underwent SMILE and 33 eyes of 33 patients underwent femto-LASIK. Corneal sensation was tested with Cochet-Bonnet esthesiometry in five corneal areas preoperatively and at 1 week and 1, 3, and 6 months postoperatively. Comparison of corneal sensation was performed for the SMILE and femto-LASIK groups. Additionally, the correlations were evaluated between the postoperative corneal sensation, preoperative spherical equivalent, and ablation depth. All tested areas within the cap or flap demonstrated corneal hypoesthesia immediately after both surgeries. SMILE-treated eyes showed less compromised corneal sensation than femto-LASIK-treated eyes at all postoperative visits in the central, inferior, nasal, and temporal areas at the 1-week and 1-month visits. In the SMILE group, the inferior, nasal, and temporal quadrants recovered faster than other areas. In the femto-LASIK group, the sensation over the flap did not recover to preoperative levels by postoperative 6 months. There was no correlation between postoperative corneal sensation, preoperative spherical equivalent, and ablation depth in both groups. The impairment of corneal sensation was less significant in the SMILE group than in the femto-LASIK group and was independent of preoperative spherical equivalent or ablation depth. Copyright 2014, SLACK Incorporated.

Econometrics in outcomes research: the use of instrumental variables.

Science.gov (United States)

Newhouse, J P; McClellan, M

1998-01-01

We describe an econometric technique, instrumental variables, that can be useful in estimating the effectiveness of clinical treatments in situations when a controlled trial has not or cannot be done. This technique relies upon the existence of one or more variables that induce substantial variation in the treatment variable but have no direct effect on the outcome variable of interest. We illustrate the use of the technique with an application to aggressive treatment of acute myocardial infarction in the elderly.

Innovative market-based policy instruments for waste management: A case study on shredder residues in Belgium.

Science.gov (United States)

Dubois, Maarten; Hoogmartens, Rob; Van Passel, Steven; Van Acker, Karel; Vanderreydt, Ive

2015-10-01

In an increasingly complex waste market, market-based policy instruments, such as disposal taxes, can give incentives for sustainable progress while leaving flexibility for innovation. However, implementation of disposal taxes is often criticised by domestic waste handlers that fear to be outcompeted by competitors in other countries. The article discusses three innovative market-based instruments that limit the impact on international competitiveness: Tradable recycling credits, refunded disposal taxes and differentiated disposal taxes. All three instruments have already been implemented for distinct environmental policies in Europe. In order to illustrate how these instruments can be used for waste policy, the literature review is complemented with a case study on shredder residues from metal-containing waste streams in Belgium. The analysis shows that a conventional disposal tax remains the most efficient, simple and transparent instrument. However, if international competition is a significant issue or if political support is weak, refunded and differentiated disposal taxes can have an added value as second-best instruments. Tradable recycling credits are not an appropriate instrument for use in small waste markets with market power. In addition, refunded taxes create similar incentives, but induce lower transactions costs. © The Author(s) 2015.

A CNES remote operations center for the MSL ChemCam instrument

Energy Technology Data Exchange (ETDEWEB)

Wiens, Roger C [Los Alamos National Laboratory; Lafaille, Vivian [CNES; Lorgny, Eric [CNES; Baroukh, Julien [CNES; Gaboriaud, Alain [CNES; Saccoccio, Muriel [CNES; Perez, Rene [CNES; Gasnault, Olivier [CNRS/CESR; Maurice, Sylvestre [CNRS/CESR; Blaney, Diana [JPL

2010-01-01

For the first time, a CNES remote operations center in Toulouse will be involved in the tactical operations of a Martian rover in order to operate the ChemCam science instrument in the framework of the NASA MSL (Mars Science Laboratory) mission in 2012. CNES/CESR and LANL have developed and delivered to JPL the ChemCam (Chemistry Camera) instrument located on the top of mast and in the body of the rover. This instrument incorporates a Laser-Induced Breakdown Spectrometer (LIBS) and a Remote Micro-Imager (RMI) for determining elemental compositions of rock targets or soil samples at remote distances from the rover (2-7 m). An agreement has been achieved for operating ChemCam, alternatively, from Toulouse (FR) and Los Alamos (NM, USA), through the JPL ground data system in Pasadena (CA, USA) for a complete Martian year (2 years on Earth). After a brief overview of the MSL mission, this paper presents the instrument, the mission operational system and JPL organization requirements for the scientific investigators (PI and Co-Is). This paper emphasizes innovations applied on the ground segment components and on the operational approach to satisfy the requirements and constraints due to these shared and distributed operations over the world.

Status of safeguards instrumentation

International Nuclear Information System (INIS)

Higinbotham, W.A.

The International Atomic Energy Agency is performing safeguards at some nuclear power reactors, 50 bulk processing facilities, and 170 research facilities. Its verification activities require the use of instruments to measure nuclear materials and of surveillance instruments to maintain continuity of knowledge of the locations of nuclear materials. Instruments that are in use and under development to measure weight, volume, concentration, and isotopic composition of nuclear materials, and the major surveillance instruments, are described in connection with their uses at representative nuclear facilities. The current status of safeguards instrumentation and the needs for future development are discussed

Early modern mathematical instruments.

Science.gov (United States)

Bennett, Jim

2011-12-01

In considering the appropriate use of the terms "science" and "scientific instrument," tracing the history of "mathematical instruments" in the early modern period is offered as an illuminating alternative to the historian's natural instinct to follow the guiding lights of originality and innovation, even if the trail transgresses contemporary boundaries. The mathematical instrument was a well-defined category, shared across the academic, artisanal, and commercial aspects of instrumentation, and its narrative from the sixteenth to the eighteenth century was largely independent from other classes of device, in a period when a "scientific" instrument was unheard of.

Instrumental Capital

Directory of Open Access Journals (Sweden)

Gabriel Valerio

2007-07-01

Full Text Available During the history of human kind, since our first ancestors, tools have represented a mean to reach objectives which might otherwise seemed impossibles. In the called New Economy, where tangibles assets appear to be losing the role as the core element to produce value versus knowledge, tools have kept aside man in his dairy work. In this article, the author's objective is to describe, in a simple manner, the importance of managing the organization's group of tools or instruments (Instrumental Capital. The characteristic conditions of this New Economy, the way Knowledge Management deals with these new conditions and the sub-processes that provide support to the management of Instrumental Capital are described.

Evaluating musical instruments

International Nuclear Information System (INIS)

Campbell, D. Murray

2014-01-01

Scientific measurements of sound generation and radiation by musical instruments are surprisingly hard to correlate with the subtle and complex judgments of instrumental quality made by expert musicians

Three common faults in current practice that influence the validity of data obtained from electronic air pollution instrumentation.

Science.gov (United States)

Dowd, G; Thomas, R S; Monkman, J L

1975-01-01

Instrumental development is now entering a more logical era, where the former artistic character of electronics is being replaced by cold technology. Because of this, one should be expect more reliability; however, there still exist many weak links in practical application. Digital readout systems and computer processing induce a false sense of security. In reality, it is the sample-measurement relationship that determines an instrument's credibility and not the number of digits on its meter. In describing three faulty practices that greatly influence an instrument's performance, it is hoped that measurement may be more closely related to the sample!

Three common faults in current practice that influence the validity of data obtained from electronic air pollution instrumentation

Energy Technology Data Exchange (ETDEWEB)

Dowd, G; Thomas, R S; Monkman, J L

1975-01-01

Instrumental development is now entering a more logical era, where the former artistic character of electronics is being replaced by cold technology. Because of this, one should expect more reliability; however, there still exist many weak links in practical application. Digital readout systems and computer processing induce a false sense of security. In reality, it is the sample-measurement relationship that determines an instrument's credibility and not the number of digits on its meter. In describing three faulty practices that greatly influence an instrument's performance, it is hoped that measurement may be more closely related to the sample.

Hubungan Lama Aktivitas Membaca dengan Derajat Miopia pada Mahasiswa Pendidikan Dokter FK Unand Angkatan 2010

Directory of Open Access Journals (Sweden)

Mutia Maulud Fauziah

2014-09-01

Full Text Available AbstrakMiopia adalah salah satu kelainan refraksi pada mata dengan prevalensi yang tinggi di dunia. Berbagai faktor yang berhubungan dengan miopia seperti faktor keturunan dan lingkungan. Faktor lingkungan yang berperan kuat adalah kerja dekat seperti membaca. Lama membaca dapat meningkatkan risiko dan progresivitas miopia. Mahasiswa kedokteran berisiko mengalami miopia karena banyak melakukan aktivitas membaca yang lama dan intensif. Penelitian ini bertujuan untuk mengetahui hubungan lama aktivitas membaca dengan derajat miopia. Metode studi menggunakan desain cross sectional analitik dengan 121 sampel. Pengumpulan data dilakukan dengan kuesioner tentang riwayat miopia dan lama membaca. Data dianalisis dengan uji chi-square (x² dengan kemaknaan (p<0,05. Hasil penelitian didapatkan bahwa kejadian miopia lebih banyak terjadi pada mahasiswa perempuan (78.5%. Miopia pertama kali paling banyak terjadi pada usia 13 tahun (19%. Pertambahan ukuran refraksi per tahun pada mahasiswa miopia rata-rata adalah 0.30 D. Sebagian mahasiswa miopia menghabiskan waktu untuk membaca lebih dari 10.7 jam/hari (52.9%, sebagian lagi kurang dari 10.7 jam/hari (47.1%. Mahasiswa miopia sebagian besar menderita miopia ringan. Analisis statistik hubungan lama aktivitas membaca dengan derajat miopia didapatkan nilai p=0,15. Penelitian ini memperlihatkan bahwa tidak terdapat hubungan yang bermakna antara lama aktivitas membaca dengan derajat myopia.Kata kunci: lama membaca, derajat miopiaAbstractMyopia is a refractive error of the eye with a high prevalence in the world. Various factors association with myopia such as heredity and environmental factor. The strongest role an environmental is near work such as reading. Reading time can increase risk and progression of myopia. Medical students have the risk of myopia because of long and intensive reading. This study aimed to determine relationship the duration of reading activities with the degree of myopia. This study used a

Combined raman/laser-induced breakdown spectrometer: space and non-space applications

NARCIS (Netherlands)

Sandtke, M.; Laan, E.C.; Ahlers, B.

2010-01-01

TNO has developed the combination of two spectroscopic analysis methods in one instrument. Raman spectroscopy and Laser-induced Breakdown Spectroscopy (LIBS) were brought together for an instrument to be flown on the ExoMars mission from the European Space Agency (ESA) to investigate the Martian

Instrument Performance and Simulation Verification of the POLAR Detector

OpenAIRE

Kole, M.; Li, Z. H.; Produit, N.; Tymieniecka, T.; Zhang, J.; Zwolinska, A.; Bao, T. W.; Bernasconi, T.; Cadoux, F.; Feng, M. Z.; Gauvin, N.; Hajdas, W.; Kong, S. W.; Li, H. C.; Li, L.

2017-01-01

POLAR is a new satellite-born detector aiming to measure the polarization of an unprecedented number of Gamma-Ray Bursts in the 50-500 keV energy range. The instrument, launched on-board the Tiangong-2 Chinese Space lab on the 15th of September 2016, is designed to measure the polarization of the hard X-ray flux by measuring the distribution of the azimuthal scattering angles of the incoming photons. A detailed understanding of the polarimeter and specifically of the systematic effects induce...

Instrument Modeling and Synthesis

Science.gov (United States)

Horner, Andrew B.; Beauchamp, James W.

During the 1970s and 1980s, before synthesizers based on direct sampling of musical sounds became popular, replicating musical instruments using frequency modulation (FM) or wavetable synthesis was one of the “holy grails” of music synthesis. Synthesizers such as the Yamaha DX7 allowed users great flexibility in mixing and matching sounds, but were notoriously difficult to coerce into producing sounds like those of a given instrument. Instrument design wizards practiced the mysteries of FM instrument design.

Instrumentation for Nuclear Applications

International Nuclear Information System (INIS)

1998-01-01

The objective of this project was to develop and coordinate nuclear instrumentation standards with resulting economies for the nuclear and radiation fields. There was particular emphasis on coordination and management of the Nuclear Instrument Module (NIM) System, U.S. activity involving the CAMAC international standard dataway system, the FASTBUS modular high-speed data acquisition and control system and processing and management of national nuclear instrumentation and detector standards, as well as a modest amount of assistance and consultation services to the Pollutant Characterization and Safety Research Division of the Office of Health and Environmental Research. The principal accomplishments were the development and maintenance of the NIM instrumentation system that is the predominant instrumentation system in the nuclear and radiation fields worldwide, the CAMAC digital interface system in coordination with the ESONE Committee of European Laboratories, the FASTBUS high-speed system and numerous national and international nuclear instrumentation standards

On Representative Spaceflight Instrument and Associated Instrument Sensor Web Framework

Science.gov (United States)

Kizhner, Semion; Patel, Umeshkumar; Vootukuru, Meg

2007-01-01

Sensor Web-based adaptation and sharing of space flight mission resources, including those of the Space-Ground and Control-User communication segment, could greatly benefit from utilization of heritage Internet Protocols and devices applied for Spaceflight (SpaceIP). This had been successfully demonstrated by a few recent spaceflight experiments. However, while terrestrial applications of Internet protocols are well developed and understood (mostly due to billions of dollars in investments by the military and industry), the spaceflight application of Internet protocols is still in its infancy. Progress in the developments of SpaceIP-enabled instrument components will largely determine the SpaceIP utilization of those investments and acceptance in years to come. Likewise SpaceIP, the development of commercial real-time and instrument colocated computational resources, data compression and storage, can be enabled on-board a spacecraft and, in turn, support a powerful application to Sensor Web-based design of a spaceflight instrument. Sensor Web-enabled reconfiguration and adaptation of structures for hardware resources and information systems will commence application of Field Programmable Arrays (FPGA) and other aerospace programmable logic devices for what this technology was intended. These are a few obvious potential benefits of Sensor Web technologies for spaceflight applications. However, they are still waiting to be explored. This is because there is a need for a new approach to spaceflight instrumentation in order to make these mature sensor web technologies applicable for spaceflight. In this paper we present an approach in developing related and enabling spaceflight instrument-level technologies based on the new concept of a representative spaceflight Instrument Sensor Web (ISW).

Optimization of instrumental activation analysis conditions

International Nuclear Information System (INIS)

Guinn, V.; Gavrilas-Guinn, M.

1993-01-01

In instrumental neutron activation analysis (INAA) work, a good commonsense rule of thumb is that the opium conditions for the measurement of any induced activity, in a multi-element sample matrix, are an irradiation time, a decay time, and a counting time each approximately equal to the half-life of the radionuclide (if feasible). The INAA Advance Computer Program (APCP) was used to test this rule on ten reference materials. For the 280 radionuclide/material combinations traced through all 14 APCP condition sets, the rule predicted the best set for 67% of them, was off by one set for 31% of them, and was only off by two sets of 2% of them. (author) 6 refs.; 1 fig.; 3 tabs

Virtual instrumentation: a new approach for control and instrumentation - application in containment studies facility

International Nuclear Information System (INIS)

Gole, N.V.; Shanware, V.M.; Sebastian, A.; Subramaniam, K.

2001-01-01

PC based data-acquisition has emerged as a rapidly developing area particularly with respect to process instrumentation. Computer based data acquisition in process instrumentation combined with Supervisory Control and Data Acquisition (SCADA) software has introduced extensive possibilities with respect to formats for presentation of information. The concept of presenting data using any instrument format with the help of software tools to simulate the instrument on screen, needs to be understood, in order to be able to make use of its vast potential. The purpose of this paper is to present the significant features of the Virtual Instrumentation concept and discuss its application in the instrumentation and control system of containment studies facility (CSF). Factors involved in the development of the virtual instrumentation based I and C system for CSF are detailed and a functional overview of the system configuration is given. (author)

Instrumentation of dynamic gas pulse loading system

Energy Technology Data Exchange (ETDEWEB)

Mohaupt, H.

1992-04-14

The overall goal of this work is to further develop and field test a system of stimulating oil and gas wells, which increases the effective radius of the well bore so that more oil can flow into it, by recording pressure during the gas generation phase in real time so that fractures can be induced more predictably in the producing formation. Task 1: Complete the laboratory studies currently underway with the prototype model of the instrumentation currently being studied. Task 2: Perform field tests of the model in the Taft/Bakersfield area, utilizing operations closest to the engineers working on the project, and optimize the unit for various conditions encountered there. Task 3: Perform field test of the model in DGPL jobs which are scheduled in the mid-continent area, and optimize the unit for downhole conditions encountered there. Task 4: Analyze and summarize the results achieved during the complete test series, documenting the steps for usage of downhole instrumentation in the field, and compile data specifying use of the technology by others. Task 5: Prepare final report for DOE, and include also a report on the field tests completed. Describe and estimate the probability of the technology being commercialized and in what time span. The project has made substantial technical progress, though we are running about a month behind schedule. Expenditures are in line with the schedule. Increased widespread interest in the use of DGPL stimulation has kept us very busy. The computer modeling and test instrumentation developed under this program is already being applied to commercial operations.

LOFT instrumentation

International Nuclear Information System (INIS)

Bixby, W.W.

1979-01-01

A description of instrumentation used in the Loss-of-Fluid Test (LOFT) large break Loss-of-Coolant Experiments is presented. Emphasis is placed on hydraulic and thermal measurements in the primary system piping and components, reactor vessel, and pressure suppression system. In addition, instrumentation which is being considered for measurement of phenomena during future small break testing is discussed. (orig.) 891 HP/orig. 892 BRE [de

Instrumentation for environmental monitoring: biomedical

International Nuclear Information System (INIS)

1979-05-01

An update is presented to Volume four of the six-volume series devoted to a survey of instruments useful for measurements in biomedicine related to environmental research and monitoring. Results of the survey are given as descriptions of the physical and operating characteristics of available instruments, critical comparisons among instrumentation methods, and recommendations of promising methodology and development of new instrumentation. Methods of detection and analysis of gaseous organic pollutants and metals, including Ni and As are presented. Instrument techniques and notes are included on atomic spectrometry and uv and visible absorption instrumentation

Intercomparison of two comparative reactivity method instruments inf the Mediterranean basin during summer 2013

Science.gov (United States)

Zannoni, N.; Dusanter, S.; Gros, V.; Sarda Esteve, R.; Michoud, V.; Sinha, V.; Locoge, N.; Bonsang, B.

2015-09-01

The hydroxyl radical (OH) plays a key role in the atmosphere, as it initiates most of the oxidation processes of volatile organic compounds (VOCs), and can ultimately lead to the formation of ozone and secondary organic aerosols (SOAs). There are still uncertainties associated with the OH budget assessed using current models of atmospheric chemistry and direct measurements of OH sources and sinks have proved to be valuable tools to improve our understanding of the OH chemistry. The total first order loss rate of OH, or total OH reactivity, can be directly measured using three different methods, such as the following: total OH loss rate measurement, laser-induced pump and probe technique and comparative reactivity method. Observations of total OH reactivity are usually coupled to individual measurements of reactive compounds in the gas phase, which are used to calculate the OH reactivity. Studies using the three methods have highlighted that a significant fraction of OH reactivity is often not explained by individually measured reactive compounds and could be associated to unmeasured or unknown chemical species. Therefore accurate and reproducible measurements of OH reactivity are required. The comparative reactivity method (CRM) has demonstrated to be an advantageous technique with an extensive range of applications, and for this reason it has been adopted by several research groups since its development. However, this method also requires careful corrections to derive ambient OH reactivity. Herein we present an intercomparison exercise of two CRM instruments, CRM-LSCE (Laboratoire des Sciences du Climat et de l'Environnement) and CRM-MD (Mines Douai), conducted during July 2013 at the Mediterranean site of Ersa, Cape Corsica, France. The intercomparison exercise included tests to assess the corrections needed by the two instruments to process the raw data sets as well as OH reactivity observations. The observation was divided in three parts: 2 days of plant

Aeroacoustics of Musical Instruments

NARCIS (Netherlands)

Fabre, B.; Gilbert, J.; Hirschberg, Abraham; Pelorson, X.

2012-01-01

We are interested in the quality of sound produced by musical instruments and their playability. In wind instruments, a hydrodynamic source of sound is coupled to an acoustic resonator. Linear acoustics can predict the pitch of an instrument. This can significantly reduce the trial-and-error process

Isotope-equipped measuring instruments

International Nuclear Information System (INIS)

Miyagawa, Kazuo; Amano, Hiroshi

1980-01-01

In the steel industry, though the investment in isotope-equipped measuring instruments is small as compared with that in machinery, they play important role in the moisture measurement in sintering and blast furnaces, the thickness measurement in rolling process and others in automatic control systems. The economic aspect of the isotope-equipped measuring instruments is described on the basis of the practices in Kimitsu Works of Nippon Steel Corporation: distribution of such instruments, evaluation of economic effects, usefulness evaluation in view of raising the accuracy, and usefulness evaluation viewed from the failure of the isotope instruments. The evaluation of economic effects was made under the premise that the isotope-equipped measuring instruments are not employed. Then, the effects of raising the accuracy are evaluated for a γ-ray plate thickness gauge and a neutron moisture gauge for coke in a blast furnace. Finally, the usefulness was evaluated, assuming possible failure of the isotope-equipped measuring instruments. (J.P.N.)

The U.S. Army Surface Ablation Study: comparison of PRK, MMC-PRK, and LASEK in moderate to high myopia.

Science.gov (United States)

Sia, Rose K; Ryan, Denise S; Edwards, Jayson D; Stutzman, Richard D; Bower, Kraig S

2014-04-01

To compare visual outcomes following photorefractive keratectomy (PRK), PRK with mitomycin C (MMC-PRK), and LASEK in moderate and high myopia in military personnel. This prospective, randomized contralateral eye study included 167 patients 21 years or older with manifest spherical equivalent -5.99 ± 1.40 diopters (D) (range: -3.88 to -9.38 D) randomized to either MMC-PRK or LASEK treatment in their dominant eye and conventional PRK without MMC in the fellow eye. All procedures were performed using the LADARVision 4000 Excimer Laser System (Alcon Surgical Inc., Ft. Worth, TX). High- and low-contrast visual acuities, manifest refraction, endothelial cell count, and corneal haze were evaluated up to 12 months postoperatively. At 12 months postoperatively, visual outcomes were comparable among the treatment groups. Corneal haze of any grade was less common in MMC-PRK compared to PRK at 1 month (21.4% vs 31.0%; P PRK compared to LASEK at 1 month (21.4% vs 55.9%; P PRK. Clinically significant haze (grade 2 or higher) developed after PRK (4 eyes) and LASEK (2 eyes), but not after MMC-PRK. MMC-PRK showed some benefits in minimizing corneal haze formation. One year after surgery, there was no discernible difference in the postoperative refractive outcomes among the three methods. Copyright 2014, SLACK Incorporated.

Prototype of a Laser-Induced Fluorescence Ground-Based Instrument for Measurements of Atmospheric Iodine Monoxide (IO)

Science.gov (United States)

Thurlow, M. E.; Co, D. T.; Hanisco, T. F.; Lapson, L. B.; Anderson, J. G.

2008-12-01

High abundances of iodine monoxide (IO) are known to exist and to participate in local photochemistry of the marine boundary layer: (1) IO participates in depletion episodes of O3 and in the removal of mercury in the Arctic polar spring by enhancing atomic Br mixing ratios. Recent observations and computer simulations suggest that mercury sequestration is closely tied to halogen photochemistry and that gaseous atomic Hg depletion can be enhanced significantly by the presence of small amounts of iodine-containing compounds. (2) IO and higher- order iodine oxides are involved in the formation of new particles in coastal marine environments. Studies using smog chamber experiments simulating coastal atmospheric conditions have demonstrated that new particles can form from condensable iodine-containing vapors and that their concentrations over the open ocean are sufficient to influence marine particle formation. (3) IO has also been shown to affect the oxidizing capacity of the troposphere by altering the partitioning of NO2/NO and HO2/HO and by activating chlorine and bromine in sea salt aerosols. In the stratosphere, these same processes can lead to enhanced ozone loss rates. Detailed photochemical models that include iodine photochemistry, however, are hampered by the lack of observational data. The distribution of IO in vertical, horizontal, and temporal coordinates is unknown, so the impact of IO on global photochemistry cannot be predicted. The resolution of these important scientific issues requires an in situ IO instrument. A fully functional nanosecond Nd:YAG-pumped Ti:Sapphire laser system and a prototype IO ground-based instrument have been built in our lab. With the current setup, the laser system was situated 10 m from the field station, and the laser light was coupled via an optical fiber. With the use of highly efficient fluorescence detection optics and photon counting techniques, sensitivities of better than 0.1 ppt in 1 s for IO was achieved in the

Effects of 530 nm green light on refractive status, melatonin, MT1 receptor, and melanopsin in the guinea pig.

Science.gov (United States)

Wang, Fei; Zhou, Jiaqi; Lu, Yi; Chu, Renyuan

2011-02-01

To investigate (i) the effect of monochromatic light on inhibiting induction of light-induced melatonin and (ii) the roles of melanopsin and MT1 receptor in light-induced myopia in the guinea pig. Forty-eight guinea pigs were randomly distributed into three treatment groups: white-light (control), green-light (530 nm), and blue-light (480 nm) groups. Levels of pineal gland melatonin were measured twice daily--10:00 a.m. and 10:00 p.m.--10 days after initial light treatment. Thirty additional guinea pigs were also assigned to these groups and treated similarly. For these latter animals, refractive status, ocular length, and vitreous depth were measured before and after light treatment. Eight weeks after light treatment, retinal and sceral levels of melanopsin, melatonin receptor type (MT) 1, and mRNA protein were determined by Western blotting, real-time polymerase chain reaction (RT-PCR), and immunohistochemistry. The level of pineal gland melatonin in the green-light group was significantly higher than that in the blue-light group. Biometric measurements showed that guinea pigs in the green-light group had a somewhat myopic refractive status. Expressions of retinal melanopsin mRNA and protein were significantly higher in the blue-light group and lower in the green-light group when compared to controls. Conversely, expressions of MT1 receptor mRNA and protein in retina and sclera were significantly higher in the green-light group and lower in the blue-light group when compared to controls. Green light appears to suppress induction of melatonin production. In addition, 530 nm of green light is involved in the development of myopia. In the guinea pig, MT1 receptor and melanopsin appear to play roles in the development of myopia induced by 530 nm of light.

Instrumentation reference book

CERN Document Server

Boyes, Walt

2002-01-01

Instrumentation is not a clearly defined subject, having a 'fuzzy' boundary with a number of other disciplines. Often categorized as either 'techniques' or 'applications' this book addresses the various applications that may be needed with reference to the practical techniques that are available for the instrumentation or measurement of a specific physical quantity or quality. This makes it of direct interest to anyone working in the process, control and instrumentation fields where these measurements are essential.* Comprehensive and authoritative collection of technical information* Writte

Jones' instrument technology

CERN Document Server

Jones, Ernest Beachcroft; Kingham, Edward G; Radnai, Rudolf

1985-01-01

Jones' Instrument Technology, Volume 5: Automatic Instruments and Measuring Systems deals with general trends in automatic instruments and measuring systems. Specific examples are provided to illustrate the principles of such devices. A brief review of a considerable number of standards is undertaken, with emphasis on the IEC625 Interface System. Other relevant standards are reviewed, including the interface and backplane bus standards. This volume is comprised of seven chapters and begins with a short introduction to the principles of automatic measurements, classification of measuring system

Bicep2. III. INSTRUMENTAL SYSTEMATICS

Energy Technology Data Exchange (ETDEWEB)

Ade, P. A. R. [School of Physics and Astronomy, Cardiff University, Cardiff, CF24 3AA (United Kingdom); Aikin, R. W.; Bock, J. J.; Brevik, J. A.; Filippini, J. P.; Golwala, S. R.; Hildebrandt, S. R. [Department of Physics, California Institute of Technology, Pasadena, CA 91125 (United States); Barkats, D. [Joint ALMA Observatory, ESO, Santiago (Chile); Benton, S. J. [Department of Physics, University of Toronto, Toronto, ON (Canada); Bischoff, C. A.; Buder, I.; Karkare, K. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street MS 42, Cambridge, MA 02138 (United States); Bullock, E. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Dowell, C. D. [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States); Duband, L. [SBT, Commissariat à l’Energie Atomique, Grenoble (France); Fliescher, S. [Department of Physics, University of Minnesota, Minneapolis, MN 55455 (United States); Halpern, M.; Hasselfield, M. [Department of Physics and Astronomy, University of British Columbia, Vancouver, BC (Canada); Hilton, G. C.; Irwin, K. D., E-mail: csheehy@uchicago.edu [National Institute of Standards and Technology, Boulder, CO 80305 (United States); Collaboration: Bicep2 Collaboration; and others

2015-12-01

In a companion paper, we have reported a >5σ detection of degree scale B-mode polarization at 150 GHz by the Bicep2 experiment. Here we provide a detailed study of potential instrumental systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a heuristic classification of beam imperfections according to their symmetries and uniformities, and discuss how resulting contamination adds or cancels in maps that combine observations made at multiple orientations of the telescope about its boresight axis. We introduce a technique, which we call “deprojection,” for filtering the leading order beam-induced contamination from time-ordered data, and show that it reduces power in Bicep2's actual and null-test BB spectra consistent with predictions using high signal-to-noise beam shape measurements. We detail the simulation pipeline that we use to directly simulate instrumental systematics and the calibration data used as input to that pipeline. Finally, we present the constraints on BB contamination from individual sources of potential systematics. We find that systematics contribute BB power that is a factor of ∼10× below Bicep2's three-year statistical uncertainty, and negligible compared to the observed BB signal. The contribution to the best-fit tensor/scalar ratio is at a level equivalent to r = (3–6) × 10{sup −3}.

Bicep2. III. INSTRUMENTAL SYSTEMATICS

International Nuclear Information System (INIS)

Ade, P. A. R.; Aikin, R. W.; Bock, J. J.; Brevik, J. A.; Filippini, J. P.; Golwala, S. R.; Hildebrandt, S. R.; Barkats, D.; Benton, S. J.; Bischoff, C. A.; Buder, I.; Karkare, K. S.; Bullock, E.; Dowell, C. D.; Duband, L.; Fliescher, S.; Halpern, M.; Hasselfield, M.; Hilton, G. C.; Irwin, K. D.

2015-01-01

In a companion paper, we have reported a >5σ detection of degree scale B-mode polarization at 150 GHz by the Bicep2 experiment. Here we provide a detailed study of potential instrumental systematic contamination to that measurement. We focus extensively on spurious polarization that can potentially arise from beam imperfections. We present a heuristic classification of beam imperfections according to their symmetries and uniformities, and discuss how resulting contamination adds or cancels in maps that combine observations made at multiple orientations of the telescope about its boresight axis. We introduce a technique, which we call “deprojection,” for filtering the leading order beam-induced contamination from time-ordered data, and show that it reduces power in Bicep2's actual and null-test BB spectra consistent with predictions using high signal-to-noise beam shape measurements. We detail the simulation pipeline that we use to directly simulate instrumental systematics and the calibration data used as input to that pipeline. Finally, we present the constraints on BB contamination from individual sources of potential systematics. We find that systematics contribute BB power that is a factor of ∼10× below Bicep2's three-year statistical uncertainty, and negligible compared to the observed BB signal. The contribution to the best-fit tensor/scalar ratio is at a level equivalent to r = (3–6) × 10 −3

Astronomical Instrumentation System Markup Language

Science.gov (United States)

Goldbaum, Jesse M.

2016-05-01

The Astronomical Instrumentation System Markup Language (AISML) is an Extensible Markup Language (XML) based file format for maintaining and exchanging information about astronomical instrumentation. The factors behind the need for an AISML are first discussed followed by the reasons why XML was chosen as the format. Next it's shown how XML also provides the framework for a more precise definition of an astronomical instrument and how these instruments can be combined to form an Astronomical Instrumentation System (AIS). AISML files for several instruments as well as one for a sample AIS are provided. The files demonstrate how AISML can be utilized for various tasks from web page generation and programming interface to instrument maintenance and quality management. The advantages of widespread adoption of AISML are discussed.

Characterization of the Goubau line for testing beam diagnostic instruments

Science.gov (United States)

Kim, S. Y.; Stulle, F.; Sung, C. K.; Yoo, K. H.; Seok, J.; Moon, K. J.; Choi, C. U.; Chung, Y.; Kim, G.; Woo, H. J.; Kwon, J.; Lee, I. G.; Choi, E. M.; Chung, M.

2017-12-01

One of the main characteristics of the Goubau line is that it supports a low-loss, non-radiated surface wave guided by a dielectric-coated metal wire. The dominant mode of the surface wave along the Goubau line is a TM01 mode, which resembles the pattern of the electromagnetic fields induced in the metallic beam pipe when the charged particle beam passes through it. Therefore, the Goubau line can be used for the preliminary bench test and performance optimization of the beam diagnostic instruments without requiring charged particle beams from the accelerators. In this paper, we discuss the basic properties of the Goubau line for testing beam diagnostic instruments and present the initial test results for button-type beam position monitors (BPMs). The experimental results are consistent with the theoretical estimations, which indicates that Goubau line allows effective testing of beam diagnostic equipment.

Soil monitoring instrumentation

International Nuclear Information System (INIS)

Umbarger, C.J.

1981-01-01

The Los Alamos Scientific Laboratory (LASL) has an extensive program for the development of nondestructive assay instrumentation for the quantitative analysis of transuranic (TRU) materials found in bulk solid wastes generated by Department of Energy facilities and by the commercial nuclear power industry. Included are wastes generated in decontamination and decommissioning of outdated nuclear facilities, as well as from old waste-burial-ground exhumation programs. The assay instrumentation is designed to have detection limits below 10 nCi/g wherever practicable. The assay instrumentation that is applied specifically to soil monitoring is discussed

Instruments to assess integrated care

DEFF Research Database (Denmark)

Lyngsø, Anne Marie; Godtfredsen, Nina Skavlan; Høst, Dorte

2014-01-01

INTRODUCTION: Although several measurement instruments have been developed to measure the level of integrated health care delivery, no standardised, validated instrument exists covering all aspects of integrated care. The purpose of this review is to identify the instruments concerning how to mea...... was prevalent. It is uncertain whether development of a single 'all-inclusive' model for assessing integrated care is desirable. We emphasise the continuing need for validated instruments embedded in theoretical contexts.......INTRODUCTION: Although several measurement instruments have been developed to measure the level of integrated health care delivery, no standardised, validated instrument exists covering all aspects of integrated care. The purpose of this review is to identify the instruments concerning how...... to measure the level of integration across health-care sectors and to assess and evaluate the organisational elements within the instruments identified. METHODS: An extensive, systematic literature review in PubMed, CINAHL, PsycINFO, Cochrane Library, Web of Science for the years 1980-2011. Selected...

Analysis on detection accuracy of binocular photoelectric instrument optical axis parallelism digital calibration instrument

Science.gov (United States)

Ying, Jia-ju; Yin, Jian-ling; Wu, Dong-sheng; Liu, Jie; Chen, Yu-dan

2017-11-01

Low-light level night vision device and thermal infrared imaging binocular photoelectric instrument are used widely. The maladjustment of binocular instrument ocular axises parallelism will cause the observer the symptom such as dizziness, nausea, when use for a long time. Binocular photoelectric equipment digital calibration instrument is developed for detecting ocular axises parallelism. And the quantitative value of optical axis deviation can be quantitatively measured. As a testing instrument, the precision must be much higher than the standard of test instrument. Analyzes the factors that influence the accuracy of detection. Factors exist in each testing process link which affect the precision of the detecting instrument. They can be divided into two categories, one category is factors which directly affect the position of reticle image, the other category is factors which affect the calculation the center of reticle image. And the Synthesize error is calculated out. And further distribute the errors reasonably to ensure the accuracy of calibration instruments.

Dopamine antagonists and brief vision distinguish lens-induced- and form-deprivation-induced myopia

OpenAIRE

Nickla, Debora L.; Totonelly, Kristen

2011-01-01

In eyes wearing negative lenses, the D2 dopamine antagonist spiperone was only partly effective in preventing the ameliorative effects of brief periods of vision (Nickla et al., 2010), in contrast to reports from studies using form deprivation. The present study was done to directly compare the effects of spiperone, and the D1 antagonist SCH-23390, on the two different myopiagenic paradigms. 12-day old chickens wore monocular diffusers (form deprivation) or − 10 D lenses attached to the feath...

Dopamine antagonists and brief vision distinguish lens-induced- and form-deprivation-induced myopia.

Science.gov (United States)

Nickla, Debora L; Totonelly, Kristen

2011-11-01

In eyes wearing negative lenses, the D2 dopamine antagonist spiperone was only partly effective in preventing the ameliorative effects of brief periods of vision (Nickla et al., 2010), in contrast to reports from studies using form-deprivation. The present study was done to directly compare the effects of spiperone, and the D1 antagonist SCH-23390, on the two different myopiagenic paradigms. 12-day old chickens wore monocular diffusers (form-deprivation) or -10 D lenses attached to the feathers with matching rings of Velcro. Each day for 4 days, 10 μl intravitreal injections of the dopamine D2/D4 antagonist spiperone (5 nmoles) or the D1 antagonist SCH-23390, were given under isoflurane anesthesia, and the diffusers (n = 16; n = 5, respectively) or lenses (n = 20; n = 6) were removed for 2 h immediately after. Saline injections prior to vision were done as controls (form-deprivation: n = 11; lenses: n = 10). Two other saline-injected groups wore the lenses (n = 12) or diffusers (n = 4) continuously. Axial dimensions were measured by high frequency A-scan ultrasonography at the start, and on the last day immediately prior to, and 3 h after the injection. Refractive errors were measured at the end of the experiment using a Hartinger's refractometer. In form-deprived eyes, spiperone, but not SCH-23390, prevented the ocular growth inhibition normally effected by the brief periods of vision (change in vitreous chamber depth, spiperone vs saline: 322 vs 211 μm; p = 0.01). By contrast, neither had any effect on negative lens-wearing eyes given similar unrestricted vision (210 and 234 μm respectively, vs 264 μm). The increased elongation in the spiperone-injected form-deprived eyes did not, however, result in a myopic shift, probably due to the inhibitory effect of the drug on anterior chamber growth (drug vs saline: 96 vs 160 μm; p effects of brief periods of unrestricted vision differ for form-deprivation versus negative lens-wear, which may imply different growth control mechanisms between the two. Copyright © 2011 Elsevier Ltd. All rights reserved.

EFFECTIVENESS AND LIMITATIONS OF MONETARY POLICY INSTRUMENTS IN ROMANIA AND THE EUROPEAN UNION

Directory of Open Access Journals (Sweden)

Zina CIORAN

2014-12-01

Full Text Available The complexity of the monetary phenomenon as well as the effects that it induces in the social and economic life of the countries around the world have represented and still represent the subject of much controversy and dispute. The current forms of the monetary circulation organization in different countries, internationally as well, represent the result of a continuous process of changes and innovations in the monetary area. The purpose of this article is to present aspects of the monetary policy and its instruments which have evolved according to the historical conditions of each period. The paper is also a presentation of effectiveness and limits of the monetary policy instruments and their role in solving the current economic problems for which the governments seek solutions. As a consequence to the analysis, it can be seen that in most cases it uses a mixture of monetary policy instruments because, when acting in a complementary way, they have a higher efficiency.

Lente fácica de câmara posterior para correção da miopia Posterior chamber phakic lens for the correction of myopia

Directory of Open Access Journals (Sweden)

Ricardo Queiroz Guimarães

2001-02-01

Full Text Available Objetivo: Avaliar a eficácia, previsibilidade e segurança do implante de lente intra-ocular de câmara posterior em pacientes com miopia moderada e elevada. Métodos: Analisamos os resultados das cirurgias realizadas em 93 olhos de 54 pacientes para implante de lente fácica de câmara posterior com a finalidade de corrigir miopia moderada e elevada. O objetivo da cirurgia era a emetropia. O acompanhamento médio foi de 9 meses, variando de 1 a 38 meses (desvio padrão 10,45. Resultados: O equivalente esférico médio pré-operatório era -13,56 D (variando de -5,75 a -20,38 D e o equivalente esférico médio pós-operatório no último exame foi -0,92 D (variando de -3,88 a +1,00 D. No último exame, 39 olhos (41,9% se encontravam entre ±0,50 D da emetropia, 64 olhos (68,8% estavam entre ±1,00 D e 88 olhos (94,6% estavam entre ±2,00 D da emetropia. Um ganho de duas ou mais linhas de visão foi observado em 45,17% (42 olhos. Em 15 olhos (16,1% ocorreu algum tipo de complicação: em 2 olhos (2,2% houve perda de células endoteliais, em 2 olhos (2,2% ocorreu bloqueio pupilar e em 11 olhos (11,8% houve alterações de transparência lenticular, assintomática em 5 olhos (5,4% e sintomática em 6 olhos (6,5%. Conclusão: O implante de lente fácica de câmara posterior para correção de miopia moderada e alta é um método eficaz, previsível e seguro. O significativo ganho de linhas de visão é uma observação freqüente nesta técnica. Um acompanhamento pós-operatório mais prolongado em um maior número de pacientes é necessário para confirmar a estabilidade dos resultados a longo prazo.Purpose: To examine the efficacy, predictability and safety of posterior chamber phakic intraocular lens implantation in patients with moderate and high myopia. Methods: We analyzed the results of 93 eyes of 54 patients who were submitted to the implantation of a posterior chamber phakic lens for the correction of their myopia. The target postoperative

Quantitative assessment of selected policy instruments using the Western European MARKAL model. Phase III EU SAVE White and Green Project: Comparison of market-based instruments to promote energy efficiency

International Nuclear Information System (INIS)

Mundaca, Luis; Santi, Federico

2004-01-01

This report summarises the modelling exercise carried out in order to assess the implications of selected policy instruments using the energy model of Western Europe (WEU) generated by the Market Allocation (MARKAL) modelling tool. The chosen methodology was the usage of the WEU MARKAL model for analysing the response of this energy system to the following policy instruments: White Certificates, Green Certificates, and Carbon Dioxide (CO 2 ) emissions trading. Results show that the order of magnitude of the effects of the analysed instruments depends on the target/cap that is applied. For the case of White Certificates, it can be observed that up to certain level (i.e., around 15% of cumulated energy savings by 2020 compared to the base case) energy savings are obtained at negative costs. Major savings occur in the residential sector for all the applied targets. Results for CO 2 emissions appear to be robust for the years 2015 and 2020, but it should also be observed that these emission trends are less robust for the years 2005 and 2010. Energy efficiency improvements for the WEU economy that are policy-induced around 6%, 9% and 15% for the low, medium and high target scenarios respectively. For the case of Green Certificates, results show that the sustained penetration of renewable energy sources is dominated by wind and biomass. By examining the autonomous fossil fuel intensity of the WEU economy, energy efficiency improvements that are policy induced account for around 1%, 4% and 6% for each scenario respectively. All the targets are technically possible. For the case of CO 2 emissions trading, due to the fact that these results address just the power sector, they must be seen as complementary of other modelling works that deal with a wider industrial coverage. In our case, the more ambitious the cap is, the lower the share of fossil fuels in electricity production becomes. The different trends for the electricity production seem to be less robust. Compared to

A Model of the Effect of Lens Development on Refraction in Schoolchildren.

Science.gov (United States)

He, Ji C

2017-12-01

The study provides a new theory on the mechanism underlying myopia development, and it could be useful in clinical practice to control myopia development in schoolchildren. To model the effect of the crystalline lens on refractive development in schoolchildren. The Zemax 13 was used to calculate Zernike aberrations and refractions across 50° horizontal visual fields. Optical effects of the anterior chamber depth, lens thickness, and radii of curvature of the lens surfaces on refractions were modeled. Refractive changes induced by lens development in emmetropic and myopic eyes, based on a previous longitudinal study from literature, were calculated. A lens thickness reduction with an anterior chamber depth deepening caused a hyperopic shift over the visual fields and even more at the periphery. Opposite effects were found when the lens was thinned without any change of the anterior chamber depth. While a flattening of the anterior lens surface produced hyperopic refractions overall, a posterior lens flattening caused a myopic shift at the periphery, but a hyperopic shift of the central refraction. In the myopic eye, lens development induced refractive change toward more hyperopic over the visual fields and more at the periphery. Lens thinning and lens axial movement participate in peripheral refractive development in schoolchildren, and lens development with a deeper anterior chamber depth and a flatter lens surface in the myopic eye could generate extra hyperopia over visual fields. The myopic lens development could be due to a backward movement of the lens, driven by a backward growth of the ciliary process, which might be a causative factor of myopia development.

Resultados refractivos obtenidos mediante la cirugía del cristalino transparente en altas miopías Refractive outcomes in the transparent crystalline surgery to treat high myopia

Directory of Open Access Journals (Sweden)

Patricia Andújar Coba

2010-06-01

patients (eyes diagnosed with high myopia, who underwent phacorefractive surgery at the "Ramón Pando Ferrer" Cuban Institute of Ophthalmology Microsurgery Service, in the period from April 2001 to April 2006. OBJECTIVES: To assess the refractive results of the transparent crystalline surgery to treat high myopia by analyzing the safety and efficacy indexes of this procedure. METHODS: Summary measures like absolute and relative (% frequency calculations and standard deviation were used to present evolutionary results and incidence of complications. Information came from pre-operative and postoperative assessments (3 months and processed by Windows SPSS system. It was presented in tables and graphs for a better understanding. RESULTS: We found that average visual acuity without correction improved from 0,2 to 0,7 in the postoperative period, the surgical procedure safety was estimated at index of 2, with three lines of average gain in Snellen´s chart and average induced astigmatism of 0,74 dioptres CONCLUSIONS: Visual acuity with/without correction after surgery. Efficacy and safety of the surgical procedure was proven thanks to the high percentage of patients with satisfactory postoperative visual acuity without correction. We identified the posterior capsule opacity as the most common complication in aphakic patients. Regarding those patients who did not undergo intraocular lens implantation, they showed the highest number of complications.

[Controlling instruments in radiology].

Science.gov (United States)

Maurer, M

2013-10-01

Due to the rising costs and competitive pressures radiological clinics and practices are now facing, controlling instruments are gaining importance in the optimization of structures and processes of the various diagnostic examinations and interventional procedures. It will be shown how the use of selected controlling instruments can secure and improve the performance of radiological facilities. A definition of the concept of controlling will be provided. It will be shown which controlling instruments can be applied in radiological departments and practices. As an example, two of the controlling instruments, material cost analysis and benchmarking, will be illustrated.