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Sample records for astigmatism

  1. Astigmatism

    Science.gov (United States)

    ... requiring new glasses or contact lenses. Laser vision correction can most often eliminate, or greatly reduce astigmatism. ... A.M. Editorial team. Related MedlinePlus Health Topics Refractive Errors Browse the Encyclopedia A.D.A.M., Inc. ...

  2. Postoperative astigmatism.

    Science.gov (United States)

    Swinger, C A

    1987-01-01

    With the numerous significant advances in surgical methodology--e.g., microinstrumentation, the operating microscope, the surgical keratometer, and intraocular lenses--that have been developed over the past two decades, both surgeons and patients have become increasingly aware of the final optic result of any surgical intervention. This is especially so since the development of refractive surgery, where good uncorrected vision is frequently the final arbiter of success. We have progressed to the stage where the optic manipulation of the cornea, whether intentional or otherwise, can be understood in terms of a number of variables. These include the preparation and closure of the surgical wound, the choice of suture material, and both intraoperative and postoperative manipulations. Where these have failed and postoperative astigmatism still occurs, a number of surgical procedures are available to reduce the astigmatic error to an acceptable level.

  3. Keratophakia--postoperative astigmatism.

    Science.gov (United States)

    Swinger, C A; Troutman, R C; Forman, J S

    1987-01-01

    Forty-nine cases of primary keratophakia and 13 cases of secondary keratophakia were analyzed for postoperative astigmatism. For primary cases, the surgically induced astigmatism was 1.55 D, whereas for secondary cases it was 0.19 D (insignificant). There was a tendency for both procedures to induce against-the-rule astigmatism, and both procedures were found capable of producing irregular astigmatism.

  4. Changes in Astigmatism, Densitometry, and Aberrations After SMILE for Low to High Myopic Astigmatism

    DEFF Research Database (Denmark)

    Pedersen, Iben Bach; Ivarsen, Anders; Hjortdal, Jesper

    2017-01-01

    PURPOSE: To evaluate 12-month changes in refraction, visual outcome, corneal densitometry, and postoperative aberrations after small incision lenticule extraction (SMILE) for myopic astigmatism. METHODS: This 12-month prospective clinical trial comprised 101 eyes (101 patients) treated with SMILE...... be identified. CONCLUSIONS: Treatment of astigmatism with SMILE seems to be predictable and effective, but with an astigmatic undercorrection of approximately 11% and a small counterclockwise rotation of the axis. [J Refract Surg. 2017;33(1):11-17.]....

  5. Visual Motor and Perceptual Task Performance in Astigmatic Students

    Directory of Open Access Journals (Sweden)

    Erin M. Harvey

    2017-01-01

    Full Text Available Purpose. To determine if spectacle corrected and uncorrected astigmats show reduced performance on visual motor and perceptual tasks. Methods. Third through 8th grade students were assigned to the low refractive error control group (astigmatism < 1.00 D, myopia < 0.75 D, hyperopia < 2.50 D, and anisometropia < 1.50 D or bilateral astigmatism group (right and left eye ≥ 1.00 D based on cycloplegic refraction. Students completed the Beery-Buktenica Developmental Test of Visual Motor Integration (VMI and Visual Perception (VMIp. Astigmats were randomly assigned to testing with/without correction and control group was tested uncorrected. Analyses compared VMI and VMIp scores for corrected and uncorrected astigmats to the control group. Results. The sample included 333 students (control group 170, astigmats tested with correction 75, and astigmats tested uncorrected 88. Mean VMI score in corrected astigmats did not differ from the control group (p=0.829. Uncorrected astigmats had lower VMI scores than the control group (p=0.038 and corrected astigmats (p=0.007. Mean VMIp scores for uncorrected (p=0.209 and corrected astigmats (p=0.124 did not differ from the control group. Uncorrected astigmats had lower mean scores than the corrected astigmats (p=0.003. Conclusions. Uncorrected astigmatism influences visual motor and perceptual task performance. Previously spectacle treated astigmats do not show developmental deficits on visual motor or perceptual tasks when tested with correction.

  6. Tubular astigmatism-tunable fluidic lens.

    Science.gov (United States)

    Kopp, Daniel; Zappe, Hans

    2016-06-15

    We demonstrate a new means to fabricate three-dimensional liquid lenses which may be tuned in focal length and astigmatism. Using actuation by electrowetting-on-dielectrics, astigmatism in arbitrary directions may be tuned independently, with almost no cross talk between orthogonal orientations. The lens is based on electrodes structured on planar polyimide foils and subsequently rolled, enabling high-resolution patterning of complex electrodes along the azimuthal and radial directions of the lens. Based on a design established through fluidic and optical simulations, the astigmatism tuning is experimentally verified by a change of the corresponding Zernike coefficients measured using a Shack-Hartmann wavefront sensor. It was seen that the back focal length can be tuned by 5 mm and 0° and 45° astigmatism by 3 μm through application of voltages in the range of 50  Vrms. It was observed that the cross talk with other aberrations is very low, suggesting a novel means for astigmatism control in imaging systems.

  7. The clinical features of simple myopic astigmatism

    Directory of Open Access Journals (Sweden)

    S. I. Abramov

    2012-01-01

    Full Text Available Purpose: Evaluation of the clinical features of simple myopic astigmatism.Methods: In the framework of the follow-up observation of surveyed 64 patients (128 eyes with the phenomena of simple myopic astigmatism in both eyes without concomitant ocular pathology.Results: the most common are weak (up to 1.0 D — 42%, 1.25-2.0 D — 28% of the value, expressed astigmatism (more than 2.0 D is observed in 30% of cases. In terms of direct myopic astigmatism up to 1.0 D the most characteristic visual acuity is 0.6-0.7, when the value of astigmatism from 1.25 up to 2.0 D the most frequently noted visual acuity is 0.3-0.5. the indicator of «primary use» statistically significantly depended on the indicator «astenopic complaints» (correlation coefficient was 0.59 is 0.72, p<0.0001.Conclusion: the emergence of the patient with visually-intensive work (especially working in conditions of shortage of time re- quires of excimer laser correction for the preservation of visual capacity and the required level of professional reliability, as well as the extension of the professional longevity of the body of view.

  8. The clinical features of simple myopic astigmatism

    Directory of Open Access Journals (Sweden)

    S. I. Abramov

    2014-07-01

    Full Text Available Purpose: Evaluation of the clinical features of simple myopic astigmatism.Methods: In the framework of the follow-up observation of surveyed 64 patients (128 eyes with the phenomena of simple myopic astigmatism in both eyes without concomitant ocular pathology.Results: the most common are weak (up to 1.0 D — 42%, 1.25-2.0 D — 28% of the value, expressed astigmatism (more than 2.0 D is observed in 30% of cases. In terms of direct myopic astigmatism up to 1.0 D the most characteristic visual acuity is 0.6-0.7, when the value of astigmatism from 1.25 up to 2.0 D the most frequently noted visual acuity is 0.3-0.5. the indicator of «primary use» statistically significantly depended on the indicator «astenopic complaints» (correlation coefficient was 0.59 is 0.72, p<0.0001.Conclusion: the emergence of the patient with visually-intensive work (especially working in conditions of shortage of time re- quires of excimer laser correction for the preservation of visual capacity and the required level of professional reliability, as well as the extension of the professional longevity of the body of view.

  9. Selective suture cutting for control of astigmatism following cataract surgery

    Directory of Open Access Journals (Sweden)

    Bansal R

    1992-01-01

    Full Text Available Use of 10-0 monofilament nylon in ECCE cataract surgery leads to high with the rule astigmatism. Many intraoperative and post operative methods have been used to minimise post operative astigmatism. We did selective suture cutting in 38 consecutive patients. Mean keratometric astigmatism at three and six weeks post operative was 5.76 and 5.42 dioptres (D respectively. 77.5% of eyes had astigmatism above 2 D. Selective suture cutting along the axis of the plus high cylinder was done after six weeks of surgery. Mean post suture cutting keratometric astigmatism was 3.3 D and 70% of the eyes had astigmatism below 2 D. After 3 months of surgery mean keratometric astigmatism was reduced to 1.84 D. Axis of the astigmatism also changed following suture cutting. 40% of the eyes showed improvement in their Snellen acuity following reduction in the cylindrical power.

  10. Three methods for correction of astigmatism during phacoemulsification

    Directory of Open Access Journals (Sweden)

    Hossein Mohammad-Rabei

    2016-01-01

    Conclusion: There was no significant difference in astigmatism reduction among the three methods of astigmatism correction during phacoemulsification. Each of these methods can be used at the discretion of the surgeon.

  11. Rectangular Laser Resonators with Astigmatic Compensation

    DEFF Research Database (Denmark)

    Skettrup, Torben

    2005-01-01

    An investigation of rectangular resonators with a view to the compensation of astigmatism has been performed. In order to have beam waists placed at the same positions in the tangential and sagittal planes, pairs of equal mirrors were considered. It was found that at least two concave mirrors...... are necessary to obtain compensation. Four-concave-mirror systems are most stable close to the quadratic geometry, although the symmetric quadratic resonator itself cannot be compensated for astigmatism. Using four equal concave mirrors, compensation of astigmatism can be obtained in two arms at the same time....... Usually several stability ranges are found for four-mirror resonators with pair-wise equal mirrors, and it is possible with these systems to obtain small compensated beam waist radii suitable for frequency conversion. Relevant formulae are given and several relevant examples are shown using simulation...

  12. [Essential features of astigmatism and its correction with excimer laser].

    Science.gov (United States)

    Vlaicu, Valeria

    2012-01-01

    The correction of astigmatism is an essential element for the refractive surgery because the majority of patients have important preoperative cylinder An uncorrected astigmatism decreases visual acuity and can also cause glare, asthenopia, headaches, monocular diplopia. It is important to remark that a complete elimination of astigmatism for the eye is very rarely achieved.

  13. Comparison of astigmatic correction after femtosecond lenticule extraction and small-incision lenticule extraction for myopic astigmatism.

    Directory of Open Access Journals (Sweden)

    Hidenaga Kobashi

    Full Text Available To compare postoperative astigmatic correction between femtosecond lenticule extraction (FLEx and small-incision lenticule extraction (SMILE in eyes with myopic astigmatism.We examined 26 eyes of 26 patients undergoing FLEx and 26 eyes of 26 patients undergoing SMILE to correct myopic astigmatism (manifest astigmatism of 1 diopter (D or more. Visual acuity, cylindrical refraction, the predictability of the astigmatic correction, and the astigmatic vector components using Alpin's method, were compared between the two groups 3 months postoperatively.We found no statistically significant difference in manifest cylindrical refraction (p=0.74 or in the percentage of eyes within ± 0.50 D of their refraction (p=0.47 after the two surgical procedures. Moreover, no statistically significant difference was detected between the groups in astigmatic vector components, namely, surgically induced astigmatism (0.80, target induced astigmatism (p=0.87, astigmatic correction index (p=0.77, angle of error (p=0.24, difference vector (p=0.76, index of success (p=0.91, flattening effect (p=0.79, and flattening index (p=0.84.Both FLEx and SMILE procedures are essentially equivalent in correcting myopic astigmatism using vector analysis, suggesting that the lifting or non-lifting of the flap does not significantly affect astigmatic outcomes after these surgical procedures.

  14. Astigmatism transfer phenomena in the optical parametric amplification process

    Science.gov (United States)

    Li, Wenkai; Chen, Yun; Li, Yanyan; Xu, Yi; Guo, Xiaoyang; Lu, Jun; Leng, Yuxin

    2017-01-01

    We numerically and experimentally investigate the astigmatism transfer phenomena in femtosecond optical parametric amplification (OPA). We model the OPA process based on the coupled second-order three-wave nonlinear propagation equations. The numerical and experimental results support that the input pump pulse astigmatism can be transferred into the idler pulse but not the signal pulse, and the idler pulse astigmatism originating from spatial walk-off is less than the idler pulse astigmatism received from the pump. Thus, we can provide a clear understanding of astigmatism transfer mechanisms in the OPA process, and make better use of broadband tunable OPA sources.

  15. Optical advantages of astigmatic aberration corrected heliostats

    Science.gov (United States)

    van Rooyen, De Wet; Schöttl, Peter; Bern, Gregor; Heimsath, Anna; Nitz, Peter

    2016-05-01

    Astigmatic aberration corrected heliostats adapt their shape in dependence of the incidence angle of the sun on the heliostat. Simulations show that this optical correction leads to a higher concentration ratio at the target and thus in a decrease in required receiver aperture in particular for smaller heliostat fields.

  16. Prevalence of corneal astigmatism before cataract surgery.

    Science.gov (United States)

    Mohammadi, Mehran; Naderan, Mohammad; Pahlevani, Rozhin; Jahanrad, Ali

    2016-12-01

    The purpose of this study was to describe and analyze the prevalence and pattern of corneal astigmatism in cataract surgery candidates. In a prospective cross-sectional study, preoperative demographics, and keratometric and refractive values of cataract surgery candidates were collected from January 2013 to December 2014. Axial length (AL) and flat and steep keratometry measurements were optically measured by a partial coherence interferometry device (IOLMaster). This study consisted of 2156 eyes of 1317 patients with a mean age of 64.92 ± 11.48 (SD) (30-88 years). The mean of AL was 23.33 ± 1.37 mm, and the mean of corneal astigmatism was 1.12 ± 1.10 diopter (D) (range 0.0-7.00), in all patients. Furthermore, the mean of flat and steep keratometry were 43.70 ± 1.70 and 44.83 ± 1.79 D, respectively. Corneal astigmatism was 1.50 D or less in 1590 eyes (73.7 %), more than 1.50 D in 566 eyes (26.2 %), 3.00 D or more in 161 eyes (7.4 %), WTR in 796 eyes (36.9 %), ATR in 1010 eyes (46.8 %), and oblique in 350 eyes (16.2 %). ATR astigmatism axis significantly increased with the increase in age. Corneal astigmatism of most cataract surgery candidates fell between 0.50 and 1.50 D. The results of our study however is confined to our demographics might provide useful data for cataract patients, surgeons, and intraocular lens manufacturers for different purposes.

  17. Effects of posterior corneal astigmatism on the accuracy of AcrySof toric intraocular lens astigmatism correction

    Science.gov (United States)

    Zhang, Bin; Ma, Jing-Xue; Liu, Dan-Yan; Guo, Cong-Rong; Du, Ying-Hua; Guo, Xiu-Jin; Cui, Yue-Xian

    2016-01-01

    AIM To evaluate the effects of posterior corneal surface measurements on the accuracy of total estimated corneal astigmatism. METHODS Fifty-seven patients with toric intraocular lens (IOL) implantation and posterior corneal astigmatism exceeding 0.5 diopter were enrolled in this retrospective study. The keratometric astigmatism (KA) and total corneal astigmatism (TA) were measured using a Pentacam rotating Scheimpflug camera to assess the outcomes of AcrySof IOL implantation. Toric IOLs were evaluated in 26 eyes using KA measurements and in 31 eyes using TA measurements. Preoperative corneal astigmatism and postoperative refractive astigmatism were recorded for statistical analysis. The cylindrical power of toric IOLs was estimated in all eyes. RESULTS In all cases, the difference of toric IOL astigmatism magnitude between KA and TA measurements for the estimation of preoperative corneal astigmatism was statistically significant. Of a total of 57 cases, the 50.88% decreased from Tn to Tn-1, and 10.53% decreased from Tn to Tn-2. In all cases, 5.26% increased from Tn to Tn+1. The mean postoperative astigmatism within the TA group was significantly lower than that in the KA group. CONCLUSION The accuracy of total corneal astigmatism calculations and the efficacy of toric IOL correction can be enhanced by measuring both the anterior and posterior corneal surfaces using a Pentacam rotating Scheimpflug camera. PMID:27672591

  18. Axially astigmatic surfaces: different types and their properties

    Science.gov (United States)

    Malacara-Doblado, Daniel; Malacara-Hernandez, Daniel; Garcia-Marquez, Jorge L.

    1996-12-01

    Axially astigmatic surfaces have different curvatures in orthogonal diameters. Toroidal and spherocylindrical optical surfaces are two mathematically different special cases of axially astigmatic surfaces as noted by Menchaca and Malacara (1986), but they are almost identical in the vicinity of the optical axis. The different between these two surfaces increases when the distance to the optical axis increases. We study the general properties of astigmatic surfaces and some special interesting cases.

  19. Kerr-lens Mode Locking Without Nonlinear Astigmatism

    CERN Document Server

    Yefet, Shi; Pe'er, Avi

    2013-01-01

    We demonstrate a Kerr-lens mode locked folded cavity using a planar (non-Brewster) Ti:sapphire crystal as a gain and Kerr medium, thus cancelling the nonlinear astigmatism caused by a Brewster cut Kerr medium. Our method uses a novel cavity folding in which the intra-cavity laser beam propagates in two perpendicular planes such that the astigmatism of one mirror is compensated by the other mirror, enabling the introduction of an astigmatic free, planar-cut gain medium. We demonstrate that this configuration is inherently free of nonlinear astigmatism, which in standard cavity folding needs a special power specific compensation.

  20. Effect of astigmatism on spectral switches of partially coherent beams

    Institute of Scientific and Technical Information of China (English)

    Zhao Guang-Pu; Xiao Xi; Lü Bai-Da

    2004-01-01

    A detailed study of the spectrum of partially coherent beams diffracted at an astigmatic aperture lens is performed.Considerable attention is paid to the effect of astigmatism on spectral switches of polychromatic Gaussian Schell-model beams. It is shown that the spectral switch can also take place in the vicinity of intensity minimum in a geometrical focal plane for the astigmatic case, but the astigmatism of the lens and the spatial correlation of the beam affect the critical position uc, spectral minimum Smin, and transition height △ of spectral switches.

  1. Astigmatic changes following pterygium removal: Comparison of 5 different methods

    Directory of Open Access Journals (Sweden)

    Rana Altan-Yaycioglu

    2013-01-01

    Full Text Available Aims: To investigate the effect of surgery type on the postoperative astigmatism in pterygium surgery. Settings and Design: Retrospective comparative clinical trial. Materials and Methods: Data of 240 eyes that underwent pterygium excision were investigated. Following removal of the pterygium, patients underwent 5 different types of surgeries: Conjunctival autograft with sutures (CAG-s or fibrin glue (CAG-g, conjunctival rotational flap (CRF, or amniotic membrane transplantation with either suture (AMT-s or with glue (AMT-g. The preoperative and postoperative keratometric measurements, evaluated using an automated keratorefractometer, were noted. Statistical Analysis: The overall changes in BCVA and astigmatic degree were evaluated using Wilcoxon signed rank test. The difference in astigmatic values between groups was calculated using one way analysis of variance (ANOVA. Results: The most commonly performed procedure was CAG-s (N = 115, followed by CAG-g (N = 53, CRF (N = 47, AMT-s (N = 15, and AMT-g (N = 10. Following surgery, astigmatic values decreased from 3.47 ± 2.50 D to 1.29 ± 1.07 D (P < 0.001, paired t test. The changes in astigmatism was significantly related to the preoperative size of the pterygium (ρ = 3.464, P = 0.005. The postoperative astigmatism correlated with preoperative astigmatism (ρ = 0.351, P < 0.001, Spearman correlation analysis. The changes in astigmatic values was not related to the method of surgery (P = 0.055, ANOVA. Conclusion: Pterygium results in high corneal astigmatism, which decreases to an acceptable level following excision. According to our study, the type of grafting as CAG, CRF or AMT or the use of suture or glue to fixate the graft does not have a significant effect on the change in astigmatism degree.

  2. Treatment of corneal astigmatism with the new small-incision lenticule extraction (SMILE) laser technique: Is treatment of high degree astigmatism equally accurate, stable and safe as treatment of low degree astigmatism?

    DEFF Research Database (Denmark)

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

    Field: Ophthalmology Introduction: SMILE has proven effective in treatment of myopia and low degrees of astigmatism (less than 2 dioptres (D)), but there are no studies on treatment of high degrees of astigmatism (2 or more D). The aim of this study was to compare results after SMILE treatment.......6%) treated for low astigmatism and four eyes (3.2%) treated for high astigmatism (P=0.02) had lost two or more lines of BSCVA after three months. Conclusion: This study is the first of its kind, and our results indicate that SMILE treatment of high degree astigmatism is equally accurate and stable...... as treatment of low degree astigmatism. More eyes treated for high degree astigmatism lose two or more lines of BSCVA up to three months after surgery. Keywords Refractive surgery, astigmatism, SMILE...

  3. Treatment of corneal astigmatism with the new small-incision lenticule extraction (SMILE) laser technique: Is treatment of high degree astigmatism equally accurate, stable and safe as treatment of low degree astigmatism?

    DEFF Research Database (Denmark)

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

    Field: Ophthalmology Introduction: SMILE has proven effective in treatment of myopia and low degrees of astigmatism (less than 2 dioptres (D)), but there are no studies on treatment of high degrees of astigmatism (2 or more D). The aim of this study was to compare results after SMILE treatment...... for low or high degrees of astigmatism concerning accuracy, stability, and safety. Methods: Retrospective study of 1017 eyes treated with SMILE for myopia with low astigmatism or myopia with high astigmatism from 2011-2013 at the Department of Ophthalmology, Odense University Hospital, Denmark. Inclusion.......6%) treated for low astigmatism and four eyes (3.2%) treated for high astigmatism (P=0.02) had lost two or more lines of BSCVA after three months. Conclusion: This study is the first of its kind, and our results indicate that SMILE treatment of high degree astigmatism is equally accurate and stable...

  4. The effects of lateral head tilt on ocular astigmatic axis

    Directory of Open Access Journals (Sweden)

    Hamid Fesharaki

    2014-01-01

    Conclusion: Any minimal angle of head tilt may cause erroneous measurement of astigmatic axis and should be avoided during refraction. One cannot rely on the compensatory function of ocular counter-torsion during the refraction.

  5. Treatment of myopic astigmatism with photorefractive keratectomy using an erodible mask.

    Science.gov (United States)

    Cherry, P M; Tutton, M K; Bell, A; Neave, C; Fichte, C

    1994-01-01

    The Summit Technology erodible mask treatment of astigmatism does not alter the keratometric astigmatism significantly, even though the refractive astigmatism appears to improve by about 50%. Myopia is satisfactorily treated with the erodible mask, but there is slightly more undercorrection compared to photorefractive keratectomy (PRK) using an expanding diaphragm. Increasing the minus power in ordering the mask cylinder improves the myopia result, but not the keratometric astigmatism result. The following factors do not influence the keratometric astigmatism result: 1) The type of astigmatism (with-, against-the-rule, or oblique); 2) The initial keratometry readings; and 3) The time from the commencement of epithelial removal to laser treatment.

  6. Goos-Hänchen and Imbert-Fedorov shifts for astigmatic Gaussian beams

    Science.gov (United States)

    Ornigotti, Marco; Aiello, Andrea

    2015-06-01

    In this work we investigate the role of the beam astigmatism in the Goos-Hänchen and Imbert-Fedorov shift. As a case study, we consider a Gaussian beam focused by an astigmatic lens and we calculate explicitly the corrections to the standard formulas for beam shifts due to the astigmatism induced by the lens. Our results show that the different focusing in the longitudinal and transverse direction introduced by an astigmatic lens may enhance the angular part of the shift.

  7. Goos-H\\"anchen and Imbert-Fedorov shifts for astigmatic Gaussian beams

    CERN Document Server

    Ornigotti, Marco

    2015-01-01

    In this work we investigate the role of the beam astigmatism in the Goos-H\\"anchen and Imbert-Fedorov shift. As a case study, we consider a Gaussian beam focused by an astigmatic lens and we calculate explicitly the corrections to the standard formulas for beam shifts due to the astigmatism induced by the lens. Our results show that astigmatism may enhance the angular part of the shift.

  8. Astigmatically compensated cw dye laser resonators using lenses

    Energy Technology Data Exchange (ETDEWEB)

    Hueffer, W.; Schieder, R.; Brinkmann, U. (Koeln Univ. (Germany, F.R.). 1. Physikalisches Inst.)

    1978-01-01

    The compensation of the astigmatism of Brewster-angled dye cells can be performed with lenses as well as with spherical mirrors. The advantages of cw dye laser resonators using lenses lie in the linear configuration of the optics and the convenient adjustability of astigmatism compensation. An output efficiency of 30% already at 1.6 W pumping power has been observed. In addition, ring laser resonators with lenses have been investigated and they delivered up to 400mW single mode power in travelling wave operation at less than 2 W pumping power.

  9. An astigmatic corrected target-aligned heliostat for high concentration

    Energy Technology Data Exchange (ETDEWEB)

    Zaibel, R.; Dagan, E.; Karni, J. [Solar Research Facility, The Weizmann Institute of Science, Rehovot (Israel); Ries, Harald [Ludwig-Maximilians-Universitaet, Sektion Physik, Munich (Germany)

    1995-05-28

    Conventional heliostats suffer from astigmatism for non-normal incidence. For tangential rays the focal length is shortened while for sagittal rays it is longer than the nominal focal length. Due to this astigmatism it is impossible to produce a sharp image of the sun, and the rays will be spread over a larger area. In order to correct this the heliostat should have different curvature radii along the sagittal and tangential direction in the heliostat plane just like a non axial part of a paraboloid. In conventional heliostats, where the first axis, fixed with respect to the ground, is vertical while the second, fixed with respect to the reflector surface, is horizontal, such an astigmatism correction is not practical because the sagittal and tangential directions rotate with respect to the reflector. We suggest an alternative mount where the first axis is oriented towards the target. The second axis, perpendicular to the first and tangent to the reflector, coincides with the tangential direction. With this mounting sagittal and tangential direction are fixed with respect to the reflector during operation. Therefore a partial astigmatism compensation is possible. We calculate the optimum correction and show the performance of the heliostat. We also show predicted yearly average concentrations

  10. Correction of low corneal astigmatism in cataract surgery

    Institute of Scientific and Technical Information of China (English)

    Pia; Leon; Marco; Rocco; Pastore; Andrea; Zanei; Ingrid; Umari; Meriem; Messai; Corrado; Negro; Daniele; Tognetto

    2015-01-01

    · AIM: To evaluate and compare aspheric toric intraocular lens(IOL) implantation and aspheric monofocal IOL implantation with limbal relaxing incisions(LRI) to manage low corneal astigmatism(1.0-2.0 D) in cataract surgery.· METHODS: A prospective randomized comparative clinical study was performed. There were randomly recruited 102 eyes(102 patients) with cataracts associated with corneal astigmatism and divided into two groups. The first group received toric IOL implantation and the second one monofocal IOL implantation with peripheral corneal relaxing incisions. Outcomes considered were: visual acuity, postoperative residual astigmatism, endothelial cell count, the need for spectacles, and patient satisfaction. To determine the postoperative toric axis, all patients who underwent the toric IOL implantation were further evaluated using an OPD Scan III(Nidek Co, Japan). Follow-up lasted 6mo.· RESULTS: The mean uncorrected distance visual acuity(UCVA) and the best corrected visual acuity(BCVA) demonstrated statistically significant improvement after surgery in both groups. At the end of the follow-up the UCVA was statistically better in the patients with toric IOL implants compared to those patients who underwent implantation of monofocal IOL plus LRI. The mean residual refractive astigmatism was of 0.4 D for the toric IOL group and 1.1 D for the LRI group(P <0.01). No difference was observed in the postoperative endothelial cell count between the two groups.· CONCLUSION: The two surgical procedures demonstrated a significant decrease in refractive astigmatism. Toric IOL implantation was more effective and predictable compared to the limbal relaxing incision.

  11. Success rates in the correction of astigmatism with toric and spherical soft contact lens fittings

    Directory of Open Access Journals (Sweden)

    Sevda Aydin Kurna

    2010-08-01

    Full Text Available Sevda Aydin Kurna, Tomris Şengör, Murat Ün, Suat AkiFatih Sultan Mehmet Education and Research Hospital, Ophthalmology Clinics, lstanbul, TurkeyObjectives: To evaluate success rates in the correction of astigmatism with toric and spherical soft contact lens fitting.Methods: 30 patients with soft toric lenses having more than 1.25 D of corneal astigmatism (25 eyes; Group A or having 0.75–1.25 D of corneal astigmatism (22 eyes; Group B and 30 patients with soft spheric lenses having 0.75–1.25 D of corneal astigmatism (28 eyes; Group C or less than 0.75 D of corneal astigmatism (23 eyes; Group D were included in the study. Corrected and uncorrected monocular visual acuity measurement with logMAR, biomicroscopic properties, autorefractometry and corneal topography were performed for all patients immediately before and at least 20 minutes after the application of contact lenses. ­Success of contact lens fitting was evaluated by three parameters: astigmatic neutralization, visual success, and retinal deviation.Results: After soft toric lens application, spheric dioptres, cylindric and keratometric astigmatism, and retinal deviation decreased significantly in Groups A and B (P < 0.05. In Group C, spheric dioptres and retinal deviation decreased (P < 0.05, while cylindric and keratometric astigmatism did not change significantly (P > 0.05. In Group D, spheric dioptres, retinal deviation, and cylindric astigmatism decreased (P < 0.05. Keratometric astigmatism did not change significantly (P > 0.05 and astigmatic neutralization even increased.Conclusions: Visual acuity and residual spherical equivalent refraction remained between tolerable limits with the use of toric and spheric contact lenses. Spherical lenses failed to mask corneal toricity during topography, while toric lenses caused central neutralization and decrease in corneal cylinder in low and moderate astigmatic eyes.Keywords: astigmatism, soft toric lenses, soft spheric lenses

  12. [Results of refractive surgery in hyperopic and combined astigmatism].

    Science.gov (United States)

    Vlaicu, Valeria

    2013-01-01

    The refractive surgery includes a lot of procedures for changing the refraction of the eye to obtain a better visual acuity with no glasses or contact lenses. LASIK is the most commonly performed laser refractive surgery today. The goal is to present the postoperative evolution of the refraction and visual acuity after LASIK for Mixed and Hyperopic Astigmatism. The results show that LASIK is safe and predictible if we have well performed interventions and well-selected patients.

  13. An Astigmatic Detection System for Polymeric Cantilever-based Sensors

    DEFF Research Database (Denmark)

    Hwu, En-Te; Liao, Hsien-Shun; Bosco, Filippo;

    2012-01-01

    We demonstrate the use of an astigmatic detection system (ADS) for resonance frequency identification of polymer microcantilever sensors. The ADS technology is based on a DVD optical head combined with an optical microscope (OM). The optical head has a signal bandwidth of 80 MHz, allowing thermal...... submicrometer-sized cantilevers. The resonant frequency of SU-8 microcantilevers is measured by both thermal fluctuation and excited vibration measurement modes of the ADS....

  14. Plasma channels during filamentation of a femtosecond laser pulse with wavefront astigmatism in air

    Energy Technology Data Exchange (ETDEWEB)

    Dergachev, A A; Kandidov, V P; Shlenov, S A [Lomonosov Moscow State University, Faculty of Physics, Moscow (Russian Federation); Ionin, A A; Mokrousova, D V; Seleznev, L V; Sinitsyn, D V; Sunchugasheva, E S; Shustikova, A P [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2014-12-31

    We have demonstrated experimentally and numerically the possibility of controlling parameters of plasma channels formed during filamentation of a femtosecond laser pulse by introducing astigmatism in the laser beam wavefront. It is found that weak astigmatism increases the length of the plasma channel in comparison with the case of aberration-free focusing and that strong astigmatism can cause splitting of the plasma channel into two channels located one after another on the filament axis. (interaction of laser radiation with matter. laser plasma)

  15. Focusing properties of Gaussian Schell-model beams by an astigmatic aperture lens

    Institute of Scientific and Technical Information of China (English)

    Pan Liu-Zhan; Ding Chao-Liang

    2007-01-01

    This paper studies the focusing properties of Gaussian Schell-model (GSM) beams by an astigmatic aperture lens.It is shown that the axial irradiance distribution, the maximum axial irradiance and its position of focused GSM beams by an astigmatic aperture lens depend upon the astigmatism of the lens, the coherence of partially coherent light, the truncation parameter of the aperture and Fresnel number. The numerical calculation results are given to illustrate how these parameters affect the focusing property.

  16. Contrast sensitivity and higher-order aberrations in patients with astigmatism

    Institute of Scientific and Technical Information of China (English)

    ZHENG Guang-ying; ZHANG Wei-xia; DU Jun; ZHANG Jin-song; LIU Su-bing; NIE Xiao-li; ZHU Xiao-hong; TANG Xiu-xia; XIN Bao-li; MAI Zhi-bin

    2007-01-01

    Background Astigmatism is one of the most significant obstacles for achieving satisfactory visual function. This study was to evaluate the influence of astigmatism on contrast sensitivity (CS) and higher-order aberrations.Methods CS, accommodation response and wavefront aberration were measured in 113 patients with astigmatism,aged 18-36 years. Both single and binocular visual performance were examined under four lighting conditions: photopia,photopia with glare, scotopia and scotopia with glare respectively. Accommodation response was classified as normal,abnormal and low. The contribution of the power and axis of astigmatism to CS, accommodation response and wavefront aberration was analyzed.Results As the dioptric power of astigmatism increased, the loss of CS spatial frequency changed from high to intermediate, and then to low frequency. CS scores varied at different illuminance levels, descending in the following sequence: photopia, photopia with glare, scotopia, and scotopia with glare. However, the normal accommodation group showed better CS values under photopia with glare than without glare. The range of influenced direction of sine-wave gratings remained mostly at the meridian line of high dioptric power, which would be expanded when optical accommadation attenuated. The patients with symmetrical astigmatism got higher CS scores with binoculus vision than with dominant eye vision, while the patients with asymmetrical astigmatism did this only at scotopia with glare. Among higher-order aberrations, coma aberration, secondary coma aberration and the total higher order aberration were influenced by astigmatism, all of which rising with the power of astigmatism increased.Conclusions Reducing astigmatism might improve the performance of visual function. Not only the power of astigmatism should be cut down, but also the binocular axes should be made symmetrically.

  17. Relaxing incision for control of postoperative astigmatism following keratoplasty.

    Science.gov (United States)

    Troutman, R C; Swinger, C

    1980-02-01

    A new technique has been presented which provides a second surgical approach to correct excessive residual astigmatism following keratoplasty. The relaxing incision procedure has advantages over wedge resection in that it can be performed at the slit lamp, it gives no initial overcorrection, and it has a much shorter postoperative course while giving rapid results without suturing. Since this technique does not appear to produce significant hyperopia and may produce a tendency toward myopia, the corneal surgeon would thus have alternative techniques from which to choose, depending, in part, on the spherical component of the refraction.

  18. Quasi two-dimensional astigmatic solitons in soft chiral metastructures

    Science.gov (United States)

    Laudyn, Urszula A.; Jung, Paweł S.; Karpierz, Mirosław A.; Assanto, Gaetano

    2016-03-01

    We investigate a non-homogeneous layered structure encompassing dual spatial dispersion: continuous diffraction in one transverse dimension and discrete diffraction in the orthogonal one. Such dual diffraction can be balanced out by one and the same nonlinear response, giving rise to light self-confinement into astigmatic spatial solitons: self-focusing can compensate for the spreading of a bell-shaped beam, leading to quasi-2D solitary wavepackets which result from 1D transverse self-localization combined with a discrete soliton. We demonstrate such intensity-dependent beam trapping in chiral soft matter, exhibiting one-dimensional discrete diffraction along the helical axis and one-dimensional continuous diffraction in the orthogonal plane. In nematic liquid crystals with suitable birefringence and chiral arrangement, the reorientational nonlinearity is shown to support bell-shaped solitary waves with simple astigmatism dependent on the medium birefringence as well as on the dual diffraction of the input wavepacket. The observations are in agreement with a nonlinear nonlocal model for the all-optical response.

  19. Alpins and thibos vectorial astigmatism analyses: proposal of a linear regression model between methods

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2013-10-01

    Full Text Available PURPOSE: To determine linear regression models between Alpins descriptive indices and Thibos astigmatic power vectors (APV, assessing the validity and strength of such correlations. METHODS: This case series prospectively assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted among two phacoemulsification groups: one assigned to receive AcrySof®Toric intraocular lens (IOL in both eyes and another assigned to have AcrySof Natural IOL associated with limbal relaxing incisions, also in both eyes. All patients were reevaluated postoperatively at 6 months, when refractive astigmatism analysis was performed using both Alpins and Thibos methods. The ratio between Thibos postoperative APV and preoperative APV (APVratio and its linear regression to Alpins percentage of success of astigmatic surgery, percentage of astigmatism corrected and percentage of astigmatism reduction at the intended axis were assessed. RESULTS: Significant negative correlation between the ratio of post- and preoperative Thibos APVratio and Alpins percentage of success (%Success was found (Spearman's ρ=-0.93; linear regression is given by the following equation: %Success = (-APVratio + 1.00x100. CONCLUSION: The linear regression we found between APVratio and %Success permits a validated mathematical inference concerning the overall success of astigmatic surgery.

  20. The Comprehensive Control of Astigmatism during and Following Intraocular Lens Implantation.

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    The operating corneoloscope and Terry operative keratometer were used respectively in 29 and 34 eyes during the intraocular lens implantation to measure the corneal astigmatism qualitatively or quantitatively,so that the tension of incision closure could be adjusted. The surgically induced astigmatism in qualitative group two weeks after the operation was 3. 5 ± 1. 70 D and that in quantitative group was 2. 56±1. 60 D. There were 55.17% and 38. 24% of the eyes with over 2. 00 D corneal astigmatism in qu...

  1. Optical analysis for simplified astigmatic correction of non-imaging focusing heliostat

    Energy Technology Data Exchange (ETDEWEB)

    Chong, K.K. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Off Jalan Genting Kelang, Setapak, 53300 Kuala Lumpur (Malaysia)

    2010-08-15

    In the previous work, non-imaging focusing heliostat that consists of m x n facet mirrors can carry out continuous astigmatic correction during sun-tracking with the use of only (m + n - 2) controllers. For this paper, a simplified astigmatic correction of non-imaging focusing heliostat is proposed for reducing the number of controllers from (m + n - 2) to only two. Furthermore, a detailed optical analysis of the new proposal has been carried out and the simulated result has shown that the two-controller system can perform comparably well in astigmatic correction with a much simpler and more cost effective design. (author)

  2. Success rates in the correction of astigmatism with toric and spherical soft contact lens fittings

    OpenAIRE

    Sevda Aydin Kurna; Tomris Şengör; Murat Ün; et al

    2010-01-01

    Sevda Aydin Kurna, Tomris Şengör, Murat Ün, Suat AkiFatih Sultan Mehmet Education and Research Hospital, Ophthalmology Clinics, lstanbul, TurkeyObjectives: To evaluate success rates in the correction of astigmatism with toric and spherical soft contact lens fitting.Methods: 30 patients with soft toric lenses having more than 1.25 D of corneal astigmatism (25 eyes; Group A) or having 0.75–1.25 D of corneal astigmatism (22 eyes; Group B ) and 30 patients with soft sp...

  3. Success rates in the correction of astigmatism with toric and spherical soft contact lens fittings

    OpenAIRE

    Aydin Kurna, Sevda; Tomris,Sengor

    2010-01-01

    Sevda Aydin Kurna, Tomris Şengör, Murat Ün, Suat AkiFatih Sultan Mehmet Education and Research Hospital, Ophthalmology Clinics, lstanbul, TurkeyObjectives: To evaluate success rates in the correction of astigmatism with toric and spherical soft contact lens fitting.Methods: 30 patients with soft toric lenses having more than 1.25 D of corneal astigmatism (25 eyes; Group A) or having 0.75–1.25 D of corneal astigmatism (22 eyes; Group B ) and 30 patients with soft s...

  4. Proximity- and Astigmatism-Tolerant Testsites For Electrical Linewidth Measurement

    Science.gov (United States)

    Lin, Burn J.

    1989-07-01

    Electrical linewidth measurement is well-known for high precision and throughput. However, the standard four-point probe testsite is only useful for measuring the width of an isolated conducting line. Line-and-space and isolated spaces can be simulated satisfactorily by adding dummy lines parallel to the active line but weak links or potential electrical shorting situations often prematurely cause these structures to fail before their true limits are reached. In this paper, fully wrapped proximity- and astigmatism-tolerant designs for line-and-space and isolated spaces are shown. They have been successfully demonstrated with printed images. An application in evaluating the exposure-defocus window of a one-layer i-line resist using the proximity-tolerant testsites is given.

  5. SURGICALLY INDUCED ASTIGMATISM AFTER 20G VS 23G PARS PLANA VITRECTOMY

    Directory of Open Access Journals (Sweden)

    Lokabhi Reddy

    2015-05-01

    Full Text Available Pars Plana Vitrectomy is done to clear the Vitreous cavity of the Eye. Trans conjunctival Sutureless Vitrectomy with 23G & 25G has become more popular over the Conventional 20G Vitrectomy in recent times. It has many advantages. Less amount of Surgically Induc ed Astigmatism is one of the Advantages with Sutureless Vitrectomy, which will have the Advantage of Early Visual rehabilitation with better Vision. An interventional comparative study was done between 20G & 23 G Pars Plana Vitrectomy in 2 Groups of 30 pat ients each to assess the amount of Post - Operative Astigmatism. The cases were followed up for 6 months to assess the long term effects. There was a significant difference in immediate Post - Operative Astigmatism. But after some time the difference is much l ess showing that the main advantage on Astigmatism with Trans conjunctival Sutureless Vitrectomy is noted mainly during the first few weeks after the Surgery.

  6. Measuring the 3D motion of particles in microchannel acoustophoresis using astigmatism particle tracking velocimetry

    DEFF Research Database (Denmark)

    Augustsson, P.; Barnkob, Rune; Bruus, Henrik;

    2012-01-01

    We introduce full three-dimensional tracking of particles in an acoustophoresis microchannel using Astigmatism Particle Tracking Velocimetry (APTV) [1]. For the first time the interaction between acoustic streaming and the primary acoustic radiation force in microchannel acoustophoresis...

  7. Assessment of refractive astigmatism and simulated therapeutic refractive surgery strategies in coma-like-aberrations-dominant corneal optics

    OpenAIRE

    ZHOU Wen; Stojanovic, Aleksandar; Utheim, Tor Paaske

    2016-01-01

    Background The aim of the study is to raise the awareness of the influence of coma-like higher-order aberrations (HOAs) on power and orientation of refractive astigmatism (RA) and to explore how to account for that influence in the planning of topography-guided refractive surgery in eyes with coma-like-aberrations-dominant corneal optics. Methods Eleven eyes with coma-like-aberrations-dominant corneal optics and with low lenticular astigmatism (LA) were selected for astigmatism analysis and f...

  8. A novel color-LED corneal topographer to assess astigmatism in pseudophakic eyes

    Science.gov (United States)

    Ferreira, Tiago B; Ribeiro, Filomena J

    2016-01-01

    Purpose To assess the accuracy of corneal astigmatism evaluation measured by four techniques, Orbscan IIz®, Lenstar LS900®, Cassini®, and Total Cassini (anterior + posterior surface), in pseudophakic eyes. Patients and methods A total of 30 patients (46 eyes) who had undergone cataract surgery with the implantation of a monofocal intraocular lens (AcrySof IQ) were assessed after surgery. For each eye, subjective assessment of astigmatism and its axis was performed. Minimum, maximum, and mean keratometry and astigmatism and its axis were evaluated using the four measurement techniques. All measurements were compared with the subjective measurements. Agreement between each measurement technique and subjective assessment was evaluated using Bland–Altman plots. Linear regressions were performed and compared. Results Linear regression analysis of astigmatism axis showed very high R2 for all models, with Total Cassini showing the least difference to the unit slope (0.052) and the least difference to a null constant (3.790), although not statistically different from the other models. Regarding astigmatism value, the Cassini and Total Cassini models were similar and statistically better than the Lenstar model. Cassini and Total Cassini showed better J0 compared with Orbscan. Conclusion On linear regression models, Cassini and Total Cassini showed the best performance regarding astigmatism value. Cassini and Total Cassini also showed the least J0 deviation from the Cartesian origin compared with Orbscan, which had the lowest performance. Total corneal measurement with the color LED topographer seems to be a better technique for astigmatism assessment. PMID:27574391

  9. CORNEAL ASTIGMATISM AFTER ECCE: A COMPARATIVE STUDY BETWEEN SILK VERSUS NYLON SUTURE

    Directory of Open Access Journals (Sweden)

    Sunita

    2013-11-01

    Full Text Available ABSTRAC T: INTRODUCTION: Cataract as a potent cause of loss of vision in old age persons is probably known since the dawn of human civilization. Post operative astigmatism after cataract extraction remains a big problem for cataract surgeons since Jacques Daviel e ra. Astigmatism is that type of refractive anomaly in which no point focus is formed owing to the unequal refraction of the incident light by the diopteric system of the eye in different meridians. The goal of modern cataract surgery is to produce a pseudo phakic with the quality of vision of a normal phakic eye. Various studies to find out any effect of IOL on post operative astigmatism were carried out but results are controversial. MATERIAL AND METHODS: 60 patients suffering from cataract and fit for extr action were enlisted during the month of August 2008 to February 2009. The general, physical and local examination including preoperative Keratometry, vision and tension were recorded. RESULTS: In the present study, male patients were 38 (63% and female p atients were 22 (37%. Out of the total 60 cases studied, corneo - scleral section of 28 cases (47% were sutured with 10 - 0 nylon suture (Group A while sections of 32 cases were sutured with 8 - 0 black virgin silk suture (Group B.Out of 28 cases of Group A, interrupted sutures were applied in 14 cases (50% (Group A 1 . Cross interrupted sutures were applied in 9 cases (32% Group A 2 , while bootlace continuous sutures were applied in 5 cases (18% (Group A 3 . Out of 32 cases of Group B, interrupted sutures we re applied in 26 cases (80% (Group B 1 , cross interrupted were applied in 3 cases (10% (Group B 2 , while bootlace continuous suture were applied in 3 cases (Group B 3 . In the present series, 19 cases (31% showed with the rule astigmatism, 21 cases (36% showed astigmatism against the rule and 20 cases (33% showed no astigmatism preoperatively, 16 cases were in the range of 0.50D to 1.0D and 12 cases were in the range of 1

  10. Preoperative corneal astigmatism among adult patients with cataract in Northern Nigeria

    Directory of Open Access Journals (Sweden)

    Mohammed Isyaku

    2014-01-01

    Full Text Available The prevalence and nature of corneal astigmatism among patients with cataract has not been well-documented in the resident African population. This retrospective study was undertaken to investigate preexisting corneal astigmatism in adult patients with cataract. We analyzed keratometric readings acquired by manual Javal-Schiotz keratometry before surgery between January 1, 2011 and December 31, 2011. There were 3,169 patients (3286 eyes aged between 16 and 110 years involved with a Male to female ratio of 1.4:1. Mean keratometry in diopters was K1 = 43.99 and K2 = 43.80. Mean corneal astigmatism was 1.16 diopter and a majority (45.92% of eyes had astigmatism between 1.00 and 1.99 diopters. Two-thirds of the eyes (66.9% in this study had preoperative corneal astigmatism equal to or above 1.00 diopter. Findings will help local cataract surgeons to estimate the potential demand for toric intraocular lenses.

  11. Off-Axis Astigmatic Gaussian Beam Combination Beyond the Paraxial Approximation

    Institute of Scientific and Technical Information of China (English)

    GAO Zeng-Hui; L(U) Bai-Da

    2007-01-01

    Taking the off-axis astigmatic Gaussian beam combination as an example, the beam-combination concept is extended to the nonparaxial regime. The closed-form propagation expressions for coherent and incoherent combinations of nonparaxial off-axis astigmatic Gaussian beams with rectangular geometry are derived and illustrated with numerical examples. It is shown that the intensity distributions of the resulting beam depend on the combination scheme and beam parameters in general, and in the paraxial approximation (i.e., for the small f-parameter)our results reduce to the paraxial ones.

  12. Toric intraocular lens orientation and residual refractive astigmatism: an analysis

    Directory of Open Access Journals (Sweden)

    Potvin R

    2016-09-01

    astigmatism as a result of misorientation. The Tecnis Toric IOL appears more likely to be misoriented in a counterclockwise direction; no such bias was observed with the AcrySof Toric, the Trulign® Toric, or the Staar Toric IOLs. Keywords: rotation, AcrySof, Tecnis, toric back-calculator, cylinder

  13. Numerical analysis of astigmatism correction in gradient refractive index lens based optical coherence tomography catheters

    NARCIS (Netherlands)

    T. Wang (Teng); A.F.W. van der Steen (Ton); G. van Soest (Gijs)

    2012-01-01

    textabstractEndoscopic optical coherence tomography (OCT) catheters comprise a transparent tube to separate the imaging instrument from tissues. This tube acts as a cylindrical lens, introducing astigmatism into the beam. In this report, we quantified this negative effect using optical simulations o

  14. Meridional lenticular astigmatism associated with bilateral concurrent uveal metastases in renal cell carcinoma

    Directory of Open Access Journals (Sweden)

    Priluck JC

    2012-11-01

    Full Text Available Joshua C Priluck, Sandeep Grover, KV ChalamDepartment of Ophthalmology, University of Florida College of Medicine, Jacksonville, FL, USAPurpose: To demonstrate a case illustrating meridional lenticular astigmatism as a result of renal cell carcinoma uveal metastases.Methods: Case report with images.Results: Clinical findings and diagnostic testing of a patient with acquired meridional lenticular astigmatism are described. The refraction revealed best-corrected visual acuity of 20/20–1 OD (−2.50 + 0.25 × 090 and 20/50 OS (−8.25 + 3.25 × 075. Bilateral concurrent renal cell carcinoma metastases to the choroid and ciliary body are demonstrated by utilizing ultrasonography, ultrawidefield fluorescein angiography, and unique spectral-domain optical coherence tomography.Conclusions: Metastatic disease should be included in the differential of acquired astigmatism. Spectral-domain optical coherence tomography, ultrawidefield fluorescein angiography, and ultrasonography have roles in delineating choroidal metastases.Keywords: astigmatism, metastasis, optical coherence tomography, renal cell carcinoma

  15. [Post-operative residual astigmatism after cataract surgery: Current surgical methods of treatment].

    Science.gov (United States)

    Pisella, P-J

    2012-03-01

    Residual astigmatism after cataract surgery can be corrected by three different techniques: classic limbal relaxing incisions, easy to perform but with limited precision; laser refractive surgery (PRK or Lasik), additionally allowing for correction of spherical equivalent; and more recently the use of a piggyback toric intraocular lens in the ciliary sulcus.

  16. Astigmatism treatment during phacoemulsification: a review of current surgical strategies and their rationale

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2013-12-01

    Full Text Available Preexisting corneal astigmatism, present at the time of cataract surgery, is reviewed in detail throughout this article on its most important aspects such as occurrence rates, clinical relevance and current treatment options. Special emphasis is given to the latter aspect. Each method's rationale, advantage and limitation ishigh lightened. Comparisons between treatment options, whenever possible, are also provided.

  17. Prevalence of Corneal Astigmatism and Anterior Segmental Biometry Characteristics Before Surgery in Chinese Congenital Cataract Patients.

    Science.gov (United States)

    Lin, Duoru; Chen, Jingjing; Liu, Zhenzhen; Wu, Xiaohang; Long, Erping; Luo, Lixia; Lin, Zhuoling; Li, Xiaoyan; Zhang, Li; Chen, Hui; Liu, Jinchao; Chen, Weirong; Lin, Haotian; Liu, Yizhi

    2016-02-25

    The prevalence and the distribution characteristics of corneal astigmatism (CA) and anterior segment biometry before surgery in Chinese congenital cataract (CC) patients are not completely understood. This study involved 400 CC patients from the Zhongshan Ophthalmic Center enrolled from February 2011 to August 2015. Data on CA, keratometry, central corneal thickness (CCT) and anterior chamber depth (ACD) were measured by the Pentacam Scheimpflug System. The mean age of patients was 54.27 months, and the ratio of boys to girls was 1.53:1. The mean CA was 2.03 diopters (D), and 39.25% of subjects had CA values ≥2 D. The most frequent (71.8%) diagnosis was with-the-rule astigmatism. Oblique astigmatism was present in 16.2% of cases, and 12% of cases had against-the-rule astigmatism. The mean keratometry measurement of cataractous eyes in bilateral patients was significantly larger than that in unilateral patients. Girls had a larger mean keratometry but a thinner CCT than did boys. The CA, CCT, and ACD of cataractous eyes were significantly larger than those of non-cataractous eyes in unilateral patients. The CA, mean keratometry, CCT, and ACD in CC patients varied with age, gender, and laterality. Fully understanding these characteristics may help inform guidelines and treatment decisions in CC patients.

  18. Prevalence of Keratoconus and Subclinical Keratoconus in Subjects with Astigmatism Using Pentacam Derived Parameters

    Directory of Open Access Journals (Sweden)

    Huseyin Serdarogullari

    2013-01-01

    Full Text Available Purpose: To determine the prevalence of keratoconus (KCN and subclinical KCN among subjects with two or more diopters (D of astigmatism, and to compare Pentacam parameters among these subjects. Methods: One hundred and twenty eight eyes of 64 subjects with astigmatism ≥2D were included in the study. All subjects underwent a complete ophthalmic examination which included refraction, visual acuity measurement, slit lamp biomicroscopy, retinoscopy, fundus examination, conventional corneal topography and elevation-based topography with Pentacam. The diagnosis of KCN and subclinical KCN was made by observing clinical findings and topographic features; and confirmed by corneal thickness and elevation maps of Pentacam. Several parameters acquired from Pentacam were analyzed employing the Mann-Whitney U Test. Results: Mean age of the study population was 29.9±9.8 (range 15-45 years which included 39 (60.9% female and 25 (39.1% male subjects. Maximum corneal power, index of vertical asymmetry, keratoconus index and elevation values were significantly higher and pachymetry was significantly thinner in eyes with clinical or subclinical KCN than normal astigmatic eyes (P< 0.05. Conclusion: The current study showed that subjects with 2D or more of astigmatism who present to outpatient clinics should undergo corneal topography screening for early diagnosis of KCN even if visual acuity is not affected. Pentacam may provide more accurate information about anterior and posterior corneal anatomy especially in suspect eyes.

  19. Extended depth of focus intra-ocular lens: a solution for presbyopia and astigmatism

    Science.gov (United States)

    Zlotnik, Alex; Raveh, Ido; Ben Yaish, Shai; Yehezkel, Oren; Belkin, Michael; Zalevsky, Zeev

    2010-02-01

    Purpose: Subjects after cataract removal and intra-ocular lens (IOL) implantation lose their accommodation capability and are left with a monofocal visual system. The IOL refraction and the precision of the surgery determine the focal distance and amount of astigmatic aberrations. We present a design, simulations and experimental bench testing of a novel, non-diffractive, non-multifocal, extended depth of focus (EDOF) technology incorporated into an IOL that allows the subject to have astigmatic and chromatic aberrations-free continuous focusing ability from 35cm to infinity as well as increased tolerance to IOL decentration. Methods: The EDOF element was engraved on a surface of a monofocal rigid IOL as a series of shallow (less than one micron deep) concentric grooves around the optical axis. These grooves create an interference pattern extending the focus from a point to a length of about one mm providing a depth of focus of 3.00D (D stands for Diopters) with negligible loss of energy at any point of the focus while significantly reducing the astigmatic aberration of the eye and that generated during the IOL implantation. The EDOF IOL was tested on an optical bench simulating the eye model. In the experimental testing we have explored the characteristics of the obtained EDOF capability, the tolerance to astigmatic aberrations and decentration. Results: The performance of the proposed IOL was tested for pupil diameters of 2 to 5mm and for various spectral illuminations. The MTF charts demonstrate uniform performance of the lens for up to 3.00D at various illumination wavelengths and pupil diameters while preserving a continuous contrast of above 25% for spatial frequencies of up to 25 cycles/mm. Capability of correcting astigmatism of up to 1.00D was measured. Conclusions: The proposed EDOF IOL technology was tested by numerical simulations as well as experimentally characterized on an optical bench. The new lens is capable of solving presbyopia and astigmatism

  20. Induced astigmatism after cataract surgery - a retrospective analysis of cases from the University of Port Harcourt Teaching Hospital, Nigeria

    Directory of Open Access Journals (Sweden)

    A. O. Adio

    2011-12-01

    Full Text Available Visual rehabilitation after cataract surgery may often be disappointing due to induction of corneal astigmatism following issues in realigning, point to point, the corneal wound margin in the process of surgery despite biometry and use of the appropriateintraocular lens. The purpose of this study is to determine the amount of surgically induced astigmatism after sutured cataract extraction-extracapsular cataract extraction (ECCE and intracapsular cataract extraction (ICCE and intraocular lens (IOLimplantation in the University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria. Folders of all cataract patients operated on in the eye theatre of the aforenamed tertiary facility between2002 and 2006 were considered.  Relevant patient details and intraoperative and postoperative management were examined and reported upon. One hundred and fourteen eyes (114 of one hundred patients who had cataract surgeries done within the five-year period of this study were examined. ECCE + IOL implantation were examined in the period under review. The post-operative refraction objectively and subjectively was retrieved from the records of each patient. The post-operative cylinderpower (total astigmatism was recorded.Of 114 eyes, only 83 eyes (72.8% had refraction results postoperatively due to loss of fol-low-up. The total number with astigmatism was 57(68.7%. Forty-two had against-the-rule (73.7%, twelve (21.1% with-the-rule, while five (0.09% were oblique. The mean post-operative astigmatism was 1.85 D. The surgically induced corneal astigmatism was highest with ECCE with PCIOL. Astigmatism less than 2 D was highest in this group (ECCE with IOL while ICCE with ACIOL had the highest number with astigmatism in the range between 2 D and 4 D. The total astigmatism which was mainly with-the-rule (vertical plus cylinder did not seem to impair severely the post-operative visual acuity of the patients.In conclusion, surgically induced astigmatism affected almost

  1. Comparison of the Keratometric Corneal Astigmatic Power after Phacoemulsification: Clear Temporal Corneal Incision versus Superior Scleral Tunnel Incision

    Directory of Open Access Journals (Sweden)

    Yongqi He

    2009-01-01

    Full Text Available Objective. This is prospective randomized control trial to compare the mean keratometric corneal astigmatism diopter power (not surgical induced astigmatism among preop and one-month and three-month postop phacoemulcification of either a clear temporal corneal incision or a superior scleral tunnel Incision, using only keratometric astigmatic power reading to evaluate the difference between the two cataract surgery incisions. Methods. 120 patients (134 eyes underwent phacoemulcification were randomly assigned to two groups: Group A, the clear temporal corneal incision group, and Group B, the superior scleral tunnel incision group. SPSS11.5 Software was used for statistical analysis to compare the postsurgical changes of cornea astigmatism on keratometry. Results. The changes of corneal astigmatic diopter in Groups A and B after 3 month postop from keratometric reading were 1.04 + 0.76 and 0.94 + 0.27, respectively (=.84>.05, which showed no statistic significance difference. Conclusion. The incision through either temporal clear cornea or superior scleral tunnel in phacoemulcification shows no statistic difference in astigmatism change on keratometry 3-month postop.

  2. AcrySof toric intraocular lens for post-keratoplasty astigmatism

    Directory of Open Access Journals (Sweden)

    Nishant Gupta

    2012-01-01

    Full Text Available We report a 63-year-old male who had undergone left eye optical penetrating keratoplasty for central leucomatous corneal opacity 10 years earlier. The eye had clear donor graft with residual astigmatism of −6.50 diopter cylinder (DC at 30°. The patient underwent clear corneal phacoemulsification with implantation of +6.0 D spherical equivalent AcrySof SN60T9 intraocular lens (IOL. Postoperatively, at 10 months, the patient had distance corrected visual acuity of 20/30 with −2.00 DC at 20°. AcrySof toric IOL offers an effective treatment option for post-keratoplasty high corneal astigmatism in patients with cataract.

  3. Designing Fresnel microlenses for focusing astigmatic multi-Gaussian beams by using fractional order Fourier transforms

    Energy Technology Data Exchange (ETDEWEB)

    Patino, A [Universidad Technologica de Bolivar, Cartagena de Indias (Colombia); Durand, P-E; Fogret, E; Pellat-Finet, P, E-mail: alberto.patino-vanegas@univ-ubs.fr [Laboratoire de mathematiques et applications des mathematiques, Universite de Bretagne Sud, B P 92116, 56321 Lorient cedex (France)

    2011-01-01

    According to a scalar theory of diffraction, light propagation can be expressed by two-dimensional fractional order Fourier transforms. Since the fractional Fourier transform of a chirp function is a Dirac distribution, focusing a light beam is optically achieved by using a diffractive screen whose transmission function is a two-dimensional chirp function. This property is applied to designing Fresnel microlenses, and the orders of the involved Fourier fractional transforms depend on diffraction distances as well as on emitter and receiver radii of curvature. If the emitter is astigmatic (with two principal radii of curvature), the diffraction phenomenon involves two one-dimensional fractional Fourier transforms whose orders are different. This degree of freedom allows us to design microlenses that can focus astigmatic Gaussian beams, as produced by a line-shaped laser diode source.

  4. Transformation of general astigmatic Gaussian beams in a four-dimensional phase space

    Institute of Scientific and Technical Information of China (English)

    Baoxin Chen

    2006-01-01

    @@ A phase space model of two-dimensional (2D) Gaussian beam propagation is generalized for threedimensional (3D) general astigmatic Gaussian beam passing through first-order optical system. The general astigmatic Gaussian beam is represented by a four-dimensional (4D) phase super-ellipsoid that defined by an associated 4 × 4 real matrix, then the transformation formula of the phase super-ellipsoid of the beam through first-order optical system is derived. In particular, in the phase space framework, the beam propagation factor M2 value is proved to be a ratio of phase area of real beam to ideal beam, and a novel approach for a qualitative examination of the properties of fractional Fourier transform (FRT) for the beam is also provided.

  5. Thermal Correction of Astigmatism in the Gravitational Wave Observatory GEO 600

    CERN Document Server

    Wittel, Holger; Affeldt, Christoph; Dooley, Katherine L; Grote, Hartmut; Leong, Jonathan R; Prijatelj, Mirko; Schreiber, Emil; Slutsky, Jacob; Strain, Kenneth A; Was, Michal; Willke, Benno; Danzmann, Karsten

    2013-01-01

    The output port of GEO 600 is dominated by unwanted high order modes (HOMs). The current thermal actuation system, a ring heater behind one of the folding mirrors, causes a significant amount of astigmatism, which produces HOMs. We have built and installed an astigmatism correction system, based on heating this folding mirror at the sides (laterally). With these side heaters and the ring heater behind the mirror, it is possible to tune its radius of curvature in the horizontal and the vertical degree of freedom. We use this system to match the mirrors in the two arms of GEO 600 to each other, thereby reducing the contrast defect. The use of the side heaters reduces the power of the HOMs at the output of GEO 600 by approximately 37%.

  6. Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

    OpenAIRE

    Chang Rae Rho; Min-Ji Kim; Choun-Ki Joo

    2016-01-01

    Purpose. To evaluate surgically induced astigmatism (SIA) and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS) implantation. Methods. The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was ...

  7. Clinical Efficacy of Toric Orthokeratology in Myopic Ado-lescent with Moderate to High Astigmatism

    Institute of Scientific and Technical Information of China (English)

    Ming Luo; Shengsheng Ma; Na Liang

    2014-01-01

    Purpose:.To observe the efficacy of toric design orthokera-tology.(ortho-k).for correcting myopia and astigmatism in my-opic adolescents with moderate to high astigmatism. Methods:.This was a self-controlled clinical study..Twenty-four subjects(42 eyes).aged 9 to 16 years with myopia of 2.50-6.00 D complicated with rule astigmatism of 1.50-3.50 D were fitted with Lucid Night Toric Ortho-k Lenses (LUCID,KO-REA)..The changes in uncorrected visual acuity (UCVA), spherical degree, refraction, axial length (AL),.and corneal status were assessed at baseline, 1 night, 1 week, 1 month, 3 months, 6 months, and 1 year after the commencement of or-tho-k lens wear. Results: The success rate of the first lens fit was 92.8%. The UCVA after ortho-k wearing was improved significantly com-pared to the baseline during each visit (all P0.05)..Grade 1 corneal staining was observed at 1 week (23.8%),.1 month (21.4%), and 1 year (16.7%) fol-lowing lens wear, and was improved by lens cleaning,.discon-tinuing lens wear, and moistening the cornea with eye drops. No severe adverse events were reported. Conclusion: The toric ortho-k lens was effective and safe for correction of low to moderate myopia in children with moder-ate to high astigmatism..The lens also effectively controlled axial length elongation during 1 year of observation..However, the long-term efficacy remains to be elucidated.

  8. Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

    Science.gov (United States)

    Rho, Chang Rae; Kim, Min-Ji

    2016-01-01

    Purpose. To evaluate surgically induced astigmatism (SIA) and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS) implantation. Methods. The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was used to evaluate the SIA. Hotelling's trace test was used to compare intraindividual changes. Results. Three months postoperatively, the combined mean polar value for SIA changed significantly (Hotelling's T2 = 0.375; P = 0.006). The SIA was 1.54 D at 99° and the average corneal power decreased significantly by 3.8 D. Conclusion. Intacs SK ICRS placement decreased the average corneal power and corneal astigmatism compared to the preoperative corneal power and astigmatism when the corneal pocket incision was made at the preoperative steep meridian. PMID:27795856

  9. Polar Value Analysis of Corneal Astigmatism in Intrastromal Corneal Ring Segment Implantation

    Directory of Open Access Journals (Sweden)

    Chang Rae Rho

    2016-01-01

    Full Text Available Purpose. To evaluate surgically induced astigmatism (SIA and the average corneal power change in symmetric intrastromal corneal ring segment (ICRS implantation. Methods. The study included 34 eyes of 34 keratoconus patients who underwent symmetric Intacs SK ICRS implantation. The corneal pocket incision meridian was the preoperative steep meridian. Corneal power data were obtained before and 3 months after Intacs SK ICRS implantation using scanning-slit topography. Polar value analysis was used to evaluate the SIA. Hotelling’s trace test was used to compare intraindividual changes. Results. Three months postoperatively, the combined mean polar value for SIA changed significantly (Hotelling’s T2=0.375; P=0.006. The SIA was 1.54 D at 99° and the average corneal power decreased significantly by 3.8 D. Conclusion. Intacs SK ICRS placement decreased the average corneal power and corneal astigmatism compared to the preoperative corneal power and astigmatism when the corneal pocket incision was made at the preoperative steep meridian.

  10. Customized toric intraocular lens implantation for correction of extreme corneal astigmatism due to corneal scarring

    Directory of Open Access Journals (Sweden)

    R Bassily

    2010-03-01

    Full Text Available R Bassily, J LuckOphthalmology Department, Royal United Hospital, Combe Park, Bath, UKAbstract: A 76-year-old woman presented with decreased visual function due to cataract formation. Twenty-five years prior she developed right sided corneal ulceration that left her with 10.8 diopters (D of irregular astigmatism at 71.8° (steep axis. Her uncorrected visual acuity was 6/24 and could only ever wear a balanced lens due to the high cylindrical error. Cataract surgery was planned with a custom designed toric intraocular lens (IOL with +16.0 D sphere inserted via a wound at the steep axis of corneal astigmatism. Postoperative refraction was -0.75/+1.50 × 177° with a visual acuity of 6/9 that has remained unchanged at six-week follow-up with no IOL rotation. This case demonstrates the value of high power toric IOLs for the correction of pathological corneal astigmatism.Keywords: intraocular lens, corneal ulceration, visual acuity, scarring

  11. Toric Intraocular Lens Implantation for Correction of Astigmatism in Cataract Patients with Corneal Ectasia

    Directory of Open Access Journals (Sweden)

    Efstratios A. Parikakis

    2013-11-01

    Full Text Available Our purpose was to examine the long-term efficacy of toric intraocular lens (IOL implantation in cataract patients with high astigmatism due to corneal ectasia, who underwent phacoemulsification cataract surgery. Five eyes of 3 cataract patients with topographically stable keratoconus or pellucid macular degeneration (PMD, in which phacoemulsification with toric IOL implantation was used to correct high astigmatism, are reported. Objective and subjective refraction, visual acuity measurement and corneal topography were performed in all cases before and after cataract surgery. In all cases, there was a significant improvement in visual acuity, as well as refraction, which remained stable over time. Specifically, in subjective refraction, all patients achieved visual acuity from 7/10 to 9/10 with up to -2.50 cyl. Corneal topography also remained stable. Postoperative follow-up was 18-28 months. Cataract surgery with toric IOL implantation seems to be safe and effective in correcting astigmatism and improving visual function in cataract patients with topographically stable keratoconus or PMD.

  12. [Optimization of broad-band flat-field holographic concave grating without astigmatism].

    Science.gov (United States)

    Kong, Peng; Tang, Yu-guo; Bayanheshig; Li, Wen-hao; Cui, Jin-jiang

    2012-02-01

    The desirable imaging locations of the flat-field holographic concave gratings should be in a plane. And the object can be imaged perfectly by the grating when the tangential focal curve and sagittal focal curve both superpose the intersection of the image plane and dispersion plane. But actually, the defocus can not be eliminated over the entire wavelength range, while the astigmatism vanishes when the grating parameters satisfy some conditions. An optimization method for broad-band flat-field holographic concave gratings with absolute astigmatism correction was proposed. The ray tracing software ZEMAX was used for investigating the imaging properties of the grating. And we made a comparison between spectral performance of gratings designed by this new method and that by conventional method, respectively. The results indicated that the spectral performance of gratings designed by using the absolute astigmatism correction method can be as good as gratings designed with the conventional method. And the focusing performance in the sagittal direction is much better, so that the S/N ratio can be greatly improved.

  13. Use of a Toric Intraocular Lens and a Limbal-Relaxing Incision for the Management of Astigmatism in Combined Glaucoma and Cataract Surgery

    Science.gov (United States)

    Gibbons, Allister

    2016-01-01

    Purpose We report the surgical management of a patient with glaucoma undergoing cataract surgery with high preexisting astigmatism. A combination of techniques was employed for her astigmatism management. Methods A 76-year-old female with 5.5 dpt of corneal astigmatism underwent surgery in her left eye consisting of one-site trabeculectomy, phacoemulsification, toric intraocular lens implantation and a single inferior limbal-relaxing incision. Results Intraocular pressure control was achieved with no medication at 11 mm Hg; before the filtering procedure, the pressure was 16 mm Hg on two topical drugs. Astigmatism was reduced to 0.75 dpt, and both corrected and uncorrected visual acuity improved. Conclusions Astigmatism management can have a good outcome in combined procedures. We encourage surgeons to address astigmatism in the preoperative planning of patients undergoing glaucoma surgery associated with phacoemulsification. PMID:27293408

  14. Corneal astigmatism change and wavefront aberration evaluation after cataract surgery: "Single" versus "paired opposite" clear corneal incisions

    Directory of Open Access Journals (Sweden)

    Hasan Razmjoo

    2014-01-01

    Full Text Available Background: Correcting the pre-existing astigmatism is an optimal goal in cataract surgery. The aim of this study is to compare the astigmatic correcting effect of a single regular 3.2 mm clear corneal incision (CCI with paired opposite CCI in cataract patients and effect of these incisions on optical aberrations using the wavefront quantitative analysis. Materials and Methods: This was a randomized controlled trial study undertaken in an ophthalmology referral center on 50 patients planned for cataract surgery who were randomized to either single 3.2 mm CCI or paired opposite CCI group. Post-operative evaluation was performed at 12 weeks and included refraction, keratometery, corneal topography and wavefront analysis. Corneal astigmatism and post-operative values were compared in two groups. Results: The mean pre-operative corneal astigmatism was 2.58 ± 1.03 D in the single incision group and 2.70 ± 0.94 D in the paired opposite incisions group. After 12 weeks of surgery, the corneal astigmatism was reached to 2.15 ± 0.82 D in single incision group and 1.63 ± 1.21 in the paired opposite incisions group. There was a statistically significant difference in two arms of treatment regarding to surgically induced astigmatism after 3 months. The mean post-operative total and higher order aberrations and values were not significantly different in two groups. Conclusion: The results of our study showed that paired opposite incisions is an effective procedure for reducing pre-existing corneal astigmatism in cataract surgery. Paired incisions did not show any beneficial effect regarding wavefront aberrations compared with conventional single incision method.

  15. ROLE OF INCISION SITE IN REDUCING SURGICALLY INDUCE D ASTIGMATISM IN MANUAL SMALL INCISION CATARACT SURGE RY

    Directory of Open Access Journals (Sweden)

    Sathish

    2013-04-01

    Full Text Available INTRODUCTION: Phacoemulsification and foldable IOLs allow modern day surgeon to aim at minimal induction of any astigmatic error as well a s correct any pre-operative refractive errors thus making patients’ life, spectacle free i.e. una ided emmetropia. But its high price and maintenance with a long learning curve for the surg eon make it unsuitable for the Indian camp scenario. Manual SICS in comparison needs a larger incision f or both nucleus removal and a rigid IOL insertion, but still provides for a sutureless and c onvenient alternative to phaco. Manual SICS does induce some amount of astigmatism by altering corneal curvatures (i.e., by coupling effect, while phaco surgery with 3 mm incision is astigmatic ally neutral. Manifold of studies have been done to compare Surgically Induced Astigmatism of ma nual SICS to phaco surgery but not much has been done to compare various techniques in manua l SICS itself. In this study an attempt has been made to analyze t he role of incision site depending on the pre operative keratometry readings in reducing su rgically induced astigmatism in manual small incision cataract surgery.

  16. Contribution of the gradient refractive index and shape to the crystalline lens spherical aberration and astigmatism.

    Science.gov (United States)

    Birkenfeld, Judith; de Castro, Alberto; Ortiz, Sergio; Pascual, Daniel; Marcos, Susana

    2013-06-28

    The optical properties of the crystalline lens are determined by its shape and refractive index distribution. However, to date, those properties have not been measured together in the same lens, and therefore their relative contributions to optical aberrations are not fully understood. The shape, the optical path difference, and the focal length of ten porcine lenses (age around 6 months) were measured in vitro using Optical Coherence Tomography and laser ray tracing. The 3D Gradient Refractive Index distribution (GRIN) was reconstructed by means of an optimization method based on genetic algorithms. The optimization method searched for the parameters of a 4-variable GRIN model that best fits the distorted posterior surface of the lens in 18 different meridians. Spherical aberration and astigmatism of the lenses were estimated using computational ray tracing, with the reconstructed GRIN lens and an equivalent homogeneous refractive index. For all lenses the posterior radius of curvature was systematically steeper than the anterior one, and the conic constant of both the anterior and posterior positive surfaces was positive. In average, the measured focal length increased with increasing pupil diameter, consistent with a crystalline lens negative spherical aberration. The refractive index of nucleus and surface was reconstructed to an average value of 1.427 and 1.364, respectively, for 633 nm. The results of the GRIN reconstruction showed a wide distribution of the index in all lens samples. The GRIN shifted spherical aberration towards negative values when compared to a homogeneous index. A negative spherical aberration with GRIN was found in 8 of the 10 lenses. The presence of GRIN also produced a decrease in the total amount of lens astigmatism in most lenses, while the axis of astigmatism was only little influenced by the presence of GRIN. To our knowledge, this study is the first systematic experimental study of the relative contribution of geometry and GRIN to

  17. Effectiveness of Toric Orthokeratology in the Treatment of Patients with Combined Myopia and Astigmatism

    Science.gov (United States)

    Lyu, Byul; Hwang, Kyu Yeon; Kim, Sun Young; Kim, Su Young

    2016-01-01

    Purpose The purpose of this multi-institute, single-group clinical trial was to evaluate the effectiveness and safety of toric orthokeratology lenses for the treatment of patients with combined myopia and astigmatism. Methods A total of 44 patients were included in this clinical trial. The patients ranged in age from 7 to 49 years, with myopia of -0.75 to -6.0 diopters (D) and astigmatism of 1.25 to 4.0 D. After excluding 21 subjects, 23 subjects (39 eyes) were analyzed after toric orthokeratology lens use. The subjects underwent ophthalmologic examination after 1 day and 1, 2, 3, and 4 weeks of wearing overnight toric orthokeratology lenses. Results A total of 19 subjects (31 eyes) completed the trial after five subjects (eight eyes) dropped out. In the patients who completed the study by wearing lenses for 4 weeks, the myopic refractive error decreased significantly by 2.60 ± 2.21 D (p refractive error were also significantly decreased by 0.63 ± 0.98 D (p = 0.001), from 2.07 ± 0.83 to 1.44 ± 0.99 D. The mean uncorrected and corrected visual acuities before wearing the lenses were 2.14 ± 0.80 logarithm of the logMAR (logMAR) and 0.05 ± 0.13 logMAR, respectively, which changed to 0.12 ± 0.30 logarithm of the logMAR (p correcting visual acuity in patients with combined myopia and astigmatism. PMID:27980362

  18. Flexible Toric Iris Claw Phakic Intraocular Lens Implantation for Myopia and Astigmatism

    Directory of Open Access Journals (Sweden)

    Mohammad Ghoreishi

    2014-01-01

    Full Text Available Purpose: To assess the visual and refractive outcomes of flexible toric iris claw phakic intraocular lens implantation for correction of moderate to high myopia with astigmatism. Methods: In this non-randomized prospective study, 31 eyes of 18 patients including 8 male and 10 female subjects with mean age of 27.62±5.53 (range 19 to 38 years with moderate to high myopia and astigmatism underwent toric Artiflex (Ophtec BV, Groningen, Netherlands phakic intraocular lens (PIOL implantation. Uncorrected distance visual acuity (UDVA and corrected distance visual acuity (CDVA were measured in logarithm of minimum angle of resolution (logMAR notations. Manifest refraction, safety, efficacy, predictability and complications were measured 6 months after surgery. Results: Pre-operatively, mean spherical equivalent (SE refractive error was -9.68±1.92 (range -14.00 to -6.00 diopter (D and mean cylinder was -2.79±1.06 (range -4.75 to -1.00 D. After a minimum of 6 months, mean SE was -0.38±0.27 (range -0.87 to 0.00 D and mean cylinder was -0.66±0.43 (range -1.50 to 0.00 D. SE was within 0.50 D of emmetropia in 63.8% and within 1.0 D of target refraction in 100% of eyes. UDVA was equal or better than 20/20 in 45.1% of eyes while CDVA was equal or better than 20/20 in 67.7%; 83.8% of eyes gained 1 or more Snellen lines of CDVA after surgery. No serious complications occurred in this series of cases. Conclusions: Implantation of the toric Artiflex PIOL is a safe and effective procedure for correction of moderate to high myopia with astigmatism.

  19. SURGICALLY INDUCED ASTIGMATISM AFTER IMPLANTATION OF FOLDABLE AND NON - FOLDABLE LENSES IN CATARACT SURGERY BY PHACOEMULSIFICATION

    Directory of Open Access Journals (Sweden)

    Vikas

    2015-01-01

    Full Text Available This prospective comparative study included 300 matched patients of different grades of senile cataract. All of them willfully underwent phacoemulsification at the hands of a single experienced surgeon, performing with a single and individual technique {Woodcutter’s technique 1 }; half of them were implanted with a foldable intraocular lens and the other half with a non - foldable PMMA intraocular lens. All the patients undergoing phacoemulsification had an improvement in vision. There was no statistically significant difference in the surgically induced astigmatism after implanting foldable or non - foldable IOL

  20. Toric Intraocular Lenses in the Correction of Astigmatism During Cataract Surgery

    DEFF Research Database (Denmark)

    Kessel, Line; Andresen, Jens; Tendal, Britta

    2016-01-01

    TOPIC: We performed a systematic review and meta-analysis to evaluate the benefit and harms associated with implantation of toric intraocular lenses (IOLs) during cataract surgery. Outcomes were postoperative uncorrected distance visual acuity (UCDVA) and distance spectacle independence. Harms were...... literature search in the Embase, PubMed, and CENTRAL databases within the Cochrane Library. We included randomized clinical trials (RCTs) if they compared toric with non-toric IOL implantation (± relaxing incision) in patients with regular corneal astigmatism and age-related cataracts. We assessed the risk...

  1. Comparison of clinical outcomes between limbal relaxing incisions and toric intraocular lenses in eyes with astigmatic corneas

    Directory of Open Access Journals (Sweden)

    Giuliano de Oliveira Freitas

    2014-01-01

    Full Text Available Objective: To compare refractive and vectorial outcomes of limbal relaxing incisions (LRI versus toric intraocular lenses (IOL in the treatment of preexisting corneal astigmatism at the time of phacoemulsification. Methods: This longitudinal observational case series assessed 62 eyes of 31 consecutive cataract patients with preoperative corneal astigmatism between 0.75 and 2.50 diopters in both eyes. Patients were randomly assorted in two groups: one assigned to receive AcrySof Toric™ IOL in both eyes, and another one assigned to have AcrySof Natural™ IOL associated with LRI, also in both eyes. All patients were re-evaluated, postoperatively, at 1, 3 and 6 months, when refractive astigmatism analysis was performed using vectorial methods proposed by Thibos. Variability of outcomes within each group and between groups were assessed and compared. Results: Manifest refractive cylinder, in diopters (D, as means ± standard deviation, in the LRI group for 1-month, 3-month and 6-month re-evalutions were respectively -0.66 ± 0.30; -0.70 ± 0.21 and -0.74 ± 0.26 when compared to -0.58 ± 0.24; -0.63 ± 0.20, and -0.62 ± 0.17 in the toric IOL group. (p value ≥ 0.06. Vectorial analysis evidenced greater astigmatism reduction in the toric IOL group in the 6th postoperative month, when postoperative mean astigmatic power vector was 0.31 D, when compared to 0.37 D in the LRI group (p value = 0.00. Conclusions: A trend of slightly better refractive outcomes favoring toric IOL group was seen, although such a trend was not statistically significant. Vectorial analysis, however, suggests that the use of toric IOL may constitute a more advantageous approach in the treatment of pre-existing corneal astigmatism, simultaneously with phacoemulsification.

  2. A COMPARATIVE STUDY OF THE AMOUNT OF ASTIGMATISM FOLLOWING CONVENTIONAL EXTRACAPSULAR CATARACT EXTRACTION AND MANUAL SMALL INCISION CATARACT SURGERY

    Directory of Open Access Journals (Sweden)

    Rajkumari Bigyabati

    2016-06-01

    Full Text Available BACKGROUND Cataract is the principal cause of avoidable blindness in India and throughout the world. Surgical removal of the cataractous lens remains the only effective treatment for management of cataract blindness. The success of cataract surgery is determined by best and earliest visual recovery. But the occurrence of postoperative astigmatism has become a major hurdle in achieving this goal. AIMS The study was designed to compare the amount of astigmatism following conventional extracapsular cataract extraction (ECCE and manual small incision cataract surgery (SICS. MATERIALS AND METHODS The study was carried out in 100 eyes of 75 patients aged between 50 and 80 years admitted for cataract surgery. Out of these, 50 eyes were operated by conventional extracapsular cataract extraction and 50 eyes by manual small incision cataract surgery. The patients were followed up at 2 nd , 4 th , 6 th and 8 th weeks. At each follow-up visual acuity, refraction and acceptance and keratometry were recorded and the findings analysed for astigmatism. RESULTS In the current study, the mean (SD astigmatism developed at the end of the 2 nd , 4 th and 6 th of follow-up was significantly lower in the SICS group as compared to the ECCE group (P<0.000. At the end of 8 weeks of follow-up, the mean (SD astigmatism of the SICS group was 0.64±0.56 D as compared to the mean (SD of the ECCE group of 1.39±86 D and the difference was found to be significant (p<0.014. CONCLUSION The current study concludes that manual small incision cataract surgery is a better technique to control postoperative astigmatism than conventional extracapsular cataract extraction.

  3. Optimization of nonimaging focusing heliostat in dynamic correction of astigmatism for a wide range of incident angles.

    Science.gov (United States)

    Chong, Kok-Keong

    2010-05-15

    To overcome astigmatism has always been a great challenge in designing a heliostat capable of focusing the sunlight on a small receiver throughout the year. In this Letter, a nonimaging focusing heliostat with a dynamic adjustment of facet mirrors in a group manner has been analyzed for optimizing the astigmatic correction in a wide range of incident angles. This what is to the author's knowledge a new heliostat is not only designed to serve the purpose of concentrating sunlight to several hundreds of suns, but also to significantly reduce the variation of the solar flux distribution with the incident angle.

  4. Independent control of beam astigmatism and ellipticity using a SLM for fs-laser waveguide writing.

    Science.gov (United States)

    Ruiz de la Cruz, A; Ferrer, A; Gawelda, W; Puerto, D; Sosa, M Galván; Siegel, J; Solis, J

    2009-11-09

    We have used a low repetition rate (1 kHz), femtosecond laser amplifier in combination with a spatial light modulator (SLM) to write optical waveguides with controllable cross-section inside a phosphate glass sample. The SLM is used to induce a controllable amount of astigmatism in the beam wavefront while the beam ellipticity is controlled through the propagation distance from the SLM to the focusing optics of the writing set-up. The beam astigmatism leads to the formation of two separate disk-shaped foci lying in orthogonal planes. Additionally, the ellipticity has the effect of enabling control over the relative peak irradiances of the two foci, making it possible to bring the peak irradiance of one of them below the material transformation threshold. This allows producing a single waveguide with controllable cross-section. Numerical simulations of the irradiance distribution at the focal region under different beam shaping conditions are compared to in situ obtained experimental plasma emission images and structures produced inside the glass, leading to a very satisfactory agreement. Finally, guiding structures with controllable cross-section are successfully produced in the phosphate glass using this approach.

  5. Characterization of a tunable astigmatic fluidic lens with adaptive optics correction for compact phoropter application

    Science.gov (United States)

    Fuh, Yiin-Kuen; Huang, Chieh-Tse

    2014-07-01

    Fluidically controlled lenses which adaptively correct prescribed refractive error without mechanically moving parts are extensively applied in the ophthalmic applications. Capable of variable-focusing properties, however, the associated aberrations due to curvature change and refractive index mismatch can inherently degrade image quality severely. Here we present the experimental study of the aberrations in tunable astigmatic lens and use of adaptive optics to compensate for the wavefront errors. Characterization of the optical properties of the individual lenses is carried out by Shack-Hartmann measurements. An adaptive optics (AO) based scheme is demonstrated for three injected fluidic volumes, resulting in a substantial reduction of the wavefront errors from -0.12, -0.25, -0.32 to 0.01, -0.01, -0.20 μm, respectively, corresponding to the optical power tenability of 0.83 to 1.84 D. Furthermore, an integrated optical phoroptor consisting of adjustable astigmatic lenses and AO correction is demonstrated such that an induced refraction error of -1 D cylinder at 180° of a model eye vision is experimentally corrected.

  6. FASTDEF: fast defocus and astigmatism estimation for high-throughput transmission electron microscopy.

    Science.gov (United States)

    Vargas, J; Otón, J; Marabini, R; Jonic, S; de la Rosa-Trevín, J M; Carazo, J M; Sorzano, C O S

    2013-02-01

    In this work we present a fast and automated algorithm for estimating the contrast transfer function (CTF) of a transmission electron microscope. The approach is very suitable for High Throughput work because: (a) it does not require any initial defocus estimation, (b) it is almost an order of magnitude faster than existing approaches, (c) it opens the way to well-defined extensions to the estimation of higher order aberrations, at the same time that provides defocus and astigmatism estimations comparable in accuracy to well established methods, such as Xmipp and CTFFIND3 approaches. The new algorithm is based on obtaining the wrapped modulating phase of the power spectra density pattern by the use of a quadrature filter. This phase is further unwrapped in order to obtain the continuous and smooth absolute phase map; then a Zernike polynomial fitting is performed and the defocus and astigmatism parameters are determined. While the method does not require an initial estimation of the defocus parameters or any non-linear optimization procedure, these approaches can be used if further refinement is desired. Results of the CTF estimation method are presented for standard negative stained images, cryo-electron microscopy images in the absence of carbon support, as well as micrographs with only ice. Additionally, we have also tested the proposed method with micrographs acquired from tilted and untilted samples, obtaining good results. The algorithm is freely available as a part of the Xmipp package [http://xmipp.cnb.csic.es].

  7. Astigmatism management in cataract surgery with Precizon® toric intraocular lens: a prospective study

    Science.gov (United States)

    Vale, Carolina; Menezes, Carlos; Firmino-Machado, J; Rodrigues, Pedro; Lume, Miguel; Tenedório, Paula; Menéres, Pedro; Brochado, Maria do Céu

    2016-01-01

    Purpose The purpose of this study was to evaluate the visual and refractive outcomes and rotational stability of the new aspheric Precizon® toric intraocular lens (IOL) for the correction of corneal astigmatism in cataract surgery. Setting Department of Ophthalmology, Hospital Geral de Santo António – Centro Hospitalar do Porto, EPE and Hospital de Pedro Hispano, Matosinhos, Portugal. Design This was a prospective clinical study. Patients and methods A total of 40 eyes of 27 patients with corneal astigmatism greater than 1.0 diopter (D) underwent cataract surgery with implantation of Precizon® toric IOL. IOL power calculation was performed using optical coherence biometry (IOLMaster®). Outcomes of uncorrected (UDVA) and best-spectacle corrected distance visual acuities (BCDVA), refraction, and IOL rotation were analyzed at the 1st week, 1st, 3rd, and 6th month’s evaluations. Results The median postoperative UDVA was better than preoperative best-spectacle corrected distance visual acuity (0.02 [0.06] logMAR vs 0.19 [0.20] logMAR, P<0.001). At 6 months, postoperative UDVA was 0.1 logMAR or better in 95% of the eyes. At last follow-up, the mean spherical equivalent was reduced from −3.35±3.10 D to −0.02±0.30 D (P<0.001) with 97.5% of the eyes within ±0.50 D of emmetropia. The mean preoperative keratometric cylinder was 2.34±0.95 D and the mean postoperative refractive cylinder was 0.24±0.27 D (P<0.001). The mean IOL rotation was 2.43°±1.55°. None of the IOLs required realignment. Conclusion Precizon® toric IOL revealed very good rotational stability and performance regarding predictability, efficacy, and safety in the correction of preexisting regular corneal astigmatism associated with cataract surgery. PMID:26855559

  8. Visual performance in cataract patients with low levels of postoperative astigmatism: full correction versus spherical equivalent correction

    Directory of Open Access Journals (Sweden)

    Lehmann RP

    2012-03-01

    Full Text Available Robert P Lehmann1, Diane M Houtman21Lehmann Eye Center, Nacogdoches, TX, 2Alcon Research Ltd, Fort Worth, TX, USAPurpose: To evaluate whether visual performance could be improved in pseudophakic subjects by correcting low levels of postoperative astigmatism.Methods: An exploratory, noninterventional study was conducted using subjects who had been implanted with an aspheric intraocular lens and had 0.5–0.75 diopter postoperative astigmatism. Monocular visual performance using full correction was compared with visual performance using spherical equivalent correction. Testing consisted of high- and low-contrast visual acuity, contrast sensitivity, and reading acuity and speed using the Radner Reading Charts.Results: Thirty-eight of 40 subjects completed testing. Visual acuities at three contrast levels (100%, 25%, and 9% were significantly better using full correction than when using spherical equivalent correction (all P < 0.001. For contrast sensitivity testing under photopic, mesopic, and mesopic with glare conditions, only one out of twelve outcomes demonstrated a significant improvement with full correction compared with spherical equivalent correction (at six cycles per degree under mesopic without glare conditions, P = 0.046. Mean reading speed was numerically faster with full correction across all print sizes, reaching statistical significance at logarithm of the reading acuity determination (logRAD 0.2, 0.7, and 1.1 (P , 0.05. Statistically significant differences also favored full correction in logRAD score (P = 0.0376, corrected maximum reading speed (P < 0.001, and logarithm of the minimum angle of resolution/logRAD ratio (P < 0.001.Conclusions: In this study of pseudophakic subjects with low levels of postoperative astigmatism, full correction yielded significantly better reading performance and high- and low-contrast visual acuity than spherical equivalent correction, suggesting that cataractous patients may benefit from surgical

  9. Analysis of familial aggregation in total, against-the-rule, with-the-rule, and oblique astigmatism by conditional and marginal models in the Tehran eye study

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    Mohammad H Rakhshani

    2012-01-01

    Full Text Available Purpose: The purpose was to determine the familial aggregation of the total, against-the-rule (ATR, with-the-rule (WTR, and oblique astigmatism by conditional and marginal models in the Tehran Eye Study. Materials and Methods: Total, ATR, WTR, and oblique astigmatism were studied in 3806 participants older than 5 years from August 2002 to December 2002 in the Tehran Eye Study. Astigmatism was defined as a cylinder worse than or equal to −0.5 D. WTR astigmatism was defined as 0 ± 19°, ATR astigmatism was defined as 90 ± 19°, and oblique when the axes were 20-70° and 110-160°. The familial aggregation was investigated with a conditional model (quadratic exponential and marginal model (alternating logistic regression after controlling for confounders. Results: Using the conditional model, the conditional familial aggregation odds ratios (OR (95% confidence interval for the total, WTR, ATRs, and oblique astigmatism were 1.49 (1.43-1.72, 1.91 (1.65-2.20, 2.00 (1.70-2.30, and 1.86 (1.37-2.54, respectively. In the marginal model, the marginal OR of the parent-offspring and sib-sib in the total astigmatism were 1.35 (1.13-1.63 and 1.54 (1.13-2.11, respectively; WTR 1.53 (1.06-2.20 and 1.94 (1.21-3.13 and; ATR 2.13 (1.01-4.50 and 2.23 (1.52-3.30. The model was statistically significant in sib-sib relationship only for oblique astigmatism with OR of 3.00 (1.25-7.20. Conclusion: The results indicate familial aggregation of astigmatism in the population in Tehran adjusted for age, gender, cataract, duration of education, and body mass index, so that the addition of a new family member affected with astigmatism, as well as having a sibling or parents with astigmatism, significantly increases the odds of exposure to the disease for all four phenotypes. This aggregation can be due to genetic and/or environmental factors. Dividing astigmatism into three phenotypes increased the odds ratios.

  10. Extended wavelet transformation to digital holographic reconstruction: application to the elliptical, astigmatic Gaussian beams.

    Science.gov (United States)

    Remacha, Clément; Coëtmellec, Sébastien; Brunel, Marc; Lebrun, Denis

    2013-02-01

    Wavelet analysis provides an efficient tool in numerous signal processing problems and has been implemented in optical processing techniques, such as in-line holography. This paper proposes an improvement of this tool for the case of an elliptical, astigmatic Gaussian (AEG) beam. We show that this mathematical operator allows reconstructing an image of a spherical particle without compression of the reconstructed image, which increases the accuracy of the 3D location of particles and of their size measurement. To validate the performance of this operator we have studied the diffraction pattern produced by a particle illuminated by an AEG beam. This study used mutual intensity propagation, and the particle is defined as a chirped Gaussian sum. The proposed technique was applied and the experimental results are presented.

  11. Digital in-line holography for the characterization of flowing particles in astigmatic optical systems

    Science.gov (United States)

    Sentis, Matthias P. L.; Bruel, Laurent; Charton, Sophie; Onofri, Fabrice R. A.; Lamadie, Fabrice

    2017-01-01

    An extended Generalized Fresnel Transform (GFT) is proposed to account for the astigmatism introduced by optical elements described, in the paraxial approximation, with a ray transfer matrix analysis. Generalized impulse response and generalized Fresnel transfer function propagators as well as sampling conditions are derived to properly implement this transformation. As a test case, the near-field diffraction patterns and in-line holograms produced by droplets flowing in a tube with cylindrical interfaces have been simulated. A best fitting approach is introduced to retrieve, from the propagated holograms, the 3D position and size of the droplets. Several hologram focusing indicators based on the analysis of droplets focus region are also proposed to further improve the estimation of the droplets position along the optical axis. Numerical simulations and experimental results confirm the applicability and accuracy of the proposed methods.

  12. Relaxation in Thin Polymer Films Mapped across the Film Thickness by Astigmatic Single-Molecule Imaging

    KAUST Repository

    Oba, Tatsuya

    2012-06-19

    We have studied relaxation processes in thin supported films of poly(methyl acrylate) at the temperature corresponding to 13 K above the glass transition by monitoring the reorientation of single perylenediimide molecules doped into the films. The axial position of the dye molecules across the thickness of the film was determined with a resolution of 12 nm by analyzing astigmatic fluorescence images. The average relaxation times of the rotating molecules do not depend on the overall thickness of the film between 20 and 110 nm. The relaxation times also do not show any dependence on the axial position within the films for the film thickness between 70 and 110 nm. In addition to the rotating molecules we observed a fraction of spatially diffusing molecules and completely immobile molecules. These molecules indicate the presence of thin (<5 nm) high-mobility surface layer and low-mobility layer at the interface with the substrate. (Figure presented) © 2012 American Chemical Society.

  13. Focal plane internal energy flows of singular beams in astigmatically aberrated low numerical aperture systems.

    Science.gov (United States)

    Bahl, Monika; Senthilkumaran, P

    2014-09-01

    Singular beams have circulating energy components. When such beams are focused by low numerical aperture systems suffering from astigmatic aberration, these circulating energy components get modified. The phase gradient introduced by this type of aberration splits the higher charge vortices. The dependence of the charge, the aberration coefficient, and the size of the aperture on the nature of the splitting process are reported in this paper. The transverse components of the Poynting vector fields that can be derived from the phase gradient vector field distributions are further decomposed into solenoidal and irrotational components using the Helmholtz-Hodge decomposition method. The solenoidal components relate to the orbital angular momentum of the beams, and the irrotational components are useful in the transport of intensity equations for phase retrieval.

  14. Orbital angular moment of a partially coherent beam propagating through an astigmatic ABCD optical system with loss or gain.

    Science.gov (United States)

    Cai, Yangjian; Zhu, Shijun

    2014-04-01

    We derive the general expression for the orbital angular momentum (OAM) flux of an astigmatic partially coherent beam carrying twist phase [i.e., twisted anisotropic Gaussian-Schell model (TAGSM) beam] propagating through an astigmatic ABCD optical system with loss or gain. The evolution properties of the OAM flux of a TAGSM beam in a Gaussian cavity or propagating through a cylindrical thin lens are illustrated numerically with the help of the derived formula. It is found that we can modulate the OAM of a partially coherent beam by varying the parameters of the cavity or the orientation angle of the cylindrical thin lens, which will be useful in some applications, such as free-space optical communications and particle trapping.

  15. Toric Intraocular Lens vs. Peripheral Corneal Relaxing Inci-sions to Correct Astigmatism in Eyes Undergoing Cataract Surgery

    Institute of Scientific and Technical Information of China (English)

    Zhiping Liu; Xiangyin Sha; Xuanwei Liang; Zhonghao Wang; Jingbo Liu; Danping Huang

    2014-01-01

    Purpose:.To compare toric intraocular lens implantation (Toric-IOL).with peripheral corneal relaxing incisions (PCRIs) for astigmatism correction in patients undergoing cataract surgery. Methods: 54 patients (54 eyes) with more than 0.75 diopter (D).of preexisting corneal astigmatism were classified as group A (0.75-1.50D) or group B (1.75-2.50D). The patients were randomized to undergo Toric-IOL or PCRIs in the steep axis with spherical IOL implantation..LogMAR uncorrected visual acuity (LogMAR UCVA), LogMAR best corrected vi sual acuity.(LogMAR BCVA),.error of vector (|EV|), surgery induced refraction correction. (|SIRC|),.and correction rates (CR) were measured 1 month and 6 months postoperatively. Results: At 6 months postoperatively, all 54 eyes had Log-MAR BCVA≤0.2. Patients who underwent PCRIs and Toric-IOL with LogMAR BCVA≤0.1 showed no significant differ-ences in group A (P=1.00) or in group B (P=0.59). Group A showed no significant differences in LogMAR UCVA (P=0.70), |EV| (P=0.13), |SIRC| (P=0.71), and CR (P=0.56) in patients underwent PCRIs and Toric-IOL. However, group B showed significant differences in LogMAR UCVA (P Conclusion:.The efficacy and stability of Toric-IOL and PCRIs were equal in low astigmatic patients..Toric-IOL achieved an enhanced effect over PCRIs in higher astigmatic patients. PCRIs had the more refractive regression than Toric-IOL in 6 months.

  16. CLINICAL ANALYSIS OF EXCIMER LASER PHOTOREFRACTIVE KERATECTOMY FOR TREATMENT OF MYOPIA AND MYOPIC ASTIGMATISM

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    To evaluate the efficacy and accuracy of photorefractive keratectomy (PRK) for myopia and myopic astigmatism .SVS APEX excimer laser with a wave length of 193 nm(Sumit Technology Inc. Waltham, Mass, USA) was applied. 316 myopic eyes of 168 patients were treated with PRK between September, 1996 and October, 1997, and 260 eyes (84%) of 150 patients were followed for more than three months, including male 68(116 eyes, 40.1%) and female 82(144 eyes, 59.9%). The preoperative spherical equivalent refractive errors ranged from -1.25D to -10.00 (mean -4.67±1.63D), and astigmatism ranged from 0 to -2.00D (means -0.33±0.45D). We divided the patients into two groups according to the referaction: group A (from -1.25D to -5.90D) and group B(from -6.00 to -10.00D). The number of eyes in the two groups were 220 and 40 respectively. In group A, on the 10th day, 68.9% has the uncorrected visual acuity (UCVA) equal to or one line better or lower than the preoperative best corrected visual acuity (BCVA). In 1,3,6 and 12 months, 90%, 96%, 95% and 94% had the UCVA equal to or one line better or lower than the preoperative BCVA respectively. In group B, on the 10 th day, in 1,3,6 and 12 months, UCVA equal to or one line better or lower than the preoperative BCVA occurred in 35.9%, 83%, 87%, 86%, and 84% of the cases respectively. Most of the haze showed 0.5~1 grades except 3 eyes with the haze of 2 grade in 3 or 6 months and it changed to 1 and 0.5 grade respectively within one year. In 10 days and 1,3,6,12 months postoperatively, the corneal haze was noted in 32.9%, 84.8%, 62.8%,9.0% and 2.8% of the treated eyes respectively. We found that 193 nm excimer laser PRK was a predictable, safe, stable, and effective refractive surgery for correcting myopia up to -10.00D in Chinese patients, and the effect was better in myopia lower than -6.00D.

  17. Surgically induced astigmatism after 3.0 mm temporal and nasal clear corneal incisions in bilateral cataract surgery

    Directory of Open Access Journals (Sweden)

    Je Hwan Yoon

    2013-01-01

    Full Text Available Aims: To compare the corneal refractive changes induced after 3.0 mm temporal and nasal corneal incisions in bilateral cataract surgery. Materials and Methods: This prospective study comprised a consecutive case series of 60 eyes from 30 patients with bilateral phacoemulsification that were implanted with a 6.0 mm foldable intraocular lens through a 3.0 mm horizontal clear corneal incision (temporal in the right eyes, nasal in the left eyes. The outcome measures were surgically induced astigmatism (SIA and uncorrected visual acuity (UCVA 1 and 3 months, post-operatively. Results: At 1 month, the mean SIA was 0.81 diopter (D for the temporal incisions and 0.92 D for nasal incisions (P = 0.139. At 3 months, the mean SIA were 0.53 D for temporal incisions and 0.62 D for nasal incisions (P = 0.309. The UCVA was similar in the 2 incision groups before surgery, and at 1 and 3 months post-operatively. Conclusion: After bilateral cataract surgery using 3.0 mm temporal and nasal horizontal corneal incisions, the induced corneal astigmatic change was similar in both incision groups. Especially in Asian eyes, both temporal and nasal incisions (3.0 mm or less would be favorable for astigmatism-neutral cataract surgery.

  18. Peculiarities of vernier monocular and binocular visual acuity in the retinal orthogonal meridians in patients with hypermetropic astigmatism

    Directory of Open Access Journals (Sweden)

    Владимир Александрович Коломиец

    2015-06-01

    Full Text Available It was carried out an examination of meridional vernier visual acuity in 100 patients 7-25 years old with a simple and compound hypermetropic astigmatism and refractive ambyiopia. An astigmatic component of refraction was in range 0,5- 2,5 dptr. Visual acuity on the sighting eyes after correction was 0,9- 1,0, on eyes with amblyopia 0,4 - 0,85 relative units.Methods. Visual acuity was defined by the Landolt rings of Sivtsev table. Vernier visual acuity was defined in seconds of arc from 5 km, using special computer program.Result. It was demonstrated that in patients with the simple hypertropic astigmatism diagnosis of meridional amblyopia can be specified by the comparison of data of monocular and binocular vernier visual acuity in orthogonal meridians of retinas.Conclusions. An effect of the rise of meridional binocular visual acuity in one of meridians and its absence in another one allows define selective meridional disturbances of the visual acuity

  19. Comparison of surgically induced astigmatism in patients with horizontal rectus muscle recession

    Institute of Scientific and Technical Information of China (English)

    Harun; akmak; Tolga; Kocatürk; Sema; Oru; Dündar

    2014-01-01

    ·AIM: To compare surgically induced astigmatism(SIA)following horizontal rectus muscle recession surgery between suspension recession with both the "hang-back" technique and conventional recession technique.·METHODS: Totally, 48 eyes of 24 patients who had undergone horizontal rectus muscle recession surgery were reviewed retrospectively. The patients were divided into two groups. Twelve patients were operated on by the hang-back technique(Group 1), and 12 by the conventional recession technique(Group 2). SIA was calculated on the 1stwk, 1stand in the 3rdmo after surgery using the SIA calculator.·RESULTS: SIA was statistically higher in the Group 1all postoperative follow-up. SIA was the highest in the 1st wk, and decreased gradually in both groups.·CONCLUSION: The suspension recession technique induced much more SIA than the conventional recession technique. This difference also continued in the following visits. Therefore, the refractive power should be checked postoperatively in order to avoid refractive amblyopia.Conventional recession surgery should be the preferred method so as to minimize the postoperative refractive changes in patients with amblyopia.

  20. Macroscopic three-dimensional particle location using stereoscopic imaging and astigmatic aberrations.

    Science.gov (United States)

    Fuchs, Thomas; Hain, Rainer; Kähler, Christian J

    2014-12-15

    This Letter presents a stereoscopic imaging concept for measuring the locations of particles in three-dimensional space. The method is derived from astigmatism particle tracking velocimetry (APTV), a powerful technique that is capable of determining 3D particle locations with a single camera. APTV locates particle xy coordinates with high accuracy, while the particle z coordinate has a larger location uncertainty. This is not a problem for 3D2C (i.e., three dimensions, two velocity components) measurements, but for highly three-dimensional flows, it is desirable to measure three velocity components with similar accuracy. The stereoscopic APTV approach discussed in this report has this capability. The technique employs APTV for giving an initial estimate of the particle locations. With this information, corresponding particle images on both sensors of the stereoscopic imaging system are matched. Particle locations are then determined by mapping the two particle image sensor locations to physical space. The measurement error of stereo APTV, determined by acquiring images of 1-μm DEHS particles in a 40 mm×40 mm×20 mm measurement volume in air at Δxyz→0 between two frames, is less than 0.012 mm for xy and 0.025 mm for z. This error analysis proves the excellent suitability of stereo APTV for the measurement of three-dimensional flows in macroscopic domains.

  1. Clinical analysis of myopia astigmatism of children aged 6-15%6-15岁儿童近视性散光的临床分析

    Institute of Scientific and Technical Information of China (English)

    段思琦; 李静姣; 钟华; 周华; 田琨; 魏嘉

    2015-01-01

    Objective To study the occurrence of astigmatism,astigmatism type,astigmatism power and astig-matism axis distrubution among 6-15 years old children,and analyzes its rule.Methods From 2012 to the first half of the 2014, 710 cases of 6-15 years old children with glasses admitted in the Ophtalmic Outpatient Clinic were enrolled in this study.In which the clinical data of 483 cases (749 eyes) with myopia astigmatism were statistically analyzed. Results Myopia astigmatism were 483 cases (749 eyes) and the detection rate was 68.03%. There were 247 cases of male and 236 cases of female,accounted for 51.14% and 48.86%. Astigmatism type has no significant difference in the age group (Χ2=3.418, P>0.05). In AWR, the 6-12 age group was 221 cases (63.14%), the 13-15 age group was 129 cases (36.86%). Astigmatism type has a significant difference in the myopic astigmatism power group (Χ2=28.878, P0.05).在顺规散光中6-12岁年龄组221例(63.14%),13-15岁年龄组129例(36.86%).各散光类型在不同近视性散光度组的发病率有明显统计学差异(Χ2=28.878, P<0.001);轻度散光组中,顺规散光315例(66.60%),逆规散光99例(20.93%),斜向散光59例(12.47%).顺规散光在轻度散光组315例(57.48%),中度散光组160例(29.20%),高度散光组73例(13.32%).各散光类型在不同屈光状态组的发病率有统计学差异(Χ2=612.598,P <0.05).顺规散光在复合近视散光组303例(86.57%),单纯近视散光组47例(13.43%).结论 近视性散光在6-15岁儿童中普遍存在,双眼较单眼发病率高,低度散光占大多数,复合近视散光较单纯近视散光更为常见.

  2. Transmissive liquid-crystal device correcting primary coma aberration and astigmatism in laser scanning microscopy

    Science.gov (United States)

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2016-03-01

    Laser scanning microscopy allows 3D cross-sectional imaging inside biospecimens. However, certain aberrations produced can degrade the quality of the resulting images. We previously reported a transmissive liquid-crystal device that could compensate for the predominant spherical aberrations during the observations, particularly in deep regions of the samples. The device, inserted between the objective lens and the microscope revolver, improved the image quality of fixed-mouse-brain slices that were observed using two-photon excitation laser scanning microscopy, which was originally degraded by spherical aberration. In this study, we developed a transmissive device that corrects primary coma aberration and astigmatism, motivated by the fact that these asymmetric aberrations can also often considerably deteriorate image quality, even near the sample surface. The device's performance was evaluated by observing fluorescent beads using single-photon excitation laser scanning microscopy. The fluorescence intensity in the image of the bead under a cover slip tilted in the y-direction was increased by 1.5 times after correction by the device. Furthermore, the y- and z-widths of the imaged bead were reduced to 66% and 65%, respectively. On the other hand, for the imaged bead sucked into a glass capillary in the longitudinal x-direction, correction with the device increased the fluorescence intensity by 2.2 times compared to that of the aberrated image. In addition, the x-, y-, and z-widths of the bead image were reduced to 75%, 53%, and 40%, respectively. Our device successfully corrected several asymmetric aberrations to improve the fluorescent signal and spatial resolution, and might be useful for observing various biospecimens.

  3. Intraocular lens implantation for the treatment of astigmatism%人工晶状体植入术矫正散光

    Institute of Scientific and Technical Information of China (English)

    施俊廷; 徐雯

    2013-01-01

    Refractive intraocular lens surgery can be used for the treatment of moderate and high regular astigmatism.Refractive intraocular lens surgery includes aphakic intraocular lens surgery and phakic intraocular lens surgery.In phakic intraocular lens surgery two types of intraocular lenses are used:iris-claw intraocular lens and posterior chamber intraocular lens.The purpose of this article is to review current knowledge of surgical treatments of astigmatism with a particular focus on toric implantable collamer lenses.%人工晶状体(IOL)植入术能矫正中、高度规则散光.矫正散光的IOL植入术可分为无晶状体眼及有晶状体眼的环曲面IOL植入两类,其中有晶状体眼的环曲面IOL又可分为虹膜夹持型及后房型.本文旨在介绍IOL矫正散光的手术治疗方法,并着重介绍有晶状体眼植入后房型IOL矫正屈光不正合并散光的治疗技术.

  4. Computation of astigmatic and trefoil figure errors and misalignments for two-mirror telescopes using nodal-aberration theory.

    Science.gov (United States)

    Ju, Guohao; Yan, Changxiang; Gu, Zhiyuan; Ma, Hongcai

    2016-05-01

    In active optics systems, one concern is how to quantitatively separate the effects of astigmatic and trefoil figure errors and misalignments that couple together in determining the total aberration fields when wavefront measurements are available at only a few field points. In this paper, we first quantitatively describe the impact of mount-induced trefoil deformation on the net aberration fields by proposing a modified theoretical formulation for the field-dependent aberration behavior of freeform surfaces based on the framework of nodal aberration theory. This formulation explicitly expresses the quantitative relationships between the magnitude of freeform surfaces and the induced aberration components where the freeform surfaces can be located away from the aperture stop and decentered from the optical axis. On this basis, and in combination with the mathematical presentation of nodal aberration theory for the effects of misalignments, we present the analytic expressions for the aberration fields of two-mirror telescopes in the presence of astigmatic primary mirror figure errors, mount-induced trefoil deformations on both mirrors, and misalignments. We quantitatively separate these effects using the analytical expressions with wavefront measurements at a few field points and pointing errors. Valuable insights are provided on how to separate these coupled effects in the computation process. Monte Carlo simulations are conducted to demonstrate the correctness and accuracy of the analytic method presented in this paper.

  5. Comparative assessment of astigmatism-corrected Czerny-Turner imaging spectrometer using off-the-shelf optics

    Science.gov (United States)

    Yuan, Qun; Zhu, Dan; Chen, Yueyang; Guo, Zhenyan; Zuo, Chao; Gao, Zhishan

    2017-04-01

    We present the optical design of a Czerny-Turner imaging spectrometer for which astigmatism is corrected using off-the-shelf optics resulting in spectral resolution of 0.1 nm. The classic Czerny-Turner imaging spectrometer, consisting of a plane grating, two spherical mirrors, and a sensor with 10-μm pixels, was used as the benchmark. We comparatively assessed three configurations of the spectrometer that corrected astigmatism with divergent illumination of the grating, by adding a cylindrical lens, or by adding a cylindrical mirror. When configured with the added cylindrical lens, the imaging spectrometer with a point field of view (FOV) and a linear sensor achieved diffraction-limited performance over a broadband width of 400 nm centered at 800 nm, while the maximum allowable bandwidth was only 200 nm for the other two configurations. When configured with the added cylindrical mirror, the imaging spectrometer with a one-dimensional field of view (1D FOV) and an area sensor showed its superiority on imaging quality, spectral nonlinearity, as well as keystone over 100 nm bandwidth and 10 mm spatial extent along the entrance slit.

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

    Directory of Open Access Journals (Sweden)

    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

  7. ASTIGMATIC OUTCOME & POST OPERATIVE RECOVERY IN PAT IENTS UNDERGOING PTERYGIUM EXCISION WITH CONJUNCTIVAL AUTOGRAFTS. COMPARISION BETWEEN SUTURE & AUTOLOGUS BLOOD FIBRIN

    Directory of Open Access Journals (Sweden)

    Smita Dileep

    2013-06-01

    Full Text Available ABSTRACT : AIMS: To review the effect of surgery type on the postop erative recovery & astigmatism in pterygium surgery. SETTINGS AND DESIGN: Randomized comparative clinical trial. MATERIALS AND METHODS: Forty six patients (46 eyes with primary pterygiu m were randomised to undergo pterygium surgery using eithe r autologous fibrin glue (23 eyes or 10-0 nylon sutures (23 eyes to attach the conjunctival autograft. The patients were followed up 1day, 1wk, 2wks & 6 w eeks. Outcome measures were keratometry changes & postope rative recovery.. The preoperative and postoperative keratometric measurements, evaluated using keratometer, were noted. RESULTS: Corneal astigmatism was significantly reduced in th e total group from 2.94(SD- 0.52 diopter to 1.91 (sd 0.57 diopter (p 0.05. The intensity of the postoperative watering, itchin g, were significantly lower in the autologous fibrin glue group than in the suture gro up (p<0.001. Postoperative redness was absent in 47.82% (11cases and mild in 52.18% (13 cases 2 weeks postoperatively in the autologous fibrin group while in sutured group 17.4% (4cases had mild redness and 82.6% (19 cases had moderate redness 2weeks postoperatively.

  8. Research progress of correction of cornea astigmatism after cataract extraction%白内障术后角膜散光矫正的研究进展

    Institute of Scientific and Technical Information of China (English)

    杨宁

    2012-01-01

    随着白内障手术由复明手术向屈光手术的转变,角膜散光已成为影响白内障术后裸眼视力的主要因素之一.矫正术前存在的角膜散光,控制手术源性散光,是解决白内障术后因散光导致的术后视力不佳的有效方法.本文将对控制和矫正白内障术后散光的治疗进展进行综述.%Cataract operation has evolved from pure vision improvement toward the optics for reducing refractive errors. The main factor affecting naked vision of postoperative cataract surgery is cornea astigmatism . To correct cornea astigmatism and decrease surgically induced astigmatism are required for resolving problems of post cataract operative refraction and improving visual acuity. The research progress of reducing and correcting astigmatism after cataract extraction was summarized in this paper.

  9. Genome-wide association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the CREAM consortium

    NARCIS (Netherlands)

    Q. Li (Qing); R. Wojciechowski (Robert); C.L. Simpson (Claire); P.G. Hysi (Pirro); V.J.M. Verhoeven (Virginie); M.K. Ikram (Kamran); R. Höhn (René); V. Vitart (Veronique); A.W. Hewit (Alex); K. Oexle (Konrad); K.M. Makela (Kari Matti); S. MacGregor (Stuart); M. Pirastu (Mario); Q. Fan (Qiao); C-Y. Cheng (Ching-Yu); B. St Pourcain (Beate); G. Mcmahon (George); J.P. Kemp (John); K. Northstone (Kate); J.S. Rahi (Jugnoo); P. Cumberland (Phillippa); N.G. Martin (Nicholas); P.G. Sanfilippo (Paul G.); Y. Lu (Yi); Y. Wang (Ying); C. Hayward (Caroline); O. Polasek (Ozren); H. Campbell (Harry); G. Bencic (Goran); A. Wright (Alan); J. Wedenoja (Juho); T. Zeller (Tanja); A. Schillert (Arne); A. Mirshahi (Alireza); K.J. Lackner (Karl); S.P. Yip (Shea Ping); M.K.H. Yap (Maurice K. H.); J.S. Ried (Janina); C. Gieger (Christian); D. Murgia (Daniela); J.F. Wilson (James F); B.W. Fleck (Brian W.); S. Yazar (Seyhan); J.R. Vingerling (Hans); A. Hofman (Albert); A.G. Uitterlinden (André); F. Rivadeneira Ramirez (Fernando); N. Amin (Najaf); L.C. Karssen (Lennart); B.A. Oostra (Ben); X. Zhou (Xin); Y.Y. Teo (Yik Ying); E.S. Tai (Shyong); E.N. Vithana (Eranga); V.A. Barathi (Veluchamy); Y. Zheng (Yingfeng); R. Siantar (Rosalynn); K. Neelam (Kumari); Y. Shin (Youchan); J. Lam (Janice); E. Yonova-Doing (Ekaterina); C. Venturini (Cristina); S.M. Hosseini (S Mohsen); H.-S. Wong (Hoi-Suen); T. Lehtimäki (Terho); M. Kähönen (Mika); O. Raitakari (Olli); N. Timpson (Nicholas); D.M. Evans (David M.); C.C. Khor; T. Aung (Tin); T.L. Young (Terri); P. Mitchell (Paul); B.E.K. Klein (Barbara); C.M. van Duijn (Cock); T. Meitinger (Thomas); J.B. Jonas (Jost B.); P.N. Baird (Paul); D.A. Mackey (David); T.Y. Wong (Tien); S-M. Saw (Seang-Mei); O. Pärssinen (Olavi); D.E. Stambolian (Dwight); C.J. Hammond (Christopher); C.C.W. Klaver (Caroline); C. Williams (Cathy); A.D. Paterson (Andrew); J.E. Bailey-Wilson (Joan E.); J. Guggenheim (Jean)

    2015-01-01

    textabstractTo identify genetic variants associated with refractive astigmatism in the general population, meta-analyses of genome-wide association studies were performed for: White Europeans aged at least 25 years (20 cohorts, N = 31,968); Asian subjects aged at least 25 years (7 cohorts, N = 9,295

  10. SURGICALLY INDUCED ASTIGMATISM AFTER 2.8 MM TEMPORAL AND NASAL CLEAR CORNEAL INCISIONS IN PHACOEMULSIFICATION CATARACT SURGERY OF SAME PATIENT

    Directory of Open Access Journals (Sweden)

    Preeti

    2015-04-01

    Full Text Available PURPOSE: To evaluate and compare the surgically induced astigmatism in phacoemulsification cataract surgery after 2.8 mm temporal and nasal clear corneal incision of same patient . MATERIAL AND METHOD : This prospective study comprised a consecutive case series of 60 eyes. Eyes from 30 patients with phacoemulsification those were implanted with a 6.00 mm foldable intraocular le ns through a 2.8 mm horizontal clear corneal incision (temporal in the right eye , nasal in the left eye. RESULTS : T he outcome measures were surgically induced astigmatism (SIA and uncorrected visual acuity (UCVA , at 1 and 3 months post - operatively. A 1 month the mean SIA was 0.81 D. for the temporal incision and 0.92 D for nasal incision (P = 0.139 at 3 months the mean SIA was 0.53 D for temporal incision and 0.62 D for nasal incision (P =0.309. The pre - operative parameters i.e. (UCVA , mean keratomet ry & keratometric cylinder between these groups were comparable. There was no statistically significant difference found between three groups pre - operatively . CONCLUSION : After cataract surgery using 2.8mm temporal and nasal horizontal corneal incision , t he induced corneal astigmatic changes was similar in both incision groups. Especially in Asian eyes , both temporal and nasal incisions (2.8 mm or less would be equally favourable for astigmatism neutral cataract surgery

  11. Changes in Refractive Trends Error of Children with Mixed Astigmatism%儿童混合性散光的屈光演变

    Institute of Scientific and Technical Information of China (English)

    杨小梅; 杨发斌; 师文; 左芸; 胡雪篱

    2011-01-01

    Objective To investigate changes in refractive trends error of children with mixed astigmatism.Method Sixty three patients (113 eyes) with mixed astigmatism between 3 and 16 years of age were confirmed as mixed astigmatism with cycloplegic retinoscopy.Participates were performed optometric examination annually over a 3 year period.Refractive status data were collected and trends of in refractive error changes were analyzed.Result The astigmatic values remained stable over three year period (F =0.175,P =0.840),which indicated the maximum and minimum refractive trends errors could help the evolvement.There was a statistically highly significant difference in degrees of spherical lens that appeared to gradually decreased (F =14.151,P =0.000).Conclusions Refractive status can evolve into myopia as growth and development of ocular optical components in children with mixed astigmatism.Early screening and cum correction is advantageous to the children with mixed astigmatism.It is also highly recommend that cycloplegic retinoscopy is a very important and necessary method for diagnosis and therapy of children with mixed astigmatism.%目的 了解混合性散光儿童屈光发展的变化规律.方法 选择门诊初诊的3~16岁儿童63例(113只眼),使用睫状肌麻痹剂检影验光后确诊为混合性散光,每年验光1次,将其连续3年的屈光结果进行追踪观察.结果 3年来散光度数改变不明显(F =0.175,P=0.840),说明其最大和最小屈光子午线的屈光状态在同步发展.而远视球镜度数逐渐降低,其差异显著有统计学意义(F =14.151,P=0.000).结论 混合性散光的儿童,随年龄增长及眼球发育,屈光状态逐渐降低甚至会向近视方向发展.该类患儿如能早期戴镜矫正,可获得较满意的视力.必须强调使用睫状肌麻痹剂检影验光对儿童混合性散光的必要性和重要性.

  12. Surgical induced astigmatism correlated with corneal pachymetry and intraocular pressure: transconjunctival sutureless 23-gauge versus 20-gauge sutured vitrectomy in diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Yan; Shao; Li-Jie; Dong; Yan; Zhang; Hui; Liu; Bo-Jie; Hu; Ju-Ping; Liu; Xiao-Rong; Li

    2015-01-01

    AIM: To determine the difference of surgical induced astigmatism between conventional 20-gauge sutured vitrectomy and 23-gauge transconjunctival sutureless vitrectomy, and the influence of corneal pachymetry and intraocular pressure(IOP) on surgical induced astigmatism in diabetic patients.METHODS: This retrospective, consecutive case series consisted of 40 eyes of 38 diabetic subjects who underwent either 20-gauge or 23-gauge vitrectomy. The corneal curvature and thickness were measured with Scheimpflug imaging before surgery and 1wk; 1, 3mo after surgery. We compared the surgical induced astigmatism(SIA) on the true net power in 23-gauge group with that in 20-gauge group. We determined the correlation between corneal thickness change ratio, IOP and SIA measured by Pentacam. RESULTS: The mean SIAs were 1.082 ±0.085 D( mean ± SEM), 0.689 ±0.070 D and 0.459 ±0.063 D at postoperative 1wk; 1, 3mo respectively in diabetic subjects. The vitrectomy induced astigmatisms were declined significantly with time(F2,36=33.629, P =0.000)postoperatively. The 23-gauge surgery group induced significantly less astigmatism than 20-gauge surgery group(F1,37=11.046, P =0.020). Corneal thickness in diabetes elevated after surgery(F3,78=10.532, P =0.000).The linear regression analysis at postoperatively 1wk went as: SIA =-4.519 +4.931 change ratio(Port3) +0.026IOP(R2=0.46, P =0.000), whereas the rate of cornealthickness change and IOP showed no correlation with the change of astigmatism at postoperatively 1 and 3mo.CONCLUSION: There are significant serial changes in both 20-gauge and 23-gauge group in diabetic subjects.23-gauge induce less astigmatism than 20-gauge and become stable more rapidly than 20-gauge. The elevation of corneal thickness and IOP was associated with increased astigmatim at the early postoperative stage both in 23-gauge and 20-gauge surgery group.

  13. 儿童高度近视性散光与眼轴长度相关性分析%A correlation analysis on children’s high myopic astigmatism and axial length

    Institute of Scientific and Technical Information of China (English)

    胡丰平; 魏春惠; 金卫平

    2014-01-01

    Objective To study the Correlation between high myopic astigmatism and axial length.Methods 148 eyes of 93 cases with high myopic astigmatism were studied,whose eye’s total astigmatism,corneal astigmatism and axial length were measured,and their cor-relation were also analyzed.Results The mean eye’s total astigmatism is (4.04 ±1.27)D,the mean corneal astigmatism is (3.74 ±1.08) D,the mean axial length is (24.23 ±1.32)mm in 148 eyes of93 cases.The Pearson Correlation Analysis was used to analyze all ofthe above data.There is no obvious correlation between the astigmatism and the axial length.Conclusion There is no obvious correlation between the astigmatism and the axial length.%目的:了解儿童高度近视性散光度与眼轴长度有无关联性。方法对93例(148眼)高度近视性散光儿童散光度和眼轴长度进行测量,分析散光度与眼轴长度之间的相关性。结果93例148眼的眼总合散光度平均为(4.04±1.27)D,角膜散光度平均为(3.74±1.08)D;眼轴长度平均为(24.23±1.32)mm,经Pearson相关分析,散光度与眼轴长度相关性没有统计学意义。结论儿童高度近视散光度与眼轴长度没有相关性。

  14. An auto-tuning method for focusing and astigmatism correction in HAADF-STEM, based on the image contrast transfer function.

    Science.gov (United States)

    Baba, N; Terayama, K; Yoshimizu, T; Ichise, N; Tanaka, N

    2001-01-01

    An auto-tuning method for high-angle annular detector dark field scanning transmission electron microscopy (HAADF-STEM) is proposed which corrects the defocus to the optimum Scherzer focus and compensates the astigmatism. Because the method is based on the image contrast transfer function formulated for the HAADF-STEM, the defocus and the astigmatism are accurately measured from input of two different defocus images. The method is designed to work independent of object function in the linear imaging model by analysing the spectral ratio between two Fourier spectra of their images, which is useful for cases where the spectrum of object function is not uniformly spread out over the reciprocal space. The method was preliminarily tested in a Hitachi HD-2000 STEM, and successful results of the auto-tunings from the viewpoint of verification of the algorithm were obtained using general specimens of Au fine particles and a thin section of a semiconductor device.

  15. Successful toric intraocular lens implantation in a patient with induced cataract and astigmatism after posterior chamber toric phakic intraocular lens implantation: a case report

    Directory of Open Access Journals (Sweden)

    Kamiya Kazutaka

    2012-04-01

    Full Text Available Abstract Introduction We report the case of a patient in whom simultaneous toric phakic intraocular lens removal and phacoemulsification with toric intraocular lens implantation were beneficial for reducing pre-existing astigmatism and acquiring good visual outcomes in eyes with implantable collamer lens-induced cataract and astigmatism. Case presentation A 53-year-old woman had undergone toric implantable collamer lens implantation three years earlier. After informed consent was obtained, we performed simultaneous toric implantable collamer lens removal and phacoemulsification with toric intraocular lens implantation. Preoperatively, the manifest refraction was 0, -0.5 × 15, with an uncorrected visual acuity of 0.7 and a best spectacle-corrected visual acuity of 0.8. Postoperatively, the manifest refraction was improved to 0, -0.5 × 180, with an uncorrected visual acuity of 1.2 and a best spectacle-corrected visual acuity of 1.5. No vision-threatening complications were observed. Conclusion Toric intraocular lens implantation may be a good surgical option for the correction of spherical and cylindrical errors in eyes with implantable collamer lens-induced cataract and astigmatism.

  16. Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2012-06-01

    Full Text Available Anastasios John KanellopoulosDepartment of Ophthalmology, New York University Medical School, New York, NY, and LaserVision.gr Eye Institute, Athens, GreeceBackground: The purpose of this study was to evaluate the safety and efficacy of topography-guided ablation using the WaveLight 400 Hz excimer laser in laser-assisted in situ keratomileusis (LASIK for hyperopia and/or hyperopic astigmatism.Methods: We prospectively evaluated 208 consecutive LASIK cases for hyperopia with or without astigmatism using the topography-guided platform of the 400 Hz Eye-Q excimer system. The mean preoperative sphere value was +3.04 ± 1.75 (range 0.75–7.25 diopters (D and the mean cylinder value was –1.24 ± 1.41 (–4.75–0 D. Flaps were created either with Intralase FS60 (AMO, Irvine, CA or FS200 (Alcon, Fort Worth, TX femtosecond lasers. Parameters evaluated included age, preoperative and postoperative refractive error, uncorrected distance visual acuity, corrected distance visual acuity, flap diameter and thickness, topographic changes, higher order aberration changes, and low contrast sensitivity. These measurements were repeated postoperatively at regular intervals for at least 24 months.Results: Two hundred and two eyes were available for follow-up at 24 months. Uncorrected distance visual acuity improved from 5.5/10 to 9.2/10. At 24 (8–37 months, 75.5% of the eyes were in the ±0.50 D range and 94.4% were in the ±1.00 D range of the refractive goal. Postoperatively, the mean sphere value was –0.39 ± 0.3 and the cylinder value was –0.35 ± 0.25. Topographic evidence showed that ablation was made in the visual axis and not in the center of the cornea, thus correlating with the angle kappa. No significant complications were encountered in this small group of patients.Conclusion: Hyperopic LASIK utilizing the topography-guided platform of the 400 Hz Eye-Q Allegretto excimer and a femtosecond laser flap appears to be safe and effective for

  17. Surgically induced astigmatism after phacoemulsification with and without correction for posture-related ocular cyclotorsion: randomized controlled study.

    LENUS (Irish Health Repository)

    Dooley, Ian

    2012-02-01

    PURPOSE: To report the impact of posture-related ocular cyclotorsion on one surgeon\\'s surgically induced astigmatism (SIA) results and the variance in SIA. SETTING: Institute of Eye Surgery, Whitfield Clinic, Waterford, Ireland. METHODS: This prospective randomized controlled study included eyes that had phacoemulsification with intraocular lens implantation. Eyes were randomly assigned to have (intervention group) or not have (control group) correction for posture-related ocular cyclotorsion. In the intervention group, the clear corneal incision was placed precisely at the 120-degree meridian with instruments designed to correct posture-related ocular cyclotorsion. In the control group, the surgeon endeavored to place the incision at the 120-degree meridian, but without markings. RESULTS: The intervention group comprised 41 eyes and the control group, 61 eyes. The mean absolute SIA was 0.74 diopters (D) in the intervention group and 0.78 D in the control group; the difference between groups was not statistically significant (P>.5, unpaired 2-tailed Student t test). The variance in SIA was 0.29 D(2) and 0.31 D(2), respectively; the difference between groups was not statistically significant (P>.5, unpaired F test). CONCLUSIONS: Attempts to correct for posture-related ocular cyclotorsion did not influence SIA or its variance in a single-surgeon series. These results should be interpreted with full appreciation of the limitations of currently available techniques to correct for posture-related ocular cyclotorsion in the clinical setting.

  18. LASIK for correcting irregular astigmatism and asymmetrical astigmatism guided by corneal topography%角膜地形图引导下准分子激光矫正角膜不规则散光及不对称性散光

    Institute of Scientific and Technical Information of China (English)

    吴震; 荆翠红; 韩九娥; 蔡娟娟; 李水仙; 王运红; 吴化宇

    2012-01-01

    目的 探讨角膜地形图引导下准分子激光个性化切削手术矫正角膜不规则散光及不对称性散光的效果和优缺点.方法 应用MEL - 70准分子激光仪及配套TOMEY -Ⅲ角膜地形图引导个性化切削系统进行准分子激光原位角膜磨镶术(LASIK)矫正不对称性或不规则角膜散光复性近视散光58例108眼.其中49例97眼为初次手术;另9例11眼为二次手术,系由不均匀切削、偏心切削或中央岛而形成的不规则散光.术前最佳矫正视力均值0.98±0.32;屈光度:球镜平均(-4.59±1.68)D,柱镜平均(-1.62±0.78)D.结果 108眼手术均顺利完成,无术中或术后并发症.术后角膜地形图显示:角膜中央3 mm切削深度平整、均匀,术后1周平均裸眼视力1.03 ±0.29.屈光度:球镜-0.50~+0.75D,平均(-0.35 ±0.29)D,柱镜0~- 0.75D,平均(-0.38 ±0.24)D.结论 TOMEY -Ⅲ角膜地形图捕捉角膜曲率信息准确,引导准分子激光个性化切削程序设计合理,系统安全可靠.用它来进行个性化LASIK可较为精确地矫正角膜不规则及不对称散光.%Objective To discuss the effect of laser in situ keratomileusis (LASIK) for correcting irregular astigmatism and asymmetrical astigmatism guided by corneal topographic map.Methods There were 58 cases( 108 eyes) with compound myopic astigmatism,asymmetric or irregular corneal astigmatism accepted LASIK under MEL- 70 excimer laser that guided by TOMEY-Ⅲ corneal topography.49 patients (97 eyes) received their first operation on the eye.9 patients ( 11 eyes) with irregular astigmatism due to uneven cutting,eccentric cutting or central island received the second operation on the same eye.The preoperative best corrected visual acuity was on average of 0.98 ± 0.32,Sphere ( - 4.59 ± 1.68 ) D,Cylinder ( - 1.62 ± 0.78) D.Results 108 operations were successfully finished without intraoperative or postoperative complications.Corneal topography showed the centra 3 mm cutting was depth uniform

  19. Artisan iris-fixated toric phakic and aphakic intraocular lens implantation for the correction of astigmatic refractive error after radial keratotomy.

    Science.gov (United States)

    Tahzib, Nayyirih G; Eggink, Fred A G J; Odenthal, Monica T P; Nuijts, Rudy M M A

    2007-03-01

    We report 2 patients who had radial keratotomy (RK) to correct myopia. The first patient developed a postoperative hyperopic shift and cataract. Nine years post RK, she had intracapsular cataract extraction and implantation of an Artisan aphakic intraocular lens (IOL). Twenty years post RK, hyperopia and astigmatism progressed to +7.0 -5.75 x 100 with a best corrected visual acuity (BCVA) of 20/20. Due to contact lens intolerance, the Artisan aphakic IOL was exchanged for an Artisan toric aphakic IOL. Three months later, the BCVA was 20/20 with +1.0 -0.50 x 130. The second patient demonstrated residual myopic astigmatism 6 years after bilateral RK and had become contact-lens intolerant. An Artisan toric phakic IOL was implanted in both eyes. Four months later, the BCVA was 20/25 with a refraction of +0.25 -1.0 x 135 and 20/20 with a refraction of -1.0 x 40. Both patients were satisfied with the visual outcomes.

  20. Combined special capsular tension ring and toric IOL implantation for management of post-DALK high regular astigmatism with subluxated traumatic cataract

    Directory of Open Access Journals (Sweden)

    Asim Kumar Kandar

    2014-01-01

    Full Text Available We report a case of 18-year-old male who has undergone phacoemulsification with implantation of toric IOL (AcrySof IQ SN6AT9 after fixation of lens capsule with Cionni′s capsular tension ring (CTR for subluxated traumatic cataract with high astigmatism after deep anterior lamellar keratoplasty (DALK. He underwent right eye DALK for advanced keratoconus four years earlier. He had history of trauma one year later with displaced clear crystalline lens into  anterior chamber and graft dehiscence, which was repaired successfully. The graft survived, but patient developed cataract with subluxated lens, for which phacoemulsification with implantation of toric IOL was done. Serial  topography showed regular corneal astigmatism of -5.50 diopter (K 1 42.75 D @130°, K 2 48.25 D @40°. At 10-month follow-up, the patient has BCVA 20/30 with + 0.75 DS/- 1.75 DC @ 110°. The capsular bag is quite stable with well-centered IOL. Combination of Cionni′s ring with toric IOL could be a good option to manage such complex cases.

  1. 白内障不同切口影响术后散光原因的分析%Analysis on the reason of impact on postoperative astigmatism of different incisions in cataract patients

    Institute of Scientific and Technical Information of China (English)

    霍璐; 张仲臣; 张佳楠

    2013-01-01

    With the increasing progress of cataract surgery, the postoperative residual astigmatism has become one of the factors that influence the desirable refractive outcome for patients. At present, the most commonly used cataract extraction is also traditional phacoemulsification cataract surgery with incision size of 3.2 mm. With the progress of Micro-incision cataract surgery (MICS), the postoperative residual astigmatism decreased. The different surgery induce different postoperative residual astigmatism. Through literature review, to analyze the causes of postoperative residual astigmatism by different incision cataract.%随着白内障手术的日益完美,术后散光成为影响患者术后理想屈光状态的主要原因之一。目前最常使用的白内障手术方法仍是切口大小为3.2mm的白内障超声乳化摘除联合人工晶体植入术,随着微小切口白内障手术的发展,术后散光相应减小。由于不同手术方式产生的术后散光不同,现通过文献回顾,综述不同切口影响白内障术后散光的原因并进行分析。

  2. Academic and Workplace-related Visual Stresses Induce Detectable Deterioration Of Performance, Measured By Basketball Trajectories and Astigmatism Impacting Athletes Or Students In Military Pilot Training.

    Science.gov (United States)

    Mc Leod, Roger D.

    2004-03-01

    Separate military establishments across the globe can confirm that a high percentage of their prospective pilots-in-training are no longer visually fit to continue the flight training portion of their programs once their academic coursework is completed. I maintain that the visual stress induced by those intensive protocols can damage the visual feedback mechanism of any healthy and dynamic system beyond its usual and ordinary ability to self-correct minor visual loss of acuity. This deficiency seems to be detectable among collegiate and university athletes by direct observation of the height of the trajectory arc of a basketball's flight. As a particular athlete becomes increasingly stressed by academic constraints requiring long periods of concentrated reading under highly static angular convergence of the eyes, along with unfavorable illumination and viewing conditions, eyesight does deteriorate. I maintain that induced astigmatism is a primary culprit because of the evidence of that basketball's trajectory! See the next papers!

  3. Simultaneous three-dimensional temperature and velocity field measurements using astigmatic imaging of non-encapsulated thermo-liquid crystal (TLC) particles.

    Science.gov (United States)

    Segura, Rodrigo; Rossi, Massimiliano; Cierpka, Christian; Kähler, Christian J

    2015-02-07

    A combination of cutting edge developments is presented to characterize three-dimensional (3D) temperature and velocity fields in microscopic flows. An emulsion of non-encapsulated thermo-liquid crystal (TLC) micro spheres, with a narrow size distribution is used to track the flow's motion and temperature distribution. A state-of-the-art light engine, which combines the spectrum of six light pipes, provides a balanced illumination which allows for strong and detectable color patterns across the TLC's temperature response range. Lastly, the ability of the TLC material to reflect select wavelength bands with an unchanging and independent circular polarization chirality is exploited by a filter that blocks background noise, while exclusively transmitting the color signal of the TLC particles. This approach takes advantage of the peculiar physical properties of TLCs to allow the estimation of individual TLC particle's 3D position, for the first time, using Astigmatism Particle Tracking Velocimetry (APTV).

  4. Astigmatism changes following hyperopia correction in accommodative esotropia children%调节性内斜视儿童远视矫正后的散光变化

    Institute of Scientific and Technical Information of China (English)

    孔香云; 王利华; 马鲁新

    2012-01-01

    Objective To assess the longitudinal changes in the astigmatism of children with accommodative esotropia.Methods Refractive errors were followed longitudinally for accommodative esotropia children complying with inclusion criteria.Cycloplegic refractions were performed using retinoscopy and full corrections were prescribed.The refractive data were analyzed for two groups of children based on their age at the time spectacles were first prescribed and then followed every year for at least 3 years.Astigmatism was analyzed using 90-180 degree astigmatism J180 and 45-135 degree astigmatism J45.Results Forty-four children were recruited aged 4.7±1.7 years with follow up of 4.3±1.4 years.In age group ≥2yrs <4yrs,the mean J180 was initially 0.35±0.34D and had a 0.28D and 0.20D increased at 2nd and 3rd year after glasses wearing,respectively.In ≥4yrs <8yrs age group,the mean J180 was initially 0.34±0.44D and had a 0.22D and 0.18D increased at 1st and 2nd year (P <0.05),respectively.J180 decreased to the initial level in later years for both groups.Over time,the mean J45 remained low level with little variation.Conclusions Astigmatism increases following prescribing and decreases to initial degree of astigmatism for children with accommodative esotropia and this change has no relation with their age when spectacle wear is initiated.Glasses wearing might influence the refractive development in certain time.%目的 观察调节性内斜视儿童远视矫正后的散光改变.方法 收集看远和看近内斜视10 PD以上、远视1.0 D以上、配戴足矫远视眼镜看远斜视度在10 PD以内的初诊病人;按初诊年龄分为≥2岁<4岁组和≥4岁<8岁组;根据睫状肌麻痹检影验光结果予以配戴足矫眼镜.每年再次验光,应用向量分解法,用90°~180°轴向的散光J180,及45°~135°轴向的散光J45作为散光统计指标.连续观察3年以上.结果 符合条件的调节性内斜视儿童共44

  5. The change of corneal astigmatism after cataract surgery with different locations of clear corneal incision%非球面和球面人工晶状体植入术后视功能观察

    Institute of Scientific and Technical Information of China (English)

    吴智敏; 徐国旭

    2011-01-01

    Objective To analyze the corneal astigmatism before cataract surgery and evaluate the astigmatism changes after cataract surgery performed using clear corneal incisions with different locations. Methods This randomized prospective clinical study comprised 295 eyes of 218 patients underwent phacoemulsification and implantation of foldable intraocular lens through a corneal tunnel incision. Patients were randomly divided into three groups depending on the different locations of the incision: temporal, superotemporal and superior. Corneal topography was performed preoperatively and 1week, 1 month, and 3 months postoperatively. Surgically induced changes were calculated by vector analyses using the Holladay-Cravy-Koch method. Results Preoperatively, in 60.68% of eyes, corneal astigmatism was between 0.5 and 1.5 diopters (D) and in 11.86%, it was 1.5 D or higher. Meanwhile,about 29.49 percent of eyes had with-the-rule (WTR) astigmatism, while 51.19% had against-the-rule (ATR) astigmatism, and the others had oblique astigmatism. At three follow-up visits postoperatively,the mean magnitude of surgically-induced astigmatism (SIA) was lowest in the temporal incision group and highest- in the superior incision group. In addition, an ATR shift was found in the superior incision group. Conclusions Corneal astigmatism less than 1.5 D is present in most cataract surgery candidates. Cataract surgery using temporal clear corneal incision induces significantly less SIA in the early postoperative period. Superior incision may lead to an ATR astigmatism shift.%目的 观察非球面人工晶状体和球面人工晶状体植入术后视功能的变化.方法 收集行超声乳化联合IOL植入术的年龄相关性白内障患者85例96只眼,其中植入非球面(Alcon SN60WF)IOL48只眼,植入球面(Alcon SN60AT)IOL48只眼,所有病例术后裸眼视力均>0.1,术后6个月对色觉、对比敏感度、表观调节力等视功能检查.结果 术后6个月Alcon SN60WF和SN60AT

  6. A clinical study of bandage soft contact lenses used as in Astigmatism%绷带型软性角膜接触镜对外伤性散光的应用研究

    Institute of Scientific and Technical Information of China (English)

    姜海峰; 张旭永; 姜慧君; 姜丽君

    2015-01-01

    目的 评价角膜穿通伤术后的患者配戴绷带型软性角膜接触镜对术后存在的角膜散光矫正的疗效.方法 对2014~2015年间入院行角膜穿通伤术后的患者54例54只眼,根据随机分为对照组(22例22只眼)和观察组(32例32只眼),观察组术后第二天即配戴绷带型软性角膜接触镜,持续21天,两组分别于术后第1天、第2天、第3天、第7天、第15天、30天、45天检查术眼裸眼视力(UC-VA)、最佳矫正视力(BCVA)、术后角膜散光及散光轴偏离情况.不同时间点的测量数据采用重复测量数据的方差分析,组间采用LSD检验.结果 对照组在术后各随访时间点的UCVA为平均(0.61±0.21,63)%≥0.5,41% ≥0.8,BCVA平均为(0.71 ±0.23,72)%≥0.5,60% ≥0.8.前15天角膜散光平均(3.64±1.34)D,30天散光平均(3.25±1.52)D,45天散光平均(2.87±1.43)D,散光轴位偏离为(3.65±1.79)°观察组在术后各随访时间点的UCVA平均为(0.73±0.25,85)%≥0.5,68%≥0.8,BC-VA平均为0.83±0.27,93%≥0.5,84% ≥0.8.前15天角膜散光平均(3.02±1.62)D,30天散光平均(2.37±1.63)D,45天散光平均(1.87±1.72)D,散光轴位偏离为(3.76±1.32)°.观察组散光均低于对照组,两组差异有统计学意义(P <0.001).结论 绷带型软性角膜接触镜对预防角膜穿通伤造成的散光及降低散光度数有有效、安全、简便的作用.%Objective To evaluate the effect of comeal penetrating injured patients who wear bandage soft contact lens for the therapy of postoperative corneal astigmatism correction.Methods Randomly divided the patients admitted corneal penetrating injury operation (54 cases 54 eye) between 2014 to 2015 into control group (22 cases 22 eye) and observation group (32 cases 32 eye),observation group wear bandages soft corneal contact lens second day after operation,continued for 21 days,two groups respectively check operation naked eye vision (UCVA),and best correction vision (BCVA

  7. Photorefractive keratectomy for myopia and myopic astigmatism correction using the WaveLight Allegretto Wave Eye-Q excimer laser system.

    Science.gov (United States)

    Costa, Esmeralda; Franqueira, Nuno; Rosa, Andreia M; Tavares, Cristina; Quadrado, Maria J; Lobo, Conceição; Murta, Joaquim N

    2014-06-01

    To analyze photorefractive keratectomy (PRK) outcomes in myopia and myopic astigmatism correction using the WaveLight Allegretto Wave Eye-Q(®) excimer laser system (WaveLight Laser Technologie AG, Erlangen, Germany). 222 eyes of 151 patients underwent PRK (mean age 33.5 ± 6.8 years). Pre-operative best spectacle-corrected visual acuity (BSCVA) ranged from 0.4 to -0.1 logMAR (mean -0.03 ± 0.06). Mean spherical equivalent (SE) was -3.29 ± 1.20 D. Efficacy, predictability and safety were evaluated. Minimum follow-up was 3 months. Accountability at 3 and 6 months was 100 and 54 %, respectively (median follow-up 5 months, mean 5.2 ± 2.6 months). At 3 months, mean uncorrected visual acuity (UCVA) was -0.02 ± 0.07 logMAR, BSCVA -0.03 ± 0.05 logMAR, efficacy index 0.98 and safety index 1.02. UCVA was ≥20/16 in 40.1 %, ≥20/20 in 86.5 % and ≥20/25 in 98.2 %. Mean SE was -0.02 ± 0.20 D. Residual refractive error was ± 0.13 D in 81.5 %, ± 0.25 D in 88.7 % and ± 0.50 D in 97.7 %. At 6 months, outcomes were similar: mean UCVA was -0.02 ± 0.07 logMAR, BSCVA -0.03 ± 0.06 logMAR, efficacy index 1.00 and safety index 1.03. UCVA was ≥20/16 in 43.7 %, ≥20/20 in 86.6 % and ≥20/25 in 96.6 %. Mean SE was -0.02 ± 0.17 D. Residual refractive error was ± 0.13 D in 86.6 %, ± 0.25 D in 93.3 % and ± 0.50 D in 98.3 %. Refractive stability was achieved at 3 months. No patient lost more than one line of BSCVA. There were no retreatments. The WaveLight Allegretto Wave Eye-Q is effective, predictable and safe in low-to-moderate myopia and myopic astigmatism PRK correction.

  8. Assessment of the effects of LASIK on astigmatism of-2.0D or above by corneal topography%LASIK手术治疗-2.0D以上散光的角膜地形图分析

    Institute of Scientific and Technical Information of China (English)

    周少博; 路晓明; 洪海烽; 苏小波; 黎健菁; 胡群英

    2010-01-01

    目的 利用角膜地形图评价LASIK治疗-2.0D以上散光疗效的准确性.方法 对25例(36只眼)散光度在-2.0D以上的近视散光患者于LASIK手术前后行角膜地形图和主觉验光检查,并将主觉验光测得的散光值换算成角膜平面的散光值,随访6月以上,比较手术前后角膜地形图测得的角膜散光的改变情况以及主觉验光所得的散光改变.结果 手术前后平均角膜地形图散光大小分别为(-2.29±0.61)D和(-1.91±0.68)D,主觉验光手术前后平均角膜平面的散光大小分别为(-2.22±0.61)D和(-0.46±0.43)D,两者手术前后差异均有统计学意义(P0.05),散光轴位平均差异为(6.53±14.19)度,而术后角膜地形图散光和术后显然验光角膜平面的散光大小差异有统计学意义(P=0.00).结论 角膜地形图测量术前-2.0D以上散光与主觉验光结果基本一致,但LASIK术后,角膜地形图往往高估术后的散光值.%Objective To investigate the accuracy of the effects of laser in situ keratomileusis (LASIK) on astigmatism of -2.0D or above assessed by corneal topography.Methods Thirty-six eyes of 25 patients with astigmatism of-2.0D or above who underwent LASIK were included in this retrospective study. Corneal topography and subjective refraction examination were performed before and at least 6 months after surgery.The astigmatism of subjective refraction was translated to cylinder diopter of corneal plane.Astigmatism measured with corneal topography and that of subjective refraction was compared before and after the surgery. Results The mean astigmatism measured by corneal topography was (-2.29±0.61) D and (-1.91±0.68) D pre- and postoperative respectively.The meaa astigmatism in corneal plane measured by manifest refraction was (-2.22±0.61) D and (-0.46±0.43) D pro- and postoperative respectively.The differences between pre- and post-operation were both statistically significant (P<0.05).The mean difference between pre- and post

  9. Glasses Principle and Treatment Effect of Amblyopia due to Mixed Astigmatism in Children%儿童混合性散光所致弱视的配镜原则和疗效观察

    Institute of Scientific and Technical Information of China (English)

    席斌; 梅妍

    2015-01-01

    探讨儿童混合性散光弱视的配镜原则和临床疗效.选择4~8岁混合性散光弱视儿童161例287眼,用1%阿托品散瞳验光配镜,并配合弱视治疗,连续5年观察屈光状态变化和弱视疗效.随访5年,所有患儿屈光状态呈现出远视等效球镜屈光度逐年减少;近视等效球镜屈光度逐年增加;散光度数及轴位基本不变的趋势.弱视有164(57.14%)只眼进步,102(35.54%)只眼基本痊愈,总有效率为266(92.68%)只眼,无效21(7.32%)只眼.混合性散光弱视的疗效与散光度数呈负相关,与戴镜治疗时间呈正相关.儿童混合性散光的配镜是难点,应根据儿童屈光特点及调节;眼位等情况综合考虑正确配镜,随着年龄增长,混合性散光有向单纯近视散光或复性近视散光发展的趋势,应每半年散瞳验光一次,及时调整镜片度数.同时配合弱视治疗能取得满意的疗效.%To explore glasses principle and treatment effect of amblyopia due to mixed astigmatism in chil-dren.287 eyes of 161 subjects with amblyopia due to mixed astigmatism aged from 4 years to 8 years are en-rolled.All cases are given mydriatic optometry by 1% atropine.Meanwhile,the amblyopia treatments are given as well.Follow -up measures include dioptric situation and amblyopia therapeutic effectiveness lasting for 5 years.Dioptric situation in all cases present that hyperopia spherical equivalent diopter decreases and myopia spherical equivalent diopter increases yearly.Degree and axis of astigmatism nearly keep unchanging.As to am-blyopia,164 eyes (57.14%) have improved,102 eyes (35.54%) have recovered nearly and 21 eyes (7.32%)have no improvement.The total effective rate is 266 cases (92.68%).The therapeutic effect of am-blyopia due to mixed astigmatism has a negative correlation with amblyopia degree and has a positive correlation with time of wearing glasses.The difficulty of children

  10. Observation of corneal astigmatism induced by 2.2mm micro-incision coaxial phacoemulsification%同轴微切口白内障超声乳化术后角膜散光的临床观察

    Institute of Scientific and Technical Information of China (English)

    林英杰; 梁先军; 何锦贤; 赵抒羽; 杨雪艳; 曾胜

    2013-01-01

    目的:评价2.2mm同轴微切口白内障超声乳化手术后角膜散光的变化.方法:老年性白内障患者56例78眼,将患者随机分为2组,2.2mm组38眼,3.0mm组40眼,分别行2.2mm同轴微切口白内障超声乳化联合人工晶状体(IOL)植入术及3.0mm常规白内障超声乳化联合IOL植入术,术后1,3mo评价术眼裸眼视力(uncorrected visual acuity,UCVA)、角膜散光、术源性角膜散光(surgically induced astigmatism,SIA).结果:术后1mo,2.2mm组角膜散光为0.85±0.42D,3.0mm组角膜散光为1.18±0.37D,两组角膜散光比较有统计学差异(P0.05).术后UCVA,在术后1mo和3mo,2.2mm组均优于3.0mm组.结论:2.2mm同轴微切口白内障超声乳化手术后能产生更小的SIA和更好的UCVA.%AIM: To evaluate the effect of 2. 2mm micro-incision coaxial phacoemulsification on corneal astigmatism and surgically induced astigmatism (SIA).METHODS: Fifty-six cataract patients (78 eyes) were randomized into two groups: 38 eyes in the 2. 2mm incision group and 40 eyes in the 3. Omm group. Torsional phacoemulsification was followed. Corneal astigmatism, SIA and uncorrected distance visual acuity (UCVA) were assessed at 30 and 90 days after cataract surgery.RESULTS: One month postoperatively, the corneal astigmatism of the 2.2mm group was 0.85±0.42D and the 3.0mm group was 1. 18 ± 0. 37D. Three months postoperatively, the corneal astigmatism of the 2. 2mm group was 0. 74 ± 0. 40D and the 3. Omm group was 1. 00 ± 0. 30D. One month and 3 months postoperatively, SIA of the 3. Omm group was greater than SIA of the 2. 2mm group ( P< 0. 05). In the 3. Omm group, mean SIA at 1 month was greater than SIA at 3 months ( P<0. 05), but SIA was similar. There was no statistical significance between the mean SIA between 1 month and 3 months. Postoperative UCVA was better in the 2. 2mm group at both 1 month and 3 months postoperatively.CONCLUSION; 2. 2mm micro - incision coaxial phacoemulsification contributed to postoperative corneal

  11. Comparison of corneal epithelial and stromal thickness distributions between eyes with keratoconus and healthy eyes with corneal astigmatism ≥ 2.0 D.

    Directory of Open Access Journals (Sweden)

    Wen Zhou

    Full Text Available PURPOSE: To identify corneal epithelial- and stromal-thickness distribution patterns in keratoconus using spectral-domain optical coherence tomography (SD-OCT. PATIENTS AND METHODS: We analyzed SD-OCT findings in 20 confirmed cases of keratoconus (group 1 and in 20 healthy subjects with corneal astigmatism ≥ 2 D (group 2. Epithelial and stromal thicknesses were measured at 11 strategic locations along the steepest and flattest meridians, previously located by corneal topography. Vertical mirrored symmetry superimposition was used in the statistical analysis. RESULTS: The mean maximum keratometry measurements in groups 1 and 2 were 47.9 ± 2.9 D (range, 41.8-52.8 and 45.6 ± 1.1 D (range, 42.3-47.5, respectively, with mean corneal cylinders of 3.3 ± 2.2 D (range, 0.5-9.5 and 3.6 ± 1.2 D (range, 2.0-6.4, respectively. The mean epithelial thickness along the steepest meridian in group 1 was the lowest (37.4 ± 4.4 µm at 1.2 mm inferotemporally and the highest (59.3 ± 4.4 µm at 1.4 mm supranasally from the corneal vertex. There was only a small deviation in thickness along the steepest meridian in group 2, as well as along the flattest meridians in both groups. The stromal thickness distribution in the two groups was similar to the epithelial, while the stromal thickness was generally lower in group 1 than in group 2. CONCLUSIONS: SD-OCT provides details about the distribution of corneal epithelial and stromal thicknesses. The epithelium and stroma in keratoconic eyes were thinner inferotemporally and thicker supranasally compared with control eyes. The distribution pattern was more distinct in epithelium than in stroma. This finding may help improve the early diagnosis of keratoconus. TRIAL REGISTRATION: ClinicalTrials.gov NCT02023619.

  12. 中国东北地区年龄相关性白内障患者角膜散光的分布情况调查%Prevalence of corneal astigmatism before cataract surgery in northeast China

    Institute of Scientific and Technical Information of China (English)

    郭作锋; 史庆成; 周衍文; 吴海娟; 李晶晶

    2016-01-01

    目的:观察和分析中国东北沈阳地区的白内障患者角膜散光的分布情况。  方法:利用回顾性研究方法观察2014年1月1日至2014年12月31日行白内障手术患者的术前角膜散光分布规律(利用IOL Master测量)。通过描述性方法分析角膜散光数据。  结果:研究包含3821名患者(平均年龄为66.36±10.38岁)4543眼。角膜散光3.0 D占8.58%。其中27.69%为顺规散光,53.84%为逆规散光。  结论:约59.46%患者的角膜散光≥1.0D。观察结果提示在白内障手术中,需要一些具有矫正散光功能的人工晶状体或特殊的手术技巧来矫正角膜散光,以保证患者术后视觉质量。%AlM: To analyze the prevalence and presentation patterns of corneal astigmatism in cataract surgery candidates of Shenyang in northeast China. METHODS:A retrospective survey was used to study the corneal astigmatism which were measured by intraocular lens( lOL) Master optical biometer before cataract surgery between Jan. 1st, 2014 and Dec. 31st, 2014. Descriptive statistics of corneal astigmatism data were analyzed. RESULTS:The keratometric data from 4 543 eyes from 3821 patients with a mean age of 66. 36±10. 38y(SD). ln 10. 50% of eyes, corneal astigmatism was between 0. 5 diopters(D) or less;in 30. 05% of eyes, it was 0. 5-1. 0 D;in 23. 60%, it was 1. 0-1. 5 D;in 13. 19%, it was 1. 5-2. 0 D;in 7. 68%, it was 2. 0-2. 5 D;in 6. 41%, it was 2. 5-3. 0 D;in 8. 58%, it was 3. 0 D or higher. With-the-rule astigmatism was found in 27. 69% of eyes, while against-the-rule was found in 53. 84% of eyes. CONCLUSlON:About 59. 46% of eyes in this study had preoperative corneal astigmatism equal to or above 1. 0 D. Findings indicated more surgical techniques or toric intraocular lenses to meet the potential demand of the cataract surgery candidates.

  13. Application of Rigid gas permeable contact lens for irregular astigmatism caused by corneal laceration%硬性透气性角膜接触镜矫正角膜裂伤愈合后的不规则散光

    Institute of Scientific and Technical Information of China (English)

    杨吟; 吴峥峥

    2015-01-01

    目的 研究硬性透气性角膜接触镜(RGP)对矫正角膜裂伤愈合后的不规则散光的作用.方法 角膜裂伤愈合后继发不规则散光20例(20眼),分别验配框架眼镜及RGP,记录其矫正视力,并在配戴RGP后随访观察3个月.结果 所有试验眼在配戴RGP后,较配戴框架眼镜视力平均提高(4.40±0.88)行(标准对数视力表).对比配戴框架眼镜,配戴RGP后的矫正视力明显提高,差异具有统计学意义(t =13.58,P=O.00).结论 配戴RGP能提高角膜裂伤愈合后不规则散光的患眼的视力.%Objective To study the effect of rigid gas permeable contact lens (RGP) on irregular astigmatism caused by corneal laceration.Methods twenty eyes of 20 patients with irregular astigmatism caused by corneal laceration were collected.The fram glasses and RGP fitting were performed,and the corrected visual acuity was recorded.The follow-up time was 3 months.Results Compared with wearing frame glasses,the corrected visual acuity of all the eyes had an average increase of (4..40 ±0.88)lines when wearing RGP.And the difference was statistically significant (t =13.58,P =0.00).Conclusion Wearing RGP could improve the visual acuity of eyes with irregular astigmatism caused by corneal laceration.

  14. 基于角膜生物力学性能的散光性角膜切开术有限元分析%Finite element analysis of astigmatic keratotomy based on corneal biomechanical properties

    Institute of Scientific and Technical Information of China (English)

    李智冬; 包芳军; 王勤美; 黄锦海

    2016-01-01

    Objective To establish a finite-element biomechanical model of astigmatic keratotomy, and to investigate the impact of surgical parameters on corneal deformation, stress distribution and astigmatism correction. Methods With Rhinoceros modeling and Abaqus finite element analysis software, a three-dimensional finite-element model of astigmatic cornea was developed, and surgical parameters such as incision optical zone, incision depth and length were varied. Postoperative corneal stress, apical deformation and astigmatism correction were assessed. Results A significant increase of stress was noticed near corneal incisions, and maximum corneal stress decreased with the increase of incision depth. Both anterior and posterior corneal surface moved slightly forward postoperatively. Maximum corneal stress was 340 392, 361 022 and 214 187 Pa, and anterior and posterior apical deformation was 49.80, 51.64, 55.53 μm and 54.15, 55.91, 59.67μm, with 45°, 60° and 90° in arc length of the incision, respectively. The refractive power decreased in steep meridian and increased in flat meridian, resulting in a total decrease of corneal astigmatism. The magnitude of astigmatism correction was 0.85, 1.59, 2.23 and 3.06 D with 30°, 45°, 60° and 90° in arc length of the incision, respectively. Conclusions The finite-element biomechanical model of astigmatic keratotomy could be used to predict the optical outcomes after surgery. The magnitude of astigmatism correction is positively correlated with the surgical incision arc length.%目的:建立散光性角膜切开术的有限元生物力学模型,初步研究各项手术参数对术后角膜形态改变、应力分布及散光矫正量的影响。方法采用Rhinoceros软件建立定量的散光角膜三维模型,设置不同的切口半径、切割深度、切口弧长等手术参数,模拟散光性角膜切开术,于Abaqus软件中完成有限元分析,得到模拟散光性角膜切开术后的角膜形态、节

  15. 闭眼和睡眠对人角膜地形和散光的影响研究%lmpact study of closing eyes and sleep on corneal topography and corneal astigmatism

    Institute of Scientific and Technical Information of China (English)

    袁韬; 陆静

    2015-01-01

    目的:观察不同时间长度闭眼和睡眠后角膜地形图、角膜散光等的变化,研究闭眼以及睡眠造成的生理性缺氧对人眼角膜形态的影响。  方法:选取年龄22~33(26.19±3.95)岁的自愿者,排除屈光介质疾病及眼部其他疾病、无角膜接触镜配戴史等,共16例32眼,其中男10眼,女22眼。主要参数采用了Zeiss角膜地形图仪获取角膜模拟K值、角膜散光值、角膜表面不规则指数( CIM )和形状因子( SF ),测量时间点分别为:日间闭眼前、闭眼后10,20,30,60,120 min;夜间临睡前、超过6h 的睡眠结束后,开眼立即检测、开眼后10,20,60,120 min。  结果:闭眼过程中,人角膜地形图、角膜散光、CIM、SF等的变化差异无统计学意义。在超过6h的睡眠结束,开眼后过程中,人角膜地形图、角膜散光、CIM、SF等的变化差异无统计学意义。  结论:闭眼和睡眠没有构成对角膜实质性损伤,所以角膜地形和散光基本不变。%•AlM: To observe the changes of corneal topography and astigmatism et al with various duration of closing eyes and sleep;and study the impact of closing eye and sleep causing physiological hypoxia on corneal topography. • METHODS: Sixteen volunteers were selected ( 32 eyes), 22-33 (26. 19 ± 3. 95) years old, without refractive errors and other eye diseases, as well as never wearing corneal contact lens, including 10 male eyes and 22 female eyes. The main parameters received corneal simulation K value, corneal astigmatism, corneal irregular measure ( ClM ) and the shape factor ( SF ) by Zeiss corneal topographer. They were measured before and after closed eyes 10, 20, 30, 60, 120min; before sleep and after over 6h sleep, they were detected immediately as soon as they opened eyes after 10, 20, 60, 120min. • RESULTS: During closing eyes, there were no statistical significance on the changes of corneal topography, corneal astigmatism, and SF. After opening

  16. 角膜地形图引导下白内障超乳手术对角膜散光的影响%Impact on corneal astigmatism during phacoemulsification guided by corneal Topography

    Institute of Scientific and Technical Information of China (English)

    陈艳; 张暹梅

    2009-01-01

    目的 观察角膜地形图引导白内障超声乳化术对角膜散光状态的影响.方法 对采用白内障超乳手术治疗的72例白内障患者进行观察,随机分为两组,34例角膜切口选择在角膜地形图垂直高曲率经线上,38例角膜切口选择在常规角膜12点左右方向,应用角膜地形图对手术前后角膜散光状态进行比较.结果根据角膜地形图曲率信息做角膜切口组散光度由术前的(1.11±0.36)D降低为术后3月的(0.96±0.32)D,常规12点左右方向角膜切口组散光度由术前的(1.08±0.54)D改变为术后3月的(1.36±0.43)D.根据角膜地形图曲率信息做角膜切口组术后1d和3月视力>0.5者27只眼(78.6%)和30只眼(87.4%),要多于常规12点左右方向角膜切口组27只眼(72.5%)和31只眼(80.4%).结论 根据角膜地形图的曲率信息在手术切口的方位和角度进行选择,可以减轻术后角膜的散光状态,对视力的恢复有益.%Objective To study the impact on corneal astigmatism during phacoemulsification guided by corneal topography.Methods The cohort consisted of 72 patients treated by phacoemulsification and intraocular lens implantation.All patients were divided into two groups randomly.Of 34 eyes were made corneal incision on the steepest meridian,while 38 eyes chose the line on the superior position.Corneal topography was used to compare the corneal astigmatism before and after operation.Results The group which made incision using curvature message in corneal topography had an astigmatism change from(1.11±0.36)D before operation to(0.96±0.32)D after operation.And in this group the vision of 27 eyes were above 0.5(78.6%)first day after operation and 30(87.4%)eyes 3 months after operation.The group which made incision on the superior position had an astigmatism change from(1.08±0.54)D before operation to(1.36±0.43)D after operation.In this group the vision of 27 eyes were above 0.5(72.5%)first day after operation and 31 eyes(80

  17. Clinical study on astigmatism of phacoemulsification incision decided by corneal topography%角膜地形图引导下的角膜切口白内障手术矫正角膜散光的研究

    Institute of Scientific and Technical Information of China (English)

    张欣; 王颖; 卢山; 何伟

    2010-01-01

    Objective To observe preoperative and postoperative astigmatism of corneal incision decided by the corneal topography. Methods A total of 240 eyes underwent phacoemulsification with corneal incision were randomly divided into three groups. Group A (80 eyes), incision at the steepest corneal meridian decided by corneal topography; group B (80 eyes), incision at 90 °; group C (80 eyes), incision at 180 °. Corneal astigmatism, visual changes of preoperative and 1 week, 1 month and 3 months postoperative were observed. Results Uncorrected visual acuity (>0.7) of group A were better than group B and C (P0.6) were the same in all three groups of the patients. Astigmatism of group A were significantly reduced (P 0.05). Astigmatism of group A were significantly reduced (P <0.05) 1 week, 1 month and 3 months postoperative compared with group B and group C (P <0.05). Conclusions The incision which located at the steepest corneal meridian under the guidance of corneal topography reduces the preoperative and postoperative astigmatism, and attains better uncorrected visual acuity postoperative.%目的 观察角膜地形图引导下的透明角膜切口白内障手术对术前及术后散光度的影响.方法 透明角膜切口晶状体超声乳化术240只眼,随机分成三组,每组80只眼.A组:切口位于角膜最大屈光轴方向;B组:切口位于90°方向;C组:切口位于180°方向.观察术前、术后1周、1月、3月角膜散光度和视力变化.结果 (1)A组术后1周、1月和3月裸眼视力> 0. 7者多于B组和C组(P < 0. 05);三组患者术后最佳矫正视力> 0. 6者基本相同.(2)A组患者术后1周、1月及3月与术前相比,散光度明显减小(P<0.01);术后1周与术后1月、3月相比,散光度也减小(P<0.05);而术后1月与3月相比,散光度基本相似(P>0.05).(3)A组与B组相比,术后1周、1月及3月时的散光度均明显减小(P<0.05);A组与C组相比,术后1周、1月及3月时

  18. 应用硬性透氧性隐形眼镜矫正不规则散光的疗效观察%Clinical efficacy of rigid gas permeable contact lens in the correction of irregular astigmatism

    Institute of Scientific and Technical Information of China (English)

    孙新成; 卢国华; 李如龙

    2012-01-01

    Objective To evaluate the clinical efficacy of rigid gas permeable contact lens (RGPCL)in the correction of mixed astigmatism. Methods Twenty - three patients (36 eyes) with irregular astigmatism confirmed by corneal topography were selected as subjects. Routine eye checks including slit lamp check, refractive error check and corneal topography were performed to exclude contraindications of RGPCL. Best corrective visual acuities with spectacles and with rigid gas permeable contact lens were analyzed. Results Corrective visual acuity of patients with RGPCL was (0. 73 ±0.31) and that with spectacles was (0. 48 ± 0. 30). The difference was statistically significant (P<0.01). No lasting complications were observed during the six- month follow - up. Conclusion RGPCL is an effective tool to correct irregular astigmatism and can improve corrected visual acuity.%目的 评价硬性透氧性隐形眼镜(RGP)矫正不规则散光的疗效.方法 对23例(34眼)做眼科检查,包括视力,裂隙灯检查及验光,角膜地形图检查.确诊为不规则散光,排除隐形眼镜佩戴禁忌证,进行硬性透氧性角膜接触镜验配,对其最佳框架矫正视力及RGP矫正视力进行统计学比较.结果 硬性透氧性角膜接触镜矫正不规则散光的最佳矫正视力(0.73±0.31),显著高于框架镜矫正值(0.48 ±0.30)(P<0.01),随访观察6个月视力稳定,无明显不良并发症.结论 RGP是矫正不规则散光有效安全方法,能够提高矫正视力及视觉质量.

  19. 硬性透气性接触镜矫治高度近视合并角膜散光%Clinical evaluation of rigid gas permeable contact lens for high myopia with corneal astigmatism

    Institute of Scientific and Technical Information of China (English)

    杨卫华; 毛良; 方晖; 孙元强

    2014-01-01

    AIM: To evaluate the effect of rigid gas permeable contact lens ( RGPCL ) for high myopia with corneal astigmatism. METHODS: Totally 72 patients ( 118 eyes ) with high myopia with corneal astigmatism were fitted with RGPCL, and the corrected visual acuity were recorded after one month. The MPMVA ( maximum plus to maximum visual acuity) were recorded by comprehensive refraction. The corrected visual acuity of RGPCL was compared with the MPMVA. RESULTS:There were 17 eyes of 4. 7 (14. 4%), 52 eyes of 4. 8 ( 44. 1%) and 49 eyes of 4. 9-5. 0 ( 41. 5%) in comprehensive refraction. There were 6 eyes of 4. 7 (5.1%), 21 eyes of 4. 8 (17. 8%) and 91 eyes of 4. 9-5. 0 ( 77. 1%) in RGPCL corrected visual acuity. RGPCL corrected visual acuity of (4. 9-5. 0) improved in 42 eyes (35. 6%), and the difference was statistically significant. CONCLUSION: The application of RGPCL can correct high myopia with corneal astigmatism, and has an excellent clinical result.%目的:评估硬性透气性接触镜( rigid gas permeable contact lens,RGPCL)对高度近视合并角膜散光的矫治效果。  方法:对高度近视合并角膜散光患者72例118眼验配RGPCL,1mo后复诊记录戴镜矫正视力。综合验光记录的最正之最佳矫正视力为对照。将RGPCL的最佳矫正视力与最正之最佳矫正视力比较。  结果:综合验光最正之最佳矫正视力情况,其中4.7共17眼(14.4%),4.8共52眼(44.1%),4.9~5.0共49眼(41.5%)。 RGPCL最佳矫正视力情况,其中4.7共6眼(5.1%),4.8共21眼(17.8%),4.9~5.0共91眼(77.1%)。 RGPCL 矫正视力4.9~5.0提高了42眼(35.6%),差异有统计学意义。  结论:RGPCL对高度近视合并角膜散光患者的矫治效果好。

  20. 圆锥角膜深板层角膜移植术后高度散光的角膜楔形切除术%Corneal wedge resection in treating progressive keratoconus astigmatism after deep anterior lamellar keratoplasty

    Institute of Scientific and Technical Information of China (English)

    毕燕龙; 吴名峰; 杜飞; 周祁; 金丽霞; 李厚硕; 黄玥晔

    2012-01-01

    Objective To investigate the clinical effect of corneal wedge resection to treat progressive keratoconus astigmatism after deep anterior lamellar keratoplasty (DALK).Methods Six cases (6 keratoconus eyes) after DALK with progressive astigmatism were retrospectively analyzed.A pair of symmetric or asymmetric host tissue wedge resections were made on the host cornea on the border of the graft - host interface.Naked or best corrected visual acuity,compute assisted refractive power examination,corneal topography were followed up for 36 months.Results Three years after corneal wedge resection,best corrected visual acuity changed from 0.62 ± 0.16 before surgery to 0.73 ± 0.16 after surgery ( P > 0.05 ).K value was progressed from 8.37 ± 2.91 before surgery to 2.86 ± 2.06 after surgery ( P < 0.01 ).Frame glasses were accepted by all the cases at the end of following up period.Conclusion Corneal wedge resection is an effective method in treating progressive keratoconus astigmatism after DALK.%目的 分析圆锥角膜深板层角膜移植术后高度散光行角膜楔形切除的临床疗效.方法 回顾性分析了圆锥角膜深板层角膜移植术后继发较高度散光的6例(6眼),采用对称或不对称的受体角膜植床组织楔形切除的方法治疗.随访内容为:裸眼视力、电脑验光结果、最佳矫正视力、角膜地形图结果.结果 术后3年,矫正视力由术前的0.62±0.16,增加到0.73 ±0.16(P>0.05).K散光由术前的(8.37±2.91)D,减低到(2.86±2.06)D(P <0.01).所有病例均能接受佩戴框架眼镜.结论 角膜楔形切除是矫正圆锥角膜深板层角膜移植术后高度散光的有效方法.

  1. Phakic posterior chamber intraocular lens implantation in high myopia with astigmatism%后房型有晶状体眼人工晶状体植入术治疗高度近视及散光

    Institute of Scientific and Technical Information of China (English)

    刘莉; 陈自新; 陈茂盛; 马金花; 陈荥培

    2011-01-01

    目的 探讨后房型有晶状体眼人工晶状体植入术治疗高度近视及散光的安全性和疗效性.方法 后房型有晶状体眼人工晶状体植人术治疗高度近视及散光22例39只眼.术前屈光度(等效球镜)为-7.0~-24.0D,平均(-14.50D±3.50)0;散光-0.50~-4.50D,平均(-2.25±1.32)D.术后检查视力、眼压、裂隙灯显微镜,前房角,前房深度,人工晶状体拱高,角膜内皮细胞计数.随访3-18个月.结果 术后3个月,38只眼视力达到或超过术前矫正视力.等效球境-0.50~-2.25D,平均(-0.75±0.38)D,散光度0.25~2.75D,平均(1.03±0.23)D,术后7只眼早期(2h后观察)眼压升高,经降眼压处理,24h内恢复正常.无一例出现青光眼、白内障、人工晶状体偏移及网脱等并发症.结论 后房型有晶状体眼人工晶状体植入术治疗高度近视及散光保留了生理性调节、并发症少、安全有效,是临床矫正高度近视散光比较理想的一种方法.%Objective To valuate the efficacy, safety stability and predictability of implanting a posterior chamber phakic intraocular lens to correct high myopia with astigmatism. Methods Thirty-nine eyes of 22 patients with high myopia were treated with ICL implantation. The range of preop-erative myopia diopters was -7.0 D to -24.0 D, mean -14.50 D±3.50 D, astigmatism ranges -0.50 D to -4.50 D, mean 2.25±1.32 D. All of 39 eyes were implanted ICL successful and had been followed up for 3 to 18 months. The follow up examination included visual acuity, refraction tonometer, slit lamp examination, chamber depth, chamber angle and space between crystal lens and IOL. Results One week after operation, the uncorrected visual acuity of 38 eyes were same or better than the pre-operative best corrected visual acuity (BCVA). The refractive diopters were from -0.50 to -2.25 D,mean -0.75±0.38 D. Astigmatism was 0.25 to 2.75 D, mean 1.03±0.23 D. Complications were seen in 7 eyes of 6 patients who had increased intraocular

  2. SMILE与LASIK矫正低中度散光效果的矢量分析和比较%Vector analysis and comprison of small incision lenticule extraction versus laser in-situ keratomileusis for low to moderate myopic astigmatism

    Institute of Scientific and Technical Information of China (English)

    张佳媚; 王雁; 陈晓琴; 李晓晶; 徐路路; 窦瑞

    2016-01-01

    Background Small incision lenticule extraction (SMILE) is lack of eye-tracking system and there is controversy in the treatment of astigmatism.It is very important to understand its correction effctiveness for myopic astigmatism.Objective This study was to evaluate the clinical outcomes in the correction of myopic astigmatism between SMILE and femtosecond laser assisted laser in situ keratomileusis (FS-LASIK).Methods In this retrospective study,95 eyes of 51 patients and 69 eyes of 40 patients with myopic astigmatism underwent the SMILE surgery and FS-LASIK surgery respectively in Tianjin Eye Hospital from December 2013 to July 2014 under the informed consent.No significant differences were found in spherical power,astigmatic power and spherical equivalent (SE) between the SMILE group and FS-LASIK group before surgery (all at P>0.05).The uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA),manifest refraction,slit-lamp microscopy,intraocular pressure and corneal topography were measured before surgery and 1 day,1 week,1 month,3 months after surgery.Vector analysis was used to calculate the components of astigmatism before and after surgery.Correction index (CI),index of success (IOS),angle of error (AofE) and flattening index (FI) were used to evaluate the correction effectiveness of astigmatism.Safety index and efficacy index were used to evaluate the recovery status of visual acuity.The corrected effectiveness was compared between the two groups,and the correlations of kappa angle with measured parameter were assessed by Spearman rank correlation analysis.Results The mean spherical power,astigmatic power and SE were (0.003±0.106),(-0.063 ± 0.126) and (-0.029 ± 0.101) D in the SMILE group,which were significantly lower than (0.112 ± 0.212),(-0.091 ± 0.142) and (0.067 ± 0.198)D in the FS-LASIK group (Z =-4.328,-3.197,both at P<0.05).Vector analysis showed the postoperative with-the-rule astigmatism in the SMILE group and oblique

  3. 人工晶体因素对白内障角膜散光患者术后获益的影响%Influence of different intraocular lenses on postoperative benefit of cataract patients with astigmatism

    Institute of Scientific and Technical Information of China (English)

    巨朝娟; 楚妙; 张骞; 林伟

    2015-01-01

    BACKGROUND:Monofocal and multifocal Toric intraocular lens that have been widely used in clinic exhibit xcelent biological and optical characteristics and have good safety and stability after implantation. OBJECTIVE:To compare the outcomes and rotation stability in patients with cataract and astigmatism after implantation of monofocal and multifocal intraocular lens. METHODS:A total of 210 patients with cataract and astigmatism who received phacoemulsification and intraocular lens implantation were included in this study. Of them, 105 patients were assigned to monofocal intraocular lens implantation and the other 105 patients to multifocal intraocular lens implantation. Uncorrected visual acuity, best corrected visual acuity, residual astigmatism were reexamined at 1, 3 weeks and 1 month after surgery. The rotation of Toric intraocular lens was determined. The incidence of complications and spectacles- independent rate were recorded. RESULTS AND CONCLUSION:Visual acuity and residual astigmatism in each group were significantly improved after 1 week of intraocular lens implantation (P < 0.05); furthermore, these two indicators became better over time. Improvement of visual acuity and residual astigmatism in multifocal intraocular lens group was more obvious than that in monofocal intraocular lens group. Postoperative intraocular lens rotation at < 5° occurred in both groups. The intraocular lens rotation degree in multifocal intraocular lens group was higher than that in monofocal intraocular lens group at different time points (P < 0.05). There were no significant differences in incidence of complications and spectacles-independent rates between two groups at 1 month after surgery. These results demonstrate that multifocal Toric intraocular lens provides better visual acuity and residual astigmatism improvement, while monofocal Toric intraocular lens provides better rotation stability.%背景:单焦点与多焦点Toric散光型人工晶体具有良好的生物

  4. 中低度近视患者LASIK术后散光矫正效果与视觉质量的关系%Relationship between the correction effect of astigmatism with low to moderate myopia by LASIK and the visual quality

    Institute of Scientific and Technical Information of China (English)

    王树林; 刘平; 王新; 孙新霞; 成立国

    2013-01-01

    目的 探讨中低度近视患者准分子激光原位角膜磨镶术(LASIK)后散光矫正效果与视觉质量的关系.方法 选取行LASIK矫正近视合并散光的206眼,分为中低度散光组104眼和高度散光组102眼;术后3个月时,用标准矢量分析法评估LASIK对散光的矫正效果,评价指标包括预期散光矫正量(IRC)、手术引起的散光矫正量(SIRC)、散光大小的误差(EM)、散光角度的误差(EA)、矢量误差(EV)、误差率(ER)、矫正率(CR);手术前后在最佳矫正视力下,采用CSV-1000E对比敏感度仪检测明视无眩光时3、6、12、18 cpd空间频率下的对比敏感度函数(CSF),以评价视觉质量.结果 术后3个月,高度散光组各空间频率的CSF低于术前(P均<0.01),中低度散光组12、18 cpd的CSF分别低于术前(P均<0.05),高度散光组的3、6、12 cpd的CSF低于中低度散光组(P均<0.05);中低度散光组的EV的绝对值(│EV│)小于高度散光组(P<0.05);高度散光组的lEV|与18 cpd的CSF呈正相关(r =0.629,P<0.01).结论 LASIK术后3个月时,中低度近视合并高度散光患者可出现明视无眩光下CSF的下降,其中高频段CSF下降的原因可能与散光矫正的EV有关.%Objective To investigate the correction effect of astigmatism with low to moderate myopia by LASIK and the relationship between the effect and visual quality.Methods A total of 206 myopic eyes with astigmatism were treated by LASIK,which were divided into low to moderate astigmatism group (-0.75 D ~-2.25 D) of 104 eyes and high astigmatism group (-2.50 D to-4.00 D) of 102 eyes.Three months later after the operation,the effect of astigmatism correction was evaluated by the standardized vector analysis,which was represented by IRC (intended refractive correction),SIRC (surgically induced refractive correction),EM (error of magnitude),EA (error of angle),EV (error vector),ER (error ratio) and CR (correction ratio).To evaluate the visual quality

  5. 白内障手术技巧对术源性散光的影响%Effect of surgical skill on surgically -induced astigmatism in cataract surgery

    Institute of Scientific and Technical Information of China (English)

    Numan Eraslan; Ufuk Elgin; Emine Sen; Pelin Yilmazbas

    2015-01-01

    目的:评估行普通白内障超声乳化术,手术经验对术源性散光( SIA)的影响。  方法:选取患者50例53眼,平均年龄64.5±10.8a,随机分为两组,一组23眼,二组30眼。手术方式均采用透明角膜切口白内障超声乳化吸除联合人工晶状体植入术。第一组由白内障专家手术,第二组则由住院医师手术。术前所有患者均接受全面眼科检查,包括角膜曲率和自动屈光检测。 SIA应用向量分析程序-Alpins法计算,于术后1d,1mo及2mo重复上述检查并记录结果变化。应用Shapiro Wilk和Mann-Whitney检验判断两组间SIA的统计学差异。  结果:两组患者人口资料差异无统计学意义。组间分析显示,一组术后1d,1mo及2mo的SIA分别为0.79±0.41 D,0.54±0.41 D及0.47±0.37 D;二组分别为1.27±0.66 D,0.98±0.56 D及0.94±0.54 D。可见一组术后1d ( P=0.002),1mo (P=0.004)及2mo (P=0.001)的SIA更小。  结论:手术经验是影响SIA的因素之一。住院医师应增加超声乳化术手术量以获取更多手术经验。%?AIM:To evaluate the effect of surgical experience on surgically-induced astigmatism ( SIA ) in patients with uncomplicated phacoemulsification surgery. ?METHODS:Fifty-three eyes of fifty patients, mean age 64.5±10.8y, were randomly divided into two groups (23 eyes and 30 eyes) .First group was underwent surgery by cataract specialists and the second was by residents.At baseline all the patients were underwent a complete opthalmological examination including keratom etry and autorefractometer measurements. Vector analysis programme including the Alpins'method was used for the calcu lation of SIA.All the measurements were repeated postoperative first day, first month and second month and changes were recorded.Shapiro Wilk and Mann-Whitney tests were applied for determiningthe statistic al differences between the SIA

  6. Long-term results of photorefractive keratectomy for myopia and myopic astigmatism Resultados a longo prazo de ceratectomia fotorefrativa para miopia e astigmatismo miópico

    Directory of Open Access Journals (Sweden)

    Ester Sakae Yamazaki

    2007-12-01

    Full Text Available PURPOSE: To assess the long-term refractive outcomes of photorefractive keratectomy in myopia and myopic astigmatism. METHODS: A retrospective study of 120 photorefractive keratectomy operated eyes with at least four-year follow-up (maximum of 96 months, mean follow-up 55 months. We divided patients into group 1 (G1 spherical equivalent (SE up to -4.00 diopters (D and group 2 (G2 SE >-4.00 D. The Summit Apex Plus® excimer laser was used for ablation. All eyes were analyzed in terms of uncorrected and best spectacle corrected visual acuity (UCVA/BSCVA and cycloplegic refraction. Data were analyzed using the Refractive Surgery Consultant Elite database software. RESULTS: G1 with 85 eyes (49 patients presented mean SE -2.42 D and G2 with 35 eyes (22 patients and mean SE of -4.45 D. Ninety-four percent of eyes in G1 and 82.9% of G2 were within ±1.00 D of emmetropia at 4 years. The UCVA was 20/30 or better in 82.0% of G1 eyes and 77.0% of G2 in the last postoperative follow-up. No patient lost more than one line in G2 compared to 13.0% in G1. Eyes that gained one or more lines after 4-year follow-up were 11.9% G1 and 2.9% in G2, respectively. A statistically significant positive correlation was found between achieved versus attempted refractive correction in both groups (r=0.925, pOBJETIVO: Relatar os resultados a longo prazo da cirurgia de ceratectomia fotorefrativa em miopia e astigmatismo miópico. MÉTODOS: Estudo retrospectivo de120 olhos operados de ceratectomia fotorefrativa com um mínimo intervalo de 4 anos de seguimento pós-operatório (máximo de 96 meses e seguimento médio de 55 meses. Dividimos em grupo 1 (G1 com equivalente esférico (SE até -4.00 dioptrias (D e grupo 2(G2 SE > -4.00 D. O excimer laser Summit Apex Plus® foi usado na ablação. Foram obtidas acuidade visual não corrigida (UCVA e melhor acuidade visual corrigida (BSCVA e refração sob cicloplegia. Os dados foram analisados utilizando o programa Refractive Surgery

  7. Astigmatic changes after horizontal rectus muscle surgery in intermittent exotropia%间歇性外斜视患者水平直肌术后的散光改变

    Institute of Scientific and Technical Information of China (English)

    王子衿; 龚琦; 刘虎

    2015-01-01

    Objective To evaluate astigmatic changes after horizontal rectus muscle surgery in intermittent exotropic patitents.Methods Seventy-one exotropic patients with intermittent exotropia were enrolled in this case-series study.The subjects were divided into two groups: group 1 with lateral rectus recession (26 patients) and group 2 with unilateral lateral rectus recession and medial rectus resection (45 patients).Non-cycloplegic refractions were measured within 1 week before surgery, at 1 week, 1 month, and 3 months after surgery.CYL0 (horizontal or vertical vector of the cylinder) and CYL45 (oblique vector of the cylinder) using Fourier power vectors were calculated to determine and compare the changes of refractive astigmatism and axis in both groups.Results In group 1, CYL0 showed significant changes at 1 week, 1 month and 3 months after surgery.In group 2, CYL0 also changed significantly between 1 week and 3 months postoperatively.CYL45 did not change significantly as time passed in both groups.There was no statistically significant difference in the mean change of CYL0 and CYL45 after the 3-month follow-up.There was no significant correlation between the amount of lateral rectus recession and the amount of CYL0 in group 1 at 1 week, 1 month and 3 months after surgery.Conclusions Intermittent exotropic patients after horizontal rectus muscle surgery tend to develop statistically significant changes in astigmatism in the with-the-rule direction.At 3 months after surgery, the astigmatic changes seem to be still remarkable.Comparison between the two groups imply that the astigmatic effect caused by medial rectus resection is likely smaller compared to that caused by lateral rectus recession and study on large sample is necessary to prove it.%目的 了解间歇性外斜视患者行水平直肌手术后的散光改变.方法 临床病例对照研究.选取2013年7~9月在江苏省人民医院眼科就诊的71例间歇性外斜视患者进行病例系列研究.按照

  8. A comparison of the differences in astigmatism used by corneal topography,retinoscopy and subjective refraction%角膜地形图和主客观验光测量散光度数及轴位的对比观察

    Institute of Scientific and Technical Information of China (English)

    杨培星; 刘才远; 丁连娥; 郑纯; 吴静

    2016-01-01

    Objective To compare the differences in astigmatism obtained by corneal topography,retinoscopy and subjective refraction in the preoperative examination of excimer laser surgery.Methods A comparison was made through the methods of corneal topography by SCHWIN,cycloplegic retinoscopy and subjective refraction in 123 patients with 195 eyes with simple and compound astigmatism.Re-sults The value of corneal astigmatism measured by corneal topography,retinoscopy and subjective refraction was mainly between-0.5 and -2.0 D.Between the corneal topography method and retinoscopy there was a statistically significant difference in the power of astigmatism (P =0.000)while there was no significant difference in the axis of astigmatism (P =0.459).The corneal topography, compared with subjective refraction,showed statistically significant difference in the power of astigmatism (P =0.000)and no signifi-cant difference in the axis (P =0.355).The retinoscopy,compared with subjective refraction,did not show statistically significant differences in the power of astigmatism and its axis (P =0.144,P =0.653,respectively).Conclusions Examination of corneal topog-raphy in the preoperative refractive surgery with excimer laser is decisive in calculating the axis of corneal astigmatism,and combined with retinoscopy and subjective refraction it can determine the final value.%目的:比较分析角膜地形图、检影验光及主觉验光三种方法在准分子激光术前检查测得散光度数和轴位的差异与关系。方法采用计算机辅助的角膜地形图法、带状光散瞳检影验光及主觉验光三种测量方法对123例195只非混合性散光进行检查并比较。结果(1)检影验光、主觉验光和角膜地形图法测得散光主要分布在-0.5~-2.0 D,三种方法测得散光主要为顺规散光。(2)角膜地形图法与检影验光相比,散光度数差异有统计学意义(P =0.000),轴向差异无统计学意义(P =0

  9. 有晶体眼后房型人工晶体植入治疗高度近视及散光%Clinical research of the implantation of phakic posterior chamber intraocular lens (ICL) for high myopia with astigmatism

    Institute of Scientific and Technical Information of China (English)

    廖荣丰; 汪永; 周艳峰; 刘伦; 刘兴华; 封利霞

    2009-01-01

    目的 观察和探讨后房型有晶体眼人工晶体植入术治疗高度近视及散光的效果及安全性.方法 后房型有晶体眼人工晶体植入术治疗高度近视及散光28例56眼.术前屈光度(等效球镜)为-7.0~-22.50D,平均(-12.42±3.50)D.散光0.37~6.5D,平均(1.92±1.32)D.所有患者随访3~24个月.术后检查视力、眼压,裂隙灯检查眼前部情况.结果 术后3个月,所有病例术后达到或超过术前最佳矫正视力.等值球镜,0.25~1.50D,平均(0.534±0.408)D.散光度0.25~1.50D,平均(0.564±0.289)D.术后并发症:4例7眼术后早期眼压升高,经降眼甩治疗,3~4天后眼压正常.结论 后房型有晶体眼人工晶体植入术治疗高度近视及散光效果确切,预测性好,手术安全.高度近视,尤其是超高度近视以及角膜薄不适合准分子激光矫正的患者是理想的治疗对象.%Objective To observe and investigate the efficacy and safety of the implantation of phakic posterior chamber intraocular lens (ICL) for high myopia with or without astigmatism. Methods 56 eyes of 28 patients with high myopia were treated with ICL implanta-tion. The range of preoperative myopia diopters was-7.0 to-22. 5D, mean-12.42±3.50 D. Astigmatism ranges 0.37 to 6.5D, mean 1.92±1.32D. All of 56 eyes were implanted ICL successfully and have been followed up for 3 to 24 months. The follow up examination included visual acu-ity, refraction, tonometer, slit lamp examination ,and space between crystal lens and IOL. Results Three months after operation, the uncor-rected visual acuity of every eye was same or better than the pre-operative best corrected visual acuity (BCVA). The refractive diopters were from 0.25 to 1.50D, mean 0.534±0.408D. Astigmatism were 0.25 to 1.50D, mean 0.564±0.289D.complications were secondary glaucoma. 7 eyes of 4 patients had increased intraocular pressure shortly after surgery. After treatment, the intraocular pressure became normal in 3 to 4 days. Con

  10. 改良SRK-T公式预测人工晶状体植入术后散光误差分析%Error prediction analysis of astigmatism after intraocular lenses implantation with modified SRK-T

    Institute of Scientific and Technical Information of China (English)

    涂云海; 俞阿勇; 宥永胜; 高潮; 吴文灿

    2011-01-01

    Objective To evaluate the feasibility and the factors of prediction error of astigmatism after intraocular lens (IOL) implantation by modified SRK-T, and to study the value of modified SRK-T using for toric intraocular lens power calculation. Methods Retrospective case seriesstudy. This study included 68 patients (106 eyes) underwent phacoemulsification during Oct 2007 to June 2008 in Eye hospital of Wenzhou Medical College. The result of the spherical equivalent calculated by SRK-T and modified SRK-T was compared, and the astigmatism error predicted by modified SRK-T and subjective refraction was compared with vector analysis. Influencing factor of modified SRK-T was analyzed with a multivariate linear regression analysis. Results Spherical equivalent calculated by modified SRK-T and SRK-T was equal. The factors of prediction error in J0 was astigmatism of cornea (KS),J0=-0.108-0.102×KS (P=0.034); and in J45 was axial length (L) and average refraction of cornea (K),J45=1.797-0.019×L-0.031×K (P=0.009). Conclusion Modified SRK-T is a good option for toric intraocular lens power calculation. The influencing factors of prediction include Ks, L and K.%目的 评价改良SRK-T公式对球面人工晶状体植入术后预测散光的可行性及其误差的影响因素,以探讨改良SRK-T公式在散光人工晶状体度数计算中的应用价值.方法 回顾性系列病例研究.分析2007年10月至2008年6月行超声乳化白内障摘除联合球面人工晶状体植入术且资料完整的白内障病例68例(106眼).比较改良SRK-T公式与SRK-T公式计算得出的术后预测等效屈光度数之间的差异.矢量分析改良SRK-T公式预测的术后散光度与实际术后散光度之间的差异,并采用多元线性回归分析其影响因素.结果 改良SRK-T公式与SRK-T公式计算得出的术后预测等效屈光度结果完全吻合.矢量分析术后散光预测误差结果示:J0预测误差的因素主要是角膜散光(KS),J0=-0.108-0.102

  11. 硬性透气性角膜接触镜矫正高度近视和散光的疗效%Clinical effects of rigid gas permeable contact lens in correcting high myopia and astigmatism

    Institute of Scientific and Technical Information of China (English)

    董泽红; 赵炜; 王雨生; 鱼晓妮; 任玉凤; 冯洁

    2015-01-01

    AlM: To evaluate the effect of rigid gas permeable contact lens ( RGP ) in correcting high myopia and astigmatism.METHODS: Forty-one patients ( 65 eyes ) with myopia (-9. 03 ± 6. 19DS, maximum -23. 00DS) and astigmatism (-1. 41 ± 1. 32DC, maximum -5. 50DC) were fitted with RGP after strict routine ophthalmological examination, objective refraction and subjective refraction. All these patients were followed after 1wk, 1, 3mo and half one year.RESULTS:Sixty-five eyes were fitted with RGP (-9. 92± 5. 96DS). RGP base curve ( BC) was majorly located within the range 7. 20 ~8. 25mm. 46. 2% eyes with RGP achieved 1. 0 ( BCVA ) and 80. 1% achieved above 0. 6 ( BCVA) . However, with spectacles, the percent was 28%(1. 0) and 60% (>0. 6), respectively. BCVA of RGP was 0. 81 ± 0. 22, but BCVA with spectacles was 0. 66 ± 0. 28, there was statistical significance (P<0. 01). There were 40 eyes (62%) fitted with RGP whose vision were enhanced more than 1 line, 24 eyes ( 37%) whose vision were not changed and 1 eye (2%) whose vision were dropped 1 line.CONCLUSlON:RGP effectively improves visual acuity of high myopia and astigmatism compared with spectacles.%目的::评价硬性透气性角膜接触镜( rigid gas permeable contact lens, RGP)矫正高度近视及散光的效果。方法:采用自身对照方法,对41例近视(平均屈光度-9.03±6.19DS,最大值-23.00DS)、散光(平均-1.41±1.32DC,最大值-5.50DC)患者,共计65眼,用RGP进行矫正,并与患者自身使用框架眼镜,在自然瞳孔下验光的最佳矫正视力进行对比。结果:近视、散光65眼配制了RGP,RGP基弧( BC)绝大多数位于7.20~8.25mm区间内,度数-9.92±5.96DS。 RGP矫正视力达到1.0的占46.2%,0.6以上的占80.1%,框架眼镜矫正视力达到1.0的占28%,0.6以上的占60%。RGP最佳矫正视力为0.81±0.22,框架眼镜的最佳矫正视力为0.66 ± 0.28。 RGP的最佳矫正视力优于框架眼镜( P<0.01)。 RGP比较框架眼镜最佳矫正视力提高1

  12. Clinical study on postoperative astigmatism of phacoemulsification guided by Astramax corneal topography%Astramax角膜综合检查站引导白内障手术术后屈光状态的临床研究

    Institute of Scientific and Technical Information of China (English)

    郑艳霞; 杨卫国; 魏宝丰; 高亚玲; 穆金卫

    2012-01-01

    目的 观察Astramax三维角膜综合检查站引导白内障超声乳化手术5.5mm透明角膜切口对术后屈光状态的影响.方法 对89例(100眼)老年性白内障患者随机分为观察组51眼及对照组49眼.观察组透明角膜切口位于角膜曲率最大子午线方向,对照组透明角膜切口位于10点位方向,2组行白内障超声乳化,植入5.5mm非折叠人工晶体.于术后1周、1个月及3个月时对患者进行视力、裂隙灯、眼底、角膜地形图检查,观察患者屈光状态的变化.结果 术后1个月及3个月观察组裸眼视力≥0.5者分别为42眼(82%)和43眼(84%),对照组分别为31眼(63%)和33眼(67%),2组比较有显著性差异(P均<0.05).观察组术后1个月、3个月角膜散光度明显减小(P<0.01);对照组术后3个月角膜散光度明显减小(P<0.05).结论 Astramax三维角膜综合检查站引导白内障超声乳化5.5mm角膜透明切口手术可以减少手术性散光、矫正角膜散光、提高术后视觉效果.%Objective It is to observe the influence of phacoemulsification guided by Astramax corneal topography system on postoperative astigmatism. Methods One hundred eyes with cataract were randomly divided into treatment groups (51 eyes, incision at the steepest corneal meridian ) and control group ( 49 eyes, incision at 10 o' clock ). The 5. 5 mm non-folded artificial lens was imbeded after phacoemulsification. The refraction state was observed after operation by sight, slit lamp, eye ground and corneal topography and compared. Results There were 42 eyes ( 82% ) and 43 eyes ( 84% ) which sight & 0. 5 at 1 and 3 month after operation in treatment group and 31 eyes ( 63% ) and 33 eyes ( 67% ) in control group with significant difference ( all P < 0.05 ). The corneal astigmatism degree was extremely significant smaller ( P < 0. 01 ) at 1 and 3 month after operation in treatment group, and was significant smaller ( P <0.05 ) at 3 month after operation in control group

  13. Lente de contato de material híbrido em pacientes com ceratocone e astigmatismo miópico composto Hybrid material contact lens in keratoconus and myopic astigmatism patients

    Directory of Open Access Journals (Sweden)

    Fernando Leal

    2007-03-01

    óculos, exceto para a freqüência B (3 cpg, maior nos usuários de óculos. As aberrações de alta ordem analisadas apresentaram diminuição estatisticamente significante, quando comparados os pacientes sem e com uso de lentes de contato, com exceção da aberração esférica e do coma. CONCLUSÃO: A lente de contato de material híbrido, quando utilizada por portadores de ceratocone e astigmatismo miópico composto, propiciaram desempenho visual e conforto satisfatórios, em níveis que não diferiram, das lentes de contato rígidas-gás-permeáveis nos dois grupos de pacientes.PURPOSE: To evaluate comfort and visual performance in relation to two different used contact lens types: hybrid material (HM and rigid-gas-permeable (RGP, in patients with regular myopic astigmatism and with keratoconus. METHODS: A randomized, double masked, prospective study of 22 patients with the diagnosis of myopic astigmatism (8 with myopic astigmatism and 14 with keratoconus was conducted. Fifteen patients were female and 7 were male, and mean age was: 32.13 ± 8.12 years. In one of the eyes a rigid-gas-permeable contact lens was adapted (DK 30, and in the other a hybrid material contact lens was adapted (DK 23. All patients were submitted to the following tests: measurement of comfort level by means of the analogical visual scale, tear break-up time, best corrected visual acuity with the Bailey-Lovie scale adapted for 4 meters, functional acuity contrast test (FACT and wavefront analysis. RESULTS: In relation to comfort, there was no association with the evaluated contact lens type (p=0.350. There was a variation in comfort level during the first 7 days. The visual acuity increased between the 7th and the 15th day of adaptation. Visual acuity stabilized right after this period. The visual acuity did not show differences in relation to the studied lens type. It was verified that there was no difference in the tear break-up time (p=0.989 in relation to the studied lenses type and

  14. Effect of 3.0mm corneal incision guided by corneal topography on corneal astigmatism in cataract surgery%角膜地形图引导下3.0mm角膜切口对白内障术后角膜散光的影响

    Institute of Scientific and Technical Information of China (English)

    陆士恒; 张忆; 吕骄

    2013-01-01

    AIM: To compare preoperative and postoperative corneal astigmatism using 3.0mm corneal incision guided by corneal topography system in phacoemulsification.METHODS: Phacoemulsification was performed on 144 cases 156 eyes with 3.0mm corneal clear incision at the steepest corneal meridian. Preoperative corneal astigmatism and the data 3 months postoperatively were observed by the corneal topography system. Statistical analysis included sample Student's t - test, one way ANOVA test, Kruskal-Wallis test and Pearson correlation test.RESULTS: According to analysis, the postoperative corneal astigmatism correlated negatively with the preoperative corneal astigmatism (r=-0. 69, P<0. 01). The corneal cylinder changed significantly in each grade after the surgery (P< 0. 05). When the preoperative corneal cylinder was between 0. 12D and 0. 25D, the postoperative corneal cylinder was higher than before. Whereas, the postoperative corneal cylinder became lower than before when the preoperative cylinder ranged from 0.37D to 1.0D.CONCLUSION: The incision located at the steepest corneal meridian under the guidance of corneal topography changes the preoperative astigmatism. For astigmatic correction, 3.0mm on - axis clear corneal incision phacoemusification is recommended with preoperative corneal astigmatism between 0.37 and 1.0D.%目的:观察角膜地形图引导下3.0mm透明角膜切口白内障超声乳化手术前后患者角膜散光的变化.方法:在角膜最大曲率子午线上做3.0mm切口行白内障超声乳化手术,对术前散光度数≤1.0D的144例156眼术前、术后3mo的资料进行回顾性分析,统计手术前后角膜地形图散光的变化.采用t检验、单因素方差分析、Pearson相关分析对数据进行统计学处理.结果:3.0mm角膜透明手术切口的术源性散光为0.77±0.53D.患者手术前后的散光对比有统计学意义(P<0.05),散光变化具有相关性(r=-0.69,P<0.01).术前角膜散光≤0.25D者术后散光增大,其

  15. 角膜地形图引导下白内障手术切口构建的变异对角膜散光影响%The Effect of the Corneal Astigmatism in Changed Cataract Surgery Incision with the Corneal Topography

    Institute of Scientific and Technical Information of China (English)

    刘文慧; 施彦; 李一壮

    2010-01-01

    Objective To observe the effect of the corneal astigmatism in cataract surgery incision which selected according to corneal topography to further reduce the preoperative corneal astigmatism. Meth-ods Computer-assisted corneal topography was used to examine the 126 eyes of 123 patients preoperatively.The cases were divided into 5 groups randomly. Group A: Manual small incision cataract surgery (MSICS) Group: Superior anti-bow sclera tunnel incision was made on 22 eyes of Group A. Group B: MSICS Group: The anti-bow sclera tunnel incision was made on the steepest meridian according to the corneal topography ex-amined preoperatively on 28 eyes. Group C: Phacoemulsification Group: Superior clear corneal incision was made on 24 eyes of group C. Group D: Phacoemulsification Group: The clear corneal incision was made on the steepest meridian according to the corneal topography examined preoperatively on 26 eyes. Group E: MSICS Group: incision was made on the steepest meridian according to the corneal topography The straight sclera tun-nel examined preoperatively on 26 eyes. The corneal topography at 1 day and 7 days after surgery was ob-served and recorded except for visual acuity and so on. Results ①Visual acuity: The differences were not sta-tistically significant among these groups which Visual acuity was above 0.5 after 1 day and 7 days except the one between Group B and Group E after 7 days. ②Astigmatism axis conversion: The conversions were not sig-nificant from Group A to Group D. There were 12 cases changed in Group E. ③Corneal astigmatism: In Group A, the differences were not statistically significant among pre-operation, 1 day and 7 days. In Group B, the val-ues of corneal astigmatism in 1 day after surgery were a little more decreased than pre-existing ones, but were statistically significant 7 days later. The values of Group C and D were a little greater in 1 day after surgery and reduced 7 days later, however the values of Group C were higher. In group E

  16. Posição viciosa de cabeça por astigmatismo mal corrigido: relato de caso Abnormal head position caused by incorrect prescription for astigmatism: case report

    Directory of Open Access Journals (Sweden)

    Flávia Augusta Attié de Castro

    2005-10-01

    Full Text Available A posição viciosa de cabeça é uma condição compensatória que visa proporcionar aos pacientes melhor rendimento visual. Pode ser causada por problemas oftalmológicos, como distúrbios oculomotores (nistagmos, estrabismos e altos astigmatismos. No entanto, compromete a estética e, a longo prazo, pode causar transtornos ortopédicos (coluna cervical e assimetrias faciais. Relatamos o caso de uma garota, JL, 8 anos, com cabeça inclinada para esquerda havia vários anos. Fazia uso de óculos prescritos em outro serviço para correção de astigmatismo misto: OD= +2,00 DE Ç -5,50 DC a 180º e OE= +2,25 DE Ç -5,75 DC a 180º. No exame oftálmico, a paciente apresentava cabeça inclinada para a esquerda e acuidade visual com correção de 0,5 no OD e 0,7 OE. Os testes de cobertura simples e alternado não evidenciaram desvio ocular. Rotações oculares, biomicroscopia e fundoscopia também não mostraram alterações. Na refratometria sob cicloplegia e teste de lentes foram encontrados: OD= +3,50 DE Ç -6,00 DC a 10º e OE= +3,50 DE Ç -6,00 DC a 170º, com acuidade visual igual a 1,0 nos olhos direito e esquerdo. Foram prescritas as lentes encontradas no exame e a paciente retornou com a correção nova sem a inclinação de cabeça. Erros refracionais mal corrigidos também podem gerar torcicolo e, muitas vezes, passam despercebidos. Refratometria sob cicloplegia e teste de lentes são fundamentais para um diagnóstico preciso.Abnormal head position is a compensatory condition which improves patients' vision. It can be caused by ophthalmological problems such as oculomotor imbalances (strabismus, nystagmus and high astigmatisms. However, it results in esthetic impairment, orthopedic trouble and facial asymmetries. We describe a case of a girl, JL, 8 years, with abnormal head position tilted to the left since the last glasses were prescribed. The correction used by the patient was: right eye = +2.00 sph à -5.5 cyl 180° and left eye = +2

  17. 随机电磁光束经像散透镜后磁场的光谱Stokes奇点∗%Magnetic sp ectral Stokes singularities of sto chastic electromagnetic b eams through an astigmatic lens

    Institute of Scientific and Technical Information of China (English)

    郑尚彬; 唐碧华; 姜云海; 高曾辉; 罗亚梅

    2016-01-01

    Much interest has been aroused in the polarization singularities. A new technique for metrology called singular Stokes polarimetry based on the detection of polarization singularities has been recently developed and used to detect deformations and displacements of samples on a submicron scale, to measure the topology of polarized speckle field and to study the biomedicine as well. The polarization singularities have been extensively studied theoretically, numerically and experimentally. However, most of the studiesare restricted within the frameworks of the fully coherent wave-fields. By using the spectral Stokes parameters introduced by Korotkova and Wolf [Korotkova O, Wolf E 2005 Opt. Lett. 30 198], Yan and Lü [Yan H, Lü B 2009 Opt. Lett. 34 1933] have extended the concept of the polarization singularities from fully coherent beams to partially coherent beams. On the other hand, Hajnal [Hajnal J V 1990 Proc. R. Soc. Lond. A 430 413] studied the electric and magnetic polarization singularities in free-space propagation experimentally with microwaves and confirmed that the electric and magnetic polarization singularities are not coincident in general. In this paper, taking the partially coherent edge dislocation beam for example, the explicit magnetic propagation expression for stochastic electromagnetic beam through an astigmatic lens is derived based on the representation of cross-spectral density matrix propagation. Using the spectral Stokes parameters the magnetic spectral singularities are studied in detail. It is shown that there exist magnetic spectral s12, s23 and s31 singularities of stochastic electromagnetic beams through an astigmatic lens. The magnetic spectral Stokes singularities correspond to the zero points of complex Stokes fields sij =0. s12 singularity corresponds to the circular polarization (C-point) of partially coherent beam, and s3 >0 (s3 <0) means right-(left-) handedness, where the orientations of the major and minor axes of the

  18. The effect of selective incisions on corneal astigmatism after ICL surgery%选择性切口对有晶状体眼后房型人工晶状体术后散光控制的临床研究

    Institute of Scientific and Technical Information of China (English)

    蒋炎云

    2014-01-01

    Objective To evaluate the effect of the selective incisions on corneal astigmatism after ICL ( Implant-able Collamer Lens ) surgeries for high myopia .Methods This study included 195 high myopic eyes of 102 patients ran-domly assigned into 2 groups.Patients either received selective corneal incision (group A, 97 eyes) or temporal corneal in-cision (Group B, 98 eyes) in ICL surgeries.On the day before operation and at 1 week, 1 month and 3 month after surger-y, each patient was examined with corneal topography to evaluate the corneal astigmatism .Results Preoperative corneal a-stigmatism was 1.26 ±0.35 D in group A and 1.28 ±0.38 D in group B ( P >0.05).At 1 week, the astigmatism was 0.93 ±0.29 D in group A and 1.32 ±0.33 D in group B.At 1 month and 3 months, the astigmatism was 0.85 ±0.16 D and 0.80 ±0.13 in group A, and was significantly higher in group B (1.27 ±0.18 D and 1.25 ±0.20 D, respectively;P<0.01).Conclusion The selective incision could significantly reduce postoperative astigmatism after ICL surgery .%探讨选择性手术切口对有晶状体眼后房型人工晶状体( ICL)术后散光控制的作用。方法高度近视102例(195只眼),随机分成选择性切口97只眼(A组)和颞侧角膜切口组98只眼(B组),通过术前、术后1周、1、3个月分别行角膜地形图检查,观察患者术后散光的变化。结果 A组术前平均角膜散光为(1.26±0.35)D,B组术前平均角膜散光为(1.28±0.38)D,两组差异无统计学意义。术后1周、1、3个月,A组平均散光分别为(0.93±0.29)D、(0.85±0.16)D、(0.80±0.13)D,B组平均散光分别为(1.32±0.33)D、(1.27±0.18)D、(1.25±0.20)D,两组差异有统计学意义。结论选择性手术切口能在一定程度上控制ICL术后散光。

  19. Application study of rigid gas permeable contact lens in patients with traumatic corneal irregular astigmatism%硬性高透氧性角膜接触镜矫正外伤性角膜散光应用研究

    Institute of Scientific and Technical Information of China (English)

    郑斌; 陈岩; 周静; 徐朝霞; 沈丽君

    2012-01-01

    Objective To evaluate the clinical value of rigid gas permeable contact lens (RGP-CL) in patients with traumatic corneal irregular astigmatism. Methods Eighteen consecutive patients (18 eyes) with traumatic corneal irregular astigmatism were fitted RGPCL.All patients were followed up at least 6 months.Preoperative data included:age,sex,eye,interval between RGPCL fitting and complete sutures removal,status of lens,uncorrected visual acuity (UCVA),spectacle visual acuity (SVA),location and size of the corneal scar,corneal astigmatism.Post-contact lens fitting data included:RGPCL visual acuity (RGPCLVA),duration of contact lens wear,the reason for drop ping out of contact lens wear,contact lens-related complications,whether or not the patient was successful in wearing the contact lcns.RGPCL fitting was considered successful if the patient judged the wearing of RGPCL to be satisfactory enough at least 8 hours of daily wear throughout the follow-up period.Decimal acuity was converted to 5-logMAR value.Data analysis used SPSS 16.0 for the paired samples t-test,two independent sample t-test and analysis of covariance. Results The average age was 20.94±13.35 years (range 5-45 years),five eyes were pseudophakic,one was aphakic and other twelve were phakic.According to the location of the corneal scar,it was found that nine eyes were in zone 1 and other nine in zone 2.The average length of scar was 4.04±2.23 mm (range 1.50-8.33 mm).The difference in the length of scar between zone 1 and zone 2 was found to be not statistically significant (t =-0.967,P =0.348).The interval from complete sutures removal to contact lens fitting was averaged 5.67±5.52 months (range 3-22 months).Mean UCVA was 4.2±0.5 (range 3.0-4.9).Mean SVA was 4.6±0.3 (range 4.0-4.9).Mean RGPCLVA was 4.9±0.1 (range 4.4-5.1).The visual acuities with contact lens were significantly better than with spectacles (t=4.143,P <0.000).RGPCLVA was 1 line better in 7 eyes,2-4 lines in 6 eyes,more than 5 lines in 4

  20. 个性超声乳化切口并不同类型人工晶状体植入术后角膜散光和视觉质量的比较%The clinical investigation of dynamic changes of corneal astigmatism and visual quality for patients after phacoemulsification surgery through different incision and implantation of different designed intraocular lens

    Institute of Scientific and Technical Information of China (English)

    王佃科; 张杰; 王杰; 李艳; 梁山; 刘育霞

    2009-01-01

    Objective To compare the corneal astigmatism and wavefront aberration differences of patients with cataract coexisting corneal astigmatism after phacoemulsification surgery through traditional superior clear corneal incision or phacoemulsification surgery through clear corneal incision guided by corneal topography and implantation of different spherical aberration intraocular lenses (IOL). Methods In a prospective randomized sample controlled clinical trial, 90 patients (90 eyes) with age-related cataract and corneal astigmatism were randomly divided into 3 groups: (Group A) traditional superior corneal incision phacoemulsification surgery and AcrySof SN60AT IOL implantation, (Group B) corneal topography guiding incision phacoemulsification surgery and AcrySof SN60AT IOL implantation and (Group C ) corneal topography guiding incision phacoemulsification surgery and AcrySof SN60WF IOL implantation. Corneal topography tests were performed at 1 week, 1 month, 3 months and 6 months postoperatively. The Wavefront aberration was measured using a custom built Tschcming wavefront sensor--ALLEGRETTO WAVE Analyze at 90 days postoperatively. Third-, 4th-, 5th-, total and higher-order aberration (HOA) root-mean-square (RMS), spherical aberration and coma aberration were compared at virtual pupil diameters of 6 mm postoperatively. Statistical analyses were performed using the analysis of chi square test, repeated measurement data analysis of variance, one-way analysis of variance (ANOVA), and multiple comparisons Studcnts-Newman-Keuls test. Results Corneal topography tests indicated that no significant difference for corneal astigmatism was found between these three groups preoperatively( F =0. 08 ,P >0. 05). The corneal astigmatism was decomposed into J0, J45 and P with a Vector-based method, and statistically analyzed . When compared with Group B and GroupC, Group A had higher values of corneal J0 ( F = 9.54, P 0. 05 ). However groups and times had interactions ( F = 13

  1. Topography-guided steep corneal cuts and Toric intraocular lens implantation for correcting astigmatism in cataract patients%角膜地形图引导的陡轴切口和 Toric晶状体治疗白内障合并角膜散光

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Objective To evaluate the clinical efficacy of topography-guided steep corneal cuts and Toric intraocu-lar lens implantation for the treatment of corneal astigmatism in cataract patients.Methods This is a retrospective obser-vational study.Author enrolled 52 patients (66 eyes) who had cataract and corneal astigmatism.Patients received either to-pography-guided steep corneal cut ( group A;40 patients, 50 eyes) or standard corneal cut with AcrySof Toric IOL implan-tation ( group B;12 patients, 16 eyes) .Uncorrected visual acuity, astigmatism and Toric IOL rotational stability were eval-uated.Results In both groups, postoperative uncorrected visual acuity improved significantly at 1 week, 1 month, and 3 months after surgery ( P <0.05).Astigmatism also significantly reduced in both groups after the surgery ( P <0.05).In group B patients, the largest IOL rotation did not exceed 4°.Conclusion The topography-guided steep corneal cuts and Toric IOL implantation for cataract patients with astigmatism is an easy, safe, and effective treatment.%目的:评估角膜地形图引导的陡轴切口和Toric晶状体对白内障合并角膜散光治疗的临床疗效。方法回顾分析对2013年1月至2014年12月白内障合并角膜散光患者52例(66只眼)A术式术后的裸眼视力、角膜散光情况,B术式术后的裸眼视力、总合散光及Toric晶状体在囊袋内的稳定性。结果 A术式术后各时间点裸眼视力与术前比较提高,术后1周、1个月、3个月与术前相比,散光度均明显减小( P <0);B术式后各时间点裸眼视力均显著高于术前,术后1周、1个月、3个月全部眼总合散光明显改善( P <0),最大IOL旋转度未超过4°。结论角膜地形图引导的陡轴切口和Toric晶状体植入是治疗白内障合并角膜散光易行、安全、有效的治疗方法。

  2. Correção do astigmatismo irregular com lente intraocular tórica em um paciente com catarata e degeneração marginal pelúcida: relato de caso Toric intraocular lens implantation for cataract and irregular astigmatism related to pellucid marginal degeneration: case report

    Directory of Open Access Journals (Sweden)

    Ana Luiza Biancardi

    2012-12-01

    Full Text Available A degeneração marginal pelúcida (DMP é uma rara ectasia corneana cuja progressão resulta em astigmatismo irregular e baixa visual não corrigidos com óculos ou lentes de contato. O presente relato descreve um paciente com catarata e DMP que foi tratado com facoemulsificação e implante de lente intraocular tórica com recuperação da acuidade visual em ambos os olhos.Pellucid marginal degeneration (PMD is a rare corneal ectasia and its progression leads to irregular astigmatism and low vision that can not have spectacles or contact lens correction. This report describes a patient with low vision due to cataract and PMD that was treated with phacoemulsification and implantation of a toric intraocular lens with a satisfactory visual acuity outcome.

  3. 有晶状体眼后房型人工晶状体植入矫正高度近视及散光疗效观察%Preliminary observation of the effect of Posterior chamber phakic intraocular lens for high myopia with or without astigmatism

    Institute of Scientific and Technical Information of China (English)

    唐晓蕾; 王晓莉; 赵媛; 曾涛; 夏敏; 邱丹

    2015-01-01

    目的 探讨有晶状体眼后房型人工晶状体植入矫正高度近视及散光的临床应用价值.方法 纳入2010年3月至2013年1月间14例(25只眼)高度近视及散光患者,其中男6例,女8例,年龄18~42岁,平均26.7岁.所有患者接受有晶状体眼后房型人工晶状体植人治疗,术后随访3个月,检查裸眼视力、最佳矫正视力、屈光度、散光度,并在裂隙灯下检查拱高和轴向移位等.结果 所有患者术后裸眼视力较术前提高,术后3个月均达到或超过术前最佳矫正视力.术前等效球镜为-7.00~-22.0D,平均-(12.52±2.50)D,术后等效球镜为-0.25~-0.75 D,平均-(0.54±0.11)D,术后屈光度较术前明显降低,差异有统计学意义(P<0.05).散光由术前-(1.83±1.12)D下降至术后-(0.55±0.21)D,差异有统计学意义(P<0.05).手术前后眼压、角膜内皮细胞密度差异无统计学意义(P>0.05).术后无拱高偏大者,1只眼拱高偏低.术后93.75% (15/16)的TICL患者轴向偏转<10°.结论 有晶状体眼后房型人工晶状体植入术矫正高度近视及散光可以获得良好的裸眼视力,为高度近视患者提供一种新的选择,但其长期稳定性及远期并发症需要进一步观察.%Objective To investigate the efficacy and safety of the implantation of posterior chamber phakic intraocular lens (ICL) for high myopia with or without astigmatism.Methods From March 2010 to January 2013,14 high myopia patients (25 eyes) with or without astigmatism including 6 males and 8 females were admitted to our department.The average age of these patients was 26.7 years old,ranging from 18 to 42.All of them were treated by implantation of posterior chamber phakic ICL.Vision and diopter,as well as the results of slit lamp examination were used to evaluate the efficacy during the follow up.Results All patients were implanted ICL successfully and adhered to follow-up.The uncorrected visual acuity of every eye after surgery had improved,same or

  4. 虹膜定位波前引导的LASIK与标准LASIK比较治疗近视散光疗效的Meta分析%Iris-Registration in Wavefront-Guided LASIK versus Conventional LASIK for Correction of Myopia and Myopic Astigmatism: A Meta-Analysis

    Institute of Scientific and Technical Information of China (English)

    李岩; 成拾明; 周霞; 许玲

    2013-01-01

    Objective To systematically evaluate the efficacy and safety of iris-registration in wavefront-guided LASIK (IR+WG LASIK) versus conventional LASIK for correction of myopia accompanied with astigmatism. Methods Such databases as PubMed, EMbase, The Cochrane library (Issue 2, 2012), CBM, CNKI, VIP, and WangFang Data were searched to collect the randomized controlled trials (RCTs) and quasi-RCTs about IR+WG LASIK versus conventional LASIK for correction of myopia accompanied with astigmatism. The retrieval time was from inception to February 2012, and the language was in both Chinese and English. Two reviewers independently screened the literature, extracted the data and assessed the quality of the included studies. Then the meta-analysis was performed by using RevMan 5.1 software. Results A total of 9 studies involving 3 903 eyes were included. The results of meta-analysis showed that, compared with the conventional LASIK group, the IR+WG LASIK group had a higher ratio in patients with postoperative un-corrected visual acuity no less than 1.0 (RR=1.03, 95%CI 1.01 to 1.05, P=0.002), as well as in patients with best-corrected visual acuity gained over 1 line (RR=1.75, 95%CI 1.49 to 2.16, P<0.000 01); it was smaller in the postoperative high order aberration RMS (WMD=-0.16, 95%CI -0.21 to -0.11, P<0.000 01), coma-like RMS (WMD=-0.05, 95%CI -0.11 to 0.00, P=0.07), spherical-like RMS (WMD=-0.15, 95%CI -0.23 to -0.07, P=0.000 2), and residual astigmatism (WMD=0.14, 95%CI 0.10 to 0.18, P<0.000 01); moreover, it was lower in the incidence of postoperative glare (RR=0.27, 95%CI 0.15 to 0.50, P<0.000 1), and it was higher in the subjective satisfaction of patients (RR=1.08, 95%CI 1.04 to 1.13, P=0.000 3). Conclusion Compared with conventional LASIK, IR+WG LASIK can more effectively reduce astigmatism, postoperative high order aberration RMS and spherical-like RMS. It can also get visual function including uncorrected visual acuity and best-corrected visual acuity

  5. 光学诱导散光对视觉信号传导及皮层反应的影响%Electrophysiological research on the effects of optic-induced astigmatism on transmission time and response intensity of visual signals in the visual cortex

    Institute of Scientific and Technical Information of China (English)

    解来青; 徐国旭; 赵堪兴

    2012-01-01

    Objective To evaluate the contribution of different degrees of astigmatism on the latency and amplitude of pattern visual evoked potentials (PVEPs).The effect of astigmatism on the transmission and response intensity of visual signals in the visual cortex was evaluated.Methods It was a random designed study.PVEPs were measured in subjects with normal or normal corrected visual acuity using a checkerboard pattern stimulus under varying conditions using different astigmatic trial lens powers in succession (0-5 D).Paired samples t test,analysis of variance and Pearson correlation was performed.Results When a lower spatial frequency (60' checkerboards stimulus) was used,there was little change in the latency of P100 (F=0.290,P>0.05).However,when a higher spatial frequency (15' checkerboards stimulus) was used,VEP latency increased with a greater degree of astigmatism (F=10.850,P<0.01; r=0.647,P<0.01).There was a gradual reduction of amplitudes of P100 as convex cylindrical lens power increased (when 60' checkerboards were used, F=3.947,P<0.01; r=-0.470,P<0.01; when 15' checkerboards were used,F=14.280,P<0.01; r=-0.699,P<0.01).Conclusion The transmission of visual signals depends on the quality of the visual image formed on the retina.Visual signal transmission time and response intensity in the visual cortex are affected not only by the defocus of the retinal image but also by the spatial frequency of the pattern stimulus.With a high spatial frequency,the transmission of visual signals is faster and the response intensity of the visual cortex is greater if the visual image formed on the retina is clear.%目的 研究光学诱导不同程度散光产生的视觉信号对皮层反应时间及强度的影响;研究散光是否可导致视觉信号传导时程异常,观察视觉信号传导时间及视皮层反应强度与散光程度的量化关系.方法 完全随机设计研究.对视力或矫正视力正常的被检者眼前依次放置0~5 D度数正

  6. 经上皮准分子激光角膜切削术治疗不规则角膜散光的视觉质量观察%An evaluation of visual performance after trans-epithelial photorefractive keratectomy for correcting irregular corneal astigmatism

    Institute of Scientific and Technical Information of China (English)

    刘静; 陈世豪; 王一博; 张佳; 汪凌; 许琛琛; 王勤美

    2014-01-01

    Objective To evaluate visual performance pre-and postoperatively in patients with irregular corneal astigmatism who were treated with topography-guided trans-epithelial photorefractive keratectomy (TPRK).Methods This non-randomized prospective clinical study was comprised of 15 eyes of 12 patients with irregular corneal astigmatism who were treated with topography-guided TPRK.The data included UCVA,BCVA,pre-and postoperative refractive data,and contrast sensitivity before surgery and at 1 and 3 months after surgery,the corneal epithelial timeline for healing,pain scores at 3 and 7 days after surgery,the classification of haze when it appeared,and the safety and efficacy indexes.Repeated measures analysis of variance was used to compare the changes over time.Results Mean UCVA increased from 4.11±0.28 preoperatively to 4.88±0.16 3 months postoperatively (F=36.706,P<0.05).Mean BSCVA increased from 4.86±0.08 to 4.98±0.09 (F=5.075,P<0.05),with no visual acuity lines lost.Safety and efficacy indexes were 1.025 and 1.004,respectively.Mean spherical equivalent (SE) was reduced from-3.73±4.62 D to-0.03±0.09 D (F=-4.034,P<0.05),and the mean cylinder was reduced from-1.71±1.43 D to +0.38±1.14 D (F=-9.192,P<0.05).Tbere were significant differences in contrast sensitivity were found between patients at 3,6,12 c/d spatial frequencies before surgery and 1 month after surgery (P>0.05).But patients at 3 months after surgery showed better contrast sensitivity than patients before surgery (P<0.05).Haze appeared in 2 eyes at 1 month postoperatively but recovered by 3 months postoperatively.Conclusion Topography-guided TPRK appears to be an effective treatment for irregular corneal astigmatism.The operation improves contrast sensitivity and visual performance in patients with irregular corneal astigmatism.%目的 观察对不规则角膜散光患者施行角膜地形图引导的经上皮准分子激光角膜切削术后患者视觉质量的改善情况.方法 非

  7. 小切口白内障手术两种切口术后视力及角膜散光的临床对比分析%Comparison of Curative Effect of Small Incision Cataract Operation in Two Different Vision Incision and Corneal Astigmatism

    Institute of Scientific and Technical Information of China (English)

    凯赛尔·麦提如则

    2014-01-01

    Objective To investigate the clear corneal tunnel incision above and temporal clear corneal tunnel incision of two kinds of incisions on the vision and corneal astigmatism. Methods In our hospital from 2012 June to 2013 September treatment of 80 cases of cataract patients, 88 eyes, were randomly divided into upper clear corneal tunnel incision group and temporal clear corneal tunnel incision group with 40 cases in each group, 44 eyes, over a transparent corneal tunnel incision group with over a transparent corneal tunnel incision for treatment, temporal side of the transparent corneal tunnel incision of two incision group with temporal clear corneal tunnel incision of two kinds of incisions were treated. Results Superior clear corneal tunnel incision group above 6 months of recovery temporal clear corneal tunnel incision group vision after 1 weeks, 3 months after the operation, after operation, 1 weeks after operation, 3 months after operation, postoperative above 6 months clear corneal tunnel incision corneal astigmatism the situation is remarkably higher than that of temporal clear corneal tunnel incision group, there were significant dif erence between two groups ( < 0.05). Conclusion Temporal clear corneal tunnel incision was bet er than the above transparent corneal tunnel incision, temporal clear corneal tunnel incision in small incision cataract operation in the first choice of incision.%目的探讨上方透明角膜隧道切口术和颞侧透明角膜隧道切口两种切口术后对视力及角膜散光的影响。方法收集我院2012年6月~2013年9月治疗的80例白内障患者,共88眼,随机分成上方透明角膜隧道切口术组和颞侧透明角膜隧道切口术组各40例,44眼,上方透明角膜隧道切口组采用上方透明角膜隧道切口术进行治疗,颞侧透明角膜隧道切口两种切口组采用颞侧透明角膜隧道切口两种切口术进行治疗。结果术后1w、术后3个月、术后6个月颞侧透明

  8. Investigation of surgically induced astigmatism resulting from femtosecond laser-assisted cataract surgery using a 2.2 mm clear corneal incision%2.2mm透明角膜切口飞秒激光辅助白内障超声乳化手术术源性散光的临床研究

    Institute of Scientific and Technical Information of China (English)

    李博; 张素华; 张哲; 刘建亭; 曹伟芳; 李晓艳; 董慧; 郭彩虹; 张海宁

    2016-01-01

    Objective To evaluate surgically induced astigmatism (SIA) resulting from femtosecond laser-assisted phacoemulsification cataract surgery with a 2.2 mm clear corneal incision.Methods A prospective,comparative analysis was performed in a case series.A total of 105 eyes of 84 patients (from No.1 cataract department of Shanxi Eye Hospital) who underwent femtosecond laser-assisted phacoemulsification cataract surgery between March 2014 and April 2016 were enrolled in this study.The main outcomes were a comparison of SIA,far visual acuity,and spherical refractive power preoperatively and 1,3,and 6 months postoperatively.Distance visual acuity was recorded as logMAR.Based on follow-up times (1,3,and 6 months postoperatively),lens nucleus hardness (grades Ⅱ,Ⅲ,Ⅳ),corneal astigmatism types (with-the-rule,against-the-rule,oblique) and laterality (left,right),SIA was analyzed using Alphins vector analysis.Data were analyzed using repeated measured ANOVA.Results The mean preoperative logMAR visual acuity was 0.65±0.24,which was significantly different from postoperative logMAR visual acuity at 1 month (0.07±0.02),3 months (0.06±0.01),and 6 months (0.06±0.01).No significant logMAR visual acuity differences were found at the three postoperative follow-up times.SIAs at 1,3,and 6 months after surgery were 0.28±0.11 D,0.25±0.13 D,0.24±0.10 D,respectively.No statistically significant differences in SIA were found when postoperative follow-up times (1,3,and 6 months) and factor groups for lens nucleus hardness (grades Ⅱ,Ⅲ,Ⅳ),corneal astigmatism types (with-the-rule,against-the-rule,oblique) and laterality (left,right) were compared.Conclusion Femtosecond laser-assisted phacoemulsification cataract surgery using a 2.2 mm clear corneal incision can provide stable SIA and better postoperative visual acuity.%目的 观察飞秒激光辅助白内障超声乳化手术中2.2 mm透明角膜切口引起的术源性散光(SIA)的影响因素.方法 前瞻性研究.纳入2014

  9. 单眼角膜散光白内障患者不同人工晶状体组合植入的对比研究%Comparison of different combinations of intraocular lenses implantation in cataract patients with unilateral astigmatism

    Institute of Scientific and Technical Information of China (English)

    田芳; 张红; 胡尊霞

    2011-01-01

    Objective To assess binocular visual function after combined implantation of toric and multifocal or monofocal intraocular lenses in unilateral astigmatism cataract patients. Methods This was a prospective case control study. A total of thirty unilateral astigmatism patients undergoing phacoemulsification were recruited. AcrySof Toric IOL were implanted in the astigmatic eye of patients, with ReSTOR (15 eyes) or AcrySof IQ (15 eyes) in the contralateral eye. Six months postoperatively, patients were assessed for visual acuity (5.0 m, 60.0 cm, 40.0 cm), contrast sensitivity, amplitude of accommodation, and stereoacuity. Patients were surveyed for visual disturbances and lifestyle visual quality. Data were analyzed with a paired t test, an independent samples t test, or chi-square test. Results At 6 months postoperatively, for Toric-ReSTOR patients, uncorrected binocular logMAR visual acuity at 5.0 m, 60.0 cm, 40.0 cm was 0.05±0.05, 0.24±0.10, and 0.14±0.06, respectively. For Toric-AcrySof IQ patients, uncorrected binocular logMAR visual acuity was 0.06±0.07, 0.26±0.08, and 0.37 ±0.10, respectively. These values between the two group did not achieve significant differences except for near visual acuity (t=5.476, P=0.000). The contrast sensitivity for ReSTOR eyes was lower at 18 cpd under photopic and photopic glare circumstance than for the AcrySof IQ eyes (0.30 ± 0.37 versus 0.94 ±0.58, t=3.476, P=0.001; 0.34 ± 0.44 versus 0.88 ±0.52, t =2.975, P= 0.006). And was lower at 12 cpd under scotopic and scotopic glare circumstance than for the AcrySof IQ eyes (0.05±0.22 versus 0.50±0.61, t=3.057, P=0.005; 0.05±0.22 versus 0.59±0.75, t=3.154, P=0.004). The amplitude curve of accommodation in Toric-ReSTOR patients had two wave peak (0 and-2.5 D), but only one (0 D) in Toric-AcrySof IQ patients. The stereopsis of Toric-ReSTOR eyes decreased slightly (53% versus 73%, x2=1.262, P=0.263). Patient satisfaction for mean near vision was significantly different: 80

  10. 准分子激光角膜表层切削术矫治疑似圆锥角膜的长期临床观察%Long-term results of excimer laser corneal surface ablation for correction of myopia and astigmatism in suspected keratoconus

    Institute of Scientific and Technical Information of China (English)

    张钰; 陈跃国; 夏英杰

    2011-01-01

    Objective To explore the long-term safety, efficacy and stability of laser epithelial keratomileusis (LASEK) and epipolis laser in situ keratomileusis (Epi-LASIK) for the correction of myopia and astigmatism in suspected keratoconus. Methods This was a retrospective clinical study.Thirty-eight patients with 55 eyes suspected to have keratoconus were enrolled in the study. All eyes were myopic, ranging from -3.25 to -7.75 D [(-5.54±2.18) D], cylinder 0 to 3 D[(0.80±0.75)D],with a central corneal thickness of 479 to 605 μm, and stage one keratoconus (KC1) detected by keratography. Refraction and keratograph were stable for at least 2 years in all eyes. Fifty-five eyes successfully underwent either LASEK (38 eyes) or Epi-LASIK (17 eyes). Visual acuity, refraction,and keratograph were checked postoperatively from 6 months to more than 2 years (2 to 5 years).A paired samples t test (normal distribution) and a Wilcoxon Signed Ranks test (non-normal distribution)were used to compare the data before and after surgery. Results More than 2 years postoperatively,uncorrected visual acuity was 1.0 or better in 48 eyes (87.3%), the efficacy index was 1.002; best spectacle-corrected visual acuity remained unchanged or improved in 51 eyes (92.7%), and one line was lost in 4 eyes (7.3%), the safety index was 1.053. Mean spherical equivalent refraction was (-0.11±0.45) D; spherical equivalent refraction was within ±0.50 D in 49 eyes (89.1%) and within ±1.00 D in 53 eyes (96.4%). Myopic refraction and astigmatism more than 2 years postoperatively were not significantly different from 6 months postoperatively (P>0.05). Mean keratoconus index was 1.08±0.01 preoperatively and 1.02±0.04 more than 2 years postoperatively (Z=-6.098, P<0.01). There was no obvious haze or keratoeonus progression during the follow-up period. Conclusion Patient's age, myopic refraction, corneal thickness and stability of refraction and keratograph are the key points to determine whether suspected

  11. 改良折叠型人工晶状体缝线固定术后角膜散光的临床观察%A clinical study on corneal astigmatism after secondary foldable intraocular with suture fixation by modified operation

    Institute of Scientific and Technical Information of China (English)

    姜皓; 刘鹏飞; 于迎娟; 刘华; 侯长军; 李峰; 王怡兰; 廖奇志

    2016-01-01

    Objective To investigate the changes of appearance of corneal surface and refraction after using modified operation with IOL Delivery System secondary foldable intraocular lens with suture fixation.Methods Twenty-three patients (23 eyes) who underwent foldable intraocular with suture fixation by modified operation,corneal topography was used to analyze preoperatively and at 3 days,1 week,1 month,3 months postoperatively.Results Average corneal astigmatism was decreased obviously 1 month after operation compared with 1 week after operation.There was not significant difference between 3 months and 1 month.Conclusions The changes of corneal topography are not obvious after using modified operation with IOL Delivery System secondary foldable intraocular lens with suture fixation,and have a better operation effect in the early stage.%目的 探讨改良折叠型人工晶状体缝线固定术后角膜表面形态、屈光状态的改变.方法 对2012年6月至2014年5月在唐山市眼科医院应用改良折叠型人工晶状体缝线固定术治疗眼外伤晶状体玻璃体切除术后患者23例(23只眼),运用角膜地形图仪检查术前,术后3d、1周、1个月、3个月的角膜散光变化.结果 平均角膜散光度术后1个月较1周明显减少,两者比较有显著性差异,3个月与1个月比较无显著性差异,即1个月时视力明显提高且趋于稳定.结论 改良折叠型人工晶状体缝线固定术具有术后角膜散光小,视力恢复快等优点,早期即可得到良好的手术效果.

  12. Visual Performance in Moderate to Severe Astigmatism : Rigid Gas-permeable Contact Lenses versus Spectacles%透气性硬性接触镜和框架眼镜矫正中高度散光视觉质量的比较

    Institute of Scientific and Technical Information of China (English)

    王雪; 马薇; 杨必; 刘陇黔

    2012-01-01

    Objective To explore whether spectacles or rigid gas-permeable (RGP) contact lenses provide better visual performance for moderate to severe astigmatism. Methods Between June 2008 and May 2011, 20 individuals (40 eyes) were fitted with both RGP lenses and spectacles. They first underwent corneal topography and refractometry, then were fitted with RGP trial lenses and lastly fitted with RGP lenses. When regularly followed up, the corrected visual acuity, wearing condition and eye health were evaluated respectively. For each type of lens, contrast visual acuity was evaluated. Each subject was asked to select the lens type of choice and to rate quality of vision in day-to-day activities through a questionnaire. Results The corrected visual acuity with RGP lenses was better than that with spectacles. But there was no difference in contrast visual acuity in all spatial frequency. Subjectively, there was no difference in vision, but most of the subjects prefer the computer-visual acuity and reading-visual acuity corrected by spectacles. About 40% of patients choose RGP contact lens as the main corrected method, and 45% of patients preferred using RGP lenses and spectacles alternately. About 10% of patients only wear RGP lenses when it was necessary. Two patients dropped out. Conclusions Both RGP lenses and spectacles leads to good results in correcting moderate to severe astigmatism. Though spectacles get higher scores in near vision, because of the better visual performance and appearance offered by RGP contact lens, a majority of patients can insist on wearing it.%目的 比较中高度散光患者配戴框架眼镜和透气性硬性接触镜(RGPCL)的主客观视觉质量.方法 选取2008年6月-2011年5月中高度角膜散光20例共40只眼进行角膜地形图、综合验光仪验光等检查后,选择合适试戴片作配适评估并定制RGPCL.要求患者戴镜后1周、1个月、3个月和6个月复查,记录矫正视力、镜片配

  13. Cancellation of RF Coupler-Induced Emittance Due to Astigmatism

    Energy Technology Data Exchange (ETDEWEB)

    Dowell, David H.; /SLAC

    2016-12-11

    It is well-known that the electron beam quality required for applications such as FEL’s and ultra-fast electron diffraction can be degraded by the asymmetric fields introduced by the RF couplers of superconducting linacs. This effect is especially troublesome in the injector where the low energy beam from the gun is captured into the first high gradient accelerator section. Unfortunately modifying the established cavity design is expensive and time consuming, especially considering that only one or two sections are needed for an injector. Instead, it is important to analyze the coupler fields to understand their characteristics and help find less costly solutions for their cancellation and mitigation. This paper finds the RF coupler-induced emittance for short bunches is mostly due to the transverse spatial sloping or tilt of the field, rather than the field’s time-dependence. It is shown that the distorting effects of the coupler can be canceled with a static (DC) quadrupole lens rotated about the z-axis.

  14. High-speed atomic force microscope based on an astigmatic detection system

    Energy Technology Data Exchange (ETDEWEB)

    Liao, H.-S.; Chen, Y.-H.; Hwu, E.-T.; Chang, C.-S.; Hwang, I.-S., E-mail: ishwang@phys.sinica.edu.tw [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Ding, R.-F.; Huang, H.-F.; Wang, W.-M. [Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan (China); Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Huang, K.-Y. [Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-10-15

    High-speed atomic force microscopy (HS-AFM) enables visualizing dynamic behaviors of biological molecules under physiological conditions at a temporal resolution of 1s or shorter. A small cantilever with a high resonance frequency is crucial in increasing the scan speed. However, detecting mechanical resonances of small cantilevers is technically challenging. In this study, we constructed an atomic force microscope using a digital versatile disc (DVD) pickup head to detect cantilever deflections. In addition, a flexure-guided scanner and a sinusoidal scan method were implemented. In this work, we imaged a grating sample in air by using a regular cantilever and a small cantilever with a resonance frequency of 5.5 MHz. Poor tracking was seen at the scan rate of 50 line/s when a cantilever for regular AFM imaging was used. Using a small cantilever at the scan rate of 100 line/s revealed no significant degradation in the topographic images. The results indicate that a smaller cantilever can achieve a higher scan rate and superior force sensitivity. This work shows the potential for using a DVD pickup head in future HS-AFM technology.

  15. Visual outcomes of conductive keratoplasty to treat hyperopia and astigmatism after laser in situ keratomileusis and photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Alireza Habibollahi

    2011-01-01

    Conclusions : CK is a predictable and reliable method to correct hyperopia after LASIK and PRK, however cylinder correction may induce irregular and unpredictable outcomes and a modified nomogram is required for further studies.

  16. Three-dimensional super-resolution imaging of the midplane protein FtsZ in live Caulobacter crescentus cells using astigmatism.

    Science.gov (United States)

    Biteen, Julie S; Goley, Erin D; Shapiro, Lucy; Moerner, W E

    2012-03-01

    Single-molecule super-resolution imaging provides a non-invasive method for nanometer-scale imaging and is ideally suited to investigations of quasi-static structures within live cells. Here, we extend the ability to image subcellular features within bacteria cells to three dimensions based on the introduction of a cylindrical lens in the imaging pathway. We investigate the midplane protein FtsZ in Caulobacter crescentus with super-resolution imaging based on fluorescent-protein photoswitching and the natural polymerization/depolymerization dynamics of FtsZ associated with the Z-ring. We quantify these dynamics and determine the FtsZ depolymerization time to be divisional stage.

  17. Transformation properties of annular beams passing through an astigmatic lens%环状光束通过像散透镜的变换特性

    Institute of Scientific and Technical Information of China (English)

    张帅; 张彬

    2008-01-01

    基于Tovar提出的平顶多高斯光束模型,给出了环状光束模型.利用广义惠更斯-菲涅耳衍射积分理论,对环状光束通过像散透镜后的传输和聚焦特性进行计算和分析,并讨论了透镜像散对环状光束经透镜变换后对光束质量的影响.研究结果表明:环状光束通过像散透镜后变为非旋转对称光束;聚焦光强随着透镜像散系数的增大而逐渐减弱,聚焦光斑的方位仅由像散系数确定;在光束阶数和入射光波波长一定的情况下,环状光束通过像散透镜的变换特性和光束质量不仅与透镜像散系数有关,还与系统菲涅耳数有关,像散系数增大或菲涅耳数减小时,光束质量变差.

  18. Laser resonators with several mirrors and lenses with the bow-tie laser resonator with compensation for astigmatism and thermal lens enects as an example

    DEFF Research Database (Denmark)

    Abitan, Haim; Skettrup, Torben

    2005-01-01

    Laser resonators with several mirrors (lenses) have been investigated in a systematic fashion. They have been grouped into classes according to their number n of mirrors/lenses. Stability polynomials, beam waist radii and locations have been obtained for each group up to n = 4. The bow-tie laser...

  19. Phakic posterior chamber intraocular lens combined with astigmatic keratotomy for high myopia with astigmatism%有晶状体眼后房型人工晶状体植入联合AK术治疗高度近视及散光的临床疗效

    Institute of Scientific and Technical Information of China (English)

    朱双倩; 俞阿勇; 薛安全; 王树林; 包芳军; 王勤美

    2009-01-01

    目的 研究有晶状体眼后房型人工晶状体(ICL)联合角膜松解术(AK)治疗高度近视及散光的安全性、有效性、预测性.方法 对21例(34眼)高度近视患者行有晶状体眼ICL植入术,对其中20眼散光度数≥1.5D的联合AK术.观察术前及术后1、3、6个月的裸眼视力、最佳矫正视力、屈光度、眼压、内皮细胞密度等.结果 所有患者成功植入ICL,手术前后等效球镜分别为(-13.5±2.2)、(-0.30±0.84)、(-0.28±0.86)、(-0.28±0.84)D;术后裸眼视力分别为4.80±0.16、4.81±0.17、4.82±0.17;手术前后最佳矫正视力分别为4.74±0.26、4.86±0.17、4.87±0.17、4.9±0.18,差异有统计学意义(P<0.01);内皮细胞密度术前为(2871±256)个/mm2,术后为(2773±267)个/mm2,差异有统计学意义(P<0.01);行AK术眼术前后散光分别为(-2.31±0.64)、(-1.22±0.57)、(-1.02±0.40)、(-0.93±0.39)D,差异有统计学意义(P<0.01).结论 有晶状体眼ICL联合AK术治疗高度近视及散光有较好的安全性、有效性、预测性,长期疗效有待进一步观察.

  20. Long-Term Comparison of Posterior Chamber Phakic Intraocular Lens With and Without a Central Hole (Hole ICL and Conventional ICL) Implantation for Moderate to High Myopia and Myopic Astigmatism

    Science.gov (United States)

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

    2016-01-01

    Abstract The study shows a promising next-generation surgical option for the correction of moderate to high ametropia. Hole implantable collamer lens (ICL), STAAR Surgical, is a posterior chamber phakic intraocular lens with a central artificial hole. As yet, however, no long-term comparison of the clinical results of the implantation of ICLs with and without such a hole has hitherto been conducted. A prospective, randomized, controlled trial was carried out in order to compare the long-term clinical outcomes of the implantation, in such eyes, of ICLs with and without a central artificial hole. Examinations were conducted of the 64 eyes of 32 consecutive patients with spherical equivalents of −7.53 ± 2.39 diopters (D) (mean ± standard deviation) in whom implantation of a Hole ICL was performed in 1 eye, and that of a conventional ICL was carried out in the other, by randomized assignment. Before 1, 3, and 6 months, and 1, 3, and 5 years after surgery, the safety, efficacy, predictability, stability, intraocular pressure, endothelial cell density, and adverse events of the 2 surgical techniques were assessed and compared over time. The measurements of LogMAR uncorrected and corrected distance visual acuity 5 years postoperatively were −0.17 ± 0.14 and −0.24 ± 0.08 in the Hole ICL group, and −0.16 ± 0.10 and −0.25 ± 0.08 in the conventional ICL group. In these 2 groups, 96% and 100% of eyes, respectively, were within 1.0 D of the targeted correction 5 years postoperatively. Manifest refraction changed by −0.17 ± 0.41 D and −0.10 ± 0.26 D occurred in from 1 month to 5 years in the Hole and conventional ICL groups, respectively. Only 1 eye (3.1%), which was in the conventional ICL group, developed an asymptomatic anterior subcapsular cataract. Both Hole and conventional ICLs corrected of ametropia successfully throughout the 5-year observation period. It appears likely that the presence of the central hole does not significantly affect these visual and refractive outcomes. Trial Registration: UMIN000018771. PMID:27057883

  1. 有晶状体眼前房型环曲面人工晶状体植入矫正散光%Artisan toric phakic intraocular lens for the correction of astigmatism

    Institute of Scientific and Technical Information of China (English)

    涂云海; 俞阿勇; 高潮

    2007-01-01

    散光的矫治一直是屈光手术的焦点,有晶状体眼前房型环曲面人工晶状体(Artisan toric phakic intraocular lens,TPIOL)矫正散光,以其矫治范围大、安全、有效,逐渐受到临床关注.本文就Artisan TPIOL的物理特征、手术患者的筛选、术前准备、手术方法,以及对其术后安全性、有效性、准确性、稳定性、最小损害等评价作一综述.

  2. Power vector analysis of the outcomes of laser subepithelial keratomileusis and laser in situ keratomileusis for high myopia astigmatism%矢量法分析LASEK和LASIK矫正高度散光的疗效

    Institute of Scientific and Technical Information of China (English)

    干德康; 周行涛; 戴锦晖; 瞿小妹; 于志强; 褚仁远

    2009-01-01

    目的 应用Thibos矢量法比较准分子激光上皮瓣下角膜磨镶术(laser subepithelial keratomileus-is,LASEK)和准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)矫正高度散光(≥-2.75 D)的疗效.方法 LASEK59例(59眼),LASIK37例(37眼).分析两组患者术前和术后裸眼视力(uncorrected visualacuity,UCVA)、最佳矫正视力(best corrected visual acuity,BCVA)、屈光度(S球镜,C柱镜,M等效球镜)和模糊指数B的差别.结果 除LASIK组BCVA外,所有患者术前和术后UCVA、BCVA、S、M、C、B差异均有统计学意义.术后两组间S、C、M、B差异均无统计学意义,BCVA较术前无一例发生下降2行.结论 LASEK和LASIK手术方式均安全、手术效果可靠,是治疗高度散光的有效方法.Thibos矢量分析能够全面地描述眼屈光异常和屈光手术疗效.(中国眼耳鼻喉科杂志,2009,9:23-25)

  3. 球性RGP角膜接触镜矫正轻度散光的临床应用%Clinical application of spherical rigid gas permeable contact lens on mild astigmatism eyes

    Institute of Scientific and Technical Information of China (English)

    李建华; 兰长骏; 廖萱; 杨阳

    2011-01-01

    目的:观察球性硬性透气性角膜接触镜(rigid gas permeable contact lens,RGP)矫正轻度散光的效果.方法:对25例42眼轻度散光眼进行球性RGP验配,对比裸眼视力、框架眼镜矫正视力和RGP矫正视力.结果:所有散光眼的框架眼镜矫正视力和球性RGP矫正视力均明显高于裸眼视力,三组视力值之间均有统计学意义(P<0.05).结论:球性RGP用于矫正轻度散光安全、有效,值得推广与应用.

  4. Correcting evaluation of rigid gas permeable contact lens for astigmatic amblyopia%硬性透气性角膜接触镜对散光性弱视的矫治作用

    Institute of Scientific and Technical Information of China (English)

    陶祥臣; 石岩; 李云杰; 张慧卿; 牟国营

    2008-01-01

    目的 评价硬性透气性角膜接触镜(rigid gas per-meable contact lens,RGPCL)对儿童散光性弱视的矫治作用及其安全性.方法 选取框架眼镜矫治效果欠佳的儿童散光性弱视23例(46眼),其中,单纯远视性散光5眼,复合远视性散光23眼,复合近视性散光14眼.混合散光4眼.依据框架眼镜矫正视力分为轻度弱视组(13眼),中度弱视组(22眼),重度弱视组(11眼).所有患儿配戴高透气性RGPCL,随访12个月,观察其矫治作用.结果 配戴RGPCL即时,矫正视力较框架眼镜提高1~4行,平均(2.7±0.9)行,达到或超过5.0者7眼(15.22%).12个月后,28眼(60.87%)的矫正视力≥5.0,其中,轻度弱视组11眼(84.62%),中度弱视组17眼(77.27%),重度弱视组无一眼达到5.0.观察期内无严重角、结膜损伤以及感染等并发症发生,无因不能耐受而停戴者.结论 RGPCL对儿童散光性弱视的矫治是有效而安全的,框架眼镜矫治效果欠佳者可优先选择RGPCL.

  5. A clinical observation of spherical RGP on the correction of high corneal astigmatism%球面透气性硬性角膜接触镜矫正高度角膜散光

    Institute of Scientific and Technical Information of China (English)

    李军; 亢晓丽; 饶玉; 栗丽; 杨丽; 汪芳润

    2007-01-01

    目的 评价球面透气性硬性角膜接触镜(rigid gas permeable contact lens,RGP)矫正高度角膜散光(≥3.00 D)时的有效性、稳定性和患者耐受性.方法 选择高度角膜散光患者41例55眼,经角膜曲率检查、电脑验光、检影验光、综合验光仪验光,确认为总散光与角膜散光基本一致者,进行试戴片配适评估、戴片验光,给予配戴球面RGP.定期回访,记录矫正视力、镜片配适及配戴情况.结果 RGP最佳矫正视力:30眼(占54.5%)高于框架镜,22眼(占40.0%)等于框架镜,3眼(占5.5%)低于框架镜.患者均获得稳定配适.随访1~65个月(平均40.5个月),3例(4眼)患者因不能适应镜片的异物感而停戴.其余38例(51眼)仍坚持配戴,并对该矫正方法满意.结论 应用球面RGP矫正高度角膜散光,可获得良好配适和满意的视力矫正效果.多数患者能够坚持长期配戴.

  6. Orbscan II、电脑验光仪、综合验光测量散光的对比观察%Comparison of computer optometer, Orbscan II and comprehensive optometry in measurement of astigmatism

    Institute of Scientific and Technical Information of China (English)

    李凯; 王育良; 吴静; 张玉娟

    2010-01-01

    目的 分析准分子手术前近视散光患者术前应用Orbscan II 眼前节分析系统,自动电脑验光仪测得的柱镜和散光轴向与综合验光测得结果的差异及关系.方法采用Orbscan II 眼前节分析系统、小瞳下电脑验光、散瞳后电脑验光和综合验光4种测量方法,对130例(250只眼)近视散光进行检查并比较.结果综合验光、小瞳电脑验光和散瞳电脑验光3种方法测得的轴向基本一致,统计学分析无显著性差异(P>0.05),而Orbscan II与综合验光测得的轴向统计学上有显著性差异(P<0.01);综合验光、小瞳电脑验光和散瞳电脑验光3种方法测得的散光度数统计学上有显著性差异(P<0.01).结论角膜地形图检查能反映角膜屈光状况,电脑验光仪对散光轴向的准确性较高,但临床检查仍应以睫状肌麻痹前后综合验光检查作为确定近视散光及散光轴的标准.

  7. Comparison of computer optometer, keratometer and retinoscope in measurement of astigmatism%电脑验光仪、角膜曲率计、检影验光测量散光的比较

    Institute of Scientific and Technical Information of China (English)

    陈振超; 谭茂卿

    2008-01-01

    目的:比较电脑验光仪、角膜曲率计和检影验光检查角膜散光三种方法.方法:采用电脑验光仪、角膜曲率、检影验光三种方法对屈光不正患者169例(338眼),进行检查.结果:本组病例中散光度数以3.50D以下为主,顺规性散光125例(250眼),占74.5%.逆规性散光44例(88眼),占25.5%.三者测出散光轴位比较,散光轴位基本相同,其中以电脑验光最准,差异无显著性(P>0.05).三者测出散光度数比较,差异有非常显著性(P<0.01).结论:电脑验光、检影验光对散光轴位和度数测量各有优点、验光中相辅相成避免误差,是一种好的工作方法.

  8. Clinical study of rigid gas-permeable lenses to correct astigmatism for keratoconus%硬性透气性隐形眼镜(RGP)矫正圆锥角膜的疗效分析

    Institute of Scientific and Technical Information of China (English)

    王丽强; 刘莉; 黄一飞

    2006-01-01

    AIM: To evaluate visual outcome and wearing times in eyes fitted with a rigid gas permeable contact lenses and to assess the role of these lenses in therapeutic contact lens practice.METHODS: Patients fitted with RGP from May 2004 to December 2005 were retrospectively reviewed. Ocular diagnosis,flat and steep curvatures by corneal topography. The data included initial base curve, power, and the number of changes made in parameters during the follow-up. The outcome data included visual acuity and the duration of follow-up and lens wear. Complications and complaints were also noted.RESULTS: Forty-Three eyes of 25 patients had keratoconus were reviewed. The mean age of patients was 19.88 ±3.11years. 26 (60.5%)eyes achieved 20/20 visual acuity;15(34.9%) eyes achieved 20/25 to 20/40; and 1 (2.3%) eyes achieved 20/50 to 20/70. 37 (86.0%) eyes achieved visual improvement. No infection or neovascularization was noted; a corneal abrasion occurred in one eye.CONCLUSION: RGP may be a better alternative in selected patients with keratoconus rather than penetrating keratoplasty.%目的:评价硬性透气性隐形眼镜(RGP)矫正圆锥角膜屈光异常的疗效.方法:选择我院2004-05/2005-12收治的25例(43眼)圆锥角膜患者配戴RGP,观察视力、角膜曲率、配适状况、舒适度及并发症.结果:RGP矫正视力均好于或等于框架球柱面联合镜.其中优于框架球柱面联合镜片者37眼(86.0%),二者视力相等者6眼(14.0%),矫正视力低于框架球柱面联合镜者0眼,经统计学处理,两者有显著性差异(P<0.01).配戴RGP 6mo时角膜曲率值没有明显变化.本组病例配适良好,合并症少而轻.结论:经6mo随访观察,RGP对圆锥角膜的视力矫正明显优于框架眼镜,是目前矫正圆锥角膜的非手术治疗的有效方法.

  9. 新型人工晶体推送器对白内障术后角膜散光影响的临床研究%Clinical study on the effect of new type intraocular lens unfolder on postoperative astigmatism

    Institute of Scientific and Technical Information of China (English)

    汤欣; 杨瑞波; 孙慧敏

    2004-01-01

    目的:评价2.6mm口径的新型人工晶体推送器(Emerald T推送器)对白内障超声乳化人工晶体植入术后角膜散光的影响.方法:将160例(160眼)老年性白内障患者随机分为两组:A组为2.6mm口径的Emerald T人工晶体推送器组;B组为3.2mm口径的Sapphire人工晶体推送器组.所有患者均行经透明角膜超声乳化人工晶体植入术,术后1周、1月、3月采用角膜地形图仪比较两组角膜散光的变化情况.结果:A、B两组术后1周、1月、3月平均手术源性角膜散光(D)分别为:0.36 0.20、0.33 0.23、0.31 0.22;0.78 0.61、0.69 0.58、0.58 0.44;两组间差别有统计学意义(P<0.05).术后1周及1月,A、B两组裸眼视力≥0.5者分别为:74眼(92.50%)、77眼(96.25%);62眼(77.50%)、70眼(87.50%),两组间差别有统计学意义(P<0.05),术后3月两组裸眼视力≥0.5者分别为:77眼(96.25%)、73眼(91.25%),两组间差别无统计学意义(P>0.05).结论:2.6mm口径的Emerald T人工晶体推送器所需手术切口小、术后散光小、视力恢复快且稳定,是目前较为理想的小切口人工晶体植入装置.

  10. Prevalência do astigmatismo e distribuição de seu eixo em pacientes de um serviço oftalmológico privado Prevalence of astigmatism and its axis in an ophthalmology private clinic

    OpenAIRE

    Tatiana Rocha Rayes; Guilherme Rocha Rayes; Felipe Eing; Heriberto Pinto Guimarães Neto; Francisco Azevedo Marquardt; Assad Rayes

    2007-01-01

    OBJETIVO: Verificar a prevalência do astigmatismo e a variação de seu eixo nas várias faixas etárias (2-99 anos) em uma população de uma clínica oftalmológica privada na cidade de Florianópolis, Santa Catarina, Brasil. MÉTODOS: Foi realizado um estudo retrospectivo, descritivo, transversal com base na análise de prontuários. Foi considerado astigmatismo uma diferença entre o maior e menor meridiano da córnea de -0,50 dioptrias(D) ou mais. Quanto ao eixo, consideramos: astigmatismo a favor da ...

  11. Vector analysis following astigmatic correction by VISX STAR S3 excimer laser%VISX STAR S3准分子激光治疗散光的向量分析

    Institute of Scientific and Technical Information of China (English)

    周少博; 路晓明; 苏小波; 洪海峰; 麦庆怡; 黎健菁; 胡群英

    2010-01-01

    目的 运用散光的向量分析法对VISX STAR S3准分子激光治疗中高度散光的疗效进行评价.方法 采用回顾性方法研究接受VISX STAR S3准分子激光角膜原位磨镶术(LASIK)的散光患者25例36眼,术前散光度2.0~4.25D,术后随访6个月以上,根据手术前后主觉验光结果,运用Alpins散光向量分析法分析目标诱导散光向量(TIA)、手术诱导散光向量(SIA)、错位角(AE)、矫正指数、成功指数(IOS)、变平指数(FI)等向量参数改变.结果 平均TIA为(2.68±0.73)D,平均SIA为(2.67±0.8)D;平均矫正指数为0.98±0.18,95%可信区间为(0.93~1.04),无显著性系统性欠矫或过矫;平均绝对AE为3.30°±3.8°;平均AE为-0.92°±4.98°,95%可信区间为(-2.55°~0.71°),无显著性系统性轴向错位;平均IOS为0.18±0.17,成功率(ROS)为0.80±0.17,平均FI为0.97±0.18.矫正指数与散光度及球镜度均无显著相关性(r=-0.16,r=0.23,P>0.05),成功指数与散光度及球镜度亦无显著相关性(P>0.05),TIA与SIA呈正相关(r=0.80,P<0.05).结论 VISX STAR S3激光矫治中高度散光的准确性和成功率均较高,向量分析提供了必要的和易于理解的散光改变信息.

  12. [Refractive regression after intraocular lens implantation].

    Science.gov (United States)

    Ma, Z Z; Momose, A

    1991-05-01

    Study of refractive changes after IOL implantation in 147 eyes revealed that astigmatism tended to increase, and the natural regressive course followed a negative exponential function, with the steep phase within 3 weeks for spherical, and 5 weeks for cylindrical errors. One (1) week after surgery, the axis of astigmatism was predominantly with the rule, and 2 months after operation, patients with preoperative WRA changed into various astigmatic axial directions, while 76.4% of the patients with preoperative ARA reverted to ARA. Those eyes in which the astigmatic axis was not horizontal 1 week after operation ended with stronger astigmatism in 2 months.

  13. Corneal relaxing incision combined with phacoemulsification and IOL implantation

    Institute of Scientific and Technical Information of China (English)

    沈晔; 童剑萍; 李毓敏

    2004-01-01

    Objective: To analyze the effectiveness and safety of corneal relaxing incisions (CRI) in correcting keratometric astigmatism during cataract surgery. Methods: A prospective study of two groups: control group and treatment group. A treatment group included 25 eyes of 25 patients who had combined clear corneal phacoemulsification, IOL implantation and CRI. A control group included 25 eyes of 25 patients who had clear corneal phacoemulsification and IOL implantation.Postoperative keratometric astigmatism was measured at 1 week, 1 month, 3 months and 6 months. Results: CRI signifi-cantly decreased keratometric astigmatism in patients with preexisting astigmatism compared with astigmatic changes in the control group. In eyes with CRI, the mean keratometric astigmatism was 0.29±0.17 D(range 0 to 0.5 D) at 1 week, 0.41±0.21 D (range 0 to 0.82 D) at 1 month, respectively reduced by 2.42 D and 2.30 D at 1 week and 1 month postoperatively (P=0.000, P=0.000), and postoperative astigmatism was stable until 6 months follow-up. The keratometric astigmatism of all patients decreased to less than 1.00 D postoperatively. Conclusions: CRI is a practical, simple, safe and effective method to reduce preexisting astigmatism during cataract surgery. A modified nomogram is proposed. The long-term effect of CRI should be investigated.

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

    DEFF Research Database (Denmark)

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

    treatments were performed at the Department of Ophthalmology, Odense University Hospital from April 2011 to December 2013. Inclusion criteria: CDVA ≤ 0.10 (logMAR) before surgery and no other ocular conditions than myopia with or without astigmatism of maximum 3 D. Exclusion criteria: Eyes having undergone...... of astigmatism, and results were overall comparable 3 months after surgery. Financial disclosures: None....

  15. 晶状体眼后房型人工晶状体/散光性后房型人工晶状体术矫正高度近视的临床观察%Clinical observation of implantation of posterior chamber intraocular lens/astigmatism posterior chamber intraocular lens for patients with high myopia

    Institute of Scientific and Technical Information of China (English)

    杨吟; 刘治容; 陈斌; 陈波; 杨萍; 吴峥峥

    2014-01-01

    目的 研究晶状体眼后房型人工晶状体(implantable contact lens,ICL)/散光性后房型人工晶状体(TICL)植入术矫正高度近视的有效性及安全性.方法 收集在我院行IC[/TICL植入术的患者77例(153只眼),在术后第1天、1周、1月、3月和6月时行视力、裂隙灯显微镜、眼底镜和眼压检查,术后1个月加做客观检影验光.对比术前最佳矫正视力及术后裸眼视力的差异.结果 153只眼均成功植入了ICL/TICL,术后144只眼(94.12%)未发现明显的并发症.术后1周时,153眼的裸眼视力为0.83±0.15,术前矫正视力与术后裸眼视力比较差异无统计学意义(P>0.05).结论 ICL/TICL植入手术治疗高度/超高度近视,是目前对于该类患者有效且安全的治疗方案.

  16. Toric硬性透气性角膜接触镜对33例高度散光眼的视力矫正作用%Evaluation on efficiency of 33 cases with high astigmatism corrected by toric rigid gas-permeable contact lens

    Institute of Scientific and Technical Information of China (English)

    唐凯; 司俊康; 杜宇翔; 吴建峰; 周蒙蒙; 毕宏生

    2014-01-01

    目的 评估Toric硬性透气性角膜接触镜(rigid gas-permeable contact lens,RG-PCL)对高度散光眼的视力矫正作用.方法 收集高度散光患者33例(62眼),单纯角膜散光或眼内散光<1.00 DC验配后环曲面RGPCL,眼内散光≥1.00 DC验配双环曲面RG-PCL.对高度散光眼配戴框架镜及Toric RGPCL的视力矫正效果进行比较;对>2.00~4.00 DC、>4.00 DC散光眼配戴Toric RGPCL相对框架镜的矫正幅度进行比较;对伴有高度近远视、低中度近远视的散光眼配戴Toric RGPCL的视力矫正效果进行比较.结果 53眼验配后环曲面RGPCL,相对裸眼视力提高0.67±0.24,9眼验配双环曲面RGPCL,相对裸眼视力提高0.50±0.24,两种Toric RGPCL对视力的矫正作用均明显优于框架镜(t=9.21,P=0.00;t =6.49,P=0.00);>2.00 ~4.00 DC、>4.00 DC散光眼配戴Toric RGPCL后相对框架镜矫正视力分别提高0.17±0.15、0.26±0.14,两者比较差异有统计学意义(t=2.47,P=0.016);伴有不同球镜度数的高度散光眼配戴Torie RGPCL后,视力矫正效果差异无统计学意义(t =0.47,P>0.05).结论 Toric RGPCL对高度散光眼有理想的矫正效果,且对于>4.00 DC散光眼矫正效果更佳,其对散光的矫正作用与球镜度无关.

  17. Small-incision lenticule extraction (SMILE)

    DEFF Research Database (Denmark)

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

    2016-01-01

    PURPOSE: To study the outcomes of small-incision lenticule extraction (SMILE) for treatment of myopia and myopic astigmatism. METHODS: Retrospective study of patients treated for myopia or myopic astigmatism with SMILE, using a VisuMax(®) femtosecond laser (Carl Zeiss Meditec, Jena, Germany...... surgery was 0.07 ± 0.03 (logMAR). However, 12 eyes (1.6 %) lost 2 or more lines of CDVA from before surgery to 3 months postoperatively. Simultaneous treatment of up to 3.00 D of astigmatism was not associated with less predictable refractive outcomes. CONCLUSIONS: In the short term, SMILE seemed...

  18. Modified Scleral Flap Incision to Reduce Corneal Astigmatisn after Intraocular Lens Implantation

    Institute of Scientific and Technical Information of China (English)

    YizhiLiu; ShaozhenLi

    1995-01-01

    Purpose:To investigate a simple method during extracapsular cataract extraction with posteior chamber intraocular lens implantation in order to reduce surgically induced corneal astig-matism.Methods:A modified scleral flap incision was used in the extracapsular cataract extraction with intraocular lens implantation and the postoperative changes in conreal astigmatism was observed.Results:The peak value of postoperative corneal astigmatism was3.60D,and the corneal astigmatism regression was 2.11D,surgically induced astigmatism was less significant in modified scleral flap incision group than that in convention-al limbal incison group(P<0.05).Conclusions:The modified scleral flap inciston is an ideal incision for cataract ex-traction with intraocular lens implantation when phacoemulsifier is not avaliable.Eye Science1995;11:136-139.

  19. Standard ophthalmic exam

    Science.gov (United States)

    ... Check for glaucoma using a method called tonometry Color blindness is tested using cards with colored dots that ... macular degeneration (ARMD) Astigmatism Blocked tear duct Cataracts Color blindness Corneal abrasion (or dystrophy) Corneal ulcers and infections ...

  20. Contact Lens Visual Rehabilitation in Keratoconus and Corneal Keratoplasty

    Directory of Open Access Journals (Sweden)

    Yelda Ozkurt

    2012-01-01

    Full Text Available Keratoconus is the most common corneal distrophy. It’s a noninflammatory progressive thinning process that leads to conical ectasia of the cornea, causing high myopia and astigmatism. Many treatment choices include spectacle correction and contact lens wear, collagen cross linking, intracorneal ring segments implantation and finally keratoplasty. Contact lenses are commonly used to reduce astigmatism and increase vision. There are various types of lenses are available. We reviewed soft contact lenses, rigid gas permeable contact lenses, piggyback contact lenses, hybrid contact lenses and scleral-semiscleral contact lenses in keratoconus management. The surgical option is keratoplasty, but even after sutur removal, high astigmatism may stil exists. Therefore, contact lens is an adequate treatment option to correct astigmatism after keratoplasty.

  1. Light with a twist : ray aspects in singular wave and quantum optics

    NARCIS (Netherlands)

    Habraken, Steven Johannes Martinus

    2010-01-01

    Light may have a very rich spatial and spectral structure. We theoretically study the structure and physical properties of coherent optical modes and quantum states of light, focusing on optical vortices, general astigmatism, orbital angular momentum and rotating light.

  2. Eyelid Problems

    Science.gov (United States)

    ... Ear Nose & Throat Emotional Problems Eyes Fever From Insects or Animals Genitals and Urinary Tract Glands & Growth ... an irregular shape (astigmatism), it will threaten normal vision development and must be corrected as early as ...

  3. Miniature anastigmatic spectrometer design with a concave toroidal mirror.

    Science.gov (United States)

    Dong, Jianing; Chen, He; Zhang, Yinchao; Chen, Siying; Guo, Pan

    2016-03-01

    An advanced optical design for a low-cost and astigmatism-corrected spectrometer with a high resolution is presented. The theory and method of astigmatism correction are determined with the use of a concave toroidal mirror. The performances of a modified spectrometer and a traditional spectrometer are compared, and the analysis is verified. Experimentally, the limiting resolution of our spectrometer is 0.1 nm full width at half-maximum, as measured for 579.1 nm.

  4. Factors Influencing Efficacy of Peripheral Corneal Relaxing Incisions during Cataract Surgery

    Directory of Open Access Journals (Sweden)

    Nino Hirnschall

    2015-01-01

    Full Text Available Purpose. To evaluate influencing factors on the residual astigmatism after performing peripheral corneal relaxing incisions (PCRIs during cataract surgery. Methods. This prospective study included patients who were scheduled for cataract surgery with PCRIs. Optical biometry (IOLMaster 500, Carl Zeiss Meditec AG, Germany was taken preoperatively, 1 week, 4 months, and 1 year postoperatively. Additionally, corneal topography (Atlas model 9000, Carl Zeiss Meditec AG, Germany, ORA (Ocular Response Analyzer, Reichert Ophthalmic Instruments, USA, and autorefraction (Autorefractometer RM 8800 Topcon were performed postoperatively. Results. Mean age of the study population n=74 was 73.5 years (±9.3; range: 53 to 90 and mean corneal astigmatism preoperatively was −1.82 D (±0.59; 1.00 to 4.50. Mean corneal astigmatism was reduced to 1.14 D (±0.67; 0.11 to 3.89 4 months postoperatively. A partial least squares regression showed that a high eccentricity of the cornea, a large deviation between keratometry and topography, and a high preoperative astigmatism resulted in a larger postoperative error concerning astigmatism. Conclusions. PCRI causes a reduction of preoperative astigmatism, though the prediction is difficult but several factors were found to be a relevant source of error.

  5. Keratometry device for surgical support

    Directory of Open Access Journals (Sweden)

    Saia Paula

    2009-12-01

    Full Text Available Abstract Background High astigmatisms are usually induced during corneal suturing subsequent to tissue transplantation or any other surgery which involves corneal suturing. One of the reasons is that the procedure is intimately dependent on the surgeon's skill for suturing identical stitches. In order to evaluate the influence of the irregularity on suturing for the residual astigmatism, a prototype for ophthalmic surgical support has been developed. The final intention of this prototype is to be an evaluation tool for guided suture and as an outcome diminish the postoperative astigmatism. Methods The system consists of hand held ring with 36 infrared LEDs, that is to be projected onto the lachrymal film of the cornea. The image is reflected back through the optics of the ocular microscope and its distortion from the original circular shape is evaluated by developed software. It provides keratometric and circularity measurements during surgery in order to guide the surgeon for uniformity in suturing. Results The system is able to provide up to 23D of astigmatism (32D - 55D range and is ± 0.25D accurate. It has been tested in 14 volunteer patients intraoperative and has been compared to a commercial keratometer Nidek Oculus Hand-held corneal topographer. The correlation factors are 0.92 for the astigmatism and 0.97 for the associated axis. Conclusion The system is potentially efficient for guiding the surgeon on uniformity of suturing, presenting preliminary data indicating an important decrease on the residual astigmatism, from an average of 8D - for patients not submitted to the prototype guidance - to 1.4D - for patients who have actually been submitted to the prototype guidance - after the first 24 hours post-surgery and in the subsequent weeks. It also indicates that the surgeon should achieve circularity greater or equal to 98% in order to avoid postoperative astigmatisms over 1D. Trial Registration Trial registration number: CAAE - 0212.0.004.000-09.

  6. Shack-Hartmann sensor based optical quality testing of whole slide imaging systems for digital pathology

    Science.gov (United States)

    Shakeri, S. M.; Hulsken, Bas; van Vliet, Lucas J.; Stallinga, Sjoerd

    2015-03-01

    Whole Slide Imaging (WSI) systems are used in the emerging field of digital pathology for capturing high-resolution images of tissue slides at high throughput. We present a technique to measure the optical aberrations of WSI systems using a Shack-Hartmann wavefront sensor as a function of field position. The resulting full-field aberration maps for the lowest order astigmatism and coma are analyzed using nodal aberration theory. According to this theory two coefficients describe the astigmatism and coma inherent to the optical design and another six coefficients are needed to describe the cumulative effects of all possible misalignments on astigmatism and coma. The nodal aberration theory appears to fit well to the experimental data. We have measured and analyzed the full-field aberration maps for two different objective lens-tube lens assemblies and found that only the optical design related astigmatism coefficient differed substantially between the two cases, but in agreement with expectations. We have also studied full-field aberration maps for intentional decenter and tilt and found that these affect the misalignment coefficient for constant coma (decenter) and the misalignment coefficient for linear astigmatism (tilt), while keeping all other nodal aberration theory coefficients constant.

  7. Observation of lens aberrations for high resolution electron microscopy II: Simple expressions for optimal estimates

    Energy Technology Data Exchange (ETDEWEB)

    Saxton, W. Owen, E-mail: wos1@cam.ac.uk

    2015-04-15

    This paper lists simple closed-form expressions estimating aberration coefficients (defocus, astigmatism, three-fold astigmatism, coma / misalignment, spherical aberration) on the basis of image shift or diffractogram shape measurements as a function of injected beam tilt. Simple estimators are given for a large number of injected tilt configurations, optimal in the sense of least-squares fitting of all the measurements, and so better than most reported previously. Standard errors are given for most, allowing different approaches to be compared. Special attention is given to the measurement of the spherical aberration, for which several simple procedures are given, and the effect of foreknowledge of this on other aberration estimates is noted. Details and optimal expressions are also given for a new and simple method of analysis, requiring measurements of the diffractogram mirror axis direction only, which are simpler to make than the focus and astigmatism measurements otherwise required. - Highlights: • Optimal estimators for CTEM lens aberrations are more accurate and/or use fewer observations. • Estimators have been found for defocus, astigmatism, three-fold astigmatism, coma and spherical aberration. • Estimators have been found relying on diffractogram shape, image shift and diffractogram orientation only, for a variety of beam tilts. • The standard error for each estimator has been found.

  8. Resolution of electro-holographic image

    Science.gov (United States)

    Son, Jung-Young; Chernyshov, Oleksii; Lee, Hyoung; Lee, Beom-Ryeol; Park, Min-Chul

    2016-06-01

    The resolution of the reconstructed image from a hologram displayed on a DMD is measured with the light field images along the propagation direction of the reconstructed image. The light field images reveal that a point and line image suffers a strong astigmatism but the line focusing distance differences for lines with different directions. This will be astigmatism too. The focusing distance of the reconstructed image is shorter than that of the object. The two lines in transverse direction are resolved when the gap between them is around 16 pixels of the DMD's in use. However, the depth direction is difficult to estimate due to the depth of focus of each line. Due to the astigmatism, the reconstructed image of a square appears as a rectangle or a rhombus.

  9. Microsurgical Treatment of Mooren's Ulcer

    Institute of Scientific and Technical Information of China (English)

    Hanping Xie; Jiaqi Chen; Xiangming Gong; Chunmao Feng; Longshan Chen; Yuesheng Lin

    2000-01-01

    Objective: To evaluate effect of microsurgery of lamellar keratoplasty (LKP) on Mooren's corneal ulcer.Methods: The effect, postoperative astigmatism, postoperative vision, ulcer recurrence of postoperation, and surgical complications of two groups of consecutive Mooren's ulcer inpatients treated respectively by non-microsurgery of LKP and microsurgery of LKP were analyzed.Results:There were significant differences of the effect, postoperative astigmatism,postoperative vision, ulcer recurrence of postoperation, and surgical complications between the two groups. The effect and postoperative vision of the microsurgery-treated groupwerebetterthanthoseofthenon-microsurgery-treatedgroup. The postoperative astigmatism, ulcer recurrence of postoperation, and surgical complications of the microsurgery-treated group were less than those of the nonmicrosurgery-treated group.Conclusion: Microsurgery of LKP of Mooren's corneal ulcer can greatly improve the ulcer healing and postoperative vision, and reduce the surgical complication and the ulcer recurrence of postoperation. Eye Science 2000; 16:56 ~ 60.

  10. Cyclopentolate as a cycloplegic drug in determination of refractive error

    Directory of Open Access Journals (Sweden)

    Bolinovska Sofija

    2008-01-01

    Full Text Available Cycloplegia is loss of the power of accommodation with inhibition of a ciliary muscle. We obtain in this way the smallest refraction of the lens and make it possible to determine the presence and size of the particular refractive error in cycloplegia by using cyclopentolate. Cyclopentolate is a synthetic anticholinergic drug and antagonist of the muscarine receptors. If applied in the eye, it blocks the effect of cholinergic stimulation on the sphincter pupillae muscle and ciliary muscle. It provokes severe mydriasis (dilation of the pupil and cycloplegia (paralysis of the accommodation. Cyclopentolate has been used occasionaly in diagnostic purposes: defining ocular refraction and in ophthalmoscopy. This is the prospective study which included 200 children (400 eyes aged 3-18 years, carried out in one ambulatory ophthalmological examination. The results were analysed using standard statistical methods. The most often refractive error in the examined group of children is hyperopia with hyperopic astigmatism, then myopia with myopic astigmatism and mixtus astigmatism are the most often in the oldest group of children. The mean value of corneal astigmatism on the right eye was 1.24 D, on the left eye 1.23 D. Anisometropy was found in 40% children. The presence of myopia, myopic and astigmatism mixtus tended to increase, and hyperopia and hyperopic astigmatism tended to decrease toward older groups of children. Refractive error could result in a poor development of visual acuity, causing amblyopia and strabismus, and because of that represents an important public health problem. As one of amblyogenic risk factors in children, it can be prevented with screening program and appropriate treatment, thus providing prevention of amblyopia as one form of blindness.

  11. Symbolic algebra approach to the calculation of intraocular lens power following cataract surgery

    Science.gov (United States)

    Hjelmstad, David P.; Sayegh, Samir I.

    2013-03-01

    We present a symbolic approach based on matrix methods that allows for the analysis and computation of intraocular lens power following cataract surgery. We extend the basic matrix approach corresponding to paraxial optics to include astigmatism and other aberrations. The symbolic approach allows for a refined analysis of the potential sources of errors ("refractive surprises"). We demonstrate the computation of lens powers including toric lenses that correct for both defocus (myopia, hyperopia) and astigmatism. A specific implementation in Mathematica allows an elegant and powerful method for the design and analysis of these intraocular lenses.

  12. Comparison of fitting stability of the different soft toric contact lenses

    OpenAIRE

    Momeni-Moghaddam, Hamed; Naroo, Shehzad A; Askarizadeh, Farshad; Tahmasebi, Fatemeh

    2014-01-01

    Purpose: To compare lens orientation and rotational recovery of five currently available soft toric lenses. Methods: Twenty subjects were recruited and trialed with each of the study lenses in a random order. Study lenses were PureVision® Toric (B&L), Air Optix® for Astigmatism (Alcon), Biofinity® Toric (CooperVision), Acuvue® Advance for Astigmatism (Vistakon), and Proclear® Toric (CooperVision). Lens orientation in primary position to determine the lens rotation form the vertical position a...

  13. Anterior segment study with the pentacam scheimpflug camera in refractive surgery candidates

    Directory of Open Access Journals (Sweden)

    Masih Hashemi

    2013-01-01

    Conclusions: Myopic eyes had steeper corneas than hyperopic eyes and anterior chamber measurements were significantly higher in the myopic eyes. In myopic eyes, AE max and PE max and K max measurements were higher, and ACD measurements were lower in the astigmatic groups.

  14. Tscherning ellipses and ray tracing in ophthalmic lenses.

    Science.gov (United States)

    Malacara, Z; Malacara, D

    1985-07-01

    In this paper the exact shape of the solutions to the equations for lenses free of oblique astigmatism, as well as those free from curvature of field or peripheral focus error, are presented. These solutions, as expected, resemble the Tscherning ellipses, but strongly deformed.

  15. Change in corneal curvature induced by surgery

    NARCIS (Netherlands)

    G. van Rij (Gabriel)

    1987-01-01

    textabstractThe first section deals with the mechanisms by which sutures, incisions and intracorneal contact lenses produce a change in corneal curvature. To clarify the mechanisms by which incisions and sutures produce astigmatism, we made incisions and placed sutures in the corneoscleral limbus of

  16. Secondary implantation of a double intraocular lens after penetrating keratoplasty.

    Science.gov (United States)

    Gayton, J L

    1998-02-01

    Penetrating keratoplasty (PKP) patients often have severe, visually disabling refractive errors. Astigmatism can be addressed by refractive surgery; however, correcting hyperopia is more problematic. Although pseudophakic PKP patients can have a lens exchange, it can be traumatic in this population. In this pseudophakic PKP patient, I added a second posterior chamber intraocular lens, correcting the hyperopia and resolving visual complaints.

  17. Refractive Errors

    Science.gov (United States)

    ... does the eye focus light? In order to see clearly, light rays from an object must focus onto the ... The refractive errors are: myopia, hyperopia and astigmatism [See figures 2 and 3]. What is hyperopia (farsightedness)? Hyperopia occurs when light rays focus behind the retina (because the eye ...

  18. Laser-Assisted in situ Keratomileusis for Hyperopic Defects

    Directory of Open Access Journals (Sweden)

    Ester Novoa Sánchez

    2014-06-01

    Full Text Available Background: currently, LASIK is one of the most common surgical procedures for refractive disorders, including hyperopic defects. Objective: to assess the results of laser-assisted in situ keratomileusis for the treatment of hyperopic defects. Methods: an ambispective study was conducted in 31 eyes (16 patients operated on for hyperopia and simple and compound hyperopic astigmatism in the Refractive Surgery Unit of the Ophthalmology Department of the Hermanos Ameijeiras Hospital between January 2009 and December 2010. Visual acuity with and without optical correction, spherical and astigmatic component before and after surgery and intra- and postoperative complications were analyzed. Results: patients aged 40 to 49 years predominated; compound hyperopic astigmatism was the most frequent defect; the mean uncorrected visual acuity improved and remained stable up to six months after surgery; the average values were 0.87 for moderate defects and 0.79 for high defects with optical correction. The mean sphero-cylindrical component decreased. The efficacy and safety rates were acceptable for moderate and high degrees of the defects and predictability was 100 % for all degrees of ametropia. Conclusion: LASIK is a safe, effective and predictable procedure to treat patients with moderate and high degrees hyperopia and hyperopic astigmatism.

  19. Implantation of Artisan toric phakic intraocular lens following Intacs in a patient with keratoconus.

    Science.gov (United States)

    Kamburoğlu, Günhal; Ertan, Aylin; Bahadir, Mehmet

    2007-03-01

    We report a 24-year-old man with bilateral keratoconus in whom Intacs (Addition Technology, Inc.) were implanted in both eyes. The procedure was followed by Artisan toric phakic intraocular lens (Ophtec) implantation to correct the residual myopic and astigmatic refractive error.

  20. Visual outcomes and optical quality after implantation of a diffractive multifocal toric intraocular lens

    Science.gov (United States)

    Chen, Xiangfei; Zhao, Ming; Shi, Yuhua; Yang, Liping; Lu, Yan; Huang, Zhenping

    2016-01-01

    Background: This study evaluated the visual function after implantation of a multifocal toric intraocular lenses (IOLs). Materials and Methods: This study involved 10 eyes from eight cataract patients with corneal astigmatism of 1.0 diopter (D) or higher who had received phacoemulsification with implantation of an AcrySof IQ ReSTOR Toric IOL. Six-month evaluations included visual acuity, spherical equivalent (SE), defocus curve, residual astigmatism, IOL rotation, contrast sensitivity (CS), wavefront aberrations, modulation transfer function (MTF), and patient satisfaction assessments. Results: At 6 months postoperatively, uncorrected distance visual acuity (logarithm of the minimum angle of resolution) was 0.09 ± 0.04, corrected distance visual acuity was 0.02 ± 0.11, and uncorrected near visual acuity was 0.12 ± 0.07. The mean SE was −0.095 ± 0.394 D (±0.50 D in 90%). Refractive astigmatism at the 6-month follow-up visit was significantly reduced to 0.35 ± 0.32 D from 1.50 ± 0.41 D presurgery (P 0.05). There was an increase in MTF results between preoperative and postoperative evaluations at all spatial frequencies. Conclusions: The diffractive multifocal toric IOL is able to provide a predictable astigmatic correction with apparently outstanding levels of optical quality after implantation. PMID:27221680

  1. Electron optics of skewed micro-Einzel lenses

    NARCIS (Netherlands)

    Van Bruggen, M.J.; Van Someren, B.; Kruit, P.

    2009-01-01

    Micro-Einzel lenses always suffer from chromatic and spherical aberration, even when the electron beam is exactly on the optical axis of the lens. When the inclination of the electron beam with respect to the lens axis increases, additional effects such as coma, astigmatism, and defocus start to dom

  2. Liquid crystal multi-mode lenses and axicons based on electronic phase shift control.

    Science.gov (United States)

    Kirby, Andrew K; Hands, Philip J; Love, Gordon D

    2007-10-17

    We report on the principle of operation, construction and testing of a liquid crystal lens which is controlled by distributing voltages across the control electrodes, which are in turn controlled by adjusting the phase of the applied voltages. As well as (positive and negative) defocus, then lenses can be used to control tip/tilt, astigmatism, and to create variable axicons.

  3. Multifocal Toric Intraocular Lens for Traumatic Cataract in a Child

    Directory of Open Access Journals (Sweden)

    Yanfeng Zeng

    2016-10-01

    Full Text Available A child suffering from traumatic cataract and corneal astigmatism of 2.14 D had a phacoemulsification operation and implantation of a ReSTOR Toric intraocular lens (IOL to correct the astigmatism. The primary outcome measurements were the uncorrected distance visual acuity (UDVA, uncorrected near vision at 40 cm, intraocular pressure, spherical equivalent refraction, residual astigmatism, corneal astigmatism, presence of unusual optical phenomena, and use of spectacles. At 7 months postoperatively, UDVA was maintained between 16/20 and 24/20, near vision was between J1 and J3, residual spherical refraction was 0–0.37 D, and residual refractive cylinder was between 0 and 0.67 D. A multifocal toric IOL can provide the possibility of satisfactory vision for both distant and near conditions without the use of spectacles to meet children’s needs when studying and doing sports. Additionally, binocular vision can be reconstructed. This intervention, therefore, seems to be a satisfactory alternative.

  4. Effect of iris registration on outcomes of LASIK for myopia with the VISX CustomVue platform

    DEFF Research Database (Denmark)

    Moshirfar, Majid; Chen, Michael C; Espandar, Ladan

    2009-01-01

    PURPOSE: To compare visual outcomes after LASIK using the VISX STAR S4 CustomVue, with and without Iris Registration technology. METHODS: In this retrospective study, LASIK was performed on 239 myopic eyes, with or without astigmatism, of 142 patients. Iris registration LASIK was performed on 121...

  5. Nationwide reduction in the number of corneal transplantations for keratoconus following the implementation of cross-linking

    NARCIS (Netherlands)

    Godefrooij, Daniel A; Gans, Renze; Imhof, Saskia M; Wisse, Robert P L

    2016-01-01

    PURPOSE: Keratoconus is characterized by corneal ectasia and irregular astigmatism, which can lead to diminished vision and corneal scarring. Approximately 10-20% of patients with keratoconus eventually require a corneal transplant. Corneal cross-linking (CXL) is a relatively new treatment that may

  6. Meta-analysis to compare the safety and efficacy of manual small incision cataract surgery and phacoemulsification

    Directory of Open Access Journals (Sweden)

    Parikshit Gogate

    2015-01-01

    Conclusion: The outcome of this meta-analysis indicated there is no difference between phacoemulsification and SICS for BCVA and UCVA of 6/18 and 6/60. Endothelial cell loss and intraoperative and postoperative complications were similar between procedures. SICS resulted in statistically greater astigmatism and UCVA of 6/9 or worse, however, near UCVA was better.

  7. Expressions for third-order aberration theory for holographic images

    Indian Academy of Sciences (India)

    S K Tripathy; S Ananda Rao

    2003-01-01

    Expressions for third-order aberration in the reconstructed wave front of point objects are established by Meier. But Smith, Neil Mohon, Sweatt independently reported that their results differ from that of Meier. We found that coefficients for spherical aberration, astigmatism, tally with Meier’s while coefficients for distortion and coma differ.

  8. The effect of pterygium surgery on contrast sensitivity and corneal topographic changes

    Directory of Open Access Journals (Sweden)

    Joo Youn Oh

    2010-04-01

    Full Text Available Joo Youn Oh, Won Ryang WeeDepartment of Ophthalmology, Seoul National University Hospital, Seoul, KoreaPurpose: To investigate the effect of pterygium surgery on corneal topography and contrast sensitivity.Patient and methods: The IRB approved this prospective, nonrandomized, self-controlled study. Computerized videokeratography (Orbscan II was performed in 36 patients with primary pterygia, both before and 1 month after pterygium excision with limbal-conjunctival autografting. The topographic parameters were compared. Spatial contrast sensitivity testing was performed using VCTS 6500. Differences between preoperative and postoperative values were evaluated statistically.Results: The mean Sim K astigmatism and irregularity index, significantly decreased after pterygium surgery. The mean refractive power significantly increased after the operation. The “with-the-rule” astigmatism induced by pterygium became “against-the-rule” astigmatism after pterygium removal (P = 0.041. The contrast sensitivity of 6, 12, and 18 cycles per degree, significantly increased from 1.55 ± 0.28, 0.97 ± 0.47, and 0.29 ± 0.16 to 1.72 ± 0.18, 1.21 ± 0.44, and 0.65 ± 0.48, respectively (P = 0.007, <0.001, <0.001, respectively.Conclusions: Pterygium surgery significantly reduces corneal topographic astigmatism and improves contrast sensitivity.Keywords: corneal topography, visual acuity

  9. NEI for Kids: Glossary

    Science.gov (United States)

    ... Eye Health and Safety First Aid Tips Healthy Vision Tips Protective Eyewear Sports and Your Eyes Fun Stuff Cool Eye Tricks Links to More Information Optical Illusions Printables ... macula, which provides sharp, central vision needed for seeing objects clearly. Astigmatism (uh-STIG- ...

  10. Ptosis - infants and children

    Science.gov (United States)

    Blepharoptosis-children; Congenital ptosis; Eyelid drooping-children; Eyelid drooping-amblyopia; Eyelid drooping-astigmatism ... Ptosis in infants and children is often due to a problem with the muscle that raises the eyelid. A nerve problem in the eyelid can ...

  11. Laser-induced scleral shrinkage for refractive surgery

    Science.gov (United States)

    Ren, Qiushi; Simon, Gabriel; Parel, Jean-Marie A.; Shen, Jin-Hui

    1994-06-01

    We investigate the laser refractive scleroplasty (LRS) as a potential minimal-invasive method for correcting post-operative astigmatism. The scleral shrinkage near limbus was induced on 6 cadaver eyes using a 200 micrometers fiber optic probe coupled to a pulsed Ho:YAG laser. The diameter of the treatment spot was 0.8 mm. The output energy measured at tip was 60.2+/- 0.6 mJ. The treatments consisted of multiple sector patterns placed along the major axis of astigmatism parallel to the limbus, and round patterns placed along the limbus. Three treatment spots were applied on each side of the sector. The separation among sectors and limbus is 1 mm. Keratometry and topography of the cornea were measured after each sector or round pattern treatment. Effect of 5 and 10 pulses at each treatment spot were compared. Histology was performed to evaluate laser tissue damage. The major axis of astigmatism was shifted 90 degrees after the sector pattern treatment and amount of dioptric change increased when adding a new treatment or using more treatment pulses. However, the spherical equivalent of the eyes was essentially unchanged. The keratometry of the corneas remained the same after the round pattern treatment. Laser refractive scleroplasty may be applied for the correction of post-operative astigmatism.

  12. [Calculations of mean refraction and variation of refraction using a dioptric space].

    Science.gov (United States)

    Touzeau, O; Costantini, E; Gaujoux, T; Borderie, V; Laroche, L

    2010-11-01

    Polar notations (sphere, cylinder, and axis) of refraction perfectly characterize a single refraction but are not suitable for statistical analysis or graphic representation. While the spherical component of refraction can be easily analyzed by the spherical equivalent, statistical analysis of astigmatism requires non-polar expressions of refraction. Indeed, the cylinder and axis of astigmatism are not independent data. In addition, axis is a directional data including a non-trigonometric cycle. Refraction can be written in a non-polar notation by three rectangular coordinates (x, y, z), which can also represent the spherocylinder by one point in a dioptric space. These three coordinates constitute three independent (orthogonal) variables that correspond to a sphere-equivalent component and a pair of Jackson cross-cylinder components, oriented at 0°/90° (WTR/ATR astigmatism) and 45°/135° (oblique astigmatism). Statistical analysis and graphical representation become less complicated when using rectangular coordinates of refraction. Rectangular coordinates of the mean refraction are obtained by average rectangular coordinates. Similarly, rectangular coordinates of refraction change are obtained by a single subtraction of rectangular coordinates between the final and initial refractions. After statistical analysis, the rectangular coordinates obtained can be converted into a polar form for a more easily understood result. Finally, non-polar notations including rectangular coordinates are useful for statistical and graphical analysis, which would be difficult with only conventional polar notations of refraction.

  13. MERSILENE (POLYESTER), A NEW SUTURE FOR PENETRATING KERATOPLASTY

    NARCIS (Netherlands)

    RAMSELAAR, JAM; BEEKHUIS, WH; RIJNEVELD, WJ; VANANDEL, MV; DIJK, F; JONGEBLOED, WL

    1992-01-01

    Mersilene (polyester monofilament) seems to be suitable for penetrating keratoplasty because it is strong, shows no degradation by ultraviolet light, is insoluble, so that it can be left in situ, and offers the possibility of regulating postoperative astigmatism by suture adjustment. In 12 patients

  14. The correlation between variation of visual acuity and the anterior chamber depth in the early period after phacoemulsification

    Directory of Open Access Journals (Sweden)

    Kai-jian CHEN

    2011-04-01

    Full Text Available Objective To investigate the correlation between the visual acuity variation and the anterior chamber depth in the early period after phacoemulsification.Methods Thirty-six eyes of 32 patients with age-related cataract underwent 3.2mm clear corneal incision phacoemulsification and intraocular lens(IOL implantation.The visual acuity was examined and horizontal curvature(K1,vertical curvature(K2,corneal astigmatism,and anterior chamber depth were measured with IOL-master preoperatively and also on 1,3,7 and 15 postoperative days.The changes in parameters were compared,and the correlations among visual acuity,corneal astigmatism and anterior chamber depth were analyzed.Results Before operation and 1d,3d,7d and 15d after operation,the corneal astigmatism was-0.87±0.40D,-1.92±1.38D,-1.69±1.13D,-1.45±0.79D and-1.36±0.74D;the anterior chamber depth was 3.08±0.35mm,4.04±0.38mm,4.28±0.29mm,4.22±0.17mm and 4.22±0.16mm;the visual acuity was 0.18±0.10,0.44±0.14,0.59±0.12,0.61±0.11 and 0.62±0.14.Significant difference was found between pre-operative and postoperative visual acuity,corneal astigmatism and anterior chamber depth,and it was also found in corneal astigmatism between 1d and 15d post operation(P < 0.05,as well as in anterior chamber depth and visual acuity between 1d and 3d post operation(P < 0.05.A positive correlation was found between visual acuity and corneal astigmatism on 1d(r=0.42,P < 0.05,3d(r=0.35,P < 0.05 and 7d(r=0.35,P < 0.05 post operation;and a negative correlation was found between visual acuity and anterior chamber depth on 3d(r=-0.29,P < 0.05,7d(r=-0.43,P < 0.01 and 15d(r=-0.37,P < 0.05 post operation.Conclusion Both the corneal astigmatism and the anterior chamber depth are correlated with the visual acuity variation in the early period after phacoemulsification.

  15. Higher-Order Aberrations in Myopic Eyes

    Directory of Open Access Journals (Sweden)

    Farid Karimian

    2010-01-01

    Full Text Available Purpose: To evaluate the correlation between refractive error and higher-order aberrations (HOAs in patients with myopic astigmatism. Methods: HOAs were measured using the Zywave II aberrometer over a 6 mm pupil. Correlations between HOAs and myopia, astigmatism, and age were analyzed. Results: One hundred and twenty-six eyes of 63 subjects with mean age of 26.4±5.9 years were studied. Mean spherical equivalent refractive error and refractive astigmatism were -4.94±1.63 D and 0.96±1.06 D, respectively. The most common higher-order aberration was primary horizontal trefoil with mean value of 0.069±0.152 μm followed by spherical aberration (-0.064±0.130 μm and primary vertical coma (-0.038±0.148 μm. As the order of aberration increased from third to fifth, its contribution to total HOA decreased: 53.9% for third order, 31.9% for fourth order, and 14.2% for fifth order aberrations. Significant correlations were observed between spherical equivalent refractive error and primary horizontal coma (R=0.231, P=0.022, and root mean square (RMS of spherical aberration (R=0.213, P=0.031; between astigmatism and RMS of total HOA (R=0.251, P=0.032, RMS of fourth order aberration (R=0.35, P<0.001, and primary horizontal coma (R=0.314, P=0.004. Spherical aberration (R=0.214, P=0.034 and secondary vertical coma (R=0.203, P=0.031 significantly increased with age. Conclusion: Primary horizontal trefoil, spherical aberration and primary vertical coma are the predominant higher-order aberrations in eyes with myopic astigmatism.

  16. Analysis of corneal biometric parameters of age-related cataract patients%年龄相关白内障患者角膜生物测量参数的分布及相互关系的研究

    Institute of Scientific and Technical Information of China (English)

    马冬梅; 张健; 方薇; 蒋慧中; 杨惠青; 刘大川

    2013-01-01

    Objective To analyze the distribution and correlation of corneal biometric parameters in patients with Aye-related cataract.Methods 1526 eyes of 1003 patients aged 40 years and older were recruited for this study.The corneal curvature and astigmatism were optically measured by partial coherence interferometry (IOLMaster).Statistical software package SPSS 13.0 was used to analyze statistically.Results The median age of the patients was 74 years (range 40 to 95 years).The mean of corneal curvature was (44.59 ± 1.68) diopter (D),normal distribution.There was negative relationship between age and corneal curvature (r =-0.073,P =0.000).The median corneal astigmatism was 0.95D,non-normal distribution.It was 1.0D or less in 831 eyes (54.4%),1.0D ~2.0D in 519 eyes(34.0%),and more than 2.0D in 176 eyes(11.4%).There was positive relationship between age and corneal astigmatism (r =0.143,P =0.000).With aging,the percent of with-the-rule (WTR) astigmatism decreased from 64.6% to 22.2%,and against-the-rule (ATR) astigmatism increased from 18.8% to 66.7%.Conclusion Corneal astigmatism less than 1.0D was present in most patients with cataract.Corneal curvature tended to decrease with aging while corneal astigmatism tended to increase.The pattern of corneal astigmatism shifted from WTR to ATR astigmatism.%目的 研究年龄相关白内障患者角膜生物测量参数分布规律及其相互关系.方法 采用光学相干生物测量仪(IOL Master)对1003名(1526眼)白内障患者进行角膜生物测量,应用SPSS 13.0统计软件对数据进行统计分析.结果 患者年龄中位数为74岁,平均角膜曲率(44.59±1.68)D,年龄与角膜曲率呈负相关关系(r=-0.073,P=0.000).角膜散光中位数为0.95 D,角膜散光<1.0D的占54.5%,1.0~2.0D的占34.0%,角膜散光>2.0D的占11.5%,年龄与角膜散光呈正相关关系(r=0.143,P=O.000).随着年龄增长,顺规散光比例由64.6%减少为22.2%,逆规散光比例由18.8%增至66.7

  17. Topography-modified refraction (TMR: adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2016-11-01

    Full Text Available Anastasios John Kanellopoulos1,2 1LaserVision Clinical and Research Institute, Athens, Greece; 2Department of Ophthalmology, NYU Medical School, New York, NY, USA Purpose: To evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies. Setting: Private clinical ophthalmology practice. Patients and methods: A total of 100 eyes (50 patients in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers were randomized for treatment as follows: one eye with the standard clinical refraction (group A and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B. All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA, uncorrected distance visual acuity (UDVA, topography (Placido-disk based and tomography (Scheimpflug-image based, wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. Results: Mean refractive error was -5.5 D of myopia and -1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over -0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B (P<0.01. The residual percentages in both groups were measured with refractive astigmatism of more than –0.5 diopters. Conclusion: Topography-modified refraction (TMR: topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings

  18. Refractive cylinder outcomes after calculating toric intraocular lens cylinder power using total corneal refractive power

    Directory of Open Access Journals (Sweden)

    Davison JA

    2015-08-01

    Full Text Available James A Davison,1 Richard Potvin21Wolfe Eye Clinic, Marshalltown, IA, USA; 2Science in Vision, Akron, NY, USAPurpose: To determine whether the total corneal refractive power (TCRP value, which is based on measurement of both anterior and posterior corneal astigmatism, is effective for toric intraocular lens (IOL calculation with AcrySof® Toric IOLsPatients and methods: A consecutive series of cataract surgery cases with AcrySof toric IOL implantation was studied retrospectively. The IOLMaster® was used for calculation of IOL sphere, the Pentacam® TCRP 3.0 mm apex/ring value was used as the keratometry input to the AcrySof Toric IOL Calculator and the VERION™ Digital Marker for surgical orientation. The keratometry readings from the VERION reference unit were recorded but not used in the actual calculation. Vector differences between expected and actual residual refractive cylinder were calculated and compared to simulated vector errors using the collected VERION keratometry data.Results: In total, 83 eyes of 56 patients were analyzed. Residual refractive cylinder was 0.25 D or lower in 58% of eyes and 0.5 D or lower in 80% of eyes. The TCRP-based calculation resulted in a statistically significantly lower vector error (P<0.01 and significantly more eyes with a vector error ≤0.5 D relative to the VERION-based calculation (P=0.02. The TCRP and VERION keratometry readings suggested a different IOL toric power in 53/83 eyes. In these 53 eyes the TCRP vector error was lower in 28 cases, the VERION error was lower in five cases, and the error was equal in 20 cases. When the anterior cornea had with-the-rule astigmatism, the VERION was more likely to suggest a higher toric power and when the anterior cornea had against-the-rule astigmatism, the VERION was less likely to suggest a higher toric power.Conclusion: Using the TCRP keratometry measurement in the AcrySof toric calculator may improve overall postoperative refractive results

  19. Segmented Vortex Telescope and its Tolerance to Diffraction Effects and Primary Aberrations

    CERN Document Server

    Treviño, Juan P; Chávez-Cerda, Sabino

    2013-01-01

    We propose the segmented Large Millimeter Telescope (LMT/GTM),as the largest spatial light modulator capable of producing vortex beams of integer topological charge. This observing mode could be applied for direct exoplanet searches in the millimeter or submillimeter regimes. We studied the stability of the vortex structure against aberrations and diffraction effects inherent to the size and segmented nature of the collector mirror. In the presence of low order aberrations the focal distribution of the system remains stable. Our results show that these effects depend on the topological charge of the vortex and the relative orientation of the aberration with respect to the antenna axis. Coma and defocus show no large effects in the image at the focal plane, nevertheless the system is very sensitive to astigmatism. Heat turbulence, simulated by random aberrations, shows that the system behaves in a similar way as astigmatism dissociating the vortices. We propose the Segmented Vortex Telescope as a novel approac...

  20. Myopia, posture and the visual environment.

    Science.gov (United States)

    Charman, W Neil

    2011-09-01

    Evidence for a possible role for the peripheral retina in the control of refractive development is discussed, together with Howland's suggestion (Paper presented at the 13th International Myopia Conference, Tubingen, Germany, July 26-29, 2010) that signals to generate appropriate growth might be derived from ocular oblique astigmatism. The dependence of this, or similar peripheral mechanisms, on exposure to a uniform field of near-zero dioptric vergence is emphasized: this is required to ensure a consistent relationship between the astigmatic image fields and the retina. This condition is satisfied by typical outdoor environments. In contrast, indoor environments are likely to be unfavourable to peripherally-based emmetropization, since dioptric stimuli may vary widely across the visual field. This is particularly the case when short working distances or markedly asymmetric head postures with respect to the visual task are adopted.

  1. SURGICAL AND VISUAL OUTCOME OF PHACOEMULSIFICATION SURGERY (ROUTINE AND MICRO - PHACO (BIMANUAL PHACO: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Sudha

    2015-03-01

    Full Text Available Cataract surgery has evolved over the past few decades with progressive decrease in the size of the incision. Originally from 12 mm intracapsular incision to bimanual phacoemulsification (Micro - Phaco that has incision size of just 700 microns. In the pres ent comparative PROSPECTIVE study best corrected visual acuity postoperatively and surgically induced astigmatism were compared in routine Phacoemulsification technique and bimanual phaco (Micro - Phaco 60 eyes were studied. There was no statistically signi ficant difference in postoperative best corrected visual acuity (BCVA of patients operated with Micro - Phaco or routine Phacoemulsification. There was difference in surgically induced astigmatism (SIA ; average SIA in microphaco was 0.5972 as against 0.832 8 in routine Phacoemulsification.

  2. Analytical beam-width characteristics of distorted cat-eye reflected beam

    Science.gov (United States)

    Zhao, Yanzhong; Shan, Congmiao; Zheng, Yonghui; Zhang, Laixian; Sun, Huayan

    2015-02-01

    The analytical expression of beam-width of distorted cat-eye reflected beam under far-field condition is deduced using the approximate three-dimensional analytical formula for oblique detection laser beam passing through cat-eye optical lens with center shelter, and using the definition of second order moment, Gamma function and integral functions. The laws the variation of divergence angle and astigmatism degree of the reflected light with incident angle, focal shift, aperture size, and center shelter ratio are established by numerical calculation, and physical analysis. The study revealed that the cat-eye reflected beam is like a beam transmitted and collimated by the target optical lens, and has the same characteristics as that of Gaussian beam. A proper choice of positive focal shift would result in a divergence angle smaller than that of no focal shift. The astigmatism is mainly caused by incidence angle.

  3. Deep anterior lamellar keratoplasty for the management of iatrogenic keratectasia occurring after hexagonal keratotomy

    Directory of Open Access Journals (Sweden)

    Paras Mehta

    2012-01-01

    Full Text Available Iatrogenic keratectasia has been reported subsequent to refractive surgery or trauma. Hexagonal keratotomy (HK is a surgical incisional technique to correct hyperopia. A number of complications have been reported following this procedure, including irregular astigmatism, wound healing abnormalities and corneal ectasia. When visual acuity is poor because of ectasia or irregular astigmatism and contact lens fitting is not possible, penetrating or lamellar keratoplasty can be performed. Since incisions in refractive keratotomy are set at 90-95% depth of cornea, intraoperative microperforations are known to occur and lamellar keratoplasty may become difficult. We describe deep anterior lamellar keratoplasty (DALK used to successfully manage keratectasia after HK. Pre DALK vision was 20/400 and post DALK vision was 20/30 two months after surgery. This report aims to show improved visual outcome in corneal ectasia secondary to HK. DALK can be a procedure of choice with proper case selection.

  4. Patch graft for corneal perforation following trivial trauma in bilateral terrien′s marginal degeneration

    Directory of Open Access Journals (Sweden)

    Merle Fernandes

    2015-01-01

    Full Text Available A young female presented with blurred vision in the left eye after she rubbed her eye. On examination of both eyes, she had 360° thinning adjacent to the limbus, lipid deposition and superficial vascularization with a perforation in the left eye. The patient was diagnosed with bilateral Terrien′s marginal degeneration (TMD with perforation. Corneal topography of the right eye revealed high oblique astigmatism confirming the diagnosis. A peripheral patch graft was performed for the left eye. At 18 months postoperatively, the best-corrected visual acuity was 20/20 in both eyes. The graft was clear. Topography of right eye was stable, and the left eye had oblique astigmatism. Bilateral advanced TMD in a young patient presenting with corneal perforation following trivial trauma is extremely uncommon. Patch graft may be an option for restoring the globe integrity in such cases. Regular follow-up is necessary as the condition progresses slowly.

  5. Topography-guided custom ablation treatment for treatment of keratoconus

    Directory of Open Access Journals (Sweden)

    Rohit Shetty

    2013-01-01

    Full Text Available Keratoconus is a progressive ectatic disorder of the cornea which often presents with fluctuating refraction and high irregular astigmatism. Correcting the vision of these patients is often a challenge because glasses are unable to correct the irregular astigmatism and regular contact lenses may not fit them very well. Topography-guided custom ablation treatment (T-CAT is a procedure of limited ablation of the cornea using excimer laser with the aim of regularizing the cornea, improving the quality of vision and possibly contact lens fit. The aim of the procedure is not to give a complete refractive correction. It has been tried with a lot of success by various groups of refractive surgeons around the world but a meticulous and methodical planning of the procedure is essential to ensure optimum results. In this paper, we attempt to elucidate the planning for a T-CAT procedure for various types of cones and asphericities.

  6. Optical path length and trajectory stability in rotationally asymmetric multipass cells.

    Science.gov (United States)

    Harden, Galen H; Cortes-Herrera, Luis E; Hoffman, Anthony J

    2016-08-22

    We describe the behavior of optical trajectories in multipass rotationally asymmetric cavities (RACs) using a phase-space motivated approach. Emphasis is placed on generating long optical paths. A trajectory with an optical path length of 18 m is generated within a 68 cm3 volume. This path length to volume ratio (26.6 cm-2) is large compared to current state of the art multipass cells such as the cylindrical multipass cell (6.6 cm-2) and astigmatic Herriott cell (9 cm-2). Additionally, the effect of small changes to the input conditions on the path length is studied and compared to the astigmatic Herriott cell. This work simplifies the process of designing RACs with long optical path lengths and could lead to broader implementation of these multipass cells.

  7. Higher-order Laguerre-Gauss modes in (non-) planar four-mirror cavities for future gravitational wave detectors.

    Science.gov (United States)

    Noack, Andreas; Bogan, Christina; Willke, Benno

    2017-02-15

    One of the limiting noise sources in the current generation of gravitational wave detectors, such as the advanced laser interferometer gravitational wave observatory (aLIGO), is the thermal noise in the interferometer's test mass coatings. One proposed method to reduce the coupling of this noise source to the gravitational wave readout is using a laser beam in the higher-order spatial LG33 mode within the interferometer. Here we show that the current four-mirror cavities of aLIGO are not compatible with Laguerre-Gauss modes due to astigmatism. A non-degeneracy of modes of the same order could be observed in experiment and simulation. We demonstrate that a non-planar cavity could be used instead as it compensates for the astigmatism and transmits the LG33 mode undisturbed.

  8. Zoom lens compensator for a cylindrical window in laser anemometer uses.

    Science.gov (United States)

    Wernet, M P; Seasholtz, R G

    1987-11-01

    In laser anemometer systems, the flow fields under study are typically enclosed by a window. Aberration of a flat window can be corrected by a shift of the object distance. A zooming correction lens eliminates the astigmatism caused by a thick cylindrical window and yields diffraction-limited performance for a monochromatic laser anemometer system. The effects of residual anamorphic distortion are discussed, and procedures for correcting these effects are presented.

  9. Exploded representation of a refracting surface

    Directory of Open Access Journals (Sweden)

    W.H. Heath

    2005-01-01

    Full Text Available The concept of the exploded refracting sur-face is useful in the optics of contact lenses and vision underwater. The purpose of this paper is to show how to represent a refracting surface as an exploded pair of surfaces separated by a gap of zero width.  The analysis is in terms of linear optics and allows for astigmatic and non-coaxial cases.

  10. ABERRATIONS MINIMIZATION FOR IMPROVING CHARACTERISTICS OF COMPACT HIGH-APERTURE DISPERSIVE SPECTROMETERS

    Directory of Open Access Journals (Sweden)

    E. S. Voropay

    2010-01-01

    Full Text Available Schemes of high-aperture and compact optical spectrometers and giperspectrometer with minimized aberrations are presented. In the first scheme usage of inclined plane-parallel plate allows decreasing of astigmatism. In the second scheme off-axis aberrations are practically removed due to axial propagation of light. For giperspectrometer narrowing of light propagation angle through the object lens and turning the light out of dispersion plane lead to minimizing of picture aberrations.

  11. [Heterotopic fundus (author's transl)].

    Science.gov (United States)

    Denden, A

    1976-07-01

    Fundus heterotopicus is the term used to describe a rare, non-hereditary curvature anomaly of the fundus in the non-myopic eye, which is characterized: 1. functionally, by a slowly increasing myopic-astigmatic refractive error, 2. by correctable bitemporal or binasal refractionscomata and 3. ophthalmoscopically by a posterior out-pouching of the nasal or temporal fundus portions, and including the optic disc and macula in the obliquely descending wall of the extasis.

  12. Diode-pumped dye laser

    Science.gov (United States)

    Burdukova, O. A.; Gorbunkov, M. V.; Petukhov, V. A.; Semenov, M. A.

    2016-10-01

    This letter reports diode pumping for dye lasers. We offer a pulsed dye laser with an astigmatism-compensated three-mirror cavity and side pumping by blue laser diodes with 200 ns pulse duration. Eight dyes were tested. Four dyes provided a slope efficiency of more than 10% and the highest slope efficiency (18%) was obtained for laser dye Coumarin 540A in benzyl alcohol.

  13. The Army Ambulatory Care Data Base (ACDB) Study: Implementation and Preliminary Data

    Science.gov (United States)

    1988-09-01

    TUBERCUL.OSIS, PULMAONARY 00491 BRONCHITIS. CHRONIC 00C760 DYSPNEA 97 .. 19 SUPERFICIAL INJURY INCLUDING (D -0 ) 496 CDPO 0: 0_-1807 FATIGUE /MALAISE ABRASION...YISTROPHIES-HIEEITARY 411111 38860 NIGHT BLINDNESS C0 3771 OPTIC ATROPHY C). 1- 3 7150 CORNEAL DYSTROPHY ’ 36250 MACULAR DEGENERATION - C 3614 PRESBYDPIA 0C.0...36720 ASTIGMATISM 0 03753 INFLAIATION. ACUTE C0 3714 CORNEAL DEGENERATION CD 0 3645 IRIS DEGENERATIONS C0 36700 HYPERlOPIA 0 0374 IFLAMMATION. CHRONIC

  14. Plenoptic microscope based on laser optical feedback imaging (LOFI)

    CERN Document Server

    Glastre, W; Jacquin, O; de Chatellus, H Guillet; Lacot, E

    2015-01-01

    We present an overview of the performances of a plenoptic microscope which combines the high sensitivity of a laser optical feedback imaging setup , the high resolution of optical synthetic aperture and a shot noise limited signal to noise ratio by using acoustic photon tagging. By using an adapted phase filtering, this microscope allows phase drift correction and numerical aberration compensation (defocusing, coma, astigmatism ...). This new kind of microscope seems to be well adapted to make deep imaging through scattering and heterogeneous media.

  15. Asymmetric wavelet reconstruction of particle hologram with an elliptical Gaussian beam illumination.

    Science.gov (United States)

    Wu, Xuecheng; Wu, Yingchun; Zhou, Binwu; Wang, Zhihua; Gao, Xiang; Gréhan, Gérard; Cen, Kefa

    2013-07-20

    We propose an asymmetric wavelet method to reconstruct a particle from a hologram illuminated by an elliptical, astigmatic Gaussian beam. The particle can be reconstructed by a convolution of the asymmetric wavelet and hologram. The reconstructed images have the same size and resolution as the recorded hologram; therefore, the reconstructed 3D field is convenient for automatic particle locating and sizing. The asymmetric wavelet method is validated by both simulated holograms of spherical particles and experimental holograms of opaque, nonspherical coal particles.

  16. Visual outcomes after implantation of a novel refractive toric multifocal intraocular lens

    Directory of Open Access Journals (Sweden)

    Talita Shimoda

    2014-04-01

    Full Text Available Purpose: To assess the postoperative outcomes of a novel toric multifocal in traocular lens (IOL in patients with cataract and corneal astigmatism. Methods: This prospective nonrandomized study included patients with cataract, corneal astigmatism, and a motivation for spectacle independence. In all patients, a Rayner M-flex® T toric IOL was implanted in the capsular bag. Three months after surgery, the distance, intermediate, and near visual acuities; spherical equivalent; residual refractive astigmatism; defocus curve; and contrast sensitivity were evaluated. A patient satisfaction and visual phenomena questionnaire was administered to all patients. Results: Thirty-four eyes of 18 patients were included in this study. Three months after surgery, the mean corrected distance visual acuity (logMAR was 0.00 ± 0.08 at 6 m, 0.20 ± 0.09 at 70 cm, and 0.08 ± 0.11 at 40 cm. Uncorrected distance vision acuity was 20/40 or better in 100% eyes. The preoperative mean refractive cylinder (RC was -2.19 (SD: ± 0.53. After a 3-month follow-up, the average RC was -0.44 D (SD: ± 0.27; p<0.001. Contrast sensitivity levels were high. At the last follow-up, 87.5% patients were spectacle-independent for near, intermediate, and distance vision, and approximately 44% patients reported halos and glare. Conclusion: Toric multifocal IOL implantation in patients with cataract and corneal astigmatism using the Rayner M-flex® T toric IOL was a simple, safe, and accurate option. This technology provides surgeons with a feasible option for meeting patient expectations of an enhanced lifestyle resulting from decreased spectacle dependence.

  17. Improvement in the field of binocular single vision following bilateral phacoemulsification with toric intraocular lens implantation in a patient with a partial third nerve palsy.

    Science.gov (United States)

    Subash, Malavika; Sloper, John J; Wilkins, Mark R

    2010-12-01

    A 44-year-old female teacher with partial third (oculomotor) nerve palsy had a small central field of binocular single vision (BSV) following three strabismus procedures. Over several years her field of BSV constricted further, coincident with the development of myopia in one eye secondary to early lens change and in the presence of significant astigmatism. Following bilateral lens extraction with toric intraocular lens implants, her field of BSV reexpanded.

  18. Design Analysis of a Space Based Chromotomographic Hyperspectral Imaging Experiment

    Science.gov (United States)

    2010-03-01

    utilized rather than a refractive lens telescopes for several reasons [26]: • Mirrors do not introduce any chromatic aberration • Mirrors provide a... aberration , but coma and astigmatism are inherent [35]. Mirrors will not cause chromatic aberration , unlike lenses [21]. A field stop is also being used...on a 20 micron pixel pitch. Image Quality: Two times diffration-limited performance or better. Zero chromatic aberration . The collimated beam

  19. Is Noncycloplegic Photorefraction Applicable for Screening Refractive Amblyopia Risk Factors?

    Directory of Open Access Journals (Sweden)

    Zhale Rajavi

    2012-01-01

    Full Text Available Purpose: To compare the accuracy of noncycloplegic photorefraction (NCP with that of cycloplegic refraction (CR for detecting refractive amblyopia risk factors (RARFs and to determine cutoff points. Methods: In this diagnostic test study, right eyes of 185 children (aged 1 to 14 years first underwent NCP using the PlusoptiX SO4 photoscreener followed by CR. Based on CR results, hyperopia (≥ +3.5 D, myopia (≥ -3 D, astigmatism (≥ 1.5 D, and anisometropia (≥ 1.5 D were set as diagnostic criteria based on AAPOS guidelines. The difference in the detection of RARFs by the two methods was the main outcome measure. Results: RARFs were present in 57 (30.8% and 52 (28.1% of cases by CR and NCP, respectively, with an 89.7% agreement. In contrast to myopia and astigmatism, mean spherical power in hyperopic eyes was significantly different based on the two methods (P < 0.001, being higher with CR (+5.96 ± 2.13 D as compared to NCP (+2.37 ± 1.36 D. Considering CR as the gold standard, specificities for NCP exceeded 93% and sensitivities were also acceptable (≥ 83% for myopia and astigmatism. Nevertheless, sensitivity of NCP for detecting hyperopia was only 45.4%. Using a cutoff point of +1.87 D, instead of +3.5 D, for hyperopia, sensitivity of NCP was increased to 81.8% with specificity of 84%. Conclusion: NCP is a relatively accurate method for detecting RARFs in myopia and astigmatism. Using an alternative cutoff point in this study, NCP may be considered an acceptable device for detecting hyperopia as well.

  20. 眼内散射光及对比敏感度检查在白内障患者真实视觉质量评估中的意义%Significance of intraocular scattered light and contrast sensitivity to assess the true visual quality in cataract patients

    Institute of Scientific and Technical Information of China (English)

    王涛

    2015-01-01

    To analyze the significance of intraocular scattered light and contrast sensitivity in cataract patient's visual quality.METHODS: Seventy-three cases of cataract patients ( 120 eyes ) in our department from January 2012 to January 2014 were selected, of which 32 cases (52 eyes) were cortical cataract, 18 cases ( 33 eyes ) were nuclear cataract, 23 cases ( 35 eyes ) were posterior subcapsular cataract, and 40 normal persons ( 40 eyes ) were as the normal group. The full-eye corneal astigmatism and total astigmatism were observed in all those enrolled. The contrast sensitivity of different perspective was checked by automatic glare contrast sensitivity tester.RESULTS: The corneal astigmatism and full eye total astigmatism in the cortical cataract group, nuclear cataract group and the posterior capsule cataract group was significantly higher than that in the normal group( P0. 05). The contrast sensitivity in the cortical cataract group, nuclear cataract group and posterior subcapsular cataract group in the whole band were significantly lower than the normal group (P0.05)。皮质性白内障组、核性白内障组和后囊下白内障组的对比敏感度在全频段均显著低于正常组(P<0.05);后囊下白内障组的对比敏感度在全频段均显著低于皮质性白内障组和核性白内障组(P<0.05)。结论:采用眼内散射光及对比敏感度联合检查,可有效评价白内障患者的视觉质量,进而早期治疗。

  1. Medical Surveillance Monthly Report (MSMR). Volume 23, Number 5, May 2016

    Science.gov (United States)

    2016-05-01

    such as service branch, gender , age, rank, deployment within 1 year after RS, and the procedural MTF. M E T H O D S The Defense Medical Surveillance...medical encounter and its date could not be identified within the DMSS. Finally, 30,091 persons were excluded due to pre- existing eye disease (other...astigmatism not present before RS), PRK/LASEK had equal or higher prevalences compared to LASIK. Figure 5 displays the estimated propor- tion of

  2. Non-paraxial Elliptical Gaussian Beam

    Institute of Scientific and Technical Information of China (English)

    WANG Zhaoying; LIN Qiang; NI Jie

    2001-01-01

    By using the methods of Hertz vector and angular spectrum transormation, the exact solution of non-paraxial elliptical Gaussion beam with general astigmatism based on Maxwell′s equations is obtained. We discussed its propagation characteristics. The results show that the orientation of the elliptical beam spot changes continuously as the beam propagates through isotropic media. Splitting or coupling of beam spots may occur for different initial spot size. This is very different from that of paraxial elliptical Gaussian beam.

  3. 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

    2014-01-01

    with or without astigmatism of maximum 3 D. Results: In total 799 eyes completed the three months follow-up examination, of which 545 eyes were treated with SMILE (mean pre-operative refraction -7.63±1.37 D, range: -6 to -14.75) and 254 with FS-LASIK (mean pre-operative refraction -7.94±1.72 D, range: -6 to -16...

  4. 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

    with or without astigmatism of maximum 3 D. Results: In total 799 eyes completed the three months follow-up examination, of which 545 eyes were treated with SMILE (mean pre-operative refraction -7.63±1.37 D, range: -6 to -14.75) and 254 with FS-LASIK (mean pre-operative refraction -7.94±1.72 D, range: -6 to -16...

  5. Controlled reshaping of the front surface of the cornea through its full-area ablation outside of the optical zone with a Gaussian ArF excimer laser beam

    Science.gov (United States)

    Semchishen, A. V.; Semchishen, V. A.

    2014-01-01

    We studied in vitro the response of the topography of the cornea to its full-area laser ablation (the laser beam spot diameter is commensurable with the size of the interface) outside of the central zone with an excimer laser having a Gaussian fluence distribution across the beam. Subject to investigation were the topographically controlled surface changes of the anterior cornea in 60 porcine eyes with a 5 ± 1.25-diopter artificially induced astigmatism, the changes being caused by laser ablation of the stromal collagen in two 3.5-mm-dia. circular areas along the weaker astigmatism axis. Experimental relationships are presented between the actual astigmatism correction and the expected correction for the intact optical zones 1, 2, 3, and 4 mm in diameter. The data for each zone were approximated by the least-squares method with the function d = a + bx. The coefficient b is given with the root-mean-square error. The statistical processing of the data yielded the following results: d = (0.14 ± 0.037)x for the 1-mm-dia. optical zone, (1.10 ± 0.036)x for the 2-mm-dia. optical zone, (1.04 ± 0.020)x for the 3-mm-dia. optical zone, and (0.55 ± 0.04)x for the 4-mm-dia. optical zone. Full astigmatism correction was achieved with ablation effected outside of the 3-mm-dia. optical zone. The surface changes of the cornea are shown to be due not only to the removal of the corneal tissue, but also to the biomechanical topographic response of the cornea to its strain caused by the formation of a dense pseudomembrane in the ablation area.

  6. Topical timolol maleate 0.5% solution for the management of deep periocular infantile hemangiomas.

    Science.gov (United States)

    Painter, Sally L; Hildebrand, Göran Darius

    2016-04-01

    This retrospective, consecutive, clinical case series examined the use of topical timolol in the treatment of 5 children with deep, periocular infantile hemangiomas that caused astigmatism, change in head posture, or ptosis. All patients were treated with timolol maleate solution 0.5% twice daily until the lesions had regressed. All 5 children showed regression of the lesion and improvement in amblyogenic risk factors within 2 weeks.

  7. 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;

    , Odense University Hospital. Inclusion criteria: Age 20-50 years at time of surgery, pre-operative CDVA ≤ 0.10 (logMAR) and no other ocular conditions than myopia with or without astigmatism of maximum 3 D. Exclusion criteria: Pregnancy and eyes having undergone re-treatment. A MEL80 flying-spot excimer......, corneal densitometry and patient satisfaction, although the long-term predictability of cPRK seemed better. Financial Disclosures: None...

  8. Visual and Refractive Outcomes after Cataract Surgery with Implantation of a New Toric Intraocular Lens

    Directory of Open Access Journals (Sweden)

    Cinzia Mazzini

    2013-06-01

    Full Text Available Purpose: The aim of this study was to evaluate and report the visual, refractive and aberrometric outcomes of cataract surgery with implantation of the new aspheric Tecnis ZCT toric intraocular lens (IOL in eyes with low to moderate corneal astigmatism. Methods: We conducted a prospective study of 19 consecutive eyes of 17 patients (mean age: 78 years with a visually significant cataract and moderate corneal astigmatism [higher than 1 diopter (D] undergoing cataract surgery with implantation of the aspheric Tecnis ZCT toric IOL (Abbott Medical Optics. Visual, refractive and aberrometric changes were evaluated during a 6-month follow-up. Ocular aberrations as well as IOL rotation were evaluated by means of the OPD-Station II (Nidek. Results: The six-month postoperative spherical equivalent and power vector components of the refractive cylinder were within ±0.50 D in all eyes (100%. Postoperative logMAR uncorrected and corrected distance visual acuities (UDVA/CDVA were 0.1 (about 20/25 or better in almost all eyes (94.74%. The mean logMAR CDVA improved significantly from 0.41 ± 0.23 to 0.02 ± 0.05 (p Conclusion: Cataract surgery with implantation of the aspheric Tecnis ZCT IOL is a predictable and effective procedure for visual rehabilitation in eyes with cataract and low to moderate corneal astigmatism, providing an excellent postoperative ocular optical quality.

  9. Refractive errors in Cameroonians diagnosed with complete oculocutaneous albinism

    Directory of Open Access Journals (Sweden)

    Eballé AO

    2013-07-01

    Full Text Available André Omgbwa Eballé1,3, Côme Ebana Mvogo2, Christelle Noche4, Marie Evodie Akono Zoua2, Andin Viola Dohvoma21Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon, 2Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon; 3Yaoundé Gynaeco-obstetric and Paediatric Hospital. Yaoundé, Cameroon; 4Faculty of Medicine, Université des Montagnes. Bangangté, CameroonBackground: Albinism causes significant eye morbidity and amblyopia in children. The aim of this study was to determine the refractive state in patients with complete oculocutaneous albinism who were treated at the Gynaeco-Obstetric and Paediatric Hospital, Yaoundé, Cameroon and evaluate its effect on vision.Methods: We carried out this retrospective study at the ophthalmology unit of our hospital. All oculocutaneous albino patients who were treated between March 1, 2003 and December 31, 2011 were included.Results: Thirty-five patients (70 eyes diagnosed with complete oculocutaneous albinism were enrolled. Myopic astigmatism was the most common refractive error (40%. Compared with myopic patients, those with myopic astigmatism and hypermetropic astigmatism were four and ten times less likely, respectively, to demonstrate significant improvement in distance visual acuity following optical correction.Conclusion: Managing refractive errors is an important way to reduce eye morbidity-associated low vision in oculocutaneous albino patients.Keywords: albinism, visual acuity, refraction, Cameroon

  10. 2-YEAR EXPERIENCE OF CORNEAL COLLAGEN CROSSLINKING IN KERATOCONUS TREATMENT

    Directory of Open Access Journals (Sweden)

    D. D. Dement’ev

    2015-01-01

    Full Text Available Aim. To assess reliability, efficacy, and stability of corneal collagen crosslinking (CXL results for stage I‑II keratoconus.Patients and methods. 2‑year (2012-2014 results of CXL were analyzed. CXL was performed on 20 eyes of 15 patients (13 men and 2 women, mean age 31 years. Stage 1 keratoconus was diagnosed in 13 eyes, stage 2 keratoconus was diagnosed in 2 eyes. Primary stage 1‑2 keratoconus was diagnosed in 17 eyes, keratoconus after corneal refractive surgery (LASIK, radial keratotomy was diagnosed in 3 eyes. Preoperative and postoperative examination included uncorrected (UCVA and best-corrected (BCVA visual acuity measurement, pachymetry, corneal topography (total astigmatism measurement, and biomicroscopy. Follow-up period varied from 1 to 24 months.Results. All patients reported on vision improvement. Preoperatively, mean UCVA and BCVA were 0.4 and 0.64, respectively. Postoperatively, mean UCVA and BCVA were 0.49 and 0.66, respectively. Preoperatively and postoperatively, total astigmatism was 2.1 D and 2.0 D, respectively, while mean central corneal thickness was 454 μm and 447 μm, respectively.Conclusions. Corneal collagen crosslinking for stage 1‑2 keratoconus provides mild UCVA and BCVA improvement, decrease in total astigmatism and central corneal thickness. CXL provides stable results of treatment of primary stage 1‑2 keratoconus and keratoconus after corneal refractive surgery. 

  11. Study on the modification of measured wavefront aberration data for customized visual correction

    Science.gov (United States)

    Liu, Ming; Zhang, Yong; Zhang, Zhidong; Quan, Wei; An, Li

    2008-12-01

    Wavefront aberration of human eye is an important foundation for customized vision correction. In most current aberrometers, near infrared light is used to measure ocular wavefront aberration, whereas for customized visual correction, wavefront aberration data in visible range are required. With the measured wavefront aberration, corneal topography and eye's axial lengths data, individual eye models for twenty normal human eyes are constructed with the optical design software ZEMAX. Changing the incidence light wavelength and the refractive indexes of eye models, the values of defocus, astigmatism, higher-order aberrations in the measuring wavelength (833nm) and at the most sensitive wavelength of human eye (555nm) are obtained. Average focus shift between 833nm and 555nm is found to be about 0.94D, and different slightly for different individuals; the differences of astigmatism and higher-order aberrations between 833nm and 555nm are quite slight. For customized visual correction, the measured defocus value should be modified, whereas the measured astigmatism and higher-order aberrations could be used directly for the current correction precision. Individual eye model is a useful tool for accurate transformation of the measured wavefront aberration data into the data for visible spectrum.

  12. In vivo human crystalline lens topography.

    Science.gov (United States)

    Ortiz, Sergio; Pérez-Merino, Pablo; Gambra, Enrique; de Castro, Alberto; Marcos, Susana

    2012-10-01

    Custom high-resolution high-speed anterior segment spectral domain optical coherence tomography (OCT) was used to characterize three-dimensionally (3-D) the human crystalline lens in vivo. The system was provided with custom algorithms for denoising and segmentation of the images, as well as for fan (scanning) and optical (refraction) distortion correction, to provide fully quantitative images of the anterior and posterior crystalline lens surfaces. The method was tested on an artificial eye with known surfaces geometry and on a human lens in vitro, and demonstrated on three human lenses in vivo. Not correcting for distortion overestimated the anterior lens radius by 25% and the posterior lens radius by more than 65%. In vivo lens surfaces were fitted by biconicoids and Zernike polynomials after distortion correction. The anterior lens radii of curvature ranged from 10.27 to 14.14 mm, and the posterior lens radii of curvature ranged from 6.12 to 7.54 mm. Surface asphericities ranged from -0.04 to -1.96. The lens surfaces were well fitted by quadrics (with variation smaller than 2%, for 5-mm pupils), with low amounts of high order terms. Surface lens astigmatism was significant, with the anterior lens typically showing horizontal astigmatism ([Formula: see text] ranging from -11 to -1 µm) and the posterior lens showing vertical astigmatism ([Formula: see text] ranging from 6 to 10 µm).

  13. 儿童睑赘皮的屈光状态分析%Refraction in children with epiblepharon

    Institute of Scientific and Technical Information of China (English)

    吴进; 肖诗艺; 张越骊; 王莉; 陈仁典; 张莉; 李雯霖; 钟晖

    2012-01-01

    Objective To study the relationship between refraction and epiblepharon in Chinese children. Methods A retrospective study of refraction was carried out in 101 children (202 eyes) with epihlepharon who need surgical correction. Results The prevalence of astigmatism (≥0.75D) in children with epiblepharon was 73.76%, which was higher than that of ordinary children (P0.05). The distribution of with the rule, against the rule, and oblique astigmatism was 82.55%, 8.05%, and 9.40% respectively. With the rule astigmatism was predominant (P < 0.001). And the proportion of ohlique astigmatism was less than that of ordinary children (P=0.0289). Conclusions The prevalence and diopter of astigmatism were higher in children with epiblepharon than those in ordinary children. In order to reduce the influence of refractive error on visual development, timely intervention should be considered on children with epihlephmn who had obvious refractive error.%目的 了解我国儿童睑赘皮的屈光状态并进一步探讨儿童睑赘皮的治疗时机.方法 对101例(202只眼)住院手术治疗的睑赘皮儿童的屈光状态进行回顾性分析.结果 睑赘皮儿童散光(≥0.75D)的患病率73.76%,高于普通儿童(P<0.001);近视(≤-0.50D)和远视(≥+2.0D)的患病率分别为40.10%和6.43%,与普通儿童相比无明显差异(P>0.05).散光的轴向分布为顺规散光82.55%,逆规散光8.05%,斜轴散光9.40%,以顺规散光为主(P<0.001),斜轴散光的比例较普通儿童减少(P=0.0289).结论 睑赘皮儿童伴有较高的散光患病率以及较高的散光度,对于伴有明显屈光异常的睑赘皮患儿,应及时干预以消除屈光异常对视觉发育的影响.

  14. Small Incision Cataract Surgery (SICS with Clear Corneal Incision and SICS with Scleral Incision – A Comparative Study

    Directory of Open Access Journals (Sweden)

    Md Shafiqul Alam

    2014-01-01

    Full Text Available Background: Age related cataract is the leading cause of blindness and visual impairment throughout the world. With the advent of microsurgical facilities simple cataract extraction surgery has been replaced by small incision cataract surgery (SICS with posterior chamber intra ocular lens implant, which can be done either with clear corneal incision or scleral incision. Objective: To compare the post operative visual outcome in these two procedures of cataract surgery. Materials and method: This comparative study was carried out in the department of Ophthalmology, Delta Medical College & Hospital, Dhaka, Bangladesh, during the period of January 2010 to December 2012. Total 60 subjects indicated for age related cataract surgery irrespective of sex with the age range of 40-80 years with predefined inclusion and exclusion criteria were enrolled in the study. Subjects were randomly and equally distributed in 2 groups; Group A for SICS with clear corneal incision and group B for SICS with scleral incision. Post operative visual out come was evaluated by determining visual acuity and astigmatism in different occasions and was compared between groups. Statistical analysis was done by SPSS for windows version12. Results: The highest age incidence (43.3% was found between 61 to 70 years of age group. Among study subjects 40 were male and 20 were female. Preoperative visual acuity and astigmatism were evenly distributed between groups. Regarding postoperative unaided visual outcome, 6/12 or better visual acuity was found in 19.98% cases in group A and 39.6% cases in group B at 1st week. At 6th week 6/6 vision was found in 36.3% in Group A and 56.1% in Group B and 46.2% in group A and 66% in group B without and with correction respectively. With refractive correction, 6/6 vision was attained in 60% subjects of group A and 86.67% of group B at 8th week. Post operative visual acuity was statistically significant in all occasions. Postoperative astigmatism of

  15. 非老视患者的近距离屈光矫正%Necessity of correcting short distance refractive error in non-presbyopia patients

    Institute of Scientific and Technical Information of China (English)

    刘文兰; 王莉; 杨扬; 刘珍

    2014-01-01

    目的:通过研究散光性屈光不正与注视距离之间的关系,探讨非老视患者近距离屈光矫正的必要性,并寻求可行的矫正方法。  方法:前瞻性临床研究。序贯选取近视性散光受试者166例(右眼),检查各受试者注视不同距离(视远眼前5m、眼前40cm、眼前20cm)的散光性屈光不正度、配戴静态屈光矫正眼镜时的近视力( distance corrected near vision acuity , DCNVA )及散光修正后的近视力( accommodative astigmatism corrected near vision acuity , ACNVA)。视近状态下的散光在视远单眼全矫基础上采用交叉柱镜进行修正,受检眼水平向前注视近视力表中其最佳视力的视标。对三个注视距离下(视远5 m、视近40 cm、视近20 cm )两两之间的散光度及轴位的差异、DCNVA与ACNVA的差异分别采用两两配对检验,若数据服从正态分布采用配对t检验,否则采用配对符号秩和检验。  结果:三个不同注视距离,两两间散光度的差异均具有统计学意义(视近40cm与视远5m:Z=-5.316,P<0.0167;视近20cm与视远5m:Z=-5.672,P<0.0167;视近20cm与视近40 cm:Z=-2.463, P<0.0167),且视近20 cm散光度(0.83DC±0.52D)>视近40cm散光度(0.78DC±0.43D)>视远5m散光度(0.63DC±0.47D);三个不同注视距离,两两间散光轴位的差异均不具有统计学意义;DCNVA与ACNVA的差异具有统计学意义,且散光修正后视力呈提高的趋势(Z=-5.741,P<0.01;Z=-6.848,P<0.01)。  结论:随注视距离移近,散光度呈增大的趋势且散光轴位朝着顺规散光的方向发展,然而这种改变对于个体来讲是随机的、个性化的,在散光改变量最大的距离处发生视疲劳的可能性较大,在该距离下进行屈光矫正可能是治疗该类视疲劳患者的有效方法。%AIM: To find out the necessity

  16. Refractive status of primary school children in Mopani district, Limpopo Province, South Africa

    Directory of Open Access Journals (Sweden)

    R.G. Mabaso

    2006-01-01

    Full Text Available This article reports part of the findings of a study carried out to determine the causes, prevalence,  and  distribution  of  ocular  dis-orders  among  rural  primary  school  children in  Mopani  district  of  Limpopo  Province, South Africa. Three hundred and eighty eight children  aged  8  to  15  years  were  randomly selected from five randomly selected schools. Non-cycloplegic retinoscopy and auto-refrac-tion were performed on each child. The preva-lence of hyperopia, myopia, and astigmatism was  73.1%,  2.5%  and  31.3%  respective-ly.  Hyperopia  (Nearest  spherical  equivalent power (FNSE ranged from +0.75 to +3.50 D for the right and left eyes with means of +1.05 ±  0.35  D  and  +1.08  ±  0.34  D  respectively. Myopia (FNSE ranged from –0.50 to –1.75 D for the right eye and –0.50 to –2.25 D for the left eye with means of –0.75 ± 0.55 D and –0.93 ± 0.55 D respectively. Regression model for myopia, shows that age had an odds ratio of  1.94  (1.15  to  3.26,  indicating  a  signifi-cant increased risk of myopia with increasing age.  Correcting  cylinders  for  the  right  eyes ranged from –0.25 to –4.50 D (mean = −0.67 ± 0.47 D and for the left eyes from –0.25 to –2.50 D (mean = −0.60 ± 0.30 D. With-the-rule  (WTR  astigmatism  (66.5%  was  more common, followed by against-the-rule (ATR astigmatism (28.1% and oblique (OBL astig-matism  (5.4%.  With-the-rule  astigmatism was  more  common  in  females  than  males; ATR astigmatism and OBL astigmatism were common in males. Regular vision screening programmes,  appropriate  referral  and  vision correction  in  primary  schools  in  Mopani district  are  recommended  in  order  to  elimi-nate  refractive  errors  among  the  children.

  17. Design of modified Czerny-Turner spectral imaging system with wide spectral region%改进的宽谱段车尔尼-特纳光谱成像系统设计

    Institute of Scientific and Technical Information of China (English)

    薛庆生; 陈伟

    2012-01-01

    A modified Czerny-Turner spectral imaging system was developed based on aberration theory to minimize the large astigmatism in classical Czerny-Turner spectrometers. The astigmatism from a plane grating placed in the divergent light beam was used to compensate the astigmatism from an objective lens. The broadband astigmatism corrected simultaneously conditions were deduced, and the a-stigmatism was corrected in a wide spectral region. The principle and method of astigmatism correction were analyzed in detail, and the initial parameter computing was programed. As an example,a Czerny-Turner imaging spectral system operating in 540 - 780 nm was designed. The ray tracing and optimization for the spectral imaging system were performed with ZEMAX-EE software. The analyzed results demonstrate that the total field-of-view modulation transfer function is higher than 0. 52 in the whole working spectra. The system shows good imaging quality due to the astigmatism to be corrected in the wide spectral region synchronously. Obtained results prove the feasibility of the modified method.%针对传统的车尔尼-特纳光谱仪像散较大的缺点,基于像差理论,提出了一种改进的车尔尼-特纳光谱成像系统.将平面光栅置于发散光中,利用平面光栅产生的像散来补偿物镜产生的像散.推导出了宽谱段像散同时校正条件,实现了宽谱段像散的同时校正.具体分析了像差校正的原理和方法,编制了初始结构快速计算程序.作为实例,设计了一个谱段为540~780 nm的宽谱段像散同时校正车尔尼-特纳光谱成像系统,利用光学设计软件ZEMAX-EE对该光谱成像系统进行了光线追迹和优化设计,并对设计结果进行了分析.结果表明,全视场调制传递函数在整个工作波段均达到0.52以上,实现了宽谱段像散的同时校正,并获得了良好的成像质量,满足了设计指标要求,结果也证实了所提出的改进方法是可行的.

  18. Analysis of 100 cases of young infant refractive status%低龄婴儿100例屈光状态分析

    Institute of Scientific and Technical Information of China (English)

    潘勇; 葛军; 张松; 郭翔

    2015-01-01

    Objective To examine the infant vision screening in 42 days after birth and analyze the distribution through vision screening instrument.Methods One hundred infants (50 males and 50 females) were examined in 42 days after birth with SureSight vision screening instrument.The dioptric situation after statistical treatment was analyzed according to the normal reference range of refractive status.Results Spherical equibalent on 42 days (Ds) was 2.15±1.54.Column lens values on 42 days (Dc) were-1.72±0.81.Astigmatism with rule on 42 days included 179 eyes, accounting for 89.5%;astigmatism against the rule had 4 eyes, accounting for 2%;oblique astigmatism had 14 eyes, accounting for 7%, no astigmatism referred to 3 eyes, accounting for 1.5%.Most of it was astigmatism with rule.Infant concave-sphere astigmatism, axial was not related to gender and left-or-right eyes.Conclusions Dioptric situation of infants in 42 days after birth mainly hyperopia, is not related to the gender and left-or-right eyes, the vast majority of the rule astigmatism.%目的 使用视力筛查仪,对出生42天的婴儿进行屈光状态检查,分析其分布状态,初步提出参考范围.方法 对2014年9月至2015年2月在盐城市妇幼保健院采用SureSight视力筛查仪,对100例出生后42天的婴幼儿男、女各50例,做屈光检查,对结果进行统计学处理后,按性别、左右眼别分析屈光状态的分布情况,初步提出该年龄段屈光数值参考范围.结果 (1) 42天球镜值为(2.15±1.54) Ds,42天柱镜值为(-1.72±0.81)Dc;顺规散光179只眼,占89.5%,逆规散光4只眼,占2%,斜轴散光14只眼,占7%,无散光3只眼,占1.5%.多为顺规散光.(2)婴幼儿的球镜、散光、轴向与性别和眼别不相关.结论 42天婴幼儿屈光状态以远视为主,绝大多数为顺规散光,且与性别、左右眼别无关.

  19. Using corneal topography design personalized cataract surgery programs%应用角膜地形图设计个性化白内障手术方案

    Institute of Scientific and Technical Information of China (English)

    黄金鸥; 陈金邦; 陈炜江; 裘义松; 魏肖红

    2014-01-01

    AIM:To investigate how to design personalized cataract surgery programs to achieve surgical correction of preoperative corneal astigmatism with surgical astigmatism under the guidance of corneal topography, improve postoperative visual quality and reduce the cost of treatment. METHODS: Totally 202 cases ( 226 eyes ) cataract patients were divided into randomized treatment group and individualized treatment group. According to the method and location of the incision, randomized treatment group were divided into 8 groups. Surgical astigmatism after different incision were calculated with the use of preoperative and postoperative corneal astigmatism through vector analysis method. Individualized treatment groups were designed personably for surgical method with reference of every surgically induced astigmatism, the surgical method chooses the type of surgical incision based on close link between preoperative corneal astigmatism and surgically induced astigmatism, and the incision was located in the steep meridian. The postoperative corneal astigmatism of individualized treatment group was observed. RESULTS: Postoperative corneal astigmatism of individualized treatment group were lower than that of 3.0mm clear corneal tunnel incision in the randomized treatment group, there were statistically significance difference, while with 3. 0mm sclera tunnel incision group there were no statistically significance difference. After 55. 8% of patients with the use of individualized surgical plan could undergo the operation of extracapsular cataract extraction with relatively low cost and rigid intraocular lens implantation, the per capita cost of treatment could be reduced. CONCLUSION: Personalized cataract surgery programs are designed to achieve surgical correction of preoperative corneal astigmatism under the use of corneal topography, improve postoperative visual quality and reduce the cost of treatment.%目的:探讨如何在角膜地形图的指导下,设计个性化

  20. Topography-guided phacoemulsification surgery on type 2 diabetic patients with age-related cataract%角膜地形图引导超声乳化治疗2型糖尿病年龄相关性白内障

    Institute of Scientific and Technical Information of China (English)

    易昀敏; 易敬林; 邵毅; 余瑶; 王慧珍; 龚菊梅; 高桂平

    2011-01-01

    Objective To observe the corneal astigmatism and tear film stability of type 2 diabetic patients with age related cataract and astigmatism after phacoemulsification surgery guided by corneal topography. Methods 80 patients with type 2 diabetic age-related cataract and astigmatism were randomly divided into two groups;group A was treated by tra ditional superior corneal incision phacoemulsification surgery and IOL implantation, group B was treated by corneal topogra phy guiding incision phacoemulsification surgery and IOL implantation. Topography tests and tear film function were per formed at 1 week and 3 months postoperative. Results For corneal vertical Jc and horizon astigmatism P, there was signifi cance statistically at preoperative and I week postoperative in group A(P0. 01 ), however, there was significance statistically at preoperative and 1 week, 3 months postoperative in group B(P <0. 01) ; when compared with group A. Group B had longer time of BUT al 1 week postoperative(P <0.05) , 3 months after surgery, the BUT of two groups return to the preoperative level. Con dusion Topography-guided phacoemulsification surgery and IOL implantation is a more favorable solution for type 2 dia betic patients with age-related cataract and astigmatism,which can correct the cornea] astigmatism, stabilize the tear film and therefore improve the visual quality.%目的 观察角膜地形图引导超声乳化治疗2型糖尿病年龄相关性白内障患者角膜散光及泪膜稳定性.方法 术前存在角膜散光的2型糖尿病年龄相关性白内障患者80例(80眼),随机分为A、B组,各40例(40眼).A组采用常规上方透明角膜切口行超声乳化白内障吸除联合人工晶状体(IOL)植入术,B组在角膜地形图引导下作切口行超声乳化白内障吸除联合IOL植入术,术后1周及3个月复查角膜地形图并观察泪膜改变情况.结果 角膜垂直散光失量Jo和水平散光失量P,A组术前与术后1周相比,P<0.01,与术后3

  1. Visual outcome and rotational stability of open loop toric intraocular lens implantation in Indian eyes

    Directory of Open Access Journals (Sweden)

    Arvind Venkataraman

    2013-01-01

    Full Text Available Purpose: To assess the visual outcome and rotational stability of single-piece open loop toric Intra Ocular Lens (IOL in a clinical setting. Materials and Methods: In a prospective study, 122 eyes of 77 patients were followed up for a period of 12 months after cataract surgery with toric open loop IOL implantation. The pre-operative markings for the position of incision and IOL placement were done under slit lamp by anterior stromal puncture. The visual acuity, refraction, and IOL position were assessed at day 1, 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. Results: The mean age of the cohort was 56 yrs (S.D. 13.88; range 16 to 87 years. The mean pre-operative cylinder of corneal astigmatism was 1.37 D. (SD 0.79, range 1.0 to 5.87 D. Mean post-operative refractive cylinder was 0.36 D (SD 0.57, range 0 to 1.50 D at 12 months. Ninety-seven percent of the eyes were within 1 D of residual astigmatism. Ninety-four percent of patients had uncorrected visual acuity of 20/30 or better. Four eyes required IOL repositioning due to rotation. At 12 months, 96.7% of the IOLs were within 10 degrees of the target axis. There was no rotation seen after 6 months. Conclusion: Toric IOLs are very effective and consistent in correcting astigmatism during the cataract surgery. IOL rotation happens mostly within a month of surgery, and if significant, requires early repositioning.

  2. An analysis of refraction and amblyopia of children with subnormal vision%视力低常儿童的屈光状态与弱视分析

    Institute of Scientific and Technical Information of China (English)

    曹宜

    2011-01-01

    Objective To analyze the refraction between the eyes with normal corrected visual acuity and the amblyopic eyes, and to evaluate the impact on children vision from different refraction. Methods The refraction in 540(1080eyes) children with subnormal naked vision was retrospectively analysed. Results The refraction of normal corrected visual acuity eyes and amblyopic eyes are mostly compound hyperopic astigmatism, the number constituent ratio and degree of astigmatism in anblyopic eyes are higher than those of the normal corrected visual acuity eyes, and the degree of hypermetropia in amblyopic eyes is obviously higher than that of the normal corrected visual acuity eyes (P<0.01). Conclusions Compound hyperopic astigmatism, middle or high hypermetropia are the main refractive errors leading to amblyopia, and early screening, rectification and treatment are conducive to the prevention and treatment of amblyopia..%目的 分析矫正视力正常眼和弱视眼的屈光状态差异,评价不同屈光状态对儿童视力的影响.方法 回顾分析540名(1080只眼)裸眼视力低常儿童的屈光状态.结果 矫正视力正常眼和弱视眼的屈光不正均以复性远视散光为主,弱视眼中的散光眼构成比和程度均高于正常眼,弱视眼的远视程度明显高于正常眼(P<0.01).结论 复性远视散光、中、高度远视是导致弱视的主要屈光异常,早期筛查、矫正和治疗,有利于弱视的防治.

  3. Clinical application of TICL implantation for ametropia following deep anterior lamellar keratoplasty for keratoconus

    Science.gov (United States)

    Qin, Qin; Yang, Liping; He, Zifang; Huang, Zhenping

    2017-01-01

    Abstract Background: This study aimed to investigate the clinical application of phakic toric intraocular collamer lens (TICL) implantation in treating ametropia following deep anterior lamellar keratoplasty (DALK) for patients with keratoconus, especially the effectiveness and safety of high astigmatism and indications of TICL implantation after corneal transplantation. Methods: Using the self-controlled case series observation approach, 9 patients with ametropia (9 eyes) who underwent DALK surgery for keratoconus 1.5 years ago with stitches removed 3 months ago were kept under observation from May 2013 to April 2014 in Ophthalmic Center of Nanjing Drum Tower Hospital affiliated to Nanjing Medical University. TICL implantation was performed in all patients. The uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) were examined before surgery and 1 week, 6 months, 1 year, and 2 years after surgery. Corneal astigmatism, corneal thickness, anterior chamber depth, corneal endothelial cell density (ECD), and preoperative and postoperative intraocular pressures at different time points were measured. Intraoperative or postoperative complications of TICL implantation were observed, and the safety of the operation was evaluated. Results: The UCVA and BCVA in all operated eyes were better 6 months after surgery than before surgery. The spherical diopter and cylindrical diopter decreased to different degrees after surgery. Six months after surgery, the deviation of TICL axis in all operated eyes was less than 10 degrees, tending to be stable. No severe intraoperative or postoperative complication occurred. Conclusion: TICL implantation was an optional choice for ametropia correction after DALK surgery, especially in patients with high astigmatism. PMID:28225492

  4. Visual acuity measures do not reliably detect childhood refractive error--an epidemiological study.

    Directory of Open Access Journals (Sweden)

    Lisa O'Donoghue

    Full Text Available PURPOSE: To investigate the utility of uncorrected visual acuity measures in screening for refractive error in white school children aged 6-7-years and 12-13-years. METHODS: The Northern Ireland Childhood Errors of Refraction (NICER study used a stratified random cluster design to recruit children from schools in Northern Ireland. Detailed eye examinations included assessment of logMAR visual acuity and cycloplegic autorefraction. Spherical equivalent refractive data from the right eye were used to classify significant refractive error as myopia of at least 1DS, hyperopia as greater than +3.50DS and astigmatism as greater than 1.50DC, whether it occurred in isolation or in association with myopia or hyperopia. RESULTS: Results are presented from 661 white 12-13-year-old and 392 white 6-7-year-old school-children. Using a cut-off of uncorrected visual acuity poorer than 0.20 logMAR to detect significant refractive error gave a sensitivity of 50% and specificity of 92% in 6-7-year-olds and 73% and 93% respectively in 12-13-year-olds. In 12-13-year-old children a cut-off of poorer than 0.20 logMAR had a sensitivity of 92% and a specificity of 91% in detecting myopia and a sensitivity of 41% and a specificity of 84% in detecting hyperopia. CONCLUSIONS: Vision screening using logMAR acuity can reliably detect myopia, but not hyperopia or astigmatism in school-age children. Providers of vision screening programs should be cognisant that where detection of uncorrected hyperopic and/or astigmatic refractive error is an aspiration, current UK protocols will not effectively deliver.

  5. Comparative evaluation of visual outcomes and corneal asphericity after laser-assisted in situ keratomileusis with the six-dimension Amaris excimer laser system

    Science.gov (United States)

    Piao, JunJie; Li, Ying-Jun; Whang, Woong-Joo; Choi, Mihyun; Kang, Min Ji; Lee, Jee Hye; Yoon, Geunyoung; Joo, Choun-Ki

    2017-01-01

    Purpose To compare the visual and refractive outcomes after laser-assisted in situ keratomileusis (LASIK) surgery for correction of myopia or myopic astigmatism using a six-dimensional Amaris excimer laser. Methods In this retrospective cohort study, we enrolled 47 eyes of 28 patients (age: 19–36 years) with myopia or myopic astigmatism. We used the Custom Ablation Manager protocol and performed ablations with the SCHWIND AMARIS system. LASIK flaps were cut with an iFS Advanced Femtosecond Laser. Mean static (SCC) and dynamic cyclotorsion (DCC) were evaluated. Visual and refractive outcomes were evaluated during 6 months’ follow-up. Corneal asphericity (Q-value) was analyzed at 4 months postoperatively. Results The spherical equivalent (SE) reduction was statistically significant reduce 1 day after refractive surgery (P Free mode (AF) and 90% in the Corneal Wavefront mode (CW). SCC measurements were within ± 5 degrees in 57% (AF) and 68% (CW) of eyes. Mean DCC was within ± 1 degree in 96% (AF) or 95% (CW) of cases. At 6 months, the uncorrected distance visual acuity was 20/25 or better in all eyes. At last follow-up, both steep and flat keratometry values had significantly flattened in both groups (P < 0.001). Corneal asphericity also increased significantly during the postoperative period for an 8-mm corneal diameter (P < 0.001). Conclusions LASIK for myopia or myopic compound astigmatism correction using the six-dimensional AMARIS 750S excimer laser is safe, effective, and predictable. Postoperative corneal asphericity can be analyzed by linear regression to predict the changes in postoperative corneal asphericity with this approach. PMID:28187180

  6. Screening for significant refractive error using a combination of distance visual acuity and near visual acuity.

    Directory of Open Access Journals (Sweden)

    Peiyao Jin

    Full Text Available To explore the effectiveness of using a series of tests combining near visual acuity (NVA and distance visual acuity (DVA for large-scale screenings for significant refractive error (SRE in primary school children.Each participant underwent DVA, NVA and cycloplegic autorefraction measurements. SREs, including high myopia, high hyperopia and high astigmatism were analyzed. Cycloplegic refraction results were considered to be the gold standard for the comparison of different screening measurements. Receiver-operating characteristic (ROC curves were constructed to compare the area under the curve (AUC and the Youden index among DVA, NVA and the series combined tests of DVA and NVA. The efficacies (including sensitivity, specificity, positive predictive value, and negative predictive value of each test were evaluated. Only the right eye data of each participant were analysed for statistical purpose.A total of 4416 children aged 6 to 12 years completed the study, among which 486 students had right eye SRE (SRE prevalence rate = 11.01%. There was no difference in the prevalence of high hyperopia and high astigmatism among different age groups. However, the prevalence of high myopia significantly increased with the age (χ² = 381.81, p<0.01. High hyperopia was the biggest SRE factor associated with amblyopia(p<0.01,OR = 167.40, 95% CI: 75.14∼372.94. The DVA test was better than the NVA test for detecting high myopia (Z = 2.71, p<0.01, but the NVA test was better for detecting high hyperopia (Z = 2.35, p = 0.02 and high astigmatism (Z = 4.45, p<0.01. The series combined DVA and NVA test had the biggest AUC and the highest Youden Index for detecting high hyperopia, myopia, astigmatism, as well as all of the SREs (all p<0.01.The series combined DVA and NVA test was more accurate for detecting SREs than either of the two tests alone. This new method could be applied to large-scale SRE screening of children, aged 6 to 12, in areas that are less

  7. Erros de refração como causas de baixa visual em crianças da rede de escolas públicas da regional de Botucatu - SP Refractive errors as causes of visual impairment in children from public schools of the Botucatu region - SP

    Directory of Open Access Journals (Sweden)

    Claudia Akemi Shiratori de Oliveira

    2009-04-01

    Full Text Available OBJETIVO: Estudar a ocorrência dos erros refracionais em escolares de nosso meio. MÉTODOS: Estudo transversal avaliando crianças da pré-escola e do ensino básico, quanto ao sexo, tipo de erro refracional, acuidade visual e tratamento realizado. RESULTADOS: Quatro mil seiscentos e vinte e três crianças foram submetidas a exame de acuidade visual, das quais 8,1% apresentaram necessidade de exame oftalmológico completo. Houve 63,2% de portadores de astigmatismo hipermetrópico, 15,7% de astigmatismo miópico, 12,5% de astigmatismo misto, 4,9% de hipermetropia e 3,7% de miopia. Foi indicada a prescrição de lentes corretoras para 48,7% da amostra estudada. A frequência de erros refracionais na população foi de 3,9%. CONCLUSÃO: O astigmatismo hipermetrópico foi o erro de refracional mais frequente, havendo necessidade de tratamento em cerca de 50% das crianças triadas com frequência de 3,9% de erro refracional passível de correção na população de estudo.PURPOSE: To evaluate the refractive errors as cause of visual impairment in school children from the Botucatu region. METHODS: A sectional study was conducted evaluating preschool and elementary school students, according to gender, refractive error, visual acuity and treatment. RESULTS: Four thousand six hundred and twenty-three (4,623 children were submitted to visual acuity evaluation and 8.1% of them were submitted to complete ocular examination. There were 63.2% hyperopic astigmatism, 15.7% myopic astigmatism, 12.5% astigmatism, 4.9% hyperopia and 3.7% myopia. Corrective lenses were prescribed for 48.7% of the evaluated children. CONCLUSION: The most frequent refractive error was hyperopic astigmatism and 50% of the children received treatment. The frequency of refractive errors was 3.9% of the studied population.

  8. New Gapless COS G140L Mode Proposed for Background-Limited Far-UV Observations

    CERN Document Server

    Redwine, Keith; Fleming, Brian; France, Kevin; Zheng, Wei; Osterman, Steven; Howk, J Christopher; Anderson, Scott F; Gaensicke, Boris T

    2016-01-01

    Here we describe the observation and calibration procedure for a new G140L observing mode for the Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope (HST). This mode, CENWAV = 800, is designed to move the far-UV band fully onto the Segment A detector, allowing for more e cient ob- servation and analysis by simplifying calibration management between the two channels, and reducing the astigmatism in this wavelength region. We also de- scribe some of the areas of scientific interest for which this new mode will be especially suited.

  9. A case of endophthalmitis associated with limbal relaxing incision

    Directory of Open Access Journals (Sweden)

    Aravind Haripriya

    2012-01-01

    Full Text Available Limbal relaxing incisions (LRIs are considered a relatively safe procedure with rapid stabilization and absence of infectious complications. Do we need to readdress this last impression? We report a case of nocardia endophthalmitis associated with an exudate at the site of an LRI in a patient who underwent routine cataract surgery. This case, to the best of our knowledge, is the first report of its kind, stressing the need for a cautious approach to the adoption of this method of astigmatic correction.

  10. Design of the Advanced Virgo non-degenerate recycling cavities

    Energy Technology Data Exchange (ETDEWEB)

    Granata, M; Barsuglia, M [Laboratoire Astroparticule et Cosmologie (APC) 10 rue Alice Domon et Leonie Duquet, 75013 Paris (France); Flaminio, R [Laboratoire des Materiaux Avances (LMA), IN2P3/CNRS F-69622 Villeurbanne, Lyon (France); Freise, A [School of Physics and Astronomy, University of Birmingham Birmingham, B15 2TT (United Kingdom); Hild, S [Institute for Gravitational Research, Department of Physics and Astronomy University of Glasgow, Glasgow, G12 8QQ (United Kingdom); Marque, J, E-mail: granata@apc.univ-paris7.f [European Gravitational Observatory (EGO) I-56021 Cascina (Italy)

    2010-05-01

    Advanced Virgo is the project to upgrade the interferometric gravitational wave detector Virgo, and it foresees the implementation of power and signal non-degenerate recycling cavities. Such cavities suppress the build-up of high order modes of the resonating sidebands, with some advantage for the commissioning of the detector and the build-up of the gravitational signal. Here we present the baseline design of the Advanced Virgo non-degenerate recycling cavities, giving some preliminary results of simulations about the tolerances of this design to astigmatism, mirror figure errors and thermal lensing.

  11. Optical Design of Spaceborne Broadband Limb Sounder for Detecting Atmospheric Trace Gas%星载宽波段大气痕量气体临边探测仪光学设计

    Institute of Scientific and Technical Information of China (English)

    薛庆生

    2012-01-01

    In order to meet the urgent requirements of delecting atmospheric trace gas in limb observation geometry, an optical system of spaceborne broadband limb sounder for detecting atmospheric trace gas is designed. The system is an imaging spectrometer with the working wavelength band from 0. 3 μm to 0. 7 μm, and its full field of view is 2. 4% focal length is 120 mm, and the relative aperture is 1 : 6. To avoid the problems of the classical Czerny-Truncr spectrometer, such as low spatial resolution caused by large astigmatism, a modified Czerny-Turner spectrometer is designed, in which astigmatism can be corrected simultaneously in a wide band. By matching the modified Czerny-Turner spectrometer with a off-axis parabolic telescope,an examplc of limb sounder optical system is designed. Ray tracing, optimization and analysing are performed by ZEMAX software. The analyzed results demonstrate that the astigmatism is substantially corrected, and the MTF for different spectral band is more than 0. 69 which satisfies the pre-designed requirement and proves the feasibility of the astigmatism-correction method.%为满足大气痕量气体临边探测的迫切需求,克服传统Czerny-Turner光谱仪由于像散大导致空间分辨率低的缺点,设计了一种可以在宽波段内同时校正像散的改进型Czerny-Turner光谱仪,光谱范围为0.3~0.7μm,全视场角为2.4°,焦距为120 mm,相对孔径为1∶6.将离轴抛物面镜与改进型Czerny-Turner光谱仪匹配设计了一个临边探测仪光学系统并运用光学设计软件ZEMAX对临边探测仪光学系统进行了光线追迹和优化并对设计结果进行了分析,结果表明该系统的像散得到充分校正,光学系统在各个谱段的光学传递函数均达到0.69以上,完全满足设计指标要求,也证明了所提出的在宽波段内同时像散校正方法是可行的.

  12. Optical Aberrations and Wavefront

    Directory of Open Access Journals (Sweden)

    Nihat Polat

    2014-08-01

    Full Text Available The deviation of light to create normal retinal image in the optical system is called aberration. Aberrations are divided two subgroup: low-order aberrations (defocus: spherical and cylindrical refractive errors and high-order aberrations (coma, spherical, trefoil, tetrafoil, quadrifoil, pentafoil, secondary astigmatism. Aberrations increase with aging. Spherical aberrations are compensated by positive corneal and negative lenticular spherical aberrations in youth. Total aberrations are elevated by positive corneal and positive lenticular spherical aberrations in elderly. In this study, we aimed to analyze the basic terms regarding optic aberrations which have gained significance recently. (Turk J Ophthalmol 2014; 44: 306-11

  13. Digital in-line holography in thick optical systems: application to visualization in pipes

    CERN Document Server

    Verrier, Nicolas; Marc, Brunel; Denis, Lebrun; 10.1364/AO.47.004147

    2012-01-01

    In this paper we apply digital in-line holography to image opaque objects through a thick plano-concave pipe. Opaque fibers and opaque particles are considered}. Analytical expression of the intensity distribution in the CCD sensor plane is derived using generalized Fresnel transform. \\textbf{The proposed model has the ability to deal with various pipe shape and thickness and compensates for the lack of versatility of classical DIH models. Holograms obtained with a 12 mm thick plano-concave pipe are then reconstructed using fractional Fourier transform (FRFT).} This method allows us to get rid of astigmatism. Numerical and experimental results are presented.

  14. High-power AlGaAs channeled substrate planar diode lasers for spaceborne communications

    Science.gov (United States)

    Connolly, J. C.; Goldstein, B.; Pultz, G. N.; Slavin, S. E.; Carlin, D. B.; Ettenberg, M.

    1988-01-01

    A high power channeled substrate planar AlGaAs diode laser with an emission wavelength of 8600 to 8800 A was developed. The optoelectronic behavior (power current, single spatial and spectral behavior, far field characteristics, modulation, and astigmatism properties) and results of computer modeling studies on the performance of the laser are discussed. Lifetest data on these devices at high output power levels is also included. In addition, a new type of channeled substrate planar laser utilizing a Bragg grating to stabilize the longitudinal mode was demonstrated. The fabrication procedures and optoelectronic properties of this new diode laser are described.

  15. GANAS: A HYBRID ANASTIGMATIC ASPHERICAL PRIME-FOCUS CORRECTOR

    Directory of Open Access Journals (Sweden)

    F. Della Prugna

    2009-01-01

    Full Text Available The Cassegrain-Coud 1 meter Car to the focal plane of the primary f/5 l Zeiss telescope at the Venezuelan National Astronomical Observatory uses six optical elements. Removal of the secondary convex mirror gives accessspheroidal mirror, but spherical aberration, coma, astigmatism and eld curvature severely hamper its imaging capabilities. In order to carry out prime-focus imaging, we designed and manufactured a corrector group, called GAnAs, to minimize these aberrations over a circular eld of 300. The corrector group is a hybrid con guration with two thin aspherical 4th-order plates and a meniscus lens.

  16. Quantum Electronics for Atomic Physics

    CERN Document Server

    Nagourney, Warren

    2010-01-01

    Quantum Electronics for Atomic Physics provides a course in quantum electronics for researchers in atomic physics. The book covers the usual topics, such as Gaussian beams, cavities, lasers, nonlinear optics and modulation techniques, but also includes a number of areas not usually found in a textbook on quantum electronics. It includes such practical matters as the enhancement of nonlinear processes in a build-up cavity, impedance matching into a cavity, laser frequencystabilization (including servomechanism theory), astigmatism in ring cavities, and atomic/molecular spectroscopic techniques

  17. Quantum electronics for atomic physics and telecommunication

    CERN Document Server

    Nagourney, Warren G

    2014-01-01

    Nagourney provides a course in quantum electronics for researchers in atomic physics and other related areas (including telecommunications). The book covers the usual topics, such as Gaussian beams, optical cavities, lasers, non-linear optics, modulation techniques and fibre optics, but also includes a number of areas not usually found in a textbook on quantum electronics, such as the enhancement of non-linear processes in a build-up cavity or periodically poled waveguide, impedance matching into a cavity and astigmatism in ring cavities.

  18. Orbital angular momentum of the laser beam and the second order intensity moments

    Institute of Scientific and Technical Information of China (English)

    高春清[1; 魏光辉[2; HorstWeber[3

    2000-01-01

    From the wave equation of a generalized beam the orbital angular momentum is studied. It is shown that the orbital angular momentum exists not only in the Laguerre-Gaussian beam, but in any beam with an angular-dependent structure. By calculating the second order intensity moments of the beam the relation between the orbital angular momentum and the second order moments 〈xθy〉, 〈yθx〉 is given. As an example the orbital angular momentum of the general astigmatic Gaussian beam is studied.

  19. [Wave front aberrations -- practical conclusions in eye with Restor 3+ difractive multifocal lens].

    Science.gov (United States)

    Staicu, Corina; Moraru, Ozana; Moraru, Cristian

    2014-01-01

    Implantation of multifocal intraocular lenses has become a rutine nowadays, but achieving good visual results requires a perfect intraoperative technique and also an adequate preoperative selection of the patients. We analysed the wave front aberrations (spherical aberations, coma and astigmatism) in the eyes implanted with ReStor + 3 IOL, and we realized some clinical correlations of these aberations with the pupil diameter in scotopic and fotopic conditions, kappa angle, IOL centration, residual refraction errors postoperatively. Taking into account the causes of postoperative high order aberration will allow the surgeon to make a good selection of the patiens and to a higher degree of satisfaction of both sides.

  20. Development of a universal toric intraocular lens calculator

    Science.gov (United States)

    Hjelmstad, David; Sayegh, Samir I.

    2014-02-01

    We present a method for calculating the ideal toric lens to implant in astigmatic patients following cataract surgery. We show that the online calculators provided by major toric IOL manufacturers are insufficient for both theoretical and practical reasons. We reveal important theoretical shortcomings in their approach, illustrated by a number of cases which demonstrate how the approach can lead to errors in lens selection. Our approach combines the spherical and cylindrical power calculations into one, and allows for lens data from any manufacturer to be used, eliminating the reliance on multiple programs.

  1. Miniaturized modules for light sheet microscopy with low chromatic aberration.

    Science.gov (United States)

    Bruns, T; Bauer, M; Bruns, S; Meyer, H; Kubin, D; Schneckenburger, H

    2016-12-01

    Two miniaturized fibre-coupled modules for light sheet-based microscopy are described and compared with respect to image quality, chromatic aberration and beam alignment. Whereas in one module the light sheet is created by an achromatic cylindrical lens, reflection by a spherical mirror and concomitant astigmatic distortion are used to create the light sheet in the second module. Test experiments with fluorescent dyes in solution and multicellular tumour spheroids are reported, and some details on construction are given for both systems. Both modules are optimized for imaging individual cell layers of 3D biological samples and can be adapted to fit commercial microscopes.

  2. Optical modeling and physical performances evaluations for the JT-60SA ECRF antenna

    Energy Technology Data Exchange (ETDEWEB)

    Platania, P., E-mail: platania@ifp.cnr.it; Figini, L.; Farina, D.; Micheletti, D.; Moro, A.; Sozzi, C. [Istituto di Fisica del Plasma “P. Caldirola”, Consiglio Nazionale delle Ricerche, Via R. Cozzi 53, 20125, Milano (Italy); Isayama, A.; Kobayashi, T.; Moriyama, S. [Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193 (Japan)

    2015-12-10

    The purpose of this work is the optical modeling and physical performances evaluations of the JT-60SA ECRF launcher system. The beams have been simulated with the electromagnetic code GRASP® and used as input for ECCD calculations performed with the beam tracing code GRAY, capable of modeling propagation, absorption and current drive of an EC Gaussion beam with general astigmatism. Full details of the optical analysis has been taken into account to model the launched beams. Inductive and advanced reference scenarios has been analysed for physical evaluations in the full poloidal and toroidal steering ranges for two slightly different layouts of the launcher system.

  3. Inflammatory Biomarkers Profile as Microenvironmental Expression in Keratoconus

    Science.gov (United States)

    Jonescu-Cuypers, Christian; Nicula, Cristina; Voinea, Liliana-Mary

    2016-01-01

    Keratoconus is a degenerative disorder with progressive stromal thinning and transformation of the normal corneal architecture towards ectasia that results in decreased vision due to irregular astigmatism and irreversible tissue scarring. The pathogenesis of keratoconus still remains unclear. Hypotheses that this condition has an inflammatory etiopathogenetic component apart from the genetic and environmental factors are beginning to escalate in the research domain. This paper covers the most relevant and recent published papers regarding the biomarkers of inflammation, their signaling pathway, and the potentially new therapeutic options in keratoconus. PMID:27563164

  4. Spectral demixing avoids registration errors and reduces noise in multicolor localization-based super-resolution microscopy

    Science.gov (United States)

    Lampe, André; Tadeus, Georgi; Schmoranzer, Jan

    2015-09-01

    Multicolor single molecule localization-based super-resolution microscopy (SMLM) approaches are challenged by channel crosstalk and errors in multi-channel registration. We recently introduced a spectral demixing-based variant of direct stochastic optical reconstruction microscopy (SD-dSTORM) to perform multicolor SMLM with minimal color crosstalk. Here, we demonstrate that the spectral demixing procedure is inherently free of errors in multicolor registration and therefore does not require multicolor channel alignment. Furthermore, spectral demixing significantly reduces single molecule noise and is applicable to astigmatism-based 3D multicolor imaging achieving 25 nm lateral and 66 nm axial resolution on cellular nanostructures.

  5. Orbital angular momentum of the laser beam and the second order intensity moments

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    From the wave equation of a generalized beam the orbital angular momentum is studied. It is shown that the orbital angular momentum exists not only in the Laguerre_Gaussian beam,but in any beam with an angular_dependent structure. By calculating the second order intensity moments of the beam the relation between the orbital angular momentum and the second order moments 〈xθy〉, 〈yθx〉 is given. As an example the orbital angular momentum of the general astigmatic Gaussian beam is studied.

  6. Measuring the Orbital Angular Momentum of Electron Beams

    CERN Document Server

    Guzzinati, Giulio; Béché, Armand; Verbeeck, Jo

    2014-01-01

    The recent demonstration of electron vortex beams has opened up the new possibility of studying orbital angular momentum (OAM) in the interaction between electron beams and matter. To this aim, methods to analyze the OAM of an electron beam are fundamentally important and a necessary next step. We demonstrate the measurement of electron beam OAM through a variety of techniques. The use of forked holographic masks, diffraction from geometric apertures, diffraction from a knife-edge and the application of an astigmatic lens are all experimentally demonstrated. The viability and limitations of each are discussed with supporting numerical simulations.

  7. Generalised Hermite-Gaussian beams and mode transformations

    CERN Document Server

    Wang, Yi; Zhang, Yanfeng; Chen, Hui; Yu, Siyuan

    2016-01-01

    Generalised Hermite-Gaussian modes (gHG modes), an extended notion of Hermite-Gaussian modes (HG modes), are formed by the summation of normal HG modes with a characteristic function $\\alpha$, which can be used to unite conventional HG modes and Laguerre-Gaussian modes (LG modes). An infinite number of normalised orthogonal modes can thus be obtained by modulation of the function $\\alpha$. The gHG mode notion provides a useful tool in analysis of the deformation and transformation phenomena occurring in propagation of HG and LG modes with astigmatic perturbation.

  8. White light interferometry in amblyopic children--a pilot study.

    Science.gov (United States)

    Vernon, S A; Hardman-Lea, S; Rubinstein, M P; Snead, M P

    1990-01-01

    Interferometric acuity using the IRAS white light interferometer was compared with Snellen acuity in nine amblyopic children between the ages of five and nine years, and nine aged matched controls. All of the amblyopic eyes achieved better grating acuities than Snellen acuities. Fifty-seven per cent of the amblyopes with a best corrected Snellen acuity of 6/18 or less in their amblyopic eye, achieved grating acuities indistinguishable from normal. The hand held white light interferometer may have a role in the assessment of meridional amblyopia and in children with high astigmatic errors.

  9. Active optics: deformable mirrors with a minimum number of actuators

    CERN Document Server

    Laslandes, Marie; Ferrari, Marc; 10.2971/jeos.2012.12036

    2012-01-01

    We present two concepts of deformable mirror to compensate for first order optical aberrations. Deformation systems are designed using both elasticity theory and Finite Element Analysis in order to minimize the number of actuators. Starting from instrument specifications, we explain the methodology to design dedicated deformable mirrors. The work presented here leads to correcting devices optimized for specific functions. The Variable Off-Axis paraboLA concept is a 3-actuators, 3-modes system able to generate independently Focus, Astigmatism and Coma. The Correcting Optimized Mirror with a Single Actuator is a 1-actuator system able to generate a given combination of optical aberrations.

  10. Vitrectomy and translocation of the anterior chamber intraocular lens to the sulcus: a closed microsurgical technique for the UGH syndrome.

    Science.gov (United States)

    Gualtieri, William; Rossini, Paolo; Forlini, Cesare

    2008-01-01

    This interventional case report presents an anterior chamber intraocular lens (AC-IOL) translocation technique to manage a case of uveitis-glaucoma-hyphema (UGH) syndrome associated with posterior dislocation of nuclear fragments and vitreitis as a consequence of capsule rupture during cataract surgery. Pars plana vitrectomy followed by an AC-IOL translocation from the anterior chamber to the sulcus without additional surgical corneal incision was performed. At 12 months' follow-up, the original AC-IOL was in stable position in the posterior chamber, with binocular refractive balance and no further astigmatism and resolution of the UGH syndrome.

  11. Deformable Membrane Mirror for Wavefront Correction (Short Communication

    Directory of Open Access Journals (Sweden)

    Amita Gupta

    2009-11-01

    Full Text Available Deformable or adaptive mirrors are used in modern adaptive optics systems for direct correction of the aberrations in the light wavefront. Conventional deformable mirrors used for this purpose are expensive electromechanical devices. Deformable membrane mirror fabricated using microelectromechanical systems (MEMS technology is a low cost, compact adaptive optical element for correction of the lower-order optical aberrations such as defocus and astigmatism. In this paper, important aspects of device design and simulation, fabrication techniques, and test results are discussed.Defence Science Journal, 2009, 59(6, pp.590-594, DOI:http://dx.doi.org/10.14429/dsj.59.1563

  12. Diode-array UV solar spectroradiometer implementing a digital micromirror device

    Science.gov (United States)

    Feldman, A.; Burnitt, T.; Porrovecchio, G.; Smid, M.; Egli, L.; Gröbner, J.; Nield, K. M.

    2014-12-01

    The solar ultraviolet spectrum captured by commercially available diode-array spectroradiometers is dominated by stray light from longer wavelengths with higher intensity. The implementation of a digital micromirror device in an array spectroradiometer has the potential to enable the precise selection of desired wavelengths as well as the ability to reduce spectral intensity of some wavelengths via selective mirror modulation, both reducing long wavelength stray light. A prototype consisting of off-the-shelf components has been assembled to verify the validity of the base concept, and initial measurements have been performed to confirm the throughput and image qualities such as spectral resolution and astigmatism.

  13. Analysis of corneal morphologic and pathologic changes in early-stage congenital aniridic keratopathy

    Science.gov (United States)

    Du, Juan; Liu, Rong-Qiang; Ye, Lei; Li, Zhi-Hui; Zhao, Feng-Tu; Jiang, Nan; Ye, Lin-Hong; Shao, Yi

    2017-01-01

    AIM To determine typical corneal changes of congenital aniridic keratopathy (CAK) using corneal topography and confocal systems, and to identify characteristics that might assist in early diagnosis. METHODS Patients with CAK and healthy control subjects underwent detailed ophthalmic examinations including axial length, corneal thickness, tear film condition, corneal topography, and laser-scanning in vivo confocal microscopy (IVCM). RESULTS In early stage aniridic keratopathy, Schirmer I test (SIT), break-up time (BUT), mean keratometry (mean K) and simulated keratometry (sim K) were reduced relative to controls (Pcorneal astigmatism (sim A) and corneal thickness were increased (Pcorneal morphology in borderline situations can be useful to confirm the diagnosis of CAK. PMID:28393028

  14. Interocular symmetry analysis of bilateral eyes.

    Science.gov (United States)

    Li, Yi; Bao, Fang Jun

    2014-05-01

    The purpose of this study was to evaluate the interocular symmetry of several biometric parameters between both eyes. The symmetry between the right and left eye of 397 subjects in 14 biometric parameters, spherical equivalent of refractive error (SE), Jackson crossed cylinder power of refractive error astigmatism with axes at 90° and 180° (RJ0) and at 45° and 135° (RJ45), best-corrected visual acuity (BCVA), average corneal curvature (CC), Jackson crossed cylinder power of corneal astigmatism (CJ0 and CJ45), corneal asphericity coefficient (Q), intraocular pressure (IOP), central corneal thickness (CCT), axial length (AL), anterior chamber depth (ACD), lens thickness (LT) and vitreous chamber depth (VCD), was assessed by comparative data analysis. Aside from RJ0 (p = 0.00), RJ45 (p = 0.02) and Q (p = 0.00), the overall interocular differences of other biometric parameters between fellow eyes were not significant (p > 0.05). The interocular correlation and Bland-Altman plots showed a good agreement between fellow eyes in 14 biometric parameters. Correlations between interocular differences in SE and that in RJ0 (p = 0.03), CC (p = 0.00), AL (p = 0.00) and VCD (p = 0.00) were statistically significant. There were similar strong linear relationships between refractive error astigmatism vectors and corneal astigmatism vectors in bilateral eyes. There were negative correlations of RJ45 and CJ45 between bilateral eyes. A potentially clinically important interocular symmetry in SE, BCVA, CC, CJ0, CJ45, IOP, CCT, AL, ACD, LT and VCD is found in this research, while the differences of RJ0, RJ45 and Q between left and right eyes seem a bit large. The negative interocular relationships of RJ45 and CJ45 demonstrate moderate mirror symmetry exists among fellow eyes. High interocular symmetry in bilateral eyes may be helpful in intraocular lens power calculation, intraocular pressure evaluation, post-operative visual acuity and refraction

  15. Wavefront aberration statistics in normal eye populations: are they well described by the Kolmogorov model?

    Science.gov (United States)

    Pailos, Eliseo; Bará, Salvador

    2014-06-01

    This Letter studies the statistics of wavefront aberrations in a sample of eyes with normal vision. Methods relying on the statistics of the measured wavefront slopes are used, not including the aberration estimation stage. Power-law aberration models, an extension of the Kolmogorov one, are rejected by χ2-tests performed on fits to the slope structure function data. This is due to the large weight of defocus and astigmatism variations in normal eyes. Models of only second-order changes are not ruled out. The results are compared with previous works in the area.

  16. New Gapless COS G140L Mode Proposed for Background-limited Far-UV Observations

    Science.gov (United States)

    Redwine, Keith; McCandliss, Stephan R.; Zheng, Wei; Fleming, Brian; France, Kevin; Osterman, Steven; Howk, J. Christopher; Anderson, Scott F.; Gäensicke, Boris T.

    2016-10-01

    Here we describe the observation and calibration procedure for a new G140L observing mode for the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST). This mode, CENWAV = 800, is designed to move the far-UV band fully onto the Segment A detector, allowing for more efficient observation and analysis by simplifying calibration management between the two channels, and reducing the astigmatism in this wavelength region. We also describe some of the areas of scientific interest for which this new mode will be especially suited.

  17. Synthesis of Planar Reflective Gratings for Silicon Interconnects

    Directory of Open Access Journals (Sweden)

    Serge Bidnyk

    2008-05-01

    Full Text Available The design and simulations of planar reflective gratings for building optical interconnects in silicon-on-insulator (SOI were studied for a range of silicon core thicknesses of 0.1 to 10 μm. The verticality of the grating facets has been shown to be the main contributing factor to the cumulative crosstalk in thick silicon cores. The dispersion property of the slab was found to limit the minimal thickness of the core for polarization-insensitive gratings. The effects of polarization-dependent confinement on optical crosstalk were studied. The findings were used to design and simulate a polarization-insensitive 18-channel coarse wavelength division demultiplexer (CWDM with a free spectral range of over 600 nm. The CWDM demultiplexer uses a 1.7 μm silicon core and combines a shallow-etch tapered rib structure and multimode silicon channels to produce box-like passbands for integrated receiver applications. The diffraction grating was constructed using double astigmatic point design with phase-corrected grating facets to reduce astigmatism. Optical properties of the planar gratings have been simulated using quasivectorial diffraction grating theory. The simulation results confirm that there is high diffraction efficiency and low optical crosstalk over the entire range of operation. Applications of planar silicon gratings to the synthesis of silicon interconnects are discussed.

  18. Paraxial Ocular Measurements and Entries in Spectral and Modal Matrices: Analogy and Application

    Directory of Open Access Journals (Sweden)

    Herven Abelman

    2014-01-01

    Full Text Available Lensometers and keratometers yield powers along perpendicular meridians even if the principal meridians of the lens and the cornea are oblique. From each such instrument, multiple raw data represented on optical crosses require conversion to determine elementary statistics. Calculations for research decisions need to be authentic. Principles common to meridians generalize formulaic methods for oblique meridians. Like a lens or a cornea, matrix latent quantities are represented on a matrix cross. Our problem is to determine the matrix whose cross represents quantities on the optical cross. All measurements on an optical cross that include corneal and lens powers and oblique meridians can be considered. Once determined, a portfolio of matrix calculations applies and is justified for ophthalmic calculation. Matrices can be unique and, like a cornea before it is measured, contain latent observations. Asymmetric power component matrices quantify a deviation of a corneal surface from smoothness and toricity. Entries may identify those measurements causing irregular astigmatism that may stem from surgical or other external intervention. Irregular astigmatism is detected primarily from significant measurements in the paraxial range. Measurements are assimilated with matrix factors in a holistic way in order to support choices with calculations and statistics.

  19. Paraxial ocular measurements and entries in spectral and modal matrices: analogy and application.

    Science.gov (United States)

    Abelman, Herven; Abelman, Shirley

    2014-01-01

    Lensometers and keratometers yield powers along perpendicular meridians even if the principal meridians of the lens and the cornea are oblique. From each such instrument, multiple raw data represented on optical crosses require conversion to determine elementary statistics. Calculations for research decisions need to be authentic. Principles common to meridians generalize formulaic methods for oblique meridians. Like a lens or a cornea, matrix latent quantities are represented on a matrix cross. Our problem is to determine the matrix whose cross represents quantities on the optical cross. All measurements on an optical cross that include corneal and lens powers and oblique meridians can be considered. Once determined, a portfolio of matrix calculations applies and is justified for ophthalmic calculation. Matrices can be unique and, like a cornea before it is measured, contain latent observations. Asymmetric power component matrices quantify a deviation of a corneal surface from smoothness and toricity. Entries may identify those measurements causing irregular astigmatism that may stem from surgical or other external intervention. Irregular astigmatism is detected primarily from significant measurements in the paraxial range. Measurements are assimilated with matrix factors in a holistic way in order to support choices with calculations and statistics.

  20. Axial Length and Corneal Curvature in Anisometropic Amblyopia in Nepalese Children

    Directory of Open Access Journals (Sweden)

    Safal Khanal, B Optom

    2014-05-01

    Full Text Available Background: Purpose/Aim: To assess ocular parameters in Nepalese children with severe anisometropic amblyopia. Methods: This was a hospital-based cross-sectional analytical study conducted in a tertiary eye center in Nepal. Twentyone children aged 7-12 years with severe anisometropic amblyopia (>3D of anisometropia were included in the study. Relevant demographic and clinical data were obtained. Axial length, corneal curvature, and anterior chamber depth were measured in both the amblyopic and fellow eye, along with detailed anterior and posterior segment evaluation. Results: In anisomyopia, amblyopic eyes had longer axial length than the fellow eyes (p<.05, while in the cases with anisohyperopia, amblyopic eyes had shorter axial lengths than the fellow eyes (p<.05. The difference in corneal astigmatism between the amblyopic and fellow eye in children with anisoastigmatism was clinically and statistically significant (p<.05. However, there was no significant difference between the axial lengths in the amblyopic and the fellow eyes (p=.84. Conclusion: Difference in axial length was responsible for the difference in spherical refractive error in children with anisometropic amblyopia with no significant difference in corneal astigmatism, whereas corneal curvature was the significant factor responsible for amblyopia resulting from anisoastigmatism.

  1. Corneal refractive surgery: Is intracorneal the way to go and what are the needs for technology?

    Science.gov (United States)

    Hjortdal, Jesper; Ivarsen, Anders

    2014-02-01

    Corneal refractive surgery aims to reduce or eliminate refractive errors of the eye by changing the refractive power of the cornea. For the last 20 years controlled excimer laser ablation of corneal tissue, either directly from the corneal stromal surface or from the corneal interior after creation of a superficial corneal flap has become widely used to correct myopia, hyperopia, and astigmatism. Recently, an intrastromal refractive procedure whereby a tissue lenticule is cut free in the corneal stroma by a femtosecond laser and removed through a small peripheral incision has been introduced. This procedure avoids creation of a corneal flap and the potential associated risks while avoiding the slow visual recovery of surface ablation procedures. Precise intrastromal femtosecond laser cutting of the fine lenticule requires very controlled laser energy delivery in order to avoid lenticule irregularities, which would compromise the refractive result and visual acuity. This newly introduced all-femtosecond based flap-free intracorneal refractive procedure has been documented to be a predictable, efficient, and safe procedure for correction of myopia and astigmatism. Technological developments related to further improved cutting quality, hyperopic and individualized treatments are desirable.

  2. Manual cataract extraction via a subconjunctival limbus oblique incision for mature cataracts

    Directory of Open Access Journals (Sweden)

    J Yang

    2014-01-01

    Full Text Available Aims: To report the technique and outcomes of sutureless manual cataract extraction via a subconjunctival limbus oblique incision for mature cataracts. Materials and Methods: This retrospective study comprised of 112 eyes of 83 patients with mature cataract who all had manual cataract extraction via a subconjunctival limbus oblique incision. A transconjunctival tunnel is fashioned with a 3.0 mm keratome, 0.5 mm behind the limbal vascular arcades. A limbal tunnel, with a transverse extent of 9 mm in the cornea and 7.0 mm in the limbus, is created beneath the conjunctival/Tenon′s tissue using an angled bevel-up crescent blade. Outcome measures included visual acuity, intraoperative complications, surgically induced astigmatism, endothelial cell loss rate and surgery time. Results: Self-sealing wound was achieved in 112 eyes (98.2%. The nucleus was delivered in whole in 108 eyes (96.4%. Intraoperative complications included hyphema in 3 eyes (2.7%, iridodialysis in 2 eyes 1.8%, posterior capsular rupture and zonular dialysis in 2 eyes (1.8%. At the 3-month follow-up, 91% patients achieved a best-corrected visual acuity of 20/20 or better, the mean of surgically induced astigmatism was -0.62 ± 0.41 Diopters and endothelial cell loss was 4.2%. Average surgical time was 3.75 min per case. Conclusion: This subconjunctival limbus oblique incision has the potential to serve as safe and effective technique for mature cataracts.

  3. Analysis of nodal aberration properties in off-axis freeform system design.

    Science.gov (United States)

    Shi, Haodong; Jiang, Huilin; Zhang, Xin; Wang, Chao; Liu, Tao

    2016-08-20

    Freeform surfaces have the advantage of balancing off-axis aberration. In this paper, based on the framework of nodal aberration theory (NAT) applied to the coaxial system, the third-order astigmatism and coma wave aberration expressions of an off-axis system with Zernike polynomial surfaces are derived. The relationship between the off-axis and surface shape acting on the nodal distributions is revealed. The nodal aberration properties of the off-axis freeform system are analyzed and validated by using full-field displays (FFDs). It has been demonstrated that adding Zernike terms, up to nine, to the off-axis system modifies the nodal locations, but the field dependence of the third-order aberration does not change. On this basis, an off-axis two-mirror freeform system with 500 mm effective focal length (EFL) and 300 mm entrance pupil diameter (EPD) working in long-wave infrared is designed. The field constant aberrations induced by surface tilting are corrected by selecting specific Zernike terms. The design results show that the nodes of third-order astigmatism and coma move back into the field of view (FOV). The modulation transfer function (MTF) curves are above 0.4 at 20 line pairs per millimeter (lp/mm) which meets the infrared reconnaissance requirement. This work provides essential insight and guidance for aberration correction in off-axis freeform system design.

  4. Decision support system for determining the contact lens for refractive errors patients with classification ID3

    Science.gov (United States)

    Situmorang, B. H.; Setiawan, M. P.; Tosida, E. T.

    2017-01-01

    Refractive errors are abnormalities of the refraction of light so that the shadows do not focus precisely on the retina resulting in blurred vision [1]. Refractive errors causing the patient should wear glasses or contact lenses in order eyesight returned to normal. The use of glasses or contact lenses in a person will be different from others, it is influenced by patient age, the amount of tear production, vision prescription, and astigmatic. Because the eye is one organ of the human body is very important to see, then the accuracy in determining glasses or contact lenses which will be used is required. This research aims to develop a decision support system that can produce output on the right contact lenses for refractive errors patients with a value of 100% accuracy. Iterative Dichotomize Three (ID3) classification methods will generate gain and entropy values of attributes that include code sample data, age of the patient, astigmatic, the ratio of tear production, vision prescription, and classes that will affect the outcome of the decision tree. The eye specialist test result for the training data obtained the accuracy rate of 96.7% and an error rate of 3.3%, the result test using confusion matrix obtained the accuracy rate of 96.1% and an error rate of 3.1%; for the data testing obtained accuracy rate of 100% and an error rate of 0.

  5. Scleral Fixation of Posteriorly Dislocated Intraocular Lenses by 23-Gauge Vitrectomy without Anterior Segment Approach

    Directory of Open Access Journals (Sweden)

    Jeroni Nadal

    2015-01-01

    Full Text Available Background. To evaluate visual outcomes, corneal changes, intraocular lens (IOL stability, and complications after repositioning posteriorly dislocated IOLs and sulcus fixation with polyester sutures. Design. Prospective consecutive case series. Setting. Institut Universitari Barraquer. Participants. 25 eyes of 25 patients with posteriorly dislocated IOL. Methods. The patients underwent 23-gauge vitrectomy via the sulcus to rescue dislocated IOLs and fix them to the scleral wall with a previously looped nonabsorbable polyester suture. Main Outcome Measures. Best corrected visual acuity (BCVA LogMAR, corneal astigmatism, endothelial cell count, IOL stability, and postoperative complications. Results. Mean follow-up time was 18.8 ± 10.9 months. Mean surgery time was 33 ± 2 minutes. Mean BCVA improved from 0.30 ± 0.48 before surgery to 0.18 ± 0.60 (p=0.015 at 1 month, which persisted to 12 months (0.18 ± 0.60. Neither corneal astigmatism nor endothelial cell count showed alterations 1 year after surgery. Complications included IOL subluxation in 1 eye (4%, vitreous hemorrhage in 2 eyes (8%, transient hypotony in 2 eyes (8%, and cystic macular edema in 1 eye (4%. No patients presented retinal detachment. Conclusion. This surgical technique proved successful in the management of dislocated IOL. Functional results were good and the complications were easily resolved.

  6. Different aberrations raise contrast thresholds for single-letter identification in line with their effect on cross-correlation-based confusability.

    Science.gov (United States)

    Young, Laura K; Love, Gordon D; Smithson, Hannah E

    2013-06-20

    We previously showed that different types of aberration defocus, coma, and secondary astigmatism affect reading performance via different mechanisms. In this paper, we show the contrary result that, for identification of isolated letters, the effects of rendering different types of aberration can be described by a single cross-correlation-based metric. Aberrations reduce the effective resolution of an optical system, quantified by the high-frequency fall-off of the modulation transfer function. They additionally cause spatial-frequency-dependent phase and contrast changes, which have a size-dependent effect on letter forms. We used contrast threshold as our performance measure, instead of distance acuity, to separate the effects of form alterations from those of resolution limits. This measure is additionally appropriate in comparing single-letter-based performance to reading at a fixed distance. The relationship between a cross-correlation-based measure of letter confusability and performance was the same for all three types of aberration. For reading, we had found a different relationship for coma than for defocus and secondary astigmatism. We conclude that even when two tasks--letter identification and reading--use the same component stimulus set, the combination of multiple letters in a reading task produces functional differences between the effects of these aberrations that are not present for isolated letters.

  7. DEVICE FOR MEASURING OF THERMAL LENS PARAMETERS IN LASER ACTIVE ELEMENTS WITH A PROBE BEAM METHOD

    Directory of Open Access Journals (Sweden)

    A. N. Zakharova

    2015-01-01

    Full Text Available We have developed a device for measuring of parameters of thermal lens (TL in laser active elements under longitudinal diode pumping. The measurements are based on the probe beam method. This device allows one to determine sign and optical power of the lens in the principal meridional planes, its sensitivity factor with respect to the absorbed pump power and astigmatism degree, fractional heat loading which make it possible to estimate integral impact of the photoelastic effect to the formation of TL in the laser element. The measurements are performed in a linearly polarized light at the wavelength of 532 nm. Pumping of the laser element is performed at 960 nm that makes it possible to study laser materials doped with Yb3+ and (Er3+, Yb3+ ions. The precision of measurements: for sensitivity factor of TL – 0,1 m-1/W, for astigmatism degree – 0,2 m-1/W, for fractional heat loading – 5 %, for the impact of the photoelastic effect – 0,5 × 10-6 K-1. This device is used for characterization of thermal lens in the laser active element from an yttrium vanadate crystal, Er3+,Yb3+:YVO .

  8. Normal modes and mode transformation of pure electron vortex beams

    Science.gov (United States)

    Thirunavukkarasu, G.; Mousley, M.; Babiker, M.; Yuan, J.

    2017-02-01

    Electron vortex beams constitute the first class of matter vortex beams which are currently routinely produced in the laboratory. Here, we briefly review the progress of this nascent field and put forward a natural quantum basis set which we show is suitable for the description of electron vortex beams. The normal modes are truncated Bessel beams (TBBs) defined in the aperture plane or the Fourier transform of the transverse structure of the TBBs (FT-TBBs) in the focal plane of a lens with the said aperture. As these modes are eigenfunctions of the axial orbital angular momentum operator, they can provide a complete description of the two-dimensional transverse distribution of the wave function of any electron vortex beam in such a system, in analogy with the prominent role Laguerre-Gaussian (LG) beams played in the description of optical vortex beams. The characteristics of the normal modes of TBBs and FT-TBBs are described, including the quantized orbital angular momentum (in terms of the winding number l) and the radial index p>0. We present the experimental realization of such beams using computer-generated holograms. The mode analysis can be carried out using astigmatic transformation optics, demonstrating close analogy with the astigmatic mode transformation between LG and Hermite-Gaussian beams. This article is part of the themed issue 'Optical orbital angular momentum'.

  9. Prospective evaluation of myopic keratomileusis.

    Science.gov (United States)

    Swinger, C A; Barker, B A

    1984-07-01

    The initial results of a prospective evaluation of myopic keratomileusis are reported. The procedure was attempted on 42 eyes, with an average follow-up of 10 months. The average reductions of myopia were 7.05 D and 11.59 D when measured by keratometry and refraction, respectively. Regular astigmatism increased by 0.50 D on keratometry, but there was no change in the refractive cylinder. The majority of patients had some irregular astigmatism on corneoscopy. The average percent correction, based on refraction, was 94.1 +/- 24%, and the correlation coefficient was 0.43. Visual rehabilitation was rapid. No patient followed for 1 year or more had a decrease in the best-corrected acuity, and 63% of this group had an average improvement of 1.5 lines with as much as five lines. The final refraction may take up to 6 months to stabilize. Complications consisted of epithelium and debris in the interface and focal necrosis of Bowman's membrane. The technique is difficult but may have application in the visual rehabilitation of the high myope.

  10. Misalignment-induced nodal aberration fields in two-mirror astronomical telescopes.

    Science.gov (United States)

    Schmid, Tobias; Thompson, Kevin P; Rolland, Jannick P

    2010-06-01

    We present the effects of misalignments on the field dependence of the third-order aberration fields of traditional, two-mirror astronomical telescopes in the context of nodal aberration theory, which we believe is the most general and extensible framework for describing and improving on-station performance. While many of the advantages of nodal aberration theory, compared to other, often power series expansion-based descriptions of misalignment effects on aberrations, become particularly important when analyzing telescopes with more than two mirrors, or in the presence of figure errors; this paper aims to provide and demonstrate the fundamental concepts needed to fully describe the state of correction of misaligned two-mirror telescopes. Importantly, it is shown that the assumption that perfect performance on axis ensures a fully aligned telescope is false, and we demonstrate that if Ritchey-Chrétien telescopes are aligned for zero coma on axis as the sole criterion, formidable misalignments will likely remain, leading to image quality degradation, particularly beyond midfield caused by astigmatism with binodal field dependence (i.e., astigmatism goes to zero at two points in the field).

  11. A Handheld Open-Field Infant Keratometer (An American Ophthalmological Society Thesis)

    Science.gov (United States)

    Miller, Joseph M.

    2010-01-01

    Purpose: To design and evaluate a new infant keratometer that incorporates an unobstructed view of the infant with both eyes (open-field design). Methods: The design of the open-field infant keratometer is presented, and details of its construction are given. The design incorporates a single-ring keratoscope for measurement of corneal astigmatism over a 4-mm region of the cornea and includes a rectangular grid target concentric within the ring to allow for the study of higher-order aberrations of the eye. In order to calibrate the lens and imaging system, a novel telecentric test object was constructed and used. The system was bench calibrated against steel ball bearings of known dimensions and evaluated for accuracy while being used in handheld mode in a group of 16 adult cooperative subjects. It was then evaluated for testability in a group of 10 infants and toddlers. Results: Results indicate that while the device achieved the goal of creating an open-field instrument containing a single-ring keratoscope with a concentric grid array for the study of higher-order aberrations, additional work is required to establish better control of the vertex distance. Conclusion: The handheld open-field infant keratometer demonstrates testability suitable for the study of infant corneal astigmatism. Use of collimated light sources in future iterations of the design must be incorporated in order to achieve the accuracy required for clinical investigation. PMID:21212850

  12. Toric人工晶状体临床应用的研究进展%Clinical applications of Toric intraocular lens

    Institute of Scientific and Technical Information of China (English)

    肖显文; 张红; 田芳

    2014-01-01

    Toric intraocular lens (IOL),known as IOL with composite surface,is a new refractive IOL to correct astigmatism by cylindrical lens combined with spherical IOL.Toric IOL has become a reasonable,effective and stable refractive method to correct preoperative astigmatism of cataract patients following the continuous development of materials and technical improvements since it was applied clinically first in 1994.The new multifocal Toric IOL provides good distance,intermediate and near functional vision and enables the complete spectacle independence for cataract patients.%散光型人工晶状体(Toric intraocular lens,Toric IOL)也称复合曲面IOL,是将矫正散光的圆柱镜与IOL的球镜相结合的一种新型屈光性IOL.自1994年第一枚Toric IOL用于临床以来,Toric IOL的材料和设计得到不断改进,现已成为矫正白内障患者术前角膜散光的一种合理、有效并且稳定的屈光矫正方式.多焦点Toric IOL的出现则为白内障患者提供良好的远中近视力,真正满足白内障患者的脱镜需求.

  13. Videokeratograph (VKS for monitoring corneal curvature during surgery

    Directory of Open Access Journals (Sweden)

    Carvalho Luis Alberto Vieira de

    2002-01-01

    Full Text Available Purpose: We have developed an instrument for computerized surgical videokeratography. A corneal central region of approximately 7.00 mm in diameter may be analyzed, providing the surgeon with information of the power and the astigmatism. Methods: The system is based on a fiber optic Placido disc projecting cone, which is attached to the objective lens of a Zeiss compatible surgical microscope. At the beam splitter we installed a monochromatic high resolution camera. A frame grabber is installed on a PC and images are digitized at a 480x640 resolution. Image processing is used for edge detection of rings. Results: Calibrating curves based on 4 spherical surfaces were generated and approximately 3600 points are calculated for each examination. Preliminary measurements on 10 healthy corneas were compared with those of an EyeSys System 2000 Corneal Topographer. Mean deviation was 0.05 for radius of curvature, 0.24 D for the power and 5.0 degrees for the cylinder. Conclusions: This surgical VKS, with some hardware and software improvements, may be used to reduce residual astigmatisms in conventional cataract and keratoplasty. It could also be used to gather preoperative data in corneal topography assisted LASIK.

  14. Microsurgical Treatment of Mooren‘s Ulcer

    Institute of Scientific and Technical Information of China (English)

    HanpingXie; JiaqiChen; 等

    2002-01-01

    Objective:To evaluate effect of lamellar keratoplasty(LKP) on Mooren's corneal ulcer.Methods:The effect ,postoperative astigmatism,postoperative vision,ulcer recurrence of postperation,and surgical complications of two groups of consecutive Mooren's ulcer inpatients treated respectively by non-microsurgery of LKP and microsurgery of LKP were analyzed.Results:There were significant differences of the effect,postoperative astigmatism,postoperative vision,ulcer recurrence of postoperation,and surgical complications be-tween the two groups.The effect and postoperative vision of the microsurgery-tyeated group were betterthan those of the non-microsurgery-treated group.The postoperative astigma-tism,ulcer recurrence of postoperation, and surgical complications of the micro-surgery-treated group were less than those of the nonmicrosurgery-treated group.Conclusion:Microsrugery of LKP of Mooren's corneal ulcer can greatly improve the ul-cer healing and postoperative vision, and reduce the surgical complication and the ulcer recurrence of postoperation.Eye Science 2000;16:56-60.

  15. Prevalence of amblyopia and refractive errors among primary school children

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    Zhale Rajavi

    2015-01-01

    Results: Amblyopia was present in 2.3% (95% CI: 1.8% to 2.9% of participants with no difference between the genders. Amblyopic subjects were significantly younger than non-amblyopic children (P=0.004. Overall, 15.9% of hyperopic and 5.9% of myopic cases had amblyopia. The prevalence of hyperopia ≥+2.00D, myopia ≤-0.50D, astigmatism ≥0.75D, and anisometropia (≥1.00D was 3.5%, 4.9%, 22.6%, and 3.9%, respectively. With increasing age, the prevalence of myopia increased (P<0.001, that of hyperopia decreased (P=0.007, but astigmatism showed no change. Strabismus was found in 2.3% of cases. Strabismus (OR=17.9 and refractive errors, especially anisometropia (OR=12.87 and hyperopia (OR=11.87, were important amblyogenic risk factors. Conclusion: The high prevalence of amblyopia in our subjects in comparison to developed countries reveals the necessity of timely and sensitive screening methods. Due to the high prevalence of amblyopia among children with refractive errors, particularly high hyperopia and anisometropia, provision of glasses should be specifically attended by parents and supported by the Ministry of Health and insurance organizations.

  16. Boston ocular surface prosthesis: An Indian experience

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    Varsha Madanlal Rathi

    2011-01-01

    Full Text Available Context: Boston ocular surface prosthesis (BOSP is a scleral contact lens used in the management of patients who are rigid gas permeable (RGP failures as with corneal ectasias such as keratoconus and in those patients who have ocular surface disease such as Stevens-Johnson syndrome (SJS. Aim: To report utilization of BOSP in a tertiary eye care center in India. Materials and Methods: We retrospectively reviewed charts of 32 patients who received BOSP from July 2008 to May 2009. Indications for fitting these lenses, improvement in visual acuity (VA before and after lens fitting and relief of symptoms of pain and photophobia were noted. Paired t-test was used for statistical analysis using SPSS version 16.0 for Windows. Results: Thirty-two patients (43 eyes received these lenses. These consisted of 23 eyes of 17 patients who failed RGP trials for irregular astigmatism and corneal ectasia such as keratoconus and post radial keratotomy and scar and 20 eyes of 15 patients with SJS. Mean age of RGP failures was 27.94 years. Pre- and post-BOSP wear mean LogMAR VA was 1.13 and 0.29, respectively, in RGP failures. The P value was statistically significant (P 2 lines in 7/20 eyes (35% with SJS, with improvement in symptoms. Conclusion: BOSP improves VA in patients who have irregular astigmatism as in ectasias and RGP failures and improves vision and symptoms in patients with SJS.

  17. [Impact of the method choice and the extent of correction on the development of visual evoked potentials in children and adolescents with refractive anomalies].

    Science.gov (United States)

    Lobanova, I V; Leshchenko, I A; Markova, E Iu; Khatsenko, I E

    2013-01-01

    The article discusses a possible impact of different refraction correction methods, providing full or partial correction, on visual acuity and the development of visual evoked potentials in children and adolescents with myopia and myopic astigmatism. The accuracy of identification of visual evoked potentials depends, as shown in the article, on the extent of the correction chosen and the method used. In childhood the visual system is very susceptible to visual afferent deficit. The permanent deficit of visual information impedes further maturation of the visual analyzer, i.e. the development of central vision, binocular vision, and stereopsis. In high myopia it is important to decide not only on the extent of the correction but also on the method to use. In patients wearing soft contact lenses the visual evoked potentials have more regular shape, amplitude, and latency. The introduction of silicone hydrogel and daily disposal contact lenses, spherical and toric (for astigmatism correction), provided an opportunity to solve hygienic problems associated with contact lens use in children and adolescents and to decrease the risk of hypoxia complications.

  18. An omnidirectional 3D sensor with line laser scanning

    Science.gov (United States)

    Xu, Jing; Gao, Bingtuan; Liu, Chuande; Wang, Peng; Gao, Shuanglei

    2016-09-01

    An active omnidirectional vision owns the advantages of the wide field of view (FOV) imaging, resulting in an entire 3D environment scene, which is promising in the field of robot navigation. However, the existing omnidirectional vision sensors based on line laser can measure points only located on the optical plane of the line laser beam, resulting in the low-resolution reconstruction. Whereas, to improve resolution, some other omnidirectional vision sensors with the capability of projecting 2D encode pattern from projector and curved mirror. However, the astigmatism property of curve mirror causes the low-accuracy reconstruction. To solve the above problems, a rotating polygon scanning mirror is used to scan the object in the vertical direction so that an entire profile of the observed scene can be obtained at high accuracy, without of astigmatism phenomenon. Then, the proposed method is calibrated by a conventional 2D checkerboard plate. The experimental results show that the measurement error of the 3D omnidirectional sensor is approximately 1 mm. Moreover, the reconstruction of objects with different shapes based on the developed sensor is also verified.

  19. Advances in very lightweight composite mirror technology

    Science.gov (United States)

    Chen, Peter C.; Bowers, Charles W.; Content, David A.; Marzouk, Marzouk; Romeo, Robert C.

    2000-09-01

    We report progress in the development of very lightweight (roll off and several waves (rms optical) of astigmatism, coma, and third-order spherical aberration. These are indications of thermal contraction in an inhomogeneous medium. This inhomogeneity is due to a systematic radial variation in density and fiber/resin ratio induced in composite plies when draped around a small and highly curved mandrel. The figure accuracy is expected to improve with larger size optics and in mirrors with longer radii of curvature. Nevertheless, the present accuracy figure is sufficient for using postfiguring techniques such as ion milling to achieve diffraction-limited performances at optical and UV wavelengths. We demonstrate active figure control using a simple apparatus of low-mass, low-force actuators to correct astigmatism. The optimized replication technique is applied to the fabrication of a 0.6-m-diam mirror with an areal density of 3.2 kg/m2. Our result demonstrates that the very lightweight, large-aperture construction used in radio telescopes can now be applied to optical telescopes.

  20. Repeatability and Comparison of Keratometry Values Measured with Potec PRK-6000 Autorefractometer, IOLMaster, and Pentacam

    Directory of Open Access Journals (Sweden)

    Adem Türk

    2014-05-01

    Full Text Available Objectives: To research the repeatability and intercompatibility of keratometry values measured with Potec PRK-6000 autorefractometer, IOL Master, and Pentacam. Materials and Methods: In this prospective study, consecutive measurements were performed in two different sessions with the mentioned three devices on 110 eyes of 55 subjects who had no additional ocular pathology except for refraction error. The consistency of flat and steep keratometry, average keratometry, and corneal astigmatism values obtained in both sessions was compared by using intraclass correlation coefficient (ICC. The measurement differences between the devices were statistically compared as well. Results: The mean age of the study subjects was 23.05±3.01 (18-30 years. ICC values of average keratometry measurements obtained in the sessions were 0.996 for Potec PRK-6000 autorefractometer, 0.997 for IOL Master, and 0.999 for Pentacam. There was high compatibility between the three devices in terms of average keratometry values in Bland-Altman analysis. However, there were statistically significant differences between the devices in terms of parameters other than corneal astigmatism. Conclusion: The repeatability of the three devices was found considerably high in keratometry measurements. However, it is not appropriate for these devices to be substituted for each other in keratometry measurements. (Turk J Ophthalmol 2014; 44: 179-83

  1. Determination of injection molding process windows for optical lenses using response surface methodology.

    Science.gov (United States)

    Tsai, Kuo-Ming; Wang, He-Yi

    2014-08-20

    This study focuses on injection molding process window determination for obtaining optimal imaging optical properties, astigmatism, coma, and spherical aberration using plastic lenses. The Taguchi experimental method was first used to identify the optimized combination of parameters and significant factors affecting the imaging optical properties of the lens. Full factorial experiments were then implemented based on the significant factors to build the response surface models. The injection molding process windows for lenses with optimized optical properties were determined based on the surface models, and confirmation experiments were performed to verify their validity. The results indicated that the significant factors affecting the optical properties of lenses are mold temperature, melt temperature, and cooling time. According to experimental data for the significant factors, the oblique ovals for different optical properties on the injection molding process windows based on melt temperature and cooling time can be obtained using the curve fitting approach. The confirmation experiments revealed that the average errors for astigmatism, coma, and spherical aberration are 3.44%, 5.62%, and 5.69%, respectively. The results indicated that the process windows proposed are highly reliable.

  2. Incidence and Tomographic Evaluation of Unilateral Keratoconus

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    Faik Oruçoğlu

    2013-04-01

    Full Text Available Pur po se: To evaluate the parameters of unilateral keratoconus on the basis of Scheimpflug tomography and to compare them with normal controls. Ma te ri al and Met hod: From all patients diagnosed with keratoconus between January 2011 and January 2012, those who had topographic signs of keratoconus in one eye were retrospectively evaluated. Unilateral keratoconus eyes were compared with the normal fellow eyes and control eyes. Anterior and posterior keratometry, topographic astigmatism, axis, asphericity and central corneal thickness, corneal and anterior chamber volume and depth in all cases were evaluated with Pentacam. ANOVA test was used for statistical analysis. Re sults: 22 (14.9% of 147 patients with keratoconus had no topographic evidence of keratoconus in the fellow eye. Statistically significant differences were noted between keratoconic eyes and fellow eyes, and between keratoconic eyes and control eyes in anterior keratometric values, posterior steep and mean keratometry, anterior and posterior astigmatism, anterior and posterior asphericity and central corneal thickness (p=0.05. Posterior flat keratometry and anterior chamber depth were different between keratoconus and control eyes (p=0.004, p=0.006 but similar between keratoconus and fellow normal eyes (p=0.069, p=1.0. Dis cus si on: The Scheimpflug parameters were similar between fellow eyes and control eyes. (Turk J Ophthalmol 2013; 43: 83-6

  3. Contribution of the cornea and internal surfaces to the change of ocular aberrations with age

    Science.gov (United States)

    Artal, Pablo; Berrio, Esther; Guirao, Antonio; Piers, Patricia

    2002-01-01

    We studied the age dependence of the relative contributions of the aberrations of the cornea and the internal ocular surfaces to the total aberrations of the eye. We measured the wave-front aberration of the eye with a Hartmann-Shack sensor and the aberrations of the anterior corneal surface from the elevation data provided by a corneal topography system. The aberrations of the internal surfaces were obtained by direct subtraction of the ocular and corneal wave-front data. Measurements were obtained for normal healthy subjects with ages ranging from 20 to 70 years. The magnitude of the RMS wave-front aberration (excluding defocus and astigmatism) of the eye increases more than threefold within the age range considered. However, the aberrations of the anterior corneal surface increase only slightly with age. In most of the younger subjects, total ocular aberrations are lower than corneal aberrations, while in the older subjects the reverse condition occurs. Astigmatism, coma, and spherical aberration of the cornea are larger than in the complete eye in younger subjects, whereas the contrary is true for the older subjects. The internal ocular surfaces compensate, at least in part, for the aberrations associated with the cornea in most younger subjects, but this compensation is not present in the older subjects. These results suggest that the degradation of the ocular optics with age can be explained largely by the loss of the balance between the aberrations of the corneal and the internal surfaces.

  4. Femtosecond laser-assisted deep anterior lamellar keratoplasty for keratoconus and keratectasia

    Institute of Scientific and Technical Information of China (English)

    Yan; Lu; Yu-Hua; Shi; Li-Ping; Yang; Yi-Rui; Ge; Xiang-Fei; Chen; Yan; Wu; Zhen-Ping; Huang

    2014-01-01

    ·AIM: To describe the initial outcomes and safety of femtosecond laser-assisted deep anterior lamellar keratoplasty(DALK) for keratoconus and post-LASIK keratectasia.·METHODS: In this non-comparative case series, 10 eyes of 9 patients underwent DALK procedures with a femtosecond laser(Carl Zeiss Meditec AG, Jena,Germany). Of the 9 patients, 7 had keratoconus and 2had post-LASIK keratectasia. A 500 kHz VisuMax femtosecond laser was used to perform corneal cuts on both donor and recipient corneas. The outcome measures were the uncorrected visual acuity(UCVA),best-corrected visual acuity(BCVA), corneal thickness,astigmatism, endothelial density count(EDC), and corneal power.·RESULTS: All eyes were successfully treated. Early postoperative evaluation showed a clear graft in all cases. Intraoperative complications included one case of a small Descemet’s membrane perforation.Postoperatively, there was one case of stromal rejection,one of loosened sutures, and one of wound dehiscence.A normal corneal pattern topography and transparency were restored, UCVA and BCVA improved significantly,and astigmatism improved slightly. There was no statistically significant decrease in EDC.· CONCLUSION: Our early results indicate that femtosecond laser-assisted deep anterior lamellar keratoplasty could improve UCVA and BCVA in patients with anterior corneal pathology. This approach shows promise as a safe and effective surgical choice in the treatment of keratoconus and post-LASIK keratectasia.

  5. Incisões relaxantes limbares durante a cirurgia de catarata: resultados após seguimento de um ano Limbal relaxing incisions during cataract surgery: one-year follow-up

    Directory of Open Access Journals (Sweden)

    João Carlos Arraes

    2006-06-01

    ções pós-operatórias significativas.PURPOSE: To evaluate astigmatism variation between preoperative, 1st and 12th postoperative month of patients who underwent cataract surgery with limbal relaxing incisions (LRI aiming to reduce the preoperative astigmatism. METHODS: Sixteen patients who underwent cataract surgery by the phacoemulsification technique with a 5.5 mm escleral incision, at the Altino Ventura Foudation, between April and July of 2002. The limbal relaxing incisions were performed according to Gills' modified nomogram (1D - 1 LRI of 6 mm; 1-2D - 2 LRI of 6 mm; 2-3D - 2 LRI of 8 mm. They were done in the most curved meridians, determined by preoperative corneal topography. RESULTS: Significant reduction in preoperative astigmatism was observed in the 1st postoperative month in 2 limbal relaxing incisions of the 6 mm group (57% topographic astigmatism and 87% refractional and in 2 limbal relaxing incisions of the 8 mm group (50% topographic astigmatism and 65% refractional, maintaining the reduction with no significant alteration until the 12th postoperative month. The 1 limbal relaxing incision of the 6 mm group did not yield significant astigmatism reduction, but there was no significant alteration until de 12th postoperative month. There were also no complications such as postoperative discomfort, glare, aniseiconia, diplopia, incision infection and corneal thinning or ectasia. CONCLUSION: Two limbal relaxing incisions of 8 and 6 mm aiming to correct preoperative astigmatism of 2 to 3D and 1 to 2D, respectively, were safe and effective with a stable effect in the first postoperative follow-up year. The 1 limbal relaxing incision of 6 mm aiming to reduce 1 diopter of preoperative astigmatism was not effective, but it did not induce any significant postoperative complications.

  6. Outcomes of corneal crosslinking for central and paracentral keratoconus

    Science.gov (United States)

    Tian, Mingxia; Ma, Ping; Zhou, Weiyan; Feng, Jie; Mu, Guoying

    2017-01-01

    Abstract Background: The aim of the study was to compare the therapy of corneal collagen crosslinking (CXL) for central and paracentral keratoconus. Methods: 64 eyes of 43 central keratoconus patients whose highest power of the cornea located in the central 3 mm zone and 24 eyes of 16 paracentral keratoconus patients whose highest power located out of the central 3 mm zone received standard corneal CXL were included. Maximum keratometry (Kmax) and astigmatism according to topography, uncorrected distant visual acuity (UDVA), corrected distant visual acuity (CDVA) were studied preoperatively and 2 years postoperatively. Results: Central group: Preoperative UDVA and CDVA were 0.9 ± 0.4 and 0.5 ± 0.4 logMAR, respectively. At 2 years, UDVA and CDVA significantly improved to 0.8 ± 0.4 and 0.4 ± 0.3 logMAR(P  0.05). Preoperative Kmax and astigmatism were 50.3 ± 5.3 and 2.4 ± 1.7 D, respectively. At 2 years, Kmax significantly decreased to 48.8 ± 4.6 (P  0.05). Conclusion: This study indicated that CXL was more effective for central keratoconus than paracentral keratoconus. PMID:28272223

  7. Myopia in schoolchildren in a rural community in the State of Mexico, Mexico

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    Garcia-Lievanos O

    2016-06-01

    Full Text Available Omar Garcia-Lievanos, Leticia Sanchez-Gonzalez, Nadia Espinosa-Cruz, Luis A Hernandez-Flores, Leonel Salmeron-Leal, Hector D Torres-Rodriguez Instituto Politecnico Nacional (IPN, Ex-Hacienda del Mayorazgo, Mexico City, Mexico Purpose: This study sought to determine the prevalence of myopia in schoolchildren of a rural population in Mexico. Methods: A cross-sectional study was conducted in 317 children between 6 and 12 years old. A complete refractive examination was performed, including static retinoscopy without cycloplegic agents. All procedures were conducted according to the Declaration of Helsinki. Results: In total, 9.7% (95% CI: 13.07–6.52 of the examined children were myopic (spherical equivalent ≤ −0.50 D, 4.4% (95% CI: 6.66–2.14 presented astigmatism (cylinder ≤ −1.50 D, and 5.4% (95% CI: 7.89–2.91 presented hyperopia (spherical equivalent ≥ +0.50 D. Conclusion: Additional research is required to assess the prevalence of refractive errors in rural areas in Mexico, to analyze the associated risk factors, and to implement appropriate eye care plans for this population. Keywords: myopia, refractive errors, hyperopia, astigmatism

  8. Deastigmatism, circularization, and focusing of a laser diode beam using a single biconvex microlens

    Science.gov (United States)

    Hasan, Md. Nazmul; Haque, Muttahid-Ull; Lee, Yung Chun

    2016-09-01

    A single biconvex microlens is proposed to correct the astigmatism and ellipticity of a laser diode (LD) beam and focus it to a smallest circular spot. The microlens has three different profiles in which one cylindrical input surface is to collimate the beam in the fast-axis (y-axis) direction. Output surface, on the other hand, holds two different parabolic profiles in fast- and slow-axis (x-axis) directions to correct the astigmatism and focus the beam into a smallest circular spot. A simulation software is used to design and optimize those lens profiles. Theoretically, the smallest focused spot size is around 4.24 μm in diameter. The three profiles are then transferred to photo-masks to fabricate the microlens on polycarbonate material using an excimer laser dragging method with alignment accuracy of 1 μm. The machined microlens is assembled with the LD using double-sided optically clear adhesive tape. The experimental focused spot is found to be 16.75 μm in diameter. Circularity of the focused spot is demonstrated by a single-shot exposure test on thin photoresist layer that shows a circular-dot diameter of 7.32 μm. The proposed technique has great potential in applications such as beam pen lithography, fiber coupling, and optical read-write head.

  9. Generalized magnification in visual optics. Part 2: Magnification as affine transformation

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2010-12-01

    Full Text Available In astigmatic systems magnification may be different in different directions.  It may also be accompanied by rotation or reflection.  These changes from object to image are examples of generalized magnification.  They are represented by  2 2×  matrices.  Because they are linear transformations they can be called linear magnifications.  Linear magnifications account for a change in appearance without regard to position.  Mathematical structure suggests a natural further generalization to a magnification that is complete in the sense that it accountsfor change in appearance and position.  It is represented by a  3 3×  matrix with a dummy third row. The transformation is called affine in linear algebra which suggests that these generalized magnifica-tions be called affine magnifications.  The purpose of the paper is to define affine magnification in the context of astigmatic optics.  Several examples are presented and illustrated graphically. (S Afr Optom 2010 69(4 166-172

  10. Ocular biometric changes after trabeculectomy

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    Azam Alvani

    2016-01-01

    Full Text Available This review article aimed to evaluate ocular biometric changes after trabeculectomy. The PubMed database was searched using the keywords “axial length” (AL, “anterior chamber depth” (ACD, “corneal astigmatism,” “corneal topography” and “trabeculectomy.” The extracted studies were categorized based on the evaluated parameters and the biometry method (contact and non-contact. Comparable studies with respect to their sample size were combined for statistical analysis. Twenty-five studies including 690 individuals which met the inclusion criteria were selected. After trabeculectomy, a significant and persistent AL reduction, with a range of 0.1-0.19 and 0.1-0.9 mm measured with contact and non-contact methods, respectively, was observed. With respect to topographic changes, 0.38-1.4 diopters (D with-the-rule (WTR astigmatism was induced postoperatively. All studies revealed ACD reduction immediately after surgery, which gradually deepened and approximated its preoperative levels on day 14. ACD reduction was not significant after that period in the majority of cases. In conclusion, changes in ACD is of small amount and of short period, thus it can be ignored; however, reported changes in AL and keratometry are of sufficient magnitude and can affect the refractive prediction of combined cataract surgery and trabeculectomy.

  11. Aperture referral in dioptric systems with stigmatic elements

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2012-12-01

    Full Text Available A previous paper develops the general theory of aperture referral in linear optics and shows how several ostensibly distinct concepts, including the blur patch on the retina, the effective cornealpatch, the projective field and the field of view, are now unified as particular applications of the general theory.  The theory allows for astigmatism and heterocentricity.  Symplecticity and the generality of the approach, however, make it difficult to gain insight and mean that the material is not accessible to readers unfamiliar with matrices and linear algebra. The purpose of this paper is to examine whatis, perhaps, the most important special case, that in which astigmatism is ignored.  Symplecticity and, hence, the mathematics become greatly simplified. The mathematics reduces largely to elementary vector algebra and, in some places, simple scalar algebra and yet retains the mathematical form of the general approach.  As a result the paper allows insight into and provides a stepping stone to the general theory.  Under referral an aperture under-goes simple scalar magnification and transverse translation.  The paper pays particular attention to referral to transverse planes in the neighbourhood of a focal point where the magnification may be positive, zero or negative.  Circular apertures are treated as special cases of elliptical apertures and the meaning of referred apertures of negative radius is explained briefly. (S Afr Optom 2012 71(1 3-11

  12. Effects of Silicone Hydrogel Contact Lens Application on Corneal High-order Aberration and Visual Guality in Patients with Corneal Opacities

    Directory of Open Access Journals (Sweden)

    Sevda Aydın Kurna

    2012-03-01

    Full Text Available Pur po se: Evaluation of the corneal high-order aberrations and visual quality changes after application of silicone hydrogel contact lenses in patients with corneal opacities due to various etiologies. Ma te ri al and Met hod: Fifteen eyes of 13 patients with corneal opacities were included in the study. During the ophthalmologic examination before and after contact lens application, visual acuity was measured with Snellen acuity chart and contrast sensitivity - with Bailey-Lowie Charts in letters. Aberrations were measured with corneal aberrometer (NIDEK Magellan Mapper under a naturally dilated pupil. Spherical aberration, coma, trefoil, irregular astigmatism and total high-order root mean square (RMS values were recorded. Measurements were repeated with balafilcon A lenses (PureVision 2 HD, B&L on all patients. Re sults: Patient age varied between 23 and 50 years. Two eyes had subepithelial infiltrates due to adenoviral keratitis, 1 had nebulae due to previous infections or trauma, and 2 had Salzmann’s nodular degeneration. We observed a mean increase of 1 line in visual acuity and 5 letters in contrast sensitivity with contact lenses versus glasses in the patients. Mean RMS values of spherical aberration, irregular astigmatism and total high-order aberrations decreased significantly with contact lenses. Dis cus si on: Silicone hydrogel soft contact lenses may improve visual quality by decreasing the corneal aberrations in patients with corneal opacities. (Turk J Ophthalmol 2012; 42: 97-102

  13. Microscopy system of atomic force based on a digital optical reading unit and a buzzer-scanner; Sistema de microscopia de fuerza atomica basada en una unidad de lectura optica digital y un escaner-zumbador

    Energy Technology Data Exchange (ETDEWEB)

    Dabirian, R.; Loza M, D. [Universidad de las Fuerzas Armadas-ESPE, Departamento de Ciencias de la Energia y Mecanica, Sangolqui (Ecuador); Wang, W. M.; Hwu, E. T., E-mail: whoand@gmail.com [Academia Sinica, Institute of Physics, Taipei, 11529 Taiwan (China)

    2015-07-01

    An astigmatic detection system (Ads) based on a compact disk/digital-versatile-disk (Cd-DVD) astigmatic optical pickup unit is presented. It can achieve a resolution better than 0.3 nm in detection of the vertical displacement and is able to detect the two-dimensional angular tilt of the object surface. Furthermore, a novel scanner design actuated by piezoelectric disk buzzers is presented. The scanner is composed of a quad-rod actuation structure and several piezoelectric disks. It can be driven directly with low-voltage and low-current sources, such as analogue outputs of a data acquisition card and enables a sufficient scanning range of up to μm. In addition, an economic, high-performance streamlined atomic force microscopy (AFM) was constructed, using the buzzer-scanner to move the sample relative to the probe, and using a Cd/DVD optical pickup unit to detect the mechanical resonance of a micro fabricated cantilever. The performance of the AFM is evaluated. The high sensitivity and high bandwidth of the detection system makes the equipment suitable for characterizing nano scale elements. An AFM using our detection system for detecting the deflection of micro fabricated cantilevers can resolve individual atomic steps on graphite surfaces. (Author)

  14. Toric设计角膜塑形镜与视觉质量%Toric design orthokeratology contact lenses and visual quality

    Institute of Scientific and Technical Information of China (English)

    杨丽娜; 周建兰; 谢培英

    2013-01-01

    Objective To observe the changes in corneal astigmatism after patients are fitted with different ortho-k contact lens (CL) designs and the influence of these lenses on visual quality.Methods In a case-control study,corneal astigmatism,corneal topography,wavefront aberrations (Pentacam),visual acuity and visual disturbance symptoms were observed in three groups (groups A,B,C) before and after CL wear.Group A (30 eyes) had lower corneal astigmatism and wore a general ortho-k contact lens design that fit quite well; group B (30 eyes) had lower corneal astigmatism and wore a general ortho-k contact lens design that did not fit well and was obviously decentered; group C (31 eyes) had higher corneal astigmatism and wore toric ortho-k contact lenses with an acceptable fit.SPSS 16.0 statistical software was used to analyze the data.Results Changes in corneal astigmatism after fitting with the ortho-k CL:astigmatism increased in group B but was lower in groups A and C.Fourier analysis from corneal topography:increases in asymmetry for all three groups at 3 mm were (-0.393±0.329)D,(-4.050±2.084)D,and (-0.494±0.522)D,respectively,all at P<0.001.Higher order aberrations in the three groups increased at 3 mm and were (-0.011±0.055)D (P>0.05),(-0.635±0.441)D (P<0.001) and (-0.055±0.082)D (P<0.01).The three groups at 3 mm regular:differences in the comparison of astigmatism,asymmetry and higher order aberrations were statistically significant,F=79.862,F=83.882,F=54.265,respectively,all at P<0.01.After fitting with ortho-k CLs,the total aberrations and total higher order aberrations for the three groups increased in varying degrees,with group B as the most significant.A comparison of the difference in aberrations:only the anterior surface of the spherical aberration had a statistically significant difference (F=18.048,P<0.01).After the CLs were removed:in group A 36.7 % achieved a UVA of 1.2,50.0% achieved 1.0 and 13.3% achieved 0.8; in group B 36.7

  15. Incidence of the refractive errors in children 3 to 9 years of age, in the city of Tetovo, Macedonia

    Institute of Scientific and Technical Information of China (English)

    Ejup Mahmudi; Vilma Mema; Nora Burda; Brikena Selimi; Sulejman Zhugli

    2013-01-01

    Objective: To determine the incidence of refractive errors at children 3 to 9 years of age in the area of Tetovo, Macedonia in rural and urban population. Methods: Population-based cross-sectional samples of children 3 to 9 years in rural and urban population were obtained through full ophthalmologic examination, and they underwent slit-lamp examination, ocular motility and refraction. They were presenting uncorrected and best-corrected visual acuity, along with refractive error under topical cycloplegia. Children 3 to 6 years of age with a visual acuity of 20/40 or worse and those 6 to 9 years of age with a visual acuity of 20/30 or worse underwent a complete ophthalmic examination to determine the cause of visual impairment. A spherical equivalent of-0.5 diopter (D) or worse was defined as myopia, +2.50 D or more was defined as hyperopia and a cylinder refraction greater than 0.75 D was considered astigmatism plus or minus. Results:The uncorrected visual acuity was 20/45 or worse in the better eye of 119 children, 59 male / 60 female (5.1% of participants). According to results of cycloplegic refraction, 1.6% of the children were myopic, 7.3% were hyperopic and the incidence rate of astigmatism was approximately 0.7%. In the multivariate logistic regression myopia and hyperopia were correlated with age (P = 0.040 and P < 0.002, respectively). Conclusions: The study showed a considerable prevalence rates of refractive errors myopia , hypermethropia , astigmatism and amblyopia at children of 3-9 years of age in Tetovo. There was no correlation between sex of the children’s and the refractive errors founds. There was a correlation with the need for corrective spectacles and the refractive errors they represent. Refractive errors was registered in high percentage at rural area than in urban area. Although with best corrected vision the prevalence of impairment was less in urban than in rural populations, blindness remained nearly twice as high in the rural

  16. Long-term bladeless LASIK outcomes with the FS200 Femtosecond and EX500 Excimer Laser workstation: the Refractive Suite

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    Kanellopoulos AJ

    2013-02-01

    Full Text Available A John Kanellopoulos,1,2 George Asimellis11Laservision.gr Institute, Athens, Greece; 2NYU Medical School, NY, USAPurpose: The evaluation of the safety, efficacy, and long-term stability of LASIK procedures utilizing novel platform comprising a femtosecond and excimer laser and multiple networked diagnostics.Setting: Private clinical ophthalmology practice.Patients and methods: In consecutive cases of myopic LASIK procedure with a novel refractive platform (FS200 Femtosecond and EX500 Excimer Laser, 190 eyes (from 109 different patients were evaluated pre- and postoperatively for the following parameters: refractive error, best corrected distance visual acuity, uncorrected distance visual acuity, topography (Placido-disc based and tomography (Scheimpflug-image based, wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12-months.Results: The change from pre- to postoperative mean refractive error was from −5.29 ± 2.39 diopters (D (range −8.0 to −0.50 D to −0.27 ± 0.09 D at the 3 month visit, −0.27 ± 0.10 D at the 6 month visit, and −0.39 ± 0.08 D at the 1-year visit. The change from pre- to postoperative refractive astigmatism was −1.07 ± 0.91 D (range −4.25 to 0 D to −0.14 ± 0.04 D at 3 months, −0.15 ± 0.04 at 6 months, and −0.16 ± 0.04 at the one-year visit. The proportion of the eyes with postoperative astigmatism within 0.5 D ranged between 95.6% and 99%. The proportion of eyes achieving uncorrected distance visual acuity of 1.0 (decimal was 93.0%.Conclusion: The myopic LASIK clinical results with the FS200 Femtosecond Laser and EX500 Excimer Laser showed outstanding efficacy, great safety, and long-term stability.Keywords: bladeless LASIK flap, femtosecond laser, myopic correction, long-term stability, regression, astigmatism correction, post-LASIK refraction

  17. The status of refractive errors in elementary school children in South Jeolla Province, South Korea

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    Jang JU

    2015-07-01

    Full Text Available Jung Un Jang,1 Inn-Jee Park2 1Department of Optometry, Eulji University, Seongnam, 2Department of Optometry, Kaya University, Gimhae, South Korea Purpose: To assess the prevalence of refractive errors among elementary school children in South Jeolla Province of South Korea. Methods: The subjects were aged 8–13 years; a total of 1,079 elementary school children from Mokpo, South Jeolla Province, were included. In all participants, uncorrected visual acuity and objective and subjective refractions were determined using auto Ref-Keratometer and phoropter. A spherical equivalent of -0.50 diopter (D or worse was defined as myopia, +0.50 D or more was defined as hyperopia, and a cylinder refraction greater than 0.75 D was defined as astigmatism. Results: Out of 1,079 elementary school children, the prevalence of uncorrected, best-corrected, and corrected visual acuity with own spectacles of 20/40 or worse in the better eye was 26.1%, 0.4%, and 20.2%, respectively. The uncorrected visual acuity was 20/200 or worse in the better eye in 5.7% of school children, and 5.2% of them already wore corrective spectacles. The prevalence of myopia, hyperopia, and astigmatism was 46.5% (95% confidence interval [CI]: 43.56–49.5, 6.2% (95% CI: 4.92–7.81, and 9.4% (95% CI: 7.76–11.25, respectively. Conclusion: The present study reveals a considerably higher prevalence of refractive error among elementary school children in South Jeolla Province of South Korea, exceeding 50% of subjects. The prevalence of myopia in the school children in Korea is similar to many other countries including People’s Republic of China, Malaysia, and Hong Kong. This may indicate that genetics and educational influences, such as studying and learning, may play a role in the progression of myopia in Korean elementary school children. Keywords: refractive error, elementary school children, visual acuity, myopia, astigmatism

  18. Comparação entre os resultados pós-operatórios de pacientes submetidos ao procedimento tríplice e transplante de córnea combinado a fixação secundária de lente intra-ocular Comparison between the postoperative results of triple procedure and combined penetrating keratoplasty/ transsclerally sutured posterior chamber lens implantation

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    Daniela Maggioni Pereira Leão

    2006-08-01

    Full Text Available OBJETIVO: Comparar os resultados pós-operatórios de 2 grupos de pacientes submetidos a transplante de córnea com técnicas e tempo cirúrgico diferentes, em relação à abordagem do cristalino e/ou lente intra-ocular. MÉTODOS: Neste estudo retrospectivo foram analisados 37 olhos de pacientes divididos em 2 grupos: extração de catarata, implante de lentes intra-oculares (LIO e transplante de córnea no mesmo tempo cirúrgico - grupo 1 (G1 e extração de catarata sem implante de lentes intra-oculares no primeiro tempo cirúrgico e fixação secundária de lentes intra-oculares associada a transplante de córnea no segundo tempo cirúrgico - grupo 2 (G2. As variáveis estudadas foram: acuidade visual, pressão intra-ocular (PIO, astigmatismo refracional, astigmatismo ceratométrico e complicações pós-operatórias. RESULTADOS: Foi observado melhora da acuidade visual nos 2 grupos (G1 pPURPOSE: To compare the outcomes of two surgical techniques of penetrating keratoplasty with different surgical time, regarding the crystalline and the intraocular lens. METHODS: This retrospective study included 37 patients' eyes divided into 2 groups: extracapsular cataract extraction, posterior chamber intraocular lens implantation and penetrating keratoplasty (Group 1, G1 and transscleral fixation of posterior chamber lens and penetrating keratoplasty (Group 2, G2. The following parameters were recorded: visual acuity, intraocular pressure, refractive astigmatism, complication and keratometric astigmatism. RESULTS: Visual acuity improved in the two groups (G1 p<0.001 and G2 p=0.008. In G2 a significant change for the worse of intraocular pressure outcome was observed when compared with the other group (p=0.014. Regarding refractive and keratometric astigmatism no significant differences between the groups were found. The follow-up was 11 months. CONCLUSION: The most important negative prognostic factor affecting visual acuity was the postkeratoplasty

  19. Determination of AcrySof(R) toric intraocular lens alignment by power vector analysis method and slitlamp observation%散光人工晶状体植入术后眼内散光轴向的矢量分析

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    罗保根; 张济明; 李龙标

    2012-01-01

    Objective To compare the derived intraocular astigmatism axis using power vector analysis method with the toric intraocular lens (TIOL) axis by slitlamp observation after cataract phacoemulsification. Methods A cohort of 39 patients (41 eyes) who had cataract phacoemulsification with Alcon AcrySof(R) toric lens implantation were studied 3 months postoperatively.Postoperative refraction and keratometric cylinder were recorded.Internal astigmatism and axes was obtained using power vector analysis method to assess the TIOL axes.The intraocular astigmatism axis and the TIOL axis observed by slitlamp were compared by linear relationship.Uncorrected distance visual acuities (UDVA) and corrected distance visual acuities (CDVA) were also measured. Results Postoperatively,the eyes had UDVA better than that of preoperatively (P <0.05).The difference between the 2 methods of assessing IOL axis was 4.64 ± 3.06 degrees (range 0 to 14.33 degrees).The correlation was significant (r =0.997,P <0.01). Conclusions Power vector analysis method is a suitable method for assessing toric IOL alignment.%目的 比较AcrySot(R)散光人工晶状体植入术后眼内散光轴向和裂隙灯观察散光人工晶状体的标记轴向的差别.方法 对39例41只眼超声乳化白内障吸除联合AcrySof(R)散光人工晶状体植入术患者,术后三个月进行远视力及屈光状态测定,用散光矢量分析方法计算得眼内散光轴向与用裂隙灯观察的散光人工晶状体的标记轴向进行直线相关分析.结果 超声乳化白内障术后裸眼视力较术前提高(P<0.05),眼内散光轴向与散光人工晶状体的标记轴向呈直线相关(r=0.997,P<0.01).结论 散光矢量分析方法可以用于超声乳化术后散光人工晶状体轴向位置测定.

  20. Assessment of the prevalence of refractive eye error and IOP during pregnancy and after delivery in patients referred to ophthalmology clinic of Boo-Ali Hospital of Qazvin in 1387

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    Mohammad Khalaj

    2009-01-01

    Full Text Available (Received 30 Jan 2010, 2010 ; Accepted 25 April, 2010AbstractBackground and purpose: Many pregnant women some of whom also suffer from refractive errors and use eyeglasses attend eye clinics The aim of this study was to assess the prevalence of refractive eye errors and changes in IOP, during pregnancy and after delivery among patients referred to ophthalmology clinic of Boo-Ali Hospital of Qazvin.Materials and methods: The study was conducted at eye clinic of Boo-Ali Hospital in Gazvin- Iran. A total of 150 pregnant women aged 17 to 38 years (mean 24.76 ± 4.61 were treated by ophthalmologist in three stages (16- and 32- week of pregnancy and 4 months after childbirth. Initially, all pregnant women were visited by a gynecologist and then they were referred to the ophthalmology clinic. The visual acuity was determined using chart Snellen from a distance of 6m and then refractive errors were measured by static retinoscopy and autorefractometer. Intraocular pressure was measured using air-puls noncontact tonometer in three stages.Results: In the first stage (16-week of pregnancy, hyperopia was seen in 12 patients (%8, myopia in 104 patients (%69.3, astigmatism in 26 patients (%17.3 and 8 patients (%5.3 were normal. The results of the second stage (32-week of pregnancy showed that 3 patients (%2 were hyperopia, 143 patients (%95 myopia, 2 patients (%1.3 astigmatism and 2 patients (%1.3 were normal. Four months after childbirth, 5 patients (%3.3 were hyperopia, 129 patients (%86 myopia, 13 patients (%13.7 astigmatism and 3 patients (%2 normal. The estimated relative risk of myopia was increased significantly in the second stage. The patients' IOP in the first stage was higher than the second stage and this difference was statistically significant (P<0.05.Conclusion: The results of this research showed that there is a significant relationship between pregnancy and myopia. IOP was reduced during pregnancy and return to the normal level after delivery

  1. “光明行动”中两种白内障超声乳化联合硬性人工晶体植入手术方式的比较%Comparison of two kinds of cataract ultrasonic emulsification combined rigid intraocular lens implant surgery in"light action"

    Institute of Scientific and Technical Information of China (English)

    张水江

    2014-01-01

    Objective:To compare and evaluate the postoperative effects of two kinds of ultrasonic emulsification combined rigid intraocular lens implant surgery.Methods:120 cases of cataract with 120 eyes were retrospectively studied.They were given cataract ultrasonic emulsification combined rigid intraocular lens implant surgery.The scleral tunnel incision was A group,and the corneal incision extended was B group.The naked eye vision and corneal astigmatism in postoperative 1 week,1 month and 3 months were compared.Results:The differences of naked eye vision and corneal astigmatism in postoperative 3 months were statistically significant(P<0.05).A group was better than B group.Conclusion:The cataract ultrasonic emulsification combined rigid intraocular lens implant surgery should choose scleral tunnel incision.It can reduce postoperative corneal astigmatism,and obtain better naked eye vision.%目的:比较与评价两种超声乳化联合硬性人工晶体植入手术方式术后效果。方法:回顾性研究120例120眼白内障行白内障超声乳化联合硬性人工晶体植入手术,巩膜隧道切口为A组,角膜切口扩大为B组,比较术后1周、1个月、3个月裸眼视力及角膜散光数值。结果:A组与B组术后3个月裸眼视力和角膜散光的差异有统计学意义(P<0.05),A组优于B组。结论:白内障超声乳化联合硬性人工晶体植入应选择巩膜隧道切口,可减少术后角膜散光,获得更好的裸眼视力。

  2. Prevalence of refractive errors in Mexican patients with keratoconus

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    Cruz-Becerril A

    2015-06-01

    Full Text Available Aníbal Cruz-Becerril,1 Alejandra Valdivia,1 Raúl Peralta,2 Ruth N Domínguez-Fernández,1 Marco A Castro-Reyes1 1Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Centro Interdisciplinario en Ciencias de la Salud, Unidad Milpa Alta, 2Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México Background: The purpose of this study was to determine the prevalence of refractive errors in Mexican patients with keratoconus (KCN and to describe their clinical characteristics.Methods: In this retrospective study, we reviewed the records of Mexican patients with KCN for the year 2012. Criteria for classifying refractive errors included the following: emmetropia -0.25 to +0.25 sphere, myopia >-0.25 sphere, hyperopia >+0.25 sphere, and astigmatism >-1.00 cylinder. Patient information was collected on refraction results, refractive diagnosis, slit-lamp examination, keratometry values, contact lens features, and best visual acuity with a contact lens. The prevalence of refractive errors was estimated by dividing the total number of eyes in the study by the number of refractive errors found.Results: The study population comprised 426 patients, including 785 eyes with KCN. KCN was found more frequently in males (55.6% than in females. The mean patient age was 28.1±10.3 years, and there was a greater frequency of moderate KCN. Compound myopic astigmatism had a prevalence of 87.3% and was present in all grades, although there are other types of refractive errors. The spherical rigid contact lens was the most frequently adapted lens (96%, and the contact lens parameters varied with disease progression.Conclusion: The most common refractive error is compound myopic astigmatism, although there are many refractive errors that have not been described to date in the KCN population. The main lens used for

  3. IOL tilt and decentration estimation from 3 dimensional reconstruction of OCT image.

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    Xiaogang Wang

    Full Text Available PURPOSE: To evaluate intraocular lens (IOL tilt and decentration by anterior segment optical coherence tomography (AS-OCT using 3-dimensional (3D reconstruction method. DESIGN: Prospective observational case series. PARTICIPANTS: Thirty-nine patients (39 eyes were included. METHODS: The IOL positions of all eyes were examined by AS-OCT. Images were obtained in 4 axes (0-180 degrees, 45-225 degrees, 90-270 degrees, and 135-315 degrees using the quadrant-scan model. The cross-sectional images were analyzed with MATLAB software. MAIN OUTCOME MEASURES: The angle (θ between the reference pupillary plane and the IOL plane, the distances between the center points of the pupil circle and the IOL on the x-axis (dx and y-axis (dy and the spatial distance (ds were calculated after 3D-reconstruction. RESULTS: The mean angle (θ between the pupillary plane and the IOL plane was 2.94±0.99 degrees. The mean IOL decentration of dx and dy was 0.32±0.26 mm and 0.40±0.27 mm, respectively. The ds of the IOL decentration was 0.56±0.31 mm. There was no significant correlation between the ocular residual astigmatism (ORA and the tilted angle or the decentration distance. There was a significant correlation between the ORA and total astigmatism (r = 0.742, P<0.001. There was no significant correlation between the postoperative best corrected visual acuity (BCVA and the ORA (r = 0.156; P = 0.344, total astigmatism (r = 0.012; P = 0.942, tilted angle (θ; r = 0.172; P = 0.295 or decentration distance (dx: r = 0.191, P = 0.244; dy: r = 0.253, P = 0.121; ds: r = 0.298, P = 0.065. CONCLUSIONS: AS-OCT can be used as an alternative for the analysis of IOL tilt and decentration using 3D-reconstruction.

  4. Acute Corneal Hydrops in Children with Primary Infantile Glaucoma: A Report of 31 Cases over 23 Years at the LVPEI.

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    Anil K Mandal

    Full Text Available Relatively little data exist regarding the outcomes of children with primary infantile glaucoma presenting with acute corneal hydrops. The aim of our study was to determine the surgical outcome of children of infantile glaucoma who presented with acute corneal hydrops.In total, 38 eyes of 31 consecutive children of infantile glaucoma presented with acute corneal hydrops who underwent primary combined trabeculotomy-trabeculectomy (CTT by a single surgeon from January 1990 to December 2012 at the LV Prasad Eye Institute (LVPEI, a tertiary eye care centre in Southern India were enrolled in this retrospective study. Primary outcome measures were intraocular pressure (IOP control (IOP ≤ 16 mmHg under anaesthesia or IOP ≤ 21 mmHg without anaesthesia and clearance of corneal edema. Secondary outcome measures were visual acuity (VA, corneal diameter, bleb appearance, intraoperative and postoperative complications.Mean age at presentation was 6.4 months (range, 2-11 months and seven eyes (23% had bilateral affliction. At presentation, all eyes (100% had moderate to severe degree of corneal edema with a mean preoperative IOP of 25.6 ±5.1 mmHg. Postoperatively, the IOP reduced to 12.0 ± 3.8 mmHg (difference = -13.6, 95% CI = -15.7 to -11.5, t = -13.18, p<0.0001, and the percentage reduction in IOP was 53.05%. Preoperatively 83% of the eyes were on antiglaucoma medication, and postoperatively 2 eyes (5.3% required 1 antiglaucoma medication for control of IOP. Preoperatively, corneal edema was present in all eyes and postoperatively it cleared in all of them. Significant myopic astigmatism was present in 28 eyes (74%, the commonest being compound myopic astigmatism (75% followed by simple myopic astigmatism (21%. Normal VA (best-corrected VA; BCVA ≥ 20/60 was achieved in 44.4% of the eyes and 22.2% eyes had low vision (BCVA, <20/60 to 20/400. Complete success (IOP control and clearance of corneal oedema was obtained in 94.7% eyes. There were no

  5. The Analysis on Corneal Topography of Trabeculectomy%小梁切除术后角膜地形图分析

    Institute of Scientific and Technical Information of China (English)

    施小茹; 韩丽娜; 于洪泉; 徐杰; 夏静

    2001-01-01

    ObjectiveTo investigate the changes of corneal topography before and after trabeculectomy and analyze the cause of astigmatism after trabeculectomy.MethodsA standard trabeculectomy procedure(4mm×5mm scleral trap door)was performed at the 90 degree meridian in 30 eyes of 30 patients and followed up for 3 months.Computer assisted topographic analysis was performed preoperatively and on 3 months postoperatively.Additional data included axial length,intraocular pressure and visual acuity.ResultVariation of corneal topography indicated three types of astigmatic findings:a relative superior corneal steepening,perior flattening and complex regional changes.In the superior steepening and superior flattening groups there was the astigmatism with the rule.There was no correlation between the change of corneal topography and intraocular pressure.ConclusionChanges in corneal curvature are induced by filtering surgery,not by changing of intraocular pressure.Computer-assisted corneal topography is the best way to analyse the complex changes in corneal curvature.%目的 应用角膜地形图仪分析小梁切除术前术后角膜地形图改变,探讨术后引起散光的原因。方法 随机选择30例(30只眼)急性闭角型青光眼患者,作常规小梁切除术,分别于术前1天,术后3个月作角膜地形图,同时作视力眼轴及眼压测定。结果 角膜地形图改变分3种情况:16只眼角膜变陡峭5只眼角膜变平坦9只眼角膜地形图改变不规则,无论是角膜变陡峭还是变平坦均产生循规性散光。结论  滤过性手术可产生角膜曲率的改变

  6. Corneal topographic analysis of small incision in cataract surgery%小切口白内障术后的早期角膜地形图分析

    Institute of Scientific and Technical Information of China (English)

    郑海华; 陈峰; 韩真真

    2001-01-01

    目的:研究白内障小切口术后角膜形态变化特点。 方法:用角膜地形图对27例(34眼)白内障小切口手术患者进行检查,分析其术前,术后1周、1月、3月的角膜地形图变化。 结果:术后1周仅产生手术源性散光0.52D,术后1月角膜散光及CIM值(角膜不规则系数)趋向稳定,裸眼视力≥0.5占26眼(76.42%),SF值(角膜形状系数)术前术后无明显变化。结论:小切口具有早期角膜形态变化小、散光稳定、视力恢复快等优点,角膜地形图可准确全面反映白内障术后角膜形态变化。%Objective:To study corneal topographic changes after cataract surgery through small incision.Methods:Corneal topography of 34 eyes in 27 patients who had undergone small incision cataract surgery was analyzed preoperatively and at 1 week, 1 month, 3 months postoperatively. Results:Surgically induced astigmatic change of 0.52D was observed at 1 week postoperatively. Corneal astigmatism and CIM remained quite stable 1 month after surgery. 26 eyes(76.42%) obtained uncorrected visual acuity to 0.5 or better. Compared with preoperative statistics, no significant change of SF was found postoperatively.Conclusion:The results suggested that the small incision produces less astigmatism postoperatively, faster postoperative recovery, less corneal topographic change early after surgery. Computerized videokeratography system is an effective way to measure precisely the change of corneal topography after cataract surgery.

  7. Topographical Evaluation of the Decentration of Orthokeratology Lenses

    Institute of Scientific and Technical Information of China (English)

    Xiao Yang; Xingwu Zhong; Xiangming Gong; Junwen Zeng

    2005-01-01

    Purpose: To evaluate the amount of lens decentration and various factors affecting decentration after orthokeratology lens wear and to observe the effect of decentration on the visual functions.Methods: Two kinds of orthokeratology lenses were fitted to 270 eyes of 135 patients [initial mean refractive error: (-3.98±1.51)D]. Humphery Instruments ATLAS 990 was used for the computer-assisted analysis of corneal topographical maps. The examination of corneal topography was performed on patients before and after 6 months of wearing orthokeratology lenses. The amount of decentration of orthokeratology lenses was measured by finding the distance between center of optic zone and the pupil center. The factors influencing the amount of decentration were analyzed, including the initial refraction error, astigmatism, keratometry values, corneal eccentricity, and the diameter of lens.Visual symptoms including monocular diplopia, glare around lights were recorded to evaluate the effects of decentration on visual functions.Results: The mean amount of decentration was (0.49±0.34) mm after one night's wear.The mean amount of decentration after 1 month, 3 months and 6 months was (0.57±0.41) mm, (0.55±0.48) mm and (0.59±0.39) mm, respectively. After one month, the amount of decentration was less than 0.50 mm in 51.1% eyes, 0.50~1.0 mm in 35.6% eyes and more than 1.00 mm in 13.3% eyes. The direction of decentration of more than 0.50 mm was mainly in the temporal quadrant (48.5%). Patients with greater initial astigmatism and smaller lenses showed greater decentration (P<0.05). There was no statistically significant difference in decentration between the two groups with different corneal eccentricities and keratometry values (P>0.05). The amount of decentration was greater in patients who complained of monocular diplopia and glare.Conclusions: The amount of decentration of orthokeratology depends on the initial refractive error, astigmatism and the design of orthokeratology

  8. Long-term outcomes of limbal relaxing incisions during cataract surgery: aberrometric analysis

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    Monaco G

    2015-08-01

    Full Text Available Gaspare Monaco, Antonio ScialdoneDepartment of Ophthalmology, Ospedale Fatebenefratelli e Oftalmico, Milan, ItalyPurpose: To compare the final changes in corneal wavefront aberration by limbal relaxing incisions (LRIs after cataract surgery.Methods: This prospective cumulative interventional nonrandomized case study included cataract and astigmatic patients undergoing LRIs and phaco with intraocular lens implantation. LRIs were planned using Donnenfeld nomogram. The root mean square of corneal wave aberration for total Z(n,i(1≤n≤8, astigmatism Z(2,±1, coma Z(3–5–7,±1, trefoil Z(3–5–7,±2, spherical Z(4–6–8,0, and higher-order aberration (HOA Z(3≤n≤8 was examined before and 3 years after surgery (optical path difference-Scan II [OPD-Scan II]. Uncorrected distance visual acuity and best-corrected distance visual acuity (CDVA for distance, keratometric cylinder, and variations in average corneal power were also analyzed.Results: Sixty-four eyes of 48 patients were included in the study. Age ranged from 42 to 92 years (70.6±8.4 years. After LRIs, uncorrected distance visual acuity and best-corrected distance visual acuity improved statistically (P<0.01. The keratometric cylinder value decreased by 40.1%, but analysis of KP90 and KP135 polar values did not show any decrease that could be statistically confirmed (P=0.22 and P=0.24. No significant changes were detected in root mean square of total (P=0.61 and HOAs (P=0.13 aberrations. LRIs did not induce alteration in central corneal power confirming a 1:1 coupling ratio.Conclusion: LRIs determined a nonsignificant alteration of corneal HOA. Therefore, LRIs can be still considered a qualitatively viable mean in those cases where toric intraocular lenses are contraindicated or not available. Yet, the authors raise the question of nonpersonalized nomograms, as in the present study, LRIs did not reach the preset target cylinder. Keywords: astigmatism, ocular wavefront, intraocular

  9. Planar Near-Field Phase Retrieval Using GPUs for Accurate THz Far-Field Prediction

    Science.gov (United States)

    Junkin, Gary

    2013-04-01

    With a view to using Phase Retrieval to accurately predict Terahertz antenna far-field from near-field intensity measurements, this paper reports on three fundamental advances that achieve very low algorithmic error penalties. The first is a new Gaussian beam analysis that provides accurate initial complex aperture estimates including defocus and astigmatic phase errors, based only on first and second moment calculations. The second is a powerful noise tolerant near-field Phase Retrieval algorithm that combines Anderson's Plane-to-Plane (PTP) with Fienup's Hybrid-Input-Output (HIO) and Successive Over-Relaxation (SOR) to achieve increased accuracy at reduced scan separations. The third advance employs teraflop Graphical Processing Units (GPUs) to achieve practically real time near-field phase retrieval and to obtain the optimum aperture constraint without any a priori information.

  10. Refractive sectors in the visual field of the pigeon eye.

    Science.gov (United States)

    Fitzke, F W; Hayes, B P; Hodos, W; Holden, A L; Low, J C

    1985-12-01

    Scheiner's principle has been used in electroretinographic optometry to refract the photoreceptor plane in different regions of the visual field of the pigeon eye. Along the horizon and in the upper visual field the eye is emmetropic, or nearly so. Below the horizon the eye becomes progressively more myopic at more negative elevations, refractive state falling to -5D at -90 deg. Lower field myopia is not an artifact of oblique astigmatism, nor of an aberration symmetrical about the optical axis. It is suggested that lower field myopia is a biological adaptation suited to keep the photoreceptors in the upper retina conjugate with the ground. Refractive state below the horizon can be fitted with a sine function by varying a parameter H (eye-ground height). The value of H agrees well with directly measured eye-ground height.

  11. A case of keratitis associated with limbal relaxing incision

    Directory of Open Access Journals (Sweden)

    Aravind Haripriya

    2016-01-01

    Full Text Available We report a case of keratitis associated with limbal relaxing incision (LRI. The patient presented with progressive loss of vision with best-corrected visual acuity 20/40. Immature cataract with 1.43D against the rule astigmatism was noted. Prophylactic topical antibiotic was administered before surgery. He underwent uneventful phacoemulsification with intraocular lens implantation with LRI. On the 33rd postoperative day (POD, he presented with infiltrate along LRI site with mild iritis. Corneal scraping was positive for Staphylococcus aureus. After the treatment with topical moxifloxacin and fortified cefazolin, the infiltrate started to resolve. On the 50th POD, the corneal infection was resolved with marked thinning at LRI site.

  12. A case of keratitis associated with limbal relaxing incision

    Science.gov (United States)

    Haripriya, Aravind; Smita, Anand

    2016-01-01

    We report a case of keratitis associated with limbal relaxing incision (LRI). The patient presented with progressive loss of vision with best-corrected visual acuity 20/40. Immature cataract with 1.43D against the rule astigmatism was noted. Prophylactic topical antibiotic was administered before surgery. He underwent uneventful phacoemulsification with intraocular lens implantation with LRI. On the 33rd postoperative day (POD), he presented with infiltrate along LRI site with mild iritis. Corneal scraping was positive for Staphylococcus aureus. After the treatment with topical moxifloxacin and fortified cefazolin, the infiltrate started to resolve. On the 50th POD, the corneal infection was resolved with marked thinning at LRI site. PMID:28112139

  13. Mudanças na refração após cirurgia de correção de esotropia Refractive changes following surgery for correction of esotropia

    Directory of Open Access Journals (Sweden)

    Marcelo F. Gaal Vadas

    2001-08-01

    Full Text Available Objetivo: Estudar o comportamento da refração e da curvatura corneana em pacientes com esotropia essencial submetidos à cirurgia monocular para correção do estrabismo. Métodos: Estudo prospectivo em que 42 olhos de 21 pacientes com esotropia essencial de ângulo moderado, sem quaisquer outros estrabismos associados, foram selecionados e submetidos ao exame oftalmológico completo e à cirurgia monocular. O olho contralateral serviu como grupo controle. Foram feitas avaliações de pré-operatório, pós-operatório de 1 mês e pós-operatório de 6 meses. O astigmatismo pré-operatório foi confrontado com os astigmatismos pós-operatórios por análise vetorial e cálculo do valor polar. Resultados: Obtivemos, nos olhos operados, redução significante (pPurpose: To evaluate changes in refraction and corneal curvature following surgery for correction of acquired esotropia. Methods: 42 eyes of 21 patients with acquired moderate angle esotropia without any other form of strabismus were prospectively enrolled and submitted to a complete ophthalmological examination followed by recess/resect procedure in a single eye. Data from the fellow eye were selected as control. Ophthalmological assessment was carried out preoperatively, 1 month after surgery and 6 months after surgery, where astigmatism was compared using vector analysis and the polar value concept. Results: The eyes submitted to surgery revealed a significant (p<0.05 decrease in spherical equivalent, from 3.28 ± 1.98 diopters to 3.05 ± 1.95 diopters. Refraction data disclosed a significant increase in the 90° component of net astigmatism, from 0.458 ± 0.594 diopters to 1.002 ± 0.718 diopters, which was also observed in keratometric readings:1.083 ± 0.560 diopters to 1.690 ± 0.591 diopters. Surgically induced astigmatism, assessed using refraction data was 0.63 ± 0.27 diopters at an average axis of 92.30 ± 14.91 degrees, and 0.71 ± 0.27 diopters at an average axis of 94.45

  14. Short time results and complications of LASIK surgery in Yazd, Iran%伊郎亚兹德LASIK中心LASIK手术短期结果和并发症研究

    Institute of Scientific and Technical Information of China (English)

    Seyed Ali Mohammad Miratashi; Mohammad Reza Besharati

    2007-01-01

    AIM: To evaluate the results and complications of LASIK surgery in Yazd, Iran.METHODS: In this descriptive study, cases were selected randomly and data from files of 230 operated eyes were filled in a questionnaire with special format. Data of patients who had been operated upon between March 2003 and March 2004 were gathered and evaluated by SPSS software program, in particular, Chi-square and Fisher statistical tests. Patients were followed up for 3 months. Residual refractive error in the range of±0.5 was considered as complete correction and more than±0.5 considered as relative correction.RESULTS: From the total of 230 eyes, 122 eyes were of women and 108 eyes belonged to men. 24 cases (10.4%)were myopic; 188 cases (81.8%) were myopic-astigmatism; 5 cases (2.2%) were hyperopic and 13 cases (5.6%) were hyperopic-astigmatism 204 eyes were in the age group of younger than 40 years and 26 eyes were in the age group of older than 40 years. Based on visual acuity recovering condition, 225 eyes (97.8%) were treated completely and 5 eyes (2.2%) were relatively corrected. Patients were followed up for 3 months after surgery. The rate for complete correction of refractive errors in myopia was 96.0%, myopic astigmatism 88.0%, hyperopia 60.0% and hyperopic astigmatism 62.0%. At 3 months after operation, 224 cases (97.4%) did not have any complications and the others had minor side effects.CONCLUSION: LASIK operation is a safe and effective procedure for correcting refractive errors with limited complications. Results are comparable with similar studies.%目的:评介LASIK手术的结果和并发症.方法:随机选择2003-03/2004-03被实施手术并填写特殊形式问卷的230只手术眼列入本研究.患者数据收集和评价采用SPSS软件进行卡方分析和Fisher统计学检验.患者术后随访时间为3mo.残余屈光度在±0.5D以内为完全矫正,大于±0.5D为相对矫正.结果:全部230眼中,女性122眼,男性108眼.24眼(10.4%)为近视,188

  15. Post Filtering Surgery Globe Massage-induced Keratoconus in an Eye with Iridocorneal Endothelial Syndrome: A Case Report and Literature Brief Review

    Science.gov (United States)

    Fakhraie, Ghasem; Vahedian, Zakieh

    2016-01-01

    Purpose: To report a case of unilateral post trabeculectomy globe massage-induced keratoconus (KCN). Case Report: A 52-year-old lady with a history of trabeculectomy due to iridocorneal endothelial syndrome in her right eye was instructed to massage her globe to control gradual rise of intraocular pressure 1.5 years after surgery. The patient experienced high astigmatism and marked inferior corneal steepening after 3 years of globe massage. The left eye was normal in all aspects. Findings in different visual examinations were compatible with the diagnosis of unilateral KCN in the right eye of our patient. Conclusion: Chronic forceful frequent eye rubbing particularly with fingertips can be assumed to be the most important causative factor for KCN formation in this patient. PMID:27621792

  16. Vision improvement by correcting higher-order aberrations with customized soft contact lenses in keratoconic eyes

    Science.gov (United States)

    Sabesan, Ramkumar; Jeong, Tae Moon; Carvalho, Luis; Cox, Ian G.; Williams, David R.; Yoon, Geunyoung

    2007-04-01

    Higher-order aberration correction in abnormal eyes can result in significant vision improvement, especially in eyes with abnormal corneas. Customized optics such as phase plates and customized contact lenses are one of the most practical, nonsurgical ways to correct these ocular higher-order aberrations. We demonstrate the feasibility of correcting higher-order aberrations and improving visual performance with customized soft contact lenses in keratoconic eyes while compensating for the static decentration and rotation of the lens. A reduction of higher-order aberrations by a factor of 3 on average was obtained in these eyes. The higher-order aberration correction resulted in an average improvement of 2.1 lines in visual acuity over the conventional correction of defocus and astigmatism alone.

  17. Three-dimensional phenomena in microbubble acoustic streaming

    CERN Document Server

    Marin, Alvaro; Rallabandi, Bhargav; Wang, Cheng; Hilgenfeldt, Sascha; Kähler, Christian J

    2015-01-01

    Ultrasound-driven oscillating micro-bubbles have been used as active actuators in microfluidic devices to perform manifold tasks such as mixing, sorting and manipulation of microparticles. A common configuration consists on side-bubbles, created by trapping air pockets in blind channels perpendicular to the main channel direction. This configuration consists of acoustically excited bubbles with a semi-cylindrical shape that generate significant streaming flow. Due to the geometry of the channels, such flows have been generally considered as quasi two-dimensional. Similar assumptions are often made in many other microfluidic systems based on \\emph{flat} micro-channels. However, in this paper we show that microparticle trajectories actually present a much richer behavior, with particularly strong out-of-plane dynamics in regions close to the microbubble interface. Using Astigmatism Particle Tracking Velocimetry, we reveal that the apparent planar streamlines are actually projections of a \\emph{streamsurface} wi...

  18. Quality descriptors of optical beams based on centred reduced moments I spot analysis

    CERN Document Server

    Castaneda, R; García-Sucerquia, J

    2003-01-01

    A method for analyzing beam spots is discussed. It is based on the central reduced moments of the spot and its associated density functions. These functions allow us to separately analyze specific spot fractions, in such a way that specific combinations of higher order moments can be interpreted as coordinates of their centre of mass and the length and orientations of their principal axis. So, the descriptors of the associated density functions deal with the quantitative estimation of spot features, such as coma-like and astigmatism-like distortions. To assure high accuracy, background noise suppression and an optimal match of the spot support onto the region [-1,1]x[- 1,1] are performed prior to the calculation of the moments. Simulations were performed for illustrating the method.

  19. Aberration measurement from specific photolithographic images: a different approach.

    Science.gov (United States)

    Nomura, H; Tawarayama, K; Kohno, T

    2000-03-01

    Techniques for measurement of higher-order aberrations of a projection optical system in photolithographic exposure tools have been established. Even-type and odd-type aberrations are independently obtained from printed grating patterns on a wafer by three-beam interference under highly coherent illumination. Even-type aberrations, i.e., spherical aberration and astigmatism, are derived from the best focus positions of vertical, horizontal, and oblique grating patterns by an optical microscope. Odd-type aberrations, i.e., coma and three-foil, are obtained by detection of relative shifts of a fine grating pattern to a large pattern by an overlay inspection tool. Quantitative diagnosis of lens aberrations with a krypton fluoride (KrF) excimer laser scanner is demonstrated.

  20. Evaluation of stereopsis in different type of ametropic amblyopia children%不同类型屈光不正性弱视儿童的立体视觉

    Institute of Scientific and Technical Information of China (English)

    李珊珊; 黄馨慧; 邱斌; 叶晗; 戴锦晖

    2010-01-01

    目的 了解屈光不正性弱视儿童立体视觉的状况.方法 对4~8岁,平均(5.2±1.8)岁,205例屈光不正性弱视儿童(其中散光性弱视65例、近视性30例、远视性110例),应用颜少明等随机立体检查图及同视机,检测不同类型屈光不正性弱视儿童远融合范围、远近立体视、近零视差、交叉视差、非交叉视差立体感知度.结果 轻、中度屈光不正性弱视三种类型近零视差差异有统计学意义,远视性弱视较小,近视性次之,散光性最差(P均<0.05);远立体视有显著差异,远视性较好散光性较差(P均<0.05);重度弱视3型近零视差和远立体视均差异无统计学意义(P>0.05);远融合范围3型差异无统计学意义(P>0.05).弱视程度对弱视患者三级视功能有明显影响(P<0.05),程度越重影响越大.结论 弱视影响儿童期立体视觉建立,散光性弱视对立体视觉的影响大于近视性、远视性弱视儿童.%Objective To evaluate the stereopsis in different types of ametropic amblyopic children.Methods A total of 205 children between 4-8 years old with recovered ametropic amblyopia, including 65 of astigmatic amblyopia and 30 of myopic and 110 of hypermetropic, were involved in the subject. Using Yan's stereogram random dot synptophore stereogram and synoptophore, the distance fusion range, distance stereoacuity, approximationg zero disparity of these children were observed separately. Results In mild and moderate amblyopia there was significant difference in approximationg zero disparity and distance stereoacuity among astigmatic amblyopia and myopic and hypermetropic, within which astigmatic amblyopia the worst and hypermetropic amblyopia the best (P<0.05). No significant difference was found in the distance fusion range (P>0.05). Different type of ametropic amblyopic led no significant difference in severe amblyopia (P>0.05) which caused worse influence to the stereopsis than mild and moderate degree (P

  1. Nonparaxial theory of curved holograms

    Science.gov (United States)

    Peng, K.-O.; Frankena, H. J.

    1986-04-01

    Nonparaxial imaging by holograms on a spherical surface, with a limited circular cross section, is formulated mathematically. Starting from a point-shaped object, the image point is redefined such that the deviation in the positions of the actual image-forming wave front and a spherical wave front centered around this point contains no terms of the first order in the hologram coordinates. Furthermore, their second-order contribution, averaged over the hologram, vanishes. The remaining terms up to the fourth order describe the primary aberrations. Compared with earlier theories, this formulation yields a more accurate position for the holographic image. In addition, expressions are obtained for the primary aberrations, which not only consist of astigmatism, coma, and spherical aberration but also contain three additional contributions, which occurred as higher-order aberrations in previous literature. Experiments support the conclusions.

  2. Collagen cross-linking in the treatment of pellucid marginal degeneration

    Directory of Open Access Journals (Sweden)

    Ziad Hassan

    2014-01-01

    Full Text Available Pellucid marginal degeneration (PMD is an uncommon cause of inferior peripheral corneal thinning disorder, characterized by irregular astigmatism. We analyzed a case of bilateral PMD patient and treated one eye with corneal collagen cross-linking (CXL therapy. Corneal topography was characteristic for PMD. Visual acuity, slitlamp examinations, tonometry, and corneal thickness were observed. Simulated keratometric and topographic index values were detected with corneal topography. Uncorrected, LogMAR visual acuity has improved from +0.8 to +0.55 during the 6 months and +0.3 during the 8 months follow-up after CXL. Pachymetry values and intraocular pressure showed no changes. Keratometric values and topografic indexes disclosed no progression of the disease. CXL may postpone or eliminate the need of corneal transplantation in cases with PMD.

  3. Assessment of diagnostic value of age for meridional amblyopia with Logistic regression and receiver operating characteristic curve%应用Logistic回归和ROC曲线评价患者年龄对儿童子午线性弱视诊断的影响

    Institute of Scientific and Technical Information of China (English)

    李辉; 许江涛; 蒋晓明; 周莹

    2013-01-01

    目的:应用Logistic多元回归分析和ROC曲线探讨年龄因素对诊断儿童子午线弱视有无影响.方法:研究对象为2008/2011年间在我院眼科门诊就诊,以散光为主要屈光异常并排除屈光参差及斜视的4~8岁儿童共1 005例1 910眼.采用Logistic多元回归分析年龄、性别、柱镜绝对值程度、球镜绝对值程度、散光类型对诊断子午线性弱视的影响,通过ROC曲线下面积(area under the ROC curve,AUC)分析进一步明确患者年龄因素对诊断子午线弱视的影响.结果:分别建立Logistic 回归模型1(包括性别、柱镜绝对值程度、球镜绝对值程度、散光类型四个变量)和模型2(前四个变量再加上年龄).两个模型的Logistic 回归分析都提示柱镜绝对值程度是诊断子午线性弱视的影响因素,模型2 的Logistic 回归分析同时提示年龄是诊断子午线性弱视的影响因素.模型1的AUC为0.64,模型2的AUC为0.74,两者比较有统计学差异(Por = 1. 00D and sphere < or = 3. 00D were present in one or both eyes. The difference of sphere between both eyes was less 1. 50D. The difference of astigmatism between both eyes was less 1. 00D. All astigmatism was calculated by the absolute value. By analyzing age, sex, astigmatism type, diopter of cylinder and diopter of sphere with Logistic regression, two mathematical models were established. Then the diagnostic efficacy of the model was assessed using the ROC curve.RESULTS: The model 1 included 4 parameters (sex, astigmatism type, diopter of cylinder and diopter of sphere). The model 2 included 5 parameters (the 4 parameters of the model 1 adding age). Using Logistic regression, the diopter of cylinder had an influence on the diagnosis of meridional amblyopia in two models. In model 2, age was another influencing factor on the diagnosis of meridional amblyopia. The model 1 area under ROC curve (AUC) was 0. 64, and the model 2 was 0.74. The area of model 2 was greater than the model 1

  4. Cost-effective solar furnace system using fixed geometry Non-Imaging Focusing Heliostat and secondary parabolic concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Chong, K.K.; Lim, C.Y.; Hiew, C.W. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Off Jalan Genting Kelang, Setapak, Kuala Lumpur 53300 (Malaysia)

    2011-05-15

    A novel cost-effective solar furnace system is proposed to be consisted of a Non-Imaging Focusing Heliostat (NIFH) and a much smaller parabolic concentrator. In order to simplify the design and hence leading to the cost reduction, a fixed geometry of the NIFH heliostat is adopted in the novel solar furnace system by omitting the requirement of continuous astigmatic correction throughout the year with the use of local controllers. The performance of this novel solar furnace configuration can be optimized when the heliostat's spinning-axis is orientated in such a way that the annual variations of incident angle and therefore the annual variations of aberrant image size are the least. To verify the new configuration, a prototype solar furnace has been constructed at Universiti Tunku Abdul Rahman. (author)

  5. Ultrasound-induced acoustophoretic motion of microparticles in three dimensions

    DEFF Research Database (Denmark)

    Muller, Peter Barkholt; Rossi, M.; Marín, Á. G.;

    2013-01-01

    We derive analytical expressions for the three-dimensional (3D) acoustophoretic motion of spherical microparticles in rectangular microchannels. The motion is generated by the acoustic radiation force and the acoustic streaming-induced drag force. In contrast to the classical theory of Rayleigh...... streaming in shallow, infinite, parallel-plate channels, our theory does include the effect of the microchannel side walls. The resulting predictions agree well with numerics and experimental measurements of the acoustophoretic motion of polystyrene spheres with nominal diameters of 0.537 and 5.33 μm. The 3......D particle motion was recorded using astigmatism particle tracking velocimetry under controlled thermal and acoustic conditions in a long, straight, rectangular microchannel actuated in one of its transverse standing ultrasound-wave resonance modes with one or two half-wavelengths. The acoustic...

  6. Ultrasound-induced acoustophoretic motion of microparticles in three dimensions

    CERN Document Server

    Muller, Peter B; Marin, Alvaro G; Barnkob, Rune; Augustsson, Per; Laurell, Thomas; Kaehler, Christian J; Bruus, Henrik

    2013-01-01

    We derive analytical expressions for the three-dimensional (3D) acoustophoretic motion of spherical microparticles in rectangular microchannels. The motion is generated by the acoustic radiation force and the acoustic streaming-induced drag force. In contrast to the classical theory of Rayleigh streaming in shallow, infinite, parallel-plate channels, our theory does include the effect of the microchannel side walls. The resulting predictions agree well with numerics and experimental measurements of the acoustophoretic motion of polystyrene spheres with nominal diameters of 0.537 um and 5.33 um. The 3D particle motion was recorded using astigmatism particle tracking velocimetry under controlled thermal and acoustic conditions in a long, straight, rectangular microchannel actuated in one of its transverse standing ultrasound-wave resonance modes with one or two half-wavelengths. The acoustic energy density is calibrated in situ based on measurements of the radiation dominated motion of large 5-um-diam particles...

  7. Focal-plane wavefront sensing for active optics in the VST based on an analytical optical aberration model

    Science.gov (United States)

    Holzlöhner, R.; Taubenberger, S.; Rakich, A. P.; Noethe, L.; Schipani, P.; Kuijken, K.

    2016-08-01

    We study a novel focal plane wavefront sensing and active optics control scheme at the VST on Cerro Paranal, an f/5.5 survey telescope with a 1x1 degree field of view and a 2.6m primary mirror. This scheme analyzes the elongation pattern of stellar PSFs across the full science image (256 Mpixels) and compares their second moments with an analytical model based on 5th-order geometrical optics. We consider 11 scalar degrees of freedom in mirror misalignments and deformations (M2 piston, tip/tilt and lateral displacement, detector tip/tilt, plus M1 figure astigmatism and trefoil). Using a numerical optimization method, we extract up to 4000 stars and complete the fitting process in under one minute. We demonstrate successful closed-loop active optics control based on maximum likelihood filtering.

  8. Corneal injection track: an unusual complication of intraocular lens implantation and review

    Institute of Scientific and Technical Information of China (English)

    Julie; Y.C.Lok; Alvin; L.Young

    2015-01-01

    Phacoemulsification is the main gold standard for cataract operation in the developed world together with foldable intraocular lens(IOL) implantation by injection,allowing for stable wound construction and less postoperative astigmatism. It is a safe procedure with high success rate with the advancement in machines,improvement of IOL injection systems and further maturation of surgeons’ techniques. Despite the large number of operations performed every day, foldable IOL injection leading to an intra-stromal corneal track is a very rare complication. We report a case of this unusual finding in a 70-year-old gentleman who has undergone cataract operation in November 2011 in our hospital and will review on the complications related to foldable IOL injection.

  9. Posterior Corneal Surface Stability after Femtosecond Laser-Assisted Keratomileusis

    Directory of Open Access Journals (Sweden)

    Carlo Cagini

    2015-01-01

    Full Text Available The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue.

  10. Alternative optical concept for electron cyclotron emission imaging

    Energy Technology Data Exchange (ETDEWEB)

    Liu, J. X., E-mail: jsliu9@berkeley.edu [Department of Physics, University of California Berkeley, Berkeley, California 94720 (United States); Milbourne, T. [Department of Physics, College of William and Mary, Williamsburg, Virginia 23185 (United States); Bitter, M.; Delgado-Aparicio, L.; Dominguez, A.; Efthimion, P. C.; Hill, K. W.; Kramer, G. J.; Kung, C.; Pablant, N. A.; Tobias, B. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States); Kubota, S. [Department of Physics, University of California Los Angeles, Los Angeles, California 90095 (United States); Kasparek, W. [Department of Electrical Engineering, University of Stuttgart, Stuttgart (Germany); Lu, J. [Department of Physics, Chongqing University, Chongqing 400044 (China); Park, H. [Ulsan National Institute of Science and Technology, Ulsan 689-798 (Korea, Republic of)

    2014-11-15

    The implementation of advanced electron cyclotron emission imaging (ECEI) systems on tokamak experiments has revolutionized the diagnosis of magnetohydrodynamic (MHD) activities and improved our understanding of instabilities, which lead to disruptions. It is therefore desirable to have an ECEI system on the ITER tokamak. However, the large size of optical components in presently used ECEI systems have, up to now, precluded the implementation of an ECEI system on ITER. This paper describes a new optical ECEI concept that employs a single spherical mirror as the only optical component and exploits the astigmatism of such a mirror to produce an image with one-dimensional spatial resolution on the detector. Since this alternative approach would only require a thin slit as the viewing port to the plasma, it would make the implementation of an ECEI system on ITER feasible. The results obtained from proof-of-principle experiments with a 125 GHz microwave system are presented.

  11. [Cataract surgery - essentials for the general practitioner].

    Science.gov (United States)

    Amstutz, Ch; Thiel, M A; Kaufmann, Claude

    2010-08-11

    Age-related cataracts are mainly caused by life-long accumulation of oxidative stress on the lens fibres. Symptoms include reduced visual acuity, requiring more light for reading, and glare. The only treatment that provides a cure for cataracts is surgery. Phacoemulsification represents the preferred method of lens removal. It involves fragmentation of the lens using ultrasound and insertion of an artificial intraocular lens. The preoperative assessment the general practitioner provides to surgeon and anesthesia team has an important share in the low complication rate of the procedure in the event of co-existing systemic disease. Growing patient expectation for spectacle independence following cataract surgery is met to some extent using techniques for astigmatism control and presbyo-pia-correcting intraocular lenses.

  12. Experimental and analytical characterization of the 3D motion of particles in acoustofluidic devices

    DEFF Research Database (Denmark)

    Rossi, M.; Barnkob, Rune; Augustsson, P.;

    2012-01-01

    and to examine the accuracy of analytical force predictions. Polystyrene spheres with diameter of 0.5µm and 5µm were displaced under controlled conditions in a long straight rectangular acoustofluidic microchannel, actuated in its 2-MHz resonance mode, a transverse half-wavelength standing acoustic wave......In this work we present an experimental and analytical study of the acoustophoretic motion of spherical polystyrene particles of different sizes. The primary aim is to understand the three-dimensional extension of the acoustic radiation force and the acoustic streaming-induced drag force....... Astigmatism Particle Tracking Velocimetry (APTV) was used to measure the three-dimensional trajectories, velocities and accelerations of the particles. The experiments show how the acoustic radiation force dominates for the large 5-µm particles, whereas the drag force from the acoustic streaming dominates...

  13. Conception of broadband stigmatic high-resolution spectrometers for the soft X-ray range

    Energy Technology Data Exchange (ETDEWEB)

    Vishnyakov, E A; Shatokhin, A N; Ragozin, E N [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-04-30

    We formulate an approach to the development of stigmatic high-resolution spectral instruments for the soft X-ray range (λ ≤ 300 Å), which is based on the combined operation of normalincidence multilayer mirrors (including broadband aperiodic ones) and grazing-incidence reflection gratings with nonequidistant grooves (so-called VLS gratings). A concave multilayer mirror serves to produce a slightly astigmatic image of the radiation source (for instance, an entrance slit), and the diffraction grating produces a set of its dispersed stigmatic spectral images. The width of the operating spectral region is determined by the aperiodic structure of the multilayer mirror and may range up to an octave in wavelength. (laser applications and other topics in quantum electronics)

  14. Consideration of corneal biomechanics in the diagnosis and management of keratoconus: is it important?

    Science.gov (United States)

    Bao, FangJun; Geraghty, Brendan; Wang, QinMei; Elsheikh, Ahmed

    2016-01-01

    Keratoconus is a bilateral, non-inflammatory, degenerative corneal disease. The occurrence and development of keratoconus is associated with corneal thinning and conical protrusion, which causes irregular astigmatism. With the disruption of the collagen organization, the cornea loses its shape and function resulting in progressive visual degradation. Currently, corneal topography is the most important tool for the diagnosis of keratoconus, which may lead to false negatives among the patient population in the subclinical phase. However, it is now hypothesised that biomechanical destabilisation of the cornea may take place ahead of the topographic evidence of keratoconus, hence possibly assisting with disease diagnosis and management. This article provides a review of the definition, diagnosis, and management strategies for keratoconus based on corneal biomechanics.

  15. Modified convolution method to reconstruct particle hologram with an elliptical Gaussian beam illumination.

    Science.gov (United States)

    Wu, Xuecheng; Wu, Yingchun; Yang, Jing; Wang, Zhihua; Zhou, Binwu; Gréhan, Gérard; Cen, Kefa

    2013-05-20

    Application of the modified convolution method to reconstruct digital inline holography of particle illuminated by an elliptical Gaussian beam is investigated. Based on the analysis on the formation of particle hologram using the Collins formula, the convolution method is modified to compensate the astigmatism by adding two scaling factors. Both simulated and experimental holograms of transparent droplets and opaque particles are used to test the algorithm, and the reconstructed images are compared with that using FRFT reconstruction. Results show that the modified convolution method can accurately reconstruct the particle image. This method has an advantage that the reconstructed images in different depth positions have the same size and resolution with the hologram. This work shows that digital inline holography has great potential in particle diagnostics in curvature containers.

  16. Il fenomeno della "goccia nera" e l'astigmatismo

    Science.gov (United States)

    Horn D'Arturo, Guido

    2004-03-01

    The Venus transit on the Solar disc was for the first time observed in 1639, using "modern" instruments, by Gassendi. Yet since the following transit, an effect was perceived which modified Venus and Sun profiles at the moments of the first and second visual contact between the two celestial bodies. This effect was called "gutta nigra", i.e. black drop. Horn d'Arturo was widely interested in studies on the vision and on its effects on astronomical observations. In the following paper, he suggested what probably was the first correct explanation of the black drop effect. As stated on the Dictionary of Scientific Biography (ad vocem), Horn "clarified the effect on vision, especially in the astigmatic eye, of the suture of the eye lens and the formation of the so-called black drop".

  17. Keratophakia and keratomileusis--clinical results.

    Science.gov (United States)

    Swinger, C A; Barraquer, J I

    1981-08-01

    A random, retrospective study was performed on 158 patients. who underwent keratophakia and keratomileusis for the correction of refractive errors. The primary indication for surgery was high anisometropia. Data on corneal curvature modification, refraction, accuracy, stability, and complications are reported. Both keratophakia and hypermetropic keratomileusis are capable of fully correcting aphakic hyperopia. Myopic keratomileusis corrected up to 16 diopters of myopia in this series. Lamellar refractive keratoplasty appears to have no significant detrimental effect on visual acuity. The majority of myopic patients had an improved best-corrected visual acuity postoperatively. High or irregular astigmatism was not noted following this surgery. The stability of the postoperative curvature appeared to be good with both keratophakia and myopic keratomileusis. Complications in this series were minimal, and one resulted in decreased vision postoperatively. Inaccuracy in achieving the desired refractive result appeared to be the major disadvantage of these techniques.

  18. THERMAL LENSING MEASUREMENTS IN THE ANISOTROPIC LASER CRYSTALS UNDER DIODE PUMPING

    Directory of Open Access Journals (Sweden)

    P. A. Loiko

    2012-01-01

    Full Text Available An experimental setup was developed for thermal lensing measurements in the anisotropic diode-pumped laser crystals. The studied crystal is placed into the stable two-mirror laser cavity operating at the fundamental transversal mode. The output beam radius is measured with respect to the pump intensity for different meridional planes (all these planes contain the light propagation direction. These dependencies are fitted using the ABCD matrix method in order to obtain the sensitivity factors showing the change of the optical power of thermal lens due to variation of the pump intensity. The difference of the sensitivity factors for two mutually orthogonal principal meridional planes describes the thermal lens astigmatism degree. By means of this approach, thermal lensing was characterized in the diode-pumped monoclinic Np-cut Nd:KGd(WO42 laser crystal at the wavelength of 1.067 μm for light polarization E || Nm.

  19. Kabuki make-up (Niikawa-Kuroki) syndrome in five Spanish children

    Energy Technology Data Exchange (ETDEWEB)

    Galan-Gomez, E.; Cardesa-Garcia, J.J. Campo-Sampedro, F.M. [Universidad de Extremadura, Badajos (Spain)] [and others

    1995-11-20

    We describe 5 Spanish children with Kabuki make-up syndrome (KMS) - 3 females and 2 males - identified in Badajoz, Spain, between 1988 and 1990. All had the characteristic clinical and radiological manifestations of the syndrome. Psychomotor/mental retardation, postnatal growth deficiency, distinctive facial appearance, sagittal vertebral clefts, and dermatoglyphic abnormalities were present in all 5. Congenital heart defects were present in 4 patients. In addition, one had myopia, astigmatism, and bilateral paralysis of the VI cranial nerve. Another had apparent fusion of the hamate and capitate. An additional patient, as well as his mother, had an apparently balanced 15/17 translocation. The fact that these patients were ascertained in a catchment area of approximately 250,000 inhabitants and in a relatively limited period of time suggests that the prevalence of the KMS may be higher than previously recognized. 30 refs., 6 figs., 2 tabs.

  20. Photographic simulation of off-axis blurring due to chromatic aberration in spectacle lenses.

    Science.gov (United States)

    Doroslovački, Pavle; Guyton, David L

    2015-02-01

    Spectacle lens materials of high refractive index (nd) tend to have high chromatic dispersion (low Abbé number [V]), which may contribute to visual blurring with oblique viewing. A patient who noted off-axis blurring with new high-refractive-index spectacle lenses prompted us to do a photographic simulation of the off-axis aberrations in 3 readily available spectacle lens materials, CR-39 (nd = 1.50), polyurethane (nd = 1.60), and polycarbonate (nd = 1.59). Both chromatic and monochromatic aberrations were found to cause off-axis image degradation. Chromatic aberration was more prominent in the higher-index materials (especially polycarbonate), whereas the lower-index CR-39 had more astigmatism of oblique incidence. It is important to consider off-axis aberrations when a patient complains of otherwise unexplained blurred vision with a new pair of spectacle lenses, especially given the increasing promotion of high-refractive-index materials with high chromatic dispersion.

  1. High-resolution, flat-field, plane-grating, f/10 spectrograph with off-axis parabolic mirrors.

    Science.gov (United States)

    Schieffer, Stephanie L; Rimington, Nathan W; Nayyar, Ved P; Schroeder, W Andreas; Longworth, James W

    2007-06-01

    A high-resolution, flat-field, plane-grating, f/10 spectrometer based on the novel design proposed by Gil and Simon [Appl. Opt. 22, 152 (1983)] is demonstrated. The spectrometer design employs off-axis parabolic collimation and camera mirrors in a configuration that eliminates spherical aberrations and minimizes astigmatism, coma, and field curvature in the image plane. In accordance with theoretical analysis, the performance of this spectrometer achieves a high spatial resolution over the large detection area, which is shown to be limited only by the quality of its optics and their proper alignment within the spatial resolution of a 13 microm x 13 microm pixelated CCD detector. With a 1500 lines/mm grating in first order, the measured spectral resolving power of lambda/Dlambda = 2.5(+/-0.5) x 10(4) allows the clear resolution of the violet Ar(I) doublet at 419.07 and 419.10 nm.

  2. A polycarbonate ophthalmic-prescription lens series.

    Science.gov (United States)

    Davis, J K

    1978-08-01

    Improvements in polycarbonate material, production techniques, and scratch-resistant coatings, combined with a process-oriented design, have resulted in a precision lens series. Surface quality is comparable to that of untreated glass ophthalmic lenses. The repeatability of the process results in closely controlled axial power and off-axis performance. For most lens prescriptions, the ANSI Z80.1 optical-center specifications for prescription accuracy are maintained through a total field of view of 40 deg for an 8-mm range of center-of-rotation distances. Off-axis astigmatism is controlled for near-point seeing. The lenses are both lighter and thinner than those of crown glass. A scratch-resistant coating reduces the reflections normally associated with high-index (1.586) materials. Impact resistance exceeds that required by ANSI Z80.7 and is many times that required by ANSI Z80.1.

  3. Main factors influencing postoperative visual function after refractive cataract surgery%屈光性白内障手术术后影响视觉质量的主要因素

    Institute of Scientific and Technical Information of China (English)

    龚敏; 刘谊

    2014-01-01

    人工晶状体( intraocular lens ,IOL)屈光力计算误差,角膜散光,前房深度以及IOL的位置等因素能导致术眼屈光状态的改变,影响白内障术后的整体视觉质量。我们将对手术过程顺利的屈光性白内障手术术后影响视觉质量的主要因素进行综述。%Factors including intraocular lens power calculation error, corneal astigmatism, anterior chamber depth and lens position can lead to the change of refractive status, they also influence the overall postoperative visual quality.This article provides a comprehensive review of the main factors affecting postoperative visual function after uneventful refractive cataract surgery.

  4. Image processing and analysis using neural networks for optometry area

    Science.gov (United States)

    Netto, Antonio V.; Ferreira de Oliveira, Maria C.

    2002-11-01

    In this work we describe the framework of a functional system for processing and analyzing images of the human eye acquired by the Hartmann-Shack technique (HS), in order to extract information to formulate a diagnosis of eye refractive errors (astigmatism, hypermetropia and myopia). The analysis is to be carried out using an Artificial Intelligence system based on Neural Nets, Fuzzy Logic and Classifier Combination. The major goal is to establish the basis of a new technology to effectively measure ocular refractive errors that is based on methods alternative those adopted in current patented systems. Moreover, analysis of images acquired with the Hartmann-Shack technique may enable the extraction of additional information on the health of an eye under exam from the same image used to detect refraction errors.

  5. Asymptotics of Bayesian error probability and source super-localization in three dimensions.

    Science.gov (United States)

    Prasad, S

    2014-06-30

    We present an asymptotic analysis of the minimum probability of error (MPE) in inferring the correct hypothesis in a Bayesian multi-hypothesis testing (MHT) formalism using many pixels of data that are corrupted by signal dependent shot noise, sensor read noise, and background illumination. We perform our analysis for a variety of combined noise and background statistics, including a pseudo-Gaussian distribution that can be employed to treat approximately the photon-counting statistics of signal and background as well as purely Gaussian sensor read-out noise and more general, exponentially peaked distributions. We subsequently evaluate both the exact and asymptotic MPE expressions for the problem of three-dimensional (3D) point source localization. We focus specifically on a recently proposed rotating-PSF imager and compare, using the MPE metric, its 3D localization performance with that of conventional and astigmatic imagers in the presence of background and sensor-noise fluctuations.

  6. Spatial shaping for generating arbitrary optical dipoles traps for ultracold degenerate gases

    CERN Document Server

    Lee, Jeffrey G

    2014-01-01

    We present two spatial-shaping approaches -- phase and amplitude -- for creating two-dimensional optical dipole potentials for ultracold neutral atoms. When combined with an attractive or repulsive Gaussian sheet formed by an astigmatically focused beam, atoms are trapped in three dimensions resulting in planar confinement with an arbitrary network of potentials -- a free-space atom chip. The first approach utilizes an adaptation of the generalized phase-contrast technique to convert a phase structure embedded in a beam after traversing a phase mask, to an identical intensity profile in the image plane. Phase masks, and a requisite phase-contrast filter, can be chemically etched into optical material (e.g., fused silica) or implemented with spatial light modulators; etching provides the highest quality while spatial light modulators enable prototyping and realtime structure modification. This approach was demonstrated on an ensemble of thermal atoms. Amplitude shaping is possible when the potential structure ...

  7. Corneal collagen crosslinking: a systematic review.

    Science.gov (United States)

    Sorkin, Nir; Varssano, David

    2014-01-01

    Keratoconus (KCN) is an ectatic disorder with progressive corneal thinning and a clinical picture of corneal protrusion, progressive irregular astigmatism, corneal fibrosis and visual deterioration. Other ectatic corneal disorders include: post-LASIK ectasia (PLE) and pellucid marginal degeneration (PMD). Corneal crosslinking (CXL) is a procedure whereby riboflavin sensitization with ultraviolet A radiation induces stromal crosslinks. This alters corneal biomechanics, causing an increase in corneal stiffness. In recent years, CXL has been an established treatment for the arrest of KCN, PLE and PMD progression. CXL has also been shown to be effective in the treatment of corneal infections, chemical burns, bullous keratopathy and other forms of corneal edema. This is a current review of CXL - its biomechanical principles, the evolution of CXL protocols in the past, present and future, indications for treatment, treatment efficacy and safety.

  8. Impact of primary aberrations on coherent lidar performance

    DEFF Research Database (Denmark)

    Hu, Qi; Rodrigo, Peter John; Iversen, Theis Faber Quist;

    2014-01-01

    In this work we investigate the performance of a monostatic coherent lidar system in which the transmit beam is under the influence of primary phase aberrations: spherical aberration (SA) and astigmatism. The experimental investigation is realized by probing the spatial weighting function...... of the lidar system using different optical transceiver configurations. A rotating belt is used as a hard target. Our study shows that the lidar weighting function suffers from both spatial broadening and shift in peak position in the presence of aberration. It is to our knowledge the first experimental...... effciency, the optimum truncation of the transmit beam and the spatial sensitivity of a CW coherent lidar system. Under strong degree of aberration, the spatial confinement is significantly degraded. However for SA, the degradation of the spatial confinement can be reduced by tuning the truncation...

  9. Traceable interferometry using binary reconfigurable holograms.

    Science.gov (United States)

    Cashmore, M T; Hall, S R G; Love, G D

    2014-08-20

    We describe the characterization of a ferroelectric-liquid-crystal-on-silicon (FLCOS) spatial light modulator (SLM) in the production of holograms for use in interferometric metrology. It has already been shown that such a device can be used in producing small-amplitude arbitrary reference surfaces with small but appreciable errors due to the contaminating effect of higher-order structures being propagated through the spatial filter. Here we further quantify the size of these residuals for increasingly large aberrations up to nine waves rms Zernike astigmatism, showing a Zernike-corrected rms wavefront error of roughly 0.06 waves with high vibrational stability. We also present measurements of a vacuum window element using the FLCOS device to drastically reduce interferometric fringe density, showing a residual wavefront error of 0.046 waves rms with dominant components originating from test piece structure rather than holographic errors.

  10. Toric implantable collamer lens for keratoconus

    Directory of Open Access Journals (Sweden)

    Mathew Kurian Kummelil

    2013-01-01

    Full Text Available Keratoconus is a progressive non-inflammatory thinning of the cornea that induces myopia and irregular astigmatism and decreases the quality of vision due to monocular diplopia, halos, or ghost images. Keratoconus patients unfit for corneal procedures and intolerant to refractive correction by spectacles or contact lenses have been implanted toric posterior chamber phakic intraocular lenses (PC pIOLs alone or combined with other surgical procedures to correct the refractive errors associated with keratoconus as an off label procedure with special informed consent from the patients. Several reports attest to the safety and efficacy of the procedure, though the associated corneal higher order aberrations would have an impact on the final visual quality.

  11. Contact lens fitting in a patient with Alport syndrome and posterior polymorphous corneal dystrophy: a case report

    Directory of Open Access Journals (Sweden)

    Juliana Maria da Silva Rosa

    2016-02-01

    Full Text Available ABSTRACT Alport Syndrome is a hereditary disease that is caused by a gene mutation and affects the production of collagen in basement membranes; this condition causes hemorrhagic nephritis associated with deafness and ocular changes. The X-linked form of this disease is the most common and mainly affects males. Typical ocular findings are dot-and-fleck retinopathy, anterior lenticonus, and posterior polymorphous corneal dystrophy. Some cases involving polymorphous corneal dystrophy and corneal ectasia have been previously described. Here we present a case report of a 33-year-old female with Alport syndrome, posterior polymorphous corneal dystrophy, and irregular astigmatism, whose visual acuity improved with a rigid gas permeable contact lens.

  12. Research on the Human Visual Indicators of Computer-Controlled Intelligence Acquisition System%人体视力指标计算机智能采集系统研究

    Institute of Scientific and Technical Information of China (English)

    邢紫阳; 李明东; 彭鼎

    2010-01-01

    依据视力采集标准,结合计算机自动控制的特点,研究并分析了计算机智能采集系统的可行性及其测法推算.该系统可以采集到较真实、可靠的近视力值,能对色盲、色弱、散光进行鉴定,采集效率极高.%Based on the national standard about visual and the characteristics of computer automatic control , research and analysis of the human visual indicators of computer-controlled intelligence acquisition system and its measurement method have been studied. We can get a more realistic and reliable values of near sight and also can identify the color-blind and astigmatism with a high efficiency.

  13. Detection of acrolein and acrylonitrile with a pulsed room temperature quantum cascade laser

    Science.gov (United States)

    Manne, J.; Jäger, W.; Tulip, J.

    2010-06-01

    We investigated the use of a pulsed, distributed feedback quantum cascade laser centered at 957 cm-1 in combination with an astigmatic Herriot cell with 250 m path length for the detection of acrolein and acrylonitrile. These molecules have been identified as hazardous air-pollutants because of their adverse health effects. The spectrometer utilizes the intra-pulse method, where a linear frequency down-chirp, that is induced when a top-hat current pulse is applied to the laser, is used for sweeping across the absorption line. Up to 450 ns long pulses were used for these measurements which resulted in a spectral window of ~2.2 cm-1. A room temperature mercury-cadmium-telluride detector was used, resulting in a completely cryogen free spectrometer. We demonstrated detection limits of ~3 ppb for acrylonitrile and ~6 ppb for acrolein with ~10 s averaging time. Laser characterization and optimization of the operational parameters for sensitivity improvement are discussed.

  14. Effects of Turbulent Aberrations on Probability Distribution of Orbital Angular Momentum for Optical Communication

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-Xin; CANG Ji

    2009-01-01

    Effects of atmospheric turbulence tilt, defocus, astigmatism and coma aberrations on the orbital angular mo-mentum measurement probability of photons propagating in weak turbulent regime are modeled with Rytov approximation. By considering the resulting wave as a superposition of angular momentum eigenstates, the or-bital angular momentum measurement probabilities of the transmitted digit axe presented. Our results show that the effect of turbulent tilt aberration on the orbital angular momentum measurement probabilities of photons is the maximum among these four kinds of aberrations. As the aberration order increases, the effects of turbulence aberrations on the measurement probabilities of orbital angular momentum generally decrease, whereas the effect of turbulence defoens can be ignored. For tilt aberration, as the difference between the measured orbital angular momentum and the original orbital angular momentum increases, the orbital angular momentum measurement probabifity decreases.

  15. [Comparison of clinical results between LASIK method and ICL implantation in high myopia].

    Science.gov (United States)

    Hrubá, H; Vlková, E; Horácková, M; Svacinová, J

    2004-05-01

    In a retrospective study the authors evaluate clinical results of the LASIK (laser in situ keratomileusis) and the implantation of the implantable posterior chamber contact lens phakic IOL (ICL) (STAAR Surgical) to correct high myopia. The purpose of the study was to assess which of those two methods is more reliable in patients to correct myopia in the range -10.0 to -23.0 diopters. The LASIK method was presented of a group of 70 eyes of 48 patients with preoperative spherical equivalent average of -12.9 +/- 3.8 diopters (Dsf) and average astigmatism of -0.99 +/- 1.2 cylindrical diopters (Dcyl). The group was divided into two parts: one part was with the desired postoperative emmetropia--46 eyes (65.7%), and part two was with the desired postoperative residual myopia up to -3.0 Dsf--24 eyes (34.3%). The method of ICL implantation was presented of a group of 36 eyes of 21 patients with preoperative spherical equivalent average of -15.21 +/- 4.0 Dsf and average astigmatism of -0.92 +/- 0.69 Dcyl. Also this group was divided into two parts: One part was with the desired postoperative emmetropia--25 eyes (69.4%), and part two was with the desired postoperative residual myopia up to -3.0 Dsf--11 eyes (30.6%). The developments of postoperative refraction in time (1 week to 3 years after the surgery), the final postoperative refraction and its stability and (6 months to 3 years after the surgery) as well as the occurrence of complications in both studied groups were evaluated. In the assessment of the postoperative refraction development in groups of desired emmetropia, the average uncorrected visual acuity (UCVA), average postoperative spherical equivalent and astigmatism were evaluated. In the groups with desired residual myopia the average best-corrected visual acuity (BCVA), average postoperative spherical equivalent, and astigmatism were followed. Three years after the surgery in groups with desired emmetropia, the average postoperative spherical equivalent was -0

  16. Recent Results from the IR Upgrade FEL at Jefferson Lab

    CERN Document Server

    Benson, S V; Behre, C P; Biallas, G H; Boyce, J; Douglas, D; Dylla, H F D; Evans, R; Grippo, A G; Gubeli, J G; Hardy, D; Hernandez-Garcia, C; Jordan, K; Merminga, L; Neil, G; Preble, J P; Shinn, M D; Siggins, T; Walker, R L; Williams, G P; Zhang, S

    2005-01-01

    After demonstrating 10 kW operation with 1 second pulses, the Jefferson Lab program switched to demonstrating high power operation at short wavelengths using a new 8 cm period wiggler and a THz suppression chicane. We report here on the lasing results to date using this new configuration. We have demonstrated a large reduction in THz heating on the mirrors. We have also eliminated heating in the mirror steering assemblies, making operation at high power much more stable. Finally, we have greatly reduced astigmatism in the optical cavity, allowing operation with a very short Rayleigh range. The laser has been tuned from 0.9 to 3.1 microns using the new wiggler. User experiments commenced in April of 2005 with the FEL Upgrade operating over the 1-3 micron range. We are in the process of installing a 5.5 cm permanent magnet wiggler that will give us even larger tuning range and higher power.

  17. Application study of skiascopie in screening and diagnosis of suspected keratoconus%检影验光在圆锥角膜筛查与诊断中的应用研究

    Institute of Scientific and Technical Information of China (English)

    刘博; 郑志刚; 方燕

    2012-01-01

    [Objective] To evaluate the diagnostic accuracy of skiascopie for suspected keratoconus. [Methods] Abnormal photokinesis of pupil area of the patients with suspected keratoconus were obtained by skiascopie, compared with the results of comeal topography and selected during November 2008 to November 2011. Any discrepancies of the results of the two methods were then analyzed. [ Results ] The results of 53 eyes of 32 patients with suspected keratoconus were diagnosed by skiascopie, and were accordant in 27 patients (43 eyes) by comeal topography and inconsistent in 5 patients (10 eyes) due to the interference of abnormal photokinesis which caused by the high myopia and myopic astigmatism, irregular astigmatism. In the 11 eyes with not suspected keratoconus were diagnosed by skiascopie, 4 eyes were accordant by corneal topography. The main reason due to the interference of mild pattern and located in the peripheral cornea, low astigmatism, so abnormal photokinesis is not obvious. [ Conclusion ] The abnormal photokinesis of skiascopie reflects the main features of the keratoconus, therefore it can be a valuable screening and diagnosis method for keratoconus, especially in the situation that corneal topography difficult to achieve the screening of high myopia and astigmatism population.%[目的]探讨分析利用检影验光在筛查与诊断圆锥角膜中的准确性.[方法]收集2008年11月-2011年11月期间利用检影验光观察瞳孔区影动形态异常方法诊断为疑似圆锥角膜病例32例53只眼,经角膜地形图仪检查明确诊断是否相符,并对诊断不符合病例进行分析.[结果]检影验光筛查诊断为疑似圆锥角膜32例53只眼中,经角膜地形图仪确诊圆锥角膜27例43只眼,不符合5例10只眼,不符合的主要原因为高度近视与散光,高度不规则散光引起的异常检影影动干扰所致.检影验光未诊断为疑似圆锥角膜的11只眼中,经角膜地形图仪确诊圆锥角膜4只眼,不符合

  18. Towards quantitative off-axis electron holographic mapping of the electric field around the tip of a sharp biased metallic needle

    Energy Technology Data Exchange (ETDEWEB)

    Beleggia, M. [Center for Electron Nanoscopy, Technical University of Denmark, Kongens Lyngby (Denmark); Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin (Germany); Kasama, T. [Center for Electron Nanoscopy, Technical University of Denmark, Kongens Lyngby (Denmark); Larson, D. J.; Kelly, T. F. [CAMECA Instruments, Inc., Madison, Wisconsin 53711 (United States); Dunin-Borkowski, R. E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungzentrum Jülich, Jülich (Germany); Pozzi, G. [Department of Physics and Astronomy, University of Bologna, Bologna (Italy)

    2014-07-14

    We apply off-axis electron holography and Lorentz microscopy in the transmission electron microscope to map the electric field generated by a sharp biased metallic tip. A combination of experimental data and modelling provides quantitative information about the potential and the field around the tip. Close to the tip apex, we measure a maximum field intensity of 82 MV/m, corresponding to a field k factor of 2.5, in excellent agreement with theory. In order to verify the validity of the measurements, we use the inferred charge density distribution in the tip region to generate simulated phase maps and Fresnel (out-of-focus) images for comparison with experimental measurements. While the overall agreement is excellent, the simulations also highlight the presence of an unexpected astigmatic contribution to the intensity in a highly defocused Fresnel image, which is thought to result from the geometry of the applied field.

  19. Infantile nystagmus and visual deprivation

    DEFF Research Database (Denmark)

    Fledelius, Hans C; Jensen, Hanne

    2014-01-01

    PURPOSE: To evaluate whether effects of early foveal motor instability due to infantile nystagmus might compare to those of experimental visual deprivation on refraction in a childhood series. METHODS: This was a retrospective analysis of data from the Danish Register for Blind and Weaksighted...... Children with infantile nystagmus recorded as prime diagnosis. We perused 90 records of children now aged 10-17 years, some of whom eventually exceeded the register borderline of 0.3 as best-corrected visual acuity. Spherical equivalent refraction was the primary outcome parameter, but visual acuity......, astigmatism, and age were further considered. The series comprised 48 children with nystagmus as single diagnosis, whereas 42 had clinical colabels (Down syndrome [13], dysmaturity [9], and mental retardation, encephalopathy [20]). RESULTS: Median binocular visual acuity was 0.3 in the full series, and median...

  20. QCL-based TDLAS sensor for detection of NO toward emission measurements from ovarian cancer cells

    Science.gov (United States)

    Köhring, M.; Huang, S.; Jahjah, M.; Jiang, W.; Ren, W.; Willer, U.; Caneba, C.; Yang, L.; Nagrath, D.; Schade, W.; Tittel, F. K.

    2014-10-01

    The development of a sensitive sensor for detecting nitric oxide (NO) emissions from biological samples is reported. The sensor is based on tunable diode laser absorption spectroscopy (TDLAS) using a continuous wave, thermoelectrically cooled quantum cascade laser (QCL) and a 100-m astigmatic Herriot cell. A 2 f-wavelength modulation spectroscopy technique was used to obtain QCL-based TDLAS NO emission measurements with an optimum signal-to-noise ratio. An absorption line at 1,900.076 cm-1 was targeted to measure NO with a minimum detection limit of 124 ppt. Positive control measurements with the NO donor DETA NONOate were performed to determine and optimize the sensor performance for measurements of biological samples. Our measurements with NO donor show the potential suitability of the sensor for monitoring NO emission from cancer cells for biological investigations.

  1. Corneal Topographical Changes Flollowing Strabismus Surgery

    Institute of Scientific and Technical Information of China (English)

    MaiGH; WangZ

    1999-01-01

    Purpose:To study corneal topographical changes after strabismus surgery.Methods:Computer-aided corneal topography was used in 43 strabismus patients(45 eyes)one or two days prior to and six or seven ays after strabismus surgery.The spherical and cylindrical equivalents were calculated based on the simulated keratometry.Results:After the surgery,only the changes at 3mm in the inferior quadrant were statistically significant.The changes at 3mm in the rest quadrants and the changes at 7mm were no significant.Significant changes in spherical equivalent were found post-operatively.neither the horizontal nor the verical meridional equivalent showed significant changes after surgery.Conclusions:The results of corneal topographical changes following strabismus surgery in our preliminary study indicated the little effect of strabismus surgery on corneal curvature and corneal astigmatism.

  2. 三种仪器测量角膜曲率的准确性比较%Compare the accuracy of corneal curvature measured by three instruments

    Institute of Scientific and Technical Information of China (English)

    陈文静; 张瑞智; 袁晓成

    2016-01-01

    目的 比较手动角膜曲率计、电脑自动验光仪、角膜地形图仪三种仪器测量角膜曲率结果的准确性,指导白内障术前测量应用.方法 仪器应用对照研究.对2014年12月至2015年4月在武清区人民医院眼科应用三种仪器分别测量拟实施白内障超声乳化及人工晶状体植入术的患者140例(140只眼)的最大、最小及平均角膜屈光力,应用电脑自动验光仪和角膜地形图仪测量角膜散光值及散光轴位,使用SPSS 20.0软件对所测参数进行统计学分析比较.结果 三种仪器测得的最大、最小及平均角膜屈光力对比差异无统计学意义(P>0.05),电脑自动验光仪和角膜地形图仪测得的角膜散光值对比差异无统计学意义(P>0.05),散光轴位对比差异有统计学意义(P<0.05).结论 三种仪器测量角膜曲率的准确性较好,均适用于白内障术前测量.%Objective To compare the accuracy of three types of keratometry:manual keratometer,auto-refractometer and corneal topography for measurement the corneal curvature.Methods Totally 140 eyes of maximum corneal refractive power,the minimum comeal refractive power and the mean corneal refractive power were measured by three different types of keratometry before cataract surgery.Corneal astigmatism degree and the axis value of corneal astigmatism by auto-refractometer and corneal topography were measured.All values were analyzed by SPSS 20.0.Results There was no significant difference in the maximum corneal refractive power,the minimum corneal refractive power and the mean corneal refractive power by three different types of keratometry (P >0.05).There was no significant difference in measuring comeal astigmatism degree (P >0.05).However,there was significant difference in measuring of the axis values of corneal astigmatism (P <0.05).Conclusions The accuracy of corneal curvature measured by different types of keratometry is good,all can be used before cataract

  3. Congenital keratoglobus with blue sclera in two siblings with overlapping Marshall/Stickler phenotype

    Directory of Open Access Journals (Sweden)

    Serhat Imamoglu

    2016-01-01

    Full Text Available We aimed to describe congenital keratoglobus with blue sclera in two siblings with overlapping Marshall/Stickler phenotype. Two sisters (ages four and six with bilateral high astigmatism were evaluated by slit-lamp microscopy. Corneal topography and pachymetry maps were also obtained. Slit-lamp examination revealed that both corneas were globular in shape with peripheral corneal thinning. Pachymetry maps showed diffuse corneal thinning. Two siblings had in common the features of keratoglobus, blue sclera, atypical face, hearing loss, and hypermobile joints. We tentatively diagnosed the sisters as having an overlapping Marshall-Stickler phenotype based on clinical and radiological findings. Marshall-Stickler syndrome may exist in the differential diagnosis of keratoglobus with blue sclera.

  4. Corneal topographic changes after 20-gauge pars plana vitrectomy associated with scleral buckling for the treatment of rhegmatogenous retinal detachment

    Directory of Open Access Journals (Sweden)

    Alexandre Achille Grandinetti

    2013-04-01

    Full Text Available PURPOSE: To evaluate the changes in corneal topography after 20-gauge pars plana vitrectomy associated with scleral buckling for the repair of rhegmatogenous retinal detachment. METHODS: Twenty-five eyes of 25 patients with rhegmatogenous retinal detachment were included in this study. 20-gauge pars plana vitrectomy associated with scleral buckling was performed in all patients. The corneal topography of each was measured before surgery and one week, one month, and three months after surgery by computer-assisted videokeratoscopy. RESULTS: A statistically significant central corneal steepening (average, 0,9 D , p<0,001 was noted one week after surgery. The total corneal astigmatism had a significant increase in the first postoperative month (p=0,007. All these topographic changes persisted for the first month but returned to preoperative values three months after the surgery. CONCLUSION: Pars plana vitrectomy with scleral buckling was found to induce transient changes in corneal topography.

  5. 手术切口大小对白内障术后视力和角膜的影响%The influence of operation incision size on postoperative visual acuity and cornea in cataract patients

    Institute of Scientific and Technical Information of China (English)

    江晓琴; 蔡方荣

    2012-01-01

      目的研究手术切口大小对白内障术后视力和角膜的影响.方法将患者分成A、B两个组后,均使用卡尔•蔡司手术显微镜(Carl Zeiss Stativ S88)和美国爱尔康白内障超声乳化仪(Alcon Infiniti Vision System),分别对两组患者进行3.5毫米透明角膜切口和6毫米反眉弓形巩膜隧道切口白内障超声乳化术628眼和336眼,然后用多美Tomey角膜地形图仪TMS-4对患者角膜形态参数进行计算分析.结果 A、B两组患者在术后7天时角膜散光度有较明显差异,3.5毫米角膜组于术后30天起无明显差异,6毫米巩膜组于术后90天才没有明显差异.术后30天,角膜组的散光度数低于巩膜组散光度数.术后7天角膜组SRI值要明显低于巩膜组,而SAI值却无组间差异.两组术后7天时,SAI及SRI值均高于术前水平,90天时恢复至术前水平.结论实施3.5毫米透明角膜切口超声乳化术效果较好,术后患者视力和散光恢复较快,角膜形态改变较小.%  Objective:To study the influence of operation incision size on postoperative visual acuity and cornea in cataract patients. METHODS:The patients were divided into A and B groups, using Carle Zeiss Stativ S88 operation microscope and American Alcon Infiniti Vision System, respectively for the two groups of patients by 3.5mm clear corneal incision and 6mm anti superciliary arch sclera tunnel incision phacoemulsification in 628 eyes and 336 eyes, and then use Tomey TMS-4 in patients with corneal topography corneal morphology parameters were calculated and analyzed. RESULTS:7 days later,A and B two group patients’s corneal astigmatism are obviously different, 3.5 mm corneal group on the 30 postoperative day without obvious difference, 6 mm scleral group from postoperative 90 days did not differ significantly. 30 days later, the degree of astigmatism corneal group below the scleral group astigmatism. 7 days later , corneal group’s SRI value was lower than the scleral

  6. Optical coherence tomography-based topography determination of corneal grafts in eye bank cultivation

    Science.gov (United States)

    Damian, Angela; Seitz, Berthold; Langenbucher, Achim; Eppig, Timo

    2017-01-01

    Vision loss due to corneal injuries or diseases can be treated by transplantation of human corneal grafts (keratoplasty). However, quality assurance in retrieving and cultivating the tissue transplants is confined to visual and microbiological testing. To identify previous refractive surgery or morphological alterations, an automatic, noncontact, sterile screening procedure is required. Twenty-three corneal grafts have been measured in organ culture with a clinical spectral-domain optical coherence tomographer. Employing a biconic surface fit with 10 degrees of freedom, the radii of curvature and conic constants could be estimated for the anterior and posterior corneal surfaces. Thereupon, central corneal thickness, refractive values, and astigmatism have been calculated. Clinical investigations are required to elaborate specific donor-host matching in the future.

  7. Femtosecond laser enabled keratoplasty for advanced keratoconus

    Directory of Open Access Journals (Sweden)

    Yathish Shivanna

    2013-01-01

    Full Text Available Purpose : To assess the efficacy and advantages of femtosecond laser enabled keratoplasty (FLEK over conventional penetrating keratoplasty (PKP in advanced keratoconus. Materials and Methods: Detailed review of literature of published randomized controlled trials of operative techniques in PKP and FLEK. Results: Fifteen studies were identified, analyzed, and compared with our outcome. FLEK was found to have better outcome in view of better and earlier stabilization uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA, and better refractive outcomes with low astigmatism as compared with conventional PKP. Wound healing also was noticed to be earlier, enabling early suture removal in FLEK. Conclusions: Studies relating to FLEK have shown better results than conventional PKP, however further studies are needed to assess the safety and intraoperative complications of the procedure.

  8. Ultrastructural morphology of the male and female genital tracts of Psoroptes spp. (Acari: Astigmata: Psoroptidae).

    Science.gov (United States)

    Lekimme, Mireille; Leclercq-Smekens, Michèle; Devignon, Chantal; Leclipteux, Thierry; Poumay, Yves; Losson, Bertrand

    2005-01-01

    The structure of the male and female genital systems of the astigmatid mite Psoroptes ovis (Hering) is described. The male genital system is composed of a paired testis, fused at its proximal part, two vasa deferentia, an ejaculatory duct, into which a single accessory gland opens, and a copulatory organ. The testis is characterized by a peripheric syncytial cell surrounding spermatogonia, spermatocytes, spermatids and spermatozoa which are distributed regularly in the gonad according to the sequence of spermatogenesis. The female genital system consists of a copulatory pore (the bursa copulatrix), a seminal receptacle, paired ovaries and oviducts, a glandular uterus and an ovipositor which leads to the oviporus. Ovaries are composed of somatic cells, germ cells and a central cell, with a multilobular nucleus, connected to oocytes by a stalk. Similarities with other astigmatic mites belonging to Psoroptidia and Acaridia are also discussed.

  9. Study of X-ray Kirkpatrick-Baez imaging with single layer

    Institute of Scientific and Technical Information of China (English)

    Baozhong Mu; Zhanshan Wang; Shengzhen Yi; Xin Wang; Shengling Huang; Jingtao Zhu; Chengchao Huang

    2009-01-01

    The X-ray Kirkpatrick-Baez(KB)imaging experiment with single layer is implemented.Based on the astigmatism aberration and residual geometric aberration of a single mirror.a KB system with 16x mean magnification and approxinlately 0.45° grazing incidence angle is designed.The mirrors are deposited with an Ir layer of 20-nm thickness.Au grids backlit by X-ray tube of 8 keV are imaged via the KB system on scintillator charge-coupled device(CCD).In the ±80 μm field,resolutions of less than 5 μm are measured.The result is in good agreenmnt with the simulated imaging.

  10. Adaptive compensation of a direct liquid-cooled solid-state MOPA system

    Science.gov (United States)

    Dong, Lizhi; Chen, Shanqiu; Chen, Xiaojun; Liu, Wenjin; Hu, Ke; Lai, Boheng; Yang, Ping; Wang, Shuai; He, Xing; Xu, Bing; Liu, Le; Liu, Yang; Wang, Zhe; Wang, Gang

    2016-09-01

    Direct liquid-cooling is a promising way of power scaling and heat management for solid-state lasers. A side-pumped direct liquid-cooled solid-state pulsed zigzag MOPA system is established based on this advanced concept. However, its beam quality is degraded by the thermal distortions in the non-zigzag direction and the flowing coolant. We develop an adaptive optics system to improve its beam quality, which primarily includes a low-order aberration compensator and a 59-actuator deformable mirror. The beam is first corrected by the low-order aberration compensator to remove large defocus and astigmatism, and its size is reshaped simultaneously to fulfill the demands of applications. Then the beam is further corrected by the deformable mirror. With collaborative operation of the low-order aberration compensator and the deformable mirror, we have achieved average beam quality of β=2.8.

  11. Incidência das ametropias no Hospital Universitário em Campo Grande (MS entre 1996 e 1998 Incidence of ametropias in the University Hospital of Campo Grande (MS between 1996 and 1998

    Directory of Open Access Journals (Sweden)

    Eduardo Velasco de Barros

    2000-06-01

    Medical Files (SAME was carried out, applying a research protocol to 2,361 charts of patients presenting some type of ametropia who were attended at the NHU between 1996 and 1998, with information on sex, age and type of ametropia (myopia, hyperopia, astigmatism or presbyopia. The data were analyzed and discussed. Results: There was prevalence of females (60% in all cases of ametropia, the greatest number of attended people being patients with presbyopia (987 cases, followed by hyperopia (701, myopia (434 and astigmatism (239. Myopia was present mostly in the age range of 20 to 29 years, hyperopia between 0 and 9 years and astigmatism between 10 and 39 years, while the highest incidence of presbyopia was in the age range over 40 years. Conclusion: The number of female patients is higher than that of males, even considering each ametropia separately. Some hypotheses are proposed. Myopia is more frequent at ages between 10 and 39 years. Hyperopia occurs more frequently in children and newborns, tending to decrease with age because of eyeball increase. Astigmatism was characterized as a defect occurring in adolescents and young adults. Presbyopia was the commonest refraction error and its incidence occurred in the age range over 40 years, similarly to data found in the literature.

  12. Endothelial keratoplasty: evolution and horizons

    Directory of Open Access Journals (Sweden)

    Gustavo Teixeira Grottone

    2012-12-01

    Full Text Available Endothelial keratoplasty has been adopted by corneal surgeons worldwide as an alternative to penetrating keratoplasty (PK in the treatment of corneal endothelial disorders. Since the first surgeries in 1998, different surgical techniques have been used to replace the diseased endothelium. Compared with penetrating keratoplasty, all these techniques may provide faster and better visual rehabilitation with minimal change in refractive power of the transplanted cornea, minimal induced astigmatism, elimination of suture-induced complications and late wound dehiscence, and a reduced demand for postoperative care. Translational research involving cell-based therapy is the next step in work on endothelial keratoplasty. The present review updates information on comparisons among different techniques and predicts the direction of future treatment.

  13. Adaptive control of modal properties of optical beams using photothermal effects.

    Science.gov (United States)

    Arain, Muzammil A; Korth, William Z; Williams, Luke F; Martin, Rodica M; Mueller, Guido; Tanner, D B; Reitze, David H

    2010-02-01

    We present an experimental demonstration of adaptive control of modal properties of optical beams. The control is achieved via heat-induced photothermal actuation of transmissive optical elements. We apply the heat using four electrical heaters in thermal contact with the element. The system is capable of controlling both symmetrical and astigmatic aberrations providing a powerful means for in situ correction and control of thermal aberrations in high power laser systems. We demonstrate a tunable lens with a focusing power varying from minus infinity to -10 m along two axes using SF57 optical glass. Applications of the proposed system include laser material processing, thermal compensation of high laser power radiation, and optical beam steering.

  14. Quantitative analysis of transformed ray transferences of optical systems in a space of augmented Hamiltonian matrices*

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2007-01-01

    Full Text Available There is a need for methods for quantitative analysis of the first-order optical character of optical systems including the eye and components of the eye.  Because of their symplectic nature ray transferences themselves are not closed under addition and multiplication by ascalar and, hence, are not amenable to conventional quantitative analysis such as the calculation of an arithmetic mean.  However transferences can be transformed into augmented Hamiltonian matrices which are amenable to such analysis.  This paper provides a general methodology and in particular shows how to calculate means and variance-covariances representing the first-order optical character of optical systems.  The systems may be astigmatic and may have decentred elements.  An accompanying paper shows application to the cornea of the human eye with allowance for thickness.

  15. Polyplanar optic display

    Energy Technology Data Exchange (ETDEWEB)

    Veligdan, J.; Biscardi, C.; Brewster, C.; DeSanto, L. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology; Beiser, L. [Leo Beiser Inc., Flushing, NY (United States)

    1997-07-01

    The Polyplanar Optical Display (POD) is a unique display screen which can be used with any projection source. This display screen is 2 inches thick and has a matte black face which allows for high contrast images. The prototype being developed is a form, fit and functional replacement display for the B-52 aircraft which uses a monochrome ten-inch display. The new display uses a 100 milliwatt green solid state laser (532 nm) as its optical source. In order to produce real-time video, the laser light is being modulated by a Digital Light Processing (DLP{trademark}) chip manufactured by Texas Instruments, Inc. A variable astigmatic focusing system is used to produce a stigmatic image on the viewing face of the POD. In addition to the optical design, the authors discuss the electronic interfacing to the DLP{trademark} chip, the opto-mechanical design and viewing angle characteristics.

  16. Laser-driven polyplanar optic display

    Energy Technology Data Exchange (ETDEWEB)

    Veligdan, J.T.; Biscardi, C.; Brewster, C.; DeSanto, L. [Brookhaven National Lab., Upton, NY (United States). Dept. of Advanced Technology; Beiser, L. [Leo Beiser Inc., Flushing, NY (United States)

    1998-01-01

    The Polyplanar Optical Display (POD) is a unique display screen which can be used with any projection source. This display screen is 2 inches thick and has a matte-black face which allows for high contrast images. The prototype being developed is a form, fit and functional replacement display for the B-52 aircraft which uses a monochrome ten-inch display. The new display uses a 200 milliwatt green solid-state laser (532 nm) as its optical source. In order to produce real-time video, the laser light is being modulated by a Digital Light Processing (DLP) chip manufactured by Texas Instruments, Inc. A variable astigmatic focusing system is used to produce a stigmatic image on the viewing face of the POD. In addition to the optical design, the authors discuss the DLP chip, the optomechanical design and viewing angle characteristics.

  17. Fator de correção para indivíduos com capacidade acomodativa baseado no uso do refrator automático Correction factor for individuals with accommodative capacity based on automated refractor

    Directory of Open Access Journals (Sweden)

    Rodrigo Ueno Takahagi

    2009-12-01

    values with and without cycloplegy effect according to age. RESULTS: The correlation between the astigmatism diopter values with and without cicloplegy ranged from 81.52% to 92.27%. Analyzing the spherical diopter values, the correlation was lower (53.57% to 87.78%. The astigmatism axis also revealed low correlation values (28.86% to 58.80%. The multiple regression model according to age demonstrated multiple determination coefficient with high values for myopia (86.38% and astigmatism (79.79%. The lowest multiple determination coefficient was observed for astigmatism axis (17.70%. CONCLUSION: It was possible to demonstrate a high correlation in refractive errors with and without cycloplegy effect on the cylindrical ametropies. Mathematical formules, for cylindrical and spherical ametropies, were presented as a correction factor for refraction of the patients not submitted to cycloplegy.

  18. 像差对星间相干光通信接收系统误码性能的影响%Effect of Aberration on Performance of the Bit Error Rate in an Inter-Satellite Coherent Optical Communication Receiving System

    Institute of Scientific and Technical Information of China (English)

    刘宏展; 纪越峰; 刘立人

    2012-01-01

    Based on the space optical communication link equation, it is given in detail that the signal-to-noise ratio (SNR) equations for the inter-satellite coherent optical communication receiving system (ISCOCRS) with different aberrations. With communication distance for 60000 km, transmission rate of 2 Gb/s binary phase shift keying (2PSK) homodyne geosynchronous orbit receiving system as an example, through numerical simulation, the effect of the tilt, defocusing, coma and astigmatism aberrations on the bit error ratio(BER) of the ISCOCRS is compared systematically. The simulation results show that effect of the tilt aberration is the BER is more seriously than the astigmatism when the different aberrations influence the ISCOCRS individually, at the same time, the different aberrations can be partly corrected by another when they effect mutually, Which leads to the lower BER. With the BER more than 10~6 as standard, through adjusting the tilt, the coma can be partly corrected when the normalized coma is more than 1. 00, and adjusting the defocusing can partly correct the astigmatism when the normalized astigmatism is more than 0. 53. Therefore, the aberrations' influence should be overlooked in the process ofdesigning the ISCOCRS. These results provide some theoretic basis for the ISCOCRS.%以空间链路方程为基础,详细推导了具有不同像差时的星间相干光通信接收系统信噪比表达式.以通信距离为60000 km、速率为2 Gb/s的2PSK零差同步轨道接收系统为例,通过数值仿真,全面比较了接收天线的倾斜、离焦、彗差和像散等像差对接收系统误码率(εBER)的影响.结果表明,不同像差单独作用时,倾斜像差的影响最大,象散的影响最小;不同像差相互作用时,它们中的某些能部分实现相互校正,从而降低误码率.以εBER≤10-6为比较标准,当彗差W31/λ≤1.00时,调整倾斜像差能实现它们之间的部分校正;当像散W22/λ≤0.53时,调整离焦能对

  19. Optical tweezers absolute calibration

    CERN Document Server

    Dutra, R S; Neto, P A Maia; Nussenzveig, H M

    2014-01-01

    Optical tweezers are highly versatile laser traps for neutral microparticles, with fundamental applications in physics and in single molecule cell biology. Force measurements are performed by converting the stiffness response to displacement of trapped transparent microspheres, employed as force transducers. Usually, calibration is indirect, by comparison with fluid drag forces. This can lead to discrepancies by sizable factors. Progress achieved in a program aiming at absolute calibration, conducted over the past fifteen years, is briefly reviewed. Here we overcome its last major obstacle, a theoretical overestimation of the peak stiffness, within the most employed range for applications, and we perform experimental validation. The discrepancy is traced to the effect of primary aberrations of the optical system, which are now included in the theory. All required experimental parameters are readily accessible. Astigmatism, the dominant effect, is measured by analyzing reflected images of the focused laser spo...

  20. Form vision in the insect dorsal ocelli: an anatomical and optical analysis of the dragonfly median ocellus.

    Science.gov (United States)

    Berry, Richard P; Stange, Gert; Warrant, Eric J

    2007-05-01

    Previous work has suggested that dragonfly ocelli are specifically adapted to resolve horizontally extended features of the world, such as the horizon. We investigate the optical and anatomical properties of the median ocellus of Hemicordulia tau and Aeshna mixta to determine the extent to which the findings support this conclusion. Dragonfly median ocelli are shown to possess a number of remarkable properties: astigmatism arising from the elliptical shape of the lens is cancelled by the bilobed shape of the inner lens surface, interference microscopy reveals complex gradients of refractive index within the lens, the morphology of the retina results in zones of high acuity, and the eye has an exceedingly high sensitivity for a diurnal terrestrial invertebrate. It is concluded that dragonfly ocelli employ a number of simple, yet elegant, anatomical and optical strategies to ensure high sensitivity, fast transduction speed, wide fields of views and a modicum of spatial resolving power.

  1. Effects of Different Zernike Terms on Optical Quality and Vision of Human Eyes

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hao-Xin; XU Bing; LI Jing; DAI Yun; YU Xiang; ZHANG Yu-Dong; JIANG Wen-Han

    2009-01-01

    The visual quality of human eyes is much restricted by high-order aberrations as well as low-order aberrations (defocus and astigmatism), but each term of high-order aberrations contributes differently. The visual acuity and contrast of the image on the retina can be gained by inducing aberrations to each term of high orders. Based on an adaptive optics system, the visual acuity of four subjects is tested by inducing aberrations to each Zernike term after correcting all the aberrations of the subjects. Zernike terms near the center of the Zernike tree affect visual quality more than those near the edge both theoretically and experimentally, and 0.1-μm aberration of these terms can clearly degrade the optical quality and vision. The results suggest that correcting the terms near the center of Zernike tree can improve the visual quality effectively in practice.

  2. Measurement of peripapillary retinal nerve fiber layer thickness and macular thickness in anisometropia using spectral domain optical coherence tomography: a prospective study

    Science.gov (United States)

    Singh, Neha; Rohatgi, Jolly; Gupta, Ved Prakash; Kumar, Vinod

    2017-01-01

    Purpose To study whether there is a difference in central macular thickness (CMT) and peripapillary retinal nerve fiber layer (RNFL) thickness between the two eyes of individuals having anisometropia >1 diopter (D) using spectral domain optical coherence tomography (OCT). Material and methods One hundred and one subjects, 31 with myopic anisometropia, 28 with astigmatic anisometropia, and 42 with hypermetropic anisometropia, were enrolled in the study. After informed consent, detailed ophthalmological examination was performed for every patient including cycloplegic refraction, best corrected visual acuity, slit lamp, and fundus examination. After routine ophthalmic examination peripapillary RNFL and CMT were measured using spectral domain OCT and the values of the two eyes were compared in the three types of anisometropia. Axial length was measured using an A Scan ultrasound biometer (Appa Scan-2000). Results The average age of subjects was 21.7±9.3 years. The mean anisometropia was 3.11±1.7 D in myopia; 2±0.99 D in astigmatism; and 3.68±1.85 D in hypermetropia. There was a statistically significant difference in axial length of the worse and better eye in both myopic and hypermetropic anisometropia (P=0.00). There was no significant difference between CMT of better and worse eyes in anisomyopia (P=0.79), anisohypermetropia (P=0.09), or anisoastigmatism (P=0.16). In anisohypermetropia only inferior quadrant RNFL was found to be significantly thicker (P=0.011) in eyes with greater refractive error. Conclusion There does not appear to be a significant difference in CMT and peripapillary RNFL thickness in anisomyopia and anisoastigmatism. However, in anisohypermetropia inferior quadrant RNFL was found to be significantly thicker. PMID:28260856

  3. Can the red-green duochrome test be used prior to correcting the refractive cylinder component?

    Directory of Open Access Journals (Sweden)

    Liat Gantz

    Full Text Available A primary task of the eye care professional is determining the refraction, or optical correction, of a patient. The duochrome red-green test is a standard tool for verification of the final refraction. Traditionally, it is recommended for use both prior to and subsequent to determining the cylindrical or astigmatic component of the refraction. In order for it to be effective when used before correcting the cylinder it is necessary that the COLC (Circle of Least Confusion be on the retina. This study examined whether it is necessarily true that the duochrome response in uncorrected astigmatism will be as trust-worthy as it is with corrected cylinders.The red-green examination was performed monocularly under the following three conditions: a. fully corrected refraction for the subgroup of eyes that had spherical refractions and for the subgroup of eyes with sphero-cylindrical refractions. b. best sphere-only correction without cylinder correction in sphero-cylindrical eyes c. an induced cylinder error in spherical eyes. The interval between the last "red" response and the first "green" response for the right eyes as a group and separately for the physiological cylinder and induced cylinder correction sub-groups was calculated and compared using a paired, two-tailed t-test.The intervals between "red" and "green" responses were not significantly different in the population as a whole and in the uncorrected physiological cylinder and induced cylinder subgroups examined.Based on the finding that the interval of red-green equality with fully corrected cylinder and without the cylindrical correction are not significantly different, the red-green duochrome test can indeed be used both before and after cylindrical correction.

  4. 冰冻保存供体的周边深板层角膜移植治疗Terrien’s角膜变性的临床疗效%Peripheral deep anterior lamellar keratoplasty using a cryopreserved donor cornea for Terrien’s marginal degeneration

    Institute of Scientific and Technical Information of China (English)

    Dan HUANG; Wen-ya QIU; Bei ZHANG; Bing-hong WANG; Yu-feng YAO‡

    2014-01-01

    Objective: To evaluate the clinical efficacy of peripheral deep anterior lamellar keratoplasty (DALK) using a cryopreserved donor cornea for Terrien’s marginal degeneration (TMD). Methods: Thirty-one eyes of 27 patients with TMD underwent peripheral DALK using cryopreserved donor corneas. According to the distance between the inner edge of the lesion and the limbus, a ring-shaped or D-shaped DALK was performed. Al grafts were stored at−20 °C. Cryopreserved corneoscleral rims were prepared for ring-shaped grafts and cryopreserved whole eyebals were prepared for D-shaped grafts. The general conditions, intraoperative performance, postoperative corneal reconstruc-tion, astigmatism, best corrected visual acuity (BCVA), and various complications were analyzed. Results: Ring-shaped DALK was performed in 28 eyes and D-shaped DALK was performed in 3 eyes. Postoperative folow-up time was (28.4±24.8) months. There was evidence of inflammation before surgery in 12 eyes (38.7%) and intraoper-ative perforation occurred in 13 eyes (41.9%). The corneal structures of al eyes were reconstructed. Postoperative astigmatism and BCVA showed improvement (bothP=0.00) except for cases that underwent D-shaped DALK. Ten eyes (32.2%) developed transient ocular hypertension and one eye (3.2%) developed secondary glaucoma. No pri-mary disease recurrence or corneal allograft rejection was observed. Conclusions: Peripheral DALK for TMD using cryopreserved donor tissue is an effective technique that eliminates rejection and extends the use of donor eyes. Inflammatory history or intraoperative perforation has no adverse effect on graft recovery. However, D-shaped DALK did not achieve good visual outcomes.

  5. Anterior iris-claw lens implantation with single paracentesis

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    Ahmet Özer

    2011-11-01

    Full Text Available In this study, the technique and results of iris-claw intraocular lens (IOL implantation with corneal incision and single paracentesis were presented. Eighteen eyes of 18 patients who underwent iris-claw implantation surgery with a single paracentesis were included in this prospective study. Iris-claw lens was grasped by its forceps and placed into the anterior chamber through superior corneal opening. While IOL was held by forceps, a blunt enclavation spatula was introduced through inferior paracentesis. Then the spatula was directed toward underneath of iris through pupil and toward sides where iris was entrapped into the claw by gentle push of iris through the slotted center of the lens haptics. Mean age of patients was 54.28±25.21 years (7-76 years. Mean anterior chamber depth was 4.07±0.32 mm and mean keratometric power was 43.01±2.73 D. Preoperative BCVA was 20/63 or better in 8 (44.4% patients. At the first postoperative month BCVA was 20/63 or better in 14 (77.8% patients. Preoperative mean spherical refraction was +11.05±2.62 D, preoperative astigmatism was 2.15±0.85. Postoperative mean spherical refraction was - 0.58±0.25 D and mean astigmatism was - 1.92±0.67 D. The most frequent postoperative complication was mild corneal edema seen in three patients that resolved completely during the first week with medical treatment. Irisclaw IOL implantation can be performed easily with corneal incision and single paracentesis. Single paracentesis does not increase surgical time or cause inconvenience during the procedure.

  6. Comparison of Senile Cataract Patients Two Kinds of Small Incision Operation%高龄白内障患者两种小切口手术的比较

    Institute of Scientific and Technical Information of China (English)

    李琳琳; 秦洁; 何中壹; 刘杰慧

    2015-01-01

    目的:探讨小切口囊外摘除术和超声乳化吸出术在高龄白内障患者中的应用疗效。方法选取高龄白内障患者56例,分别行小切口囊外摘除术(A组,26例)和超声乳化吸出术(B组,30例),同时一期植入同型号硬性人工晶体。观察比较两组患者的视力、散光及术后角膜水肿。结果术后1周B组视力明显高于A组(P0.05)。两组患者术后1个月内散光均明显高于术前(P0.05);术后不同时期两组间散光差异均无统计学意义(P>0.05)。术后A组角膜水肿发生率低于B组(P0.05. Astigmatism was obviously higher after operation in the first month in two groups(P0.05). There was no significant difference in astigmatism between the two groups after the operation(P>0.05). Incidence of postoperative corneal edema of group A was lower than group B (P<0.05), and both groups in the first week back to normal after surgery.Conclusion The effect between manual small incision cataract surgery and cataract phacoemulsiifcation surgery is similar, even the manual small incision cataract surgery is simpler and cheaper, so it is more suitabler for basic-level hospitals.

  7. Incisões relaxantes limbares ou incisões no meridiano mais curvo associadas a facoemulsificação com implante de lente intra-ocular multifocal: relato de três casos Limbal relaxing incision or the more curved meridian incision associated to phacoemulsification with multifocal intraocular lens implant: three case reports

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    Wilson Takashi Hida

    2008-04-01

    Full Text Available O implante de lentes intra-oculares (LIOs multifocais é um grande avanço na reabilitação de pacientes permitindo boa acuidade visual sem correção óptica para longe e perto. Contudo pacientes com alguns graus de astigmatismo corneano tem indicação limitada. Este artigo relata três pacientes que foram submetidas a facoemulsificação com implante de lentes intra-oculares multifocais (AcrySof® Restor®, Alcon Labs após incisão relaxante limbar (IRL no olho dominante e incisão no eixo mais curvo da topografia no olho contralateral. Não foi encontrado nenhuma análise relacionada a dominância ocular e relaxante limbar na literatura. Acredita-se que essa associação pode ampliar as indicações de implante das lentes intra-oculares multifocais em pacientes com astigmatismo corneano significativo, devendo-se confirmar esta possibilidade por meio de futuros estudos.The use of multifocal intraocular lenses (IOLs is a great advance in the treatment of patients with cataract allowing near and distance uncorrected visual acuity recovery. However patients with some degrees of corneal astigmatism have some limitations. We present 3 cases that were indicated for phacoemulsitfication and multifocal intraocular lens implant (AcrySof® Restor®, Alcon Labs after limbal relaxing incision (LRI in the dominant eye and axis topographic incision in the fellow eye. There was no similar case report in the literature. It is believed that this association can extend the indications for multifocal intraocular lens implants in patients with significant corneal astigmatism and this possibility should be confirmed by future studies.

  8. PREVALENCE OF REFRACTIVE ERRORS AMONG CHILDREN IN RURA L AREAS OF CHITTOOR DISTRICT, A . P

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    Sadana

    2015-08-01

    Full Text Available BACKGROUND: The uncorrected refractive errors are the main cause of low vision which hampers performance at school, reduces productivity and impairs quality of life. It is considered to be one of the most important priorities in the global initiation for the elimination of avoidable blindness. The refractive errors are especially common among children as they do not complain and adjust with circumstances. School children constitute an ideal group for study of refractive errors because most of them go to school, easily accessible and offer excellent opportunity for services and health education. MATERIAL & METHODS: This is a cross sectional study conducted among 2,568 children attending various government schools in the rural areas of Chittoor district. The study was carried out during January to June 2015. A preliminary examination of visual acuity was determined by Snellen’s chart and those with defective vision were subjected to detailed eye examination by a specialist. The results were analyzed using MS excel software and Epiinfo 7 software version using percentages and Chi - square test. RESULTS: The overall prevalence of refractive errors among children was found to be 11.3%. (Astigmatism - 5.8%; myopia - 4.2%; hypermetropia - 1.4%. The prevalence of refractive errors increased steadily from 5.7% in 5 - 7 years age group to 14.7% in 14 - 16 years group. The prevalence was found to be similar in male and female children. The prevalence of myopia and astigmatism was found to increase steadily with age while hypermetropia showed an inverse trend CONCLUSIONS: Examination of school children for refractive errors is a useful strategy for early diagnosis and intervention.

  9. Automatic low-order aberration correction based on geometry optics: simulations

    Science.gov (United States)

    Yu, Xin; Dong, Lizhi; Liu, Yong; Yang, Ping; Tang, Guomao; Xu, Bing

    2016-10-01

    The slab laser is a promising architecture to achieve high beam quality and high power. By propagating the laser beams in zigzag geometries, the temperature gradient in the gain medium can be well averaged, and the beam quality in this direction can be excellent. However, the temperature gradient in the non-zigzag direction is not compensated, resulting in aberrations in this direction which lead to poorer beam quality. Among the overall aberrations, the main contributors are two low-order aberrations: astigmatism and defocus. These aberrations will magnify beam divergence angle and degrade beam quality. If the beam divergence angles in both directions are almost zero, the astigmatism and defocus are well corrected. Besides, the output beams of slab lasers are generally in a rectangular aperture with high aspect ratio (normally 1:10), which need to be reshaped into square in many applications. In this paper, a new method is proposed to correct low-order aberrations and reshape the beams of slab lasers. Three lenses are adapted, one is a spherical lens and the others are cylindrical lenses. These lenses work as a beam shaping system, which converts the beam from rectangular into square and the low-order aberrations are compensated simultaneously. Two wavefront sensors are used to detect input and output beam parameters. The initial size of the beam is 4mm×20mm, and peak to valley (PV) value of the wavefront is several tens of microns. Simulation results show that after correction, the dimension becomes 40mm×40mm, and peak to valley (PV) value of the wavefront is less than 1microns.

  10. Clinical Outcomes after Uncomplicated Cataract Surgery with Implantation of the Tecnis Toric Intraocular Lens

    Science.gov (United States)

    Lubiński, Wojciech; Kaźmierczak, Beata; Gronkowska-Serafin, Jolanta; Podborączyńska-Jodko, Karolina

    2016-01-01

    Purpose. To evaluate the clinical outcomes after uncomplicated cataract surgery with implantation of an aspheric toric intraocular lens (IOL) during a 6-month follow-up. Methods. Prospective study including 27 consecutive eyes of 18 patients (mean age: 66.1 ± 11.4 years) with a visually significant cataract and corneal astigmatism ≥ 0.75 D and undergoing uncomplicated cataract surgery with implantation of the Tecnis ZCT toric IOL (Abbott Medical Optics). Visual, refractive, and keratometric outcomes as well as IOL rotation were evaluated during a 6-month follow-up. At the end of the follow-up, patient satisfaction and perception of optical/visual disturbances were also evaluated using a subjective questionnaire. Results. At 6 months after surgery, mean LogMAR uncorrected (UDVA) and corrected distance visual acuity (CDVA) were 0.19 ± 0.12 and 0.14 ± 0.10, respectively. Postoperative UDVA of 20/40 or better was achieved in 92.6% of eyes. Mean refractive cylinder decreased significantly from −3.73 ± 1.96 to −1.42 ± 0.88 D (p < 0.001), while keratometric cylinder did not change significantly (p = 0.44). Mean absolute IOL rotation was 1.1 ± 2.4°, with values of more than 5° in only 2 eyes (6.9%). Mean patient satisfaction score was 9.70 ± 0.46, using a scale from 0 (not at all satisfied) to 10 (very satisfied). No postoperative optical/visual disturbances were reported. Conclusion. Cataract surgery with implantation of the Tecnis toric IOL is an effective method of refractive correction in eyes with corneal astigmatism due to the good IOL positional stability, providing high levels of patient's satisfaction. PMID:27022478

  11. Retreatments after multifocal intraocular lens implantation: an analysis

    Science.gov (United States)

    Gundersen, Kjell Gunnar; Makari, Sarah; Ostenstad, Steffen; Potvin, Rick

    2016-01-01

    Purpose To determine the incidence and etiology of required retreatment after multifocal intraocular lens (IOL) implantation and to evaluate the methods and clinical outcomes of retreatment. Patients and methods A retrospective chart review of 416 eyes of 209 patients from one site that underwent uncomplicated cataract surgery with multifocal IOL implantation. Biometry, the IOL, and refractive data were recorded after the original implantation, with the same data recorded after retreatment. Comments related to vision were obtained both before and after retreatment for retreated patients. Results The multifocal retreatment rate was 10.8% (45/416 eyes). The eyes that required retreatment had significantly higher residual refractive astigmatism compared with those who did not require retreatment (1.21±0.51 D vs 0.51±0.39 D, P<0.01). The retreatment rate for the two most commonly implanted primary IOLs, blended bifocal (10.5%, 16/152) and bilateral trifocal (6.9%, 14/202) IOLs, was not statistically significantly different (P=0.12). In those requiring retreatment, refractive-related complaints were most common. Retreatment with refractive corneal surgery, in 11% of the eyes, and piggyback IOLs, in 89% of the eyes, was similarly successful, improving patient complaints 78% of the time. Conclusion Complaints related to ametropia were the main reasons for retreatment. Residual astigmatism appears to be an important determinant of retreatment rate after multifocal IOL implantation. Retreatment can improve symptoms for a high percentage of patients; a piggyback IOL is a viable retreatment option. PMID:27041983

  12. Reversible femtosecond laser-assisted myopia correction: a non-human primate study of lenticule re-implantation after refractive lenticule extraction.

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    Andri K Riau

    Full Text Available LASIK (laser-assisted in situ keratomileusis is a common laser refractive procedure for myopia and astigmatism, involving permanent removal of anterior corneal stromal tissue by excimer ablation beneath a hinged flap. Correction of refractive error is achieved by the resulting change in the curvature of the cornea and is limited by central corneal thickness, as a thin residual stromal bed may result in biomechanical instability of the cornea. A recently developed alternative to LASIK called Refractive Lenticule Extraction (ReLEx utilizes solely a femtosecond laser (FSL to incise an intrastromal refractive lenticule (RL, which results in reshaping the corneal curvature and correcting the myopia and/or astigmatism. As the RL is extracted intact in the ReLEx, we hypothesized that it could be cryopreserved and re-implanted at a later date to restore corneal stromal volume, in the event of keratectasia, making ReLEx a potentially reversible procedure, unlike LASIK. In this study, we re-implanted cryopreserved RLs in a non-human primate model of ReLEx. Mild intrastromal haze, noted during the first 2 weeks after re-implantation, subsided after 8 weeks. Refractive parameters including corneal thickness, anterior curvature and refractive error indices were restored to near pre-operative values after the re-implantation. Immunohistochemistry revealed no myofibroblast formation or abnormal collagen type I expression after 8 weeks, and a significant attenuation of fibronectin and tenascin expression from week 8 to 16 after re-implantation. In addition, keratocyte re-population could be found along the implanted RL interfaces. Our findings suggest that RL cryopreservation and re-implantation after ReLEx appears feasible, suggesting the possibility of potential reversibility of the procedure, and possible future uses of RLs in treating other corneal disorders and refractive errors.

  13. Modification, calibration, and comparative testing of an automated surgical keratometer.

    Science.gov (United States)

    Simon, G; Parel, J M; Nose, I; Lee, W

    1991-01-01

    A new digital surgical keratometer (SK-1, Canon Inc) designed to fit existing operating microscopes and provide quantitative measurements at a nominal 2.0- and 3.6-mm diameter optical zone of the central cornea was modified for single foot-switch operation by the surgeon. The instrument was tested against three calibrated steel spheres, an astigmatic test-jig, and compared with a standard clinical keratometer (CLC, A.O. Co) in two studies involving six eye bank eyes and five healthy human corneas. Assessed with the steel spheres, the SK-1 calibration error was -0.042 diopters at the 3.6-mm diameter and +0.207 D at the 2.0-mm chord, while it was -0.120 D for the CLC. With cylindrical power greater than 0.50 D, the astigmatic angle was accurate to +/- 1 degree. After correction for calibration error, the CLC readings on eye bank eyes were 1.00 D higher in average (range +0.45 to +1.90) than those obtained with the SK-1 which gave lower keratometric values at the 2-mm chord diameter (-0.254 D, range: +0.05 to -0.7). The human subject corrected readings at the 3.6-mm chord were within 0.137 D (range -0.09 to +0.41) from the CLC values. A mean corrected difference of +0.068 D (range -0.27 to +0.30) was found between the two chords. The SK-1 instrument was easier to use than the CLC. A more accurate calibration and the addition of automated averaging and video display of readings as well as of a motorized Placido disc would further augment its clinical usefulness.

  14. Screening Preschool Children for Visual Disorders: A Pilot Study

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    Suman Adhikari, BOptom

    2013-12-01

    Full Text Available Purpose: Ocular and/or vision defects are one of the most common reasons for the referral of young children to the hospital. Vision disorders are the fourth most common disability of children and the leading cause of handicapping conditions in childhood. In preschool-age children, amblyopia and amblyogenic risk factors, such as strabismus and significant refractive errors, are the most prevalent and important visual disorders. The purpose of this pilot study was to determine the prevalence of visual disorders in preschool children in Kathmandu Valley, Nepal.Methods: Four hundred and eighty-four children attending eight preschools in Kathmandu Valley underwent detailed optometric examination. Visual acuity was assessed with either Sheridan Gardiner or Kay Picture chart monocularly. Binocularity was assessed with cover test and prism bar neutralisation. Refraction was carried out in all children. In most instances this was done without the use of a cycloplegic agent. Stereopsis was assessed with the Lang stereo test. Anterior and posterior segment abnormalities were assessed by using a pen light, hand-held slit lamp, and direct ophthalmoscope.Results: Refractive error was the most common visual disorder. Considering our criteria of refractive error for myopia ≥ 0.50 D, hyperopia ≥ 1.50 D, astigmatism ≥ 1.00 D, and anisometropia ≥ 1.00 D, the overall prevalence of refractive error in our study was 31.82%. The overall prevalence of myopia, hyperopia, and astigmatism was 24.17%, 2.48%, and 5.17%, respectively. Anisometropia was present in 1.65% of the participants, and 2%, 1.4%, and 0.2% had strabismus, amblyopia, and nystagmus, respectively.Conclusion: The relatively high prevalence of refractive error in our studied population needs more attention. The results suggest that there is a need for a large-scale community-based preschool screening program in Nepal so that affected children can be identified early and appropriate treatment can be

  15. Refractive Errors in Northern China Between the Residents with Drinking Water Containing Excessive Fluorine and Normal Drinking Water.

    Science.gov (United States)

    Bin, Ge; Liu, Haifeng; Zhao, Chunyuan; Zhou, Guangkai; Ding, Xuchen; Zhang, Na; Xu, Yongfang; Qi, Yanhua

    2016-10-01

    The purpose of this study was to evaluate the refractive errors and the demographic associations between drinking water with excessive fluoride and normal drinking water among residents in Northern China. Of the 1843 residents, 1415 (aged ≥40 years) were divided into drinking-water-excessive fluoride (DWEF) group (>1.20 mg/L) and control group (≤1.20 mg/L) on the basis of the fluoride concentrations in drinking water. Of the 221 subjects in the DWEF group, with 1.47 ± 0.25 mg/L (fluoride concentrations in drinking water), the prevalence rates of myopia, hyperopia, and astigmatism were 38.5 % (95 % confidence interval [CI] = 32.1-45.3), 19.9 % (95 % CI = 15-26), and 41.6 % (95 % CI = 35.1-48.4), respectively. Of the 1194 subjects in the control group with 0.20 ± 0.18 mg/L, the prevalence of myopia, hyperopia, and astigmatism were 31.5 % (95 % CI = 28.9-34.2), 27.6 % (95 % CI = 25.1-30.3), and 45.6 % (95 % CI = 42.8-48.5), respectively. A statistically significant difference was not observed in the association of spherical equivalent and fluoride concentrations in drinking water (P = 0.84 > 0.05). This report provides the data of the refractive state of the residents consuming drinking water with excess amounts of fluoride in northern China. The refractive errors did not result from ingestion of mild excess amounts of fluoride in the drinking water.

  16. Results of endocapsular phacofracture debulking of hard cataracts

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    Davison JA

    2015-07-01

    Full Text Available James A Davison Wolfe Eye Clinic, Marshalltown, IA, USA Purpose/aim of the study: To present a phacoemulsification technique for hard cataracts and compare postoperative results using two different ultrasonic tip motions during quadrant removal.Materials and methods: A phacoemulsification technique which employs in situ fracture and endocapsular debulking for hard cataracts is presented. The prospective study included 56 consecutive cases of hard cataract (LOCS III NC [Lens Opacification Classification System III, nuclear color], average 4.26, which were operated using the Infiniti machine and the Partial Kelman tip. Longitudinal tip movement was used for sculpting for all cases which were randomized to receive longitudinal or torsional/interjected longitudinal (Intelligent Phaco [IP] strategies for quadrant removal. Measurements included cumulative dissipated energy (CDE, 3 months postoperative surgically induced astigmatism (SIA, and corneal endothelial cell density (ECD losses.Results: No complications were recorded in any of the cases. Respective overall and longitudinal vs IP means were as follows: CDE, 51.6±15.6 and 55.7±15.5 vs 48.6±15.1; SIA, 0.36±0.2 D and 0.4±0.2 D vs 0.3±0.2 D; and mean ECD loss, 4.1%±10.8% and 5.9%±13.4% vs 2.7%±7.8%. The differences between longitudinal and IP were not significant for any of the three categories.Conclusion: The endocapsular phacofracture debulking technique is safe and effective for phacoemulsification of hard cataracts using longitudinal or torsional IP strategies for quadrant removal with the Infiniti machine and Partial Kelman tip. Keywords: astigmatism, cataract, corneal endothelium, phacoemulsification, viscoelastic

  17. Prevalence of refractive errors in Villa Maria, Córdoba, Argentina

    Institute of Scientific and Technical Information of China (English)

    Victoria M Snchez; Claudio P Juarez; Rafael Iribarren; Santiago G Latino; Victor E Torres; Ana L Gramajo; Mara N Artal; Mara B Yadarola; Patricia R Garay; Jos D Luna

    2016-01-01

    Background: Refractive errors are among the most frequent reasons for demand of eye-care services. Publications on refractive errors prevalence in our country are few. This study has the purpose to assess the prevalence of refractive errors in an adult population of Villa Maria, Córdoba, Argentina. Methods: The Villa Maria Eye Study is a population-based cross-sectional study conducted in the city of Villa Maria, Córdoba, Argentina from May 2008 to November 2009. Subject’s aged 40+ received a demographic interview and complete ophthalmological exam. Visual acuity was obtained with an ETDRS chart. Cycloplegic auto refraction was performed. The spherical equivalent was highly correlated between right and left eyes, so only data of right eyes are presented. Myopia and hyperopia were defined with a ±0.50 diopters (D) criterion and astigmatism >1 D. Results: This study included 646 subjects, aged 40 to 90 (mean age: 59.6±10.3 years old). Four hundred and sixty two (71.5%) were females. The mean spherical equivalent was +0.714±2.41 D (range, −22.00 to+8.25 D) and the power of the cylinder was, on average, −0.869±0.91 D (range, 0 to −6.50 D). In this sample, 61.6% subjects were hyperopic, and 13.5% were myopic. Myopia prevalence was lower in men (9.8% versus 14.9%) but this difference among genders was not statistically signiifcant. There were 141 subjects (21.8%) with anisometropia greater than 1 D, and 168 subjects (26.0%) with astigmatism greater than 1 D. Conclusions: The present study shows the prevalence of cycloplegic refractive errors in an adult population of Argentina. The prevalence of hyperopia was high, while myopia prevalence was very low.

  18. 硬性透氧性角膜接触镜矫正特殊类型屈光不正的效果观察%The rigid gas permeable contact lens for the correction of special ametropia

    Institute of Scientific and Technical Information of China (English)

    常枫; 沈政伟; 陈云辉; 魏润菁; 周和政

    2011-01-01

    Objective To evaluate the effectiveness and safety of rigid gas permeable contact lenses (RGPCL) for special ametropia. Methods Of 61 patients (98 eyes), including high myopia 29 (55 eyes), high degree of astigmatism 9 (18 eyes), 20 non-lens high hyperopia (20 eyes), anisometropia 3 (5 eyes), were fitted with RGPCLs. They were followed up for 6 to 12 months. Results High myopia to wear spectacles and RGPCLs, Best corrected visual acuity (BCVA) ≥ 4.9 were 37 eyes (67.27%) and 47 (85.46%) respectively, the average BCVA RGPCLs better than spectacles (P 0.05). In the high astigmatism group, BCVA was better than 4.9 in 20 eyes (100%) with RGPCLs and in 15 eyes (75%) with spectacles. The average BCVA, RGPCLs were better than spectacles (P 0.05);高度散光组佩戴框架眼镜和RGPCL后矫正视力≥4.9分别为15只眼(75%)、20只眼(100%),平均最佳矫正视力RGPCL好于框架眼镜(P<0.05);屈光参差者佩戴RGP后达到双眼平衡.随访未发现明显眼部并发症.结论 对于特殊类型屈光不正,RGPCL的视觉效果明显优于框架眼镜,并有较高地安全性,无明显并发症发生.

  19. Outcomes of Penetrating Keratoplasty for Macular Corneal Dystrophy

    Science.gov (United States)

    Karimian, Farid; Baradaran-Rafii, Ali-Reza; Feizi, Sepehr; Zare, Mohammad; Jafarinasab, Mohammad-Reza; Javadi, Mohammad-Ali; Mirdehghan, S. Ali; Einollahi, Bahram

    2009-01-01

    Purpose To report the outcomes of penetrating keratoplasty (PKP) in patients with macular corneal dystrophy (MCD). Methods This retrospective case series includes consecutive patients with MCD who underwent PKP from 1986 to 2006 with at least 6 months’ follow-up. Main outcome measures included best spectacle-corrected visual acuity (BSCVA), postoperative astigmatism and graft survival. Results Sixty-two eyes of 39 patients with mean age of 34.0±10.5 (range 13–58) years at the time of keratoplasty were included for analysis. After a mean follow-up period of 52.0±47.3 (range 6–190) months, BSCVA improved from 1.4±0.4 logMAR (4/100) preoperatively to 0.2±0.3 logMAR (20/32) at final follow-up (P<0.001).Mean postoperative BSCVA was 0.15±0.40 logMAR in patients (36 eyes) aged less than 35 years at the time of surgery as compared to 0.26±0.25 logMAR in subjects (26 eyes) older than 35 years (P=0.005). Final astigmatism was comparable with different suturing techniques including separate, continuous, and combined sutures (P=0.9). All grafts were clear at final follow-up except a single case of MCD with visually insignificant recurrence.Episodes of immunologic graft rejection occurred in 12 eyes (19.4%) but none led to graft failure. Conclusion PKP for MCD entails favorable outcomes in terms of graft survival and visual improvement. Final visual acuity seems to be better when transplantation is performed before the age of 35 years. PMID:23056668

  20. Simultaneous Phacoemulsification and Graft Refractive Surgery in Penetrating Keratoplasty Eyes

    Science.gov (United States)

    Feizi, Sepehr; Zare, Mohammad; Einollahi, Bahram

    2011-01-01

    Purpose. To report outcomes of graft refractive surgery (GRS) along with clear-cornea phacoemulsification and intraocular lens (IOL) implantation in penetrating keratoplasty (PKP) eyes. Methods. Fourteen eyes of 13 patients who had received PKP underwent simultaneous GRS (relaxing incisions with or without counter-quadrant compression sutures) and clear-cornea phacoemulsification with IOL implantation. To calculate IOL power, preoperative keratometry readings and the SRK-T formula were used. Results. Mean patient age and follow-up period were 50.5 ± 14.4 years and 14.6 ± 7.1 months, respectively. A significant increase was observed in best spectacle-corrected visual acuity (from 0.55 ± 0.18 logMAR to 0.33 ± 0.18 logMAR, P = 0.001). There was a significant decrease in vector keratometric astigmatism by 6.22 D (P = 0.03). Spherical equivalent refraction was reduced from −3.31 ± 3.96 D to −1.69 ± 2.38 D (P = 0.02) which did not significantly differ from the target refraction (−0.76 ± 0.14 D, P = 0.20). No complications developed and all the grafts remained clear at the final examination. Conclusion. Simultaneous phacoemulsification and GRS is a safe and effective method to address post-PKP astigmatism and lens opacity. IOL power can be calculated from preoperative keratometry readings with an acceptable accuracy. However, patients should be informed about the possibility of high refractive errors postoperatively. PMID:24527227

  1. Optometry Experience of 23 Cases of Suspected Keratoconus%23例可疑圆锥角膜验光体会

    Institute of Scientific and Technical Information of China (English)

    黄海; 黄学文

    2013-01-01

    Objective:To understand the early suspicious keratoconus refractive changes by optometry. Methods:Follow up in 2 years through 23 cases of myopia and astigmatism increased in patients with refractive errors,refractive status,cycloplegic refraction computer optometry suspected keratoconus,corneal topography examination follow-up to understand the circumstances that may occur keratoconus.Results:Confirmed 4 cases of keratoconus,9 cases of suspected keratoconus,10 cases no keratoconus possible. Conclusion:The progressive increase in myopia and astigmatism,corneal curvature increased significantly people should be take keratoconus investigation.%  目的:通过验光了解可疑圆锥角膜的早期屈光改变。方法:通过23例近视及散光进行性增加的屈光不正患者2年的屈光状况的散瞳验光电脑验光追踪随访,怀疑圆锥角膜进行角膜地形图检查,随访了解可能发生圆锥角膜的情况。结果:4例确诊圆锥角膜,9例可疑圆锥角膜,10例暂时没有圆锥角膜发生可能。结论:对近视及散光进行性增加,角膜曲率增加明显者应行圆锥角膜排查。

  2. Prevalence of refractive errors among primary school children in a tropical area,Southeastern Iran

    Institute of Scientific and Technical Information of China (English)

    Monireh Mahjoob; Samira Heydarian; Jalil Nejati; Alireza Ansari-Moghaddam; Nahid Ravandeh

    2016-01-01

    Objective: To determine the prevalence of refractive errors among primary school children in Zahedan District, Southeastern Iran, as a tropical area.Methods: In this cross sectional study, a total of 400 students were selected randomly using multi-stage sampling technique. Myopia was defined as spherical equivalent(SE)of-0.5 diopter(D) or more, hyperopia was defined as SE of +2.00 D or more and a cylinder refraction greater than 0.75 D was considered astigmatism. Anisometropia was defined as a difference of 1 D or more between two eyes. Cycloplegic refractive status was measured using auto-refractometer(Topcon 8800). Data were analyzed using SPSS,version 22 software program.Results: Mean ± SD of SE was(1.71 ± 1.16) D. A total of 20 students [6.3%, 95%confidence interval(CI): 3.96%–9.64%] were myopic(-0.5 D), 186 students(58.1%,95% CI: 52.50%–63.56%) were hyperopic( +2.00 D) and 114 students(35.6%, 95%CI: 30.43%–41.18%) were emmetropic. The prevalence of astigmatism( 0.75 D)among students was 3.4%(95% CI: 1.82%–6.25%). Anisometropia of 1 D or more was found in 21.3%(95% CI: 16.98%–26.23%) of the studied population. The prevalence of refractive errors was higher among girls than boys(73.1% vs. 55.6%, P = 0.001), but it was not significantly different among different age groups(P = 0.790).Conclusions: Refractive errors affect a sizable portion of students in Zahedan. Although myopia is not very prevalent, the high rate of hyperopia in the studied population emphasizes its need for attention.

  3. Measuring higher order optical aberrations of the human eye: techniques and applications

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    L. Alberto V. Carvalho

    2002-11-01

    Full Text Available In the present paper we discuss the development of "wave-front", an instrument for determining the lower and higher optical aberrations of the human eye. We also discuss the advantages that such instrumentation and techniques might bring to the ophthalmology professional of the 21st century. By shining a small light spot on the retina of subjects and observing the light that is reflected back from within the eye, we are able to quantitatively determine the amount of lower order aberrations (astigmatism, myopia, hyperopia and higher order aberrations (coma, spherical aberration, etc.. We have measured artificial eyes with calibrated ametropia ranging from +5 to -5 D, with and without 2 D astigmatism with axis at 45º and 90º. We used a device known as the Hartmann-Shack (HS sensor, originally developed for measuring the optical aberrations of optical instruments and general refracting surfaces in astronomical telescopes. The HS sensor sends information to a computer software for decomposition of wave-front aberrations into a set of Zernike polynomials. These polynomials have special mathematical properties and are more suitable in this case than the traditional Seidel polynomials. We have demonstrated that this technique is more precise than conventional autorefraction, with a root mean square error (RMSE of less than 0.1 µm for a 4-mm diameter pupil. In terms of dioptric power this represents an RMSE error of less than 0.04 D and 5º for the axis. This precision is sufficient for customized corneal ablations, among other applications.

  4. Automatic multidiagnosis system for slit lamp

    Science.gov (United States)

    Ventura, Liliane; Chiaradia, Caio; Vieira Messias, Andre M.; Faria de Sousa, Sidney J.; Isaac, Flavio; Caetano, Cesar A. C.; Rosa Filho, Andre B.

    2001-06-01

    We have developed a system for several automatic diagnose in Slit Lamp in order to provide 04 additional measurements to the biomicroscope: (1) counting of the endothelial cells of donated corneas; (2) automatic keratometry; (3) corneal ulcer evaluation; (4) measurement of linear distances and areas of the ocular image. The system consists in a Slit Lamp, a beam-splitter, some optical components, a CCD detector, a frame grabber and a PC. The optical components attached to the beam-splitter are the same for all the functions, except for 1. For function 1, we have developed an optical system that magnifies the image 290X and a software that counts the cells interactively and automatically. Results are in good agreement with commercial specular microscopes (correlation coefficient is 0,98081). The automatic keratometry function is able to measure cylinders over 30 di and also irregular astigmatisms. The system consists of projecting a light ring at the patient's cornea and the further analysis of the deformation of the ring provides the radius of curvature as well as the axis of the astigmatism. The nominal precision is 0,005 mm for the curvature radius and 2 degree(s) for the axis component. The results are in good agreement with commercial systems (correlation coefficient of 0,99347). For function 3, the ulcer is isolated by the usual clinical ways and the image of the green area is automatically detected by the developed software in order to evaluate the evolution of the disease. Function 4 simply allows the clinician do any linear or area measurement of the ocular image. The system is a low cost multi evaluation equipment and it is being used in a public hospital in Brazil.

  5. Corneal Topographic and Aberrometric Measurements Obtained with a Multidiagnostic Device in Healthy Eyes: Intrasession Repeatability

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    David P. Piñero

    2017-01-01

    Full Text Available Purpose. To evaluate the intrasession repeatability of corneal curvature, eccentricity, and aberrometric measurements obtained with a multidiagnostic device in healthy eyes. Methods. This study enrolled 107 eyes of 107 patients ranging in age from 23 to 65 years. All of them underwent a complete anterior segment examination with the VX120 system (Visionix-Luneau Technologies, Chartres, France. Three consecutive measurements were obtained. The within-subject standard deviation (Sw, intrasubject precision (1.96×Sw, and intraclass correlation coefficient (ICC were calculated. Results. All Sw for corneal power measurements were below 0.26 D, with ICC above 0.982. The Sw for corneal astigmatism at different areas (3, 5, and 7 mm was below 0.21 D, with ICC above 0.913. Concerning the axis of astigmatism, its Sw was below 11.27°, with ICC above 0.975. The Sw and ICC for corneal eccentricity were 0.067 and 0.957, respectively. The Sw and ICC for high-order aberration root mean square (RMS were 0.048 µm and 0.901, respectively. For 3rd- and 4th-order aberrometric parameters, all Sw were below 0.037 µm and all ICC were higher than 0.84, except for quadrafoil RMS (ICC: 0.689. Conclusions. The multidiagnostic device evaluated is able to provide consistent measurements of corneal power, eccentricity, and third- and fourth-order aberrations in healthy eyes.

  6. Mathematical analysis of corneal remodelling after intracorneal ring surgery in keratoconus

    Science.gov (United States)

    Jarade, Elias F.; Slim, Elise; Cherfan, Carole; El Rami, Hala; Hassan, Toufic; Chelala, Elias

    2017-01-01

    AIM To represent mathematically the intersection between the ectatic corneal geometry and the plane of intracorneal ring implants (ICRS) in order to determine the corneal response to ICRS surgery in keratoconus (KC). Thereafter, to present the concept and early results of a newly derived topography-guided nomogram for ICRS surgery for the treatment of keratectasia. METHODS The corneal rings plane intersection was modelled to a conic section. Ring effect was the result of: the ring size, position (steep vs flat), location (distance from the geometric centre of the cornea), and the discrepancy between the ring's curvature and the tunnel's curvature. Femtosecond laser was used to create the tunnels and the incision sites were chosen according to the nomogram in order to place the thickest ring in the steepest portion of the cornea regardless of the astigmatism axis of refraction. RESULTS The conic section had a more prolate shape in the steep area of the cornea than in the flat area, depending on the corneal sagittal curvature. Equal ring size had more flattening effect in the steep area than in the flat area. Thick segment should be implanted under the steep portion of the cornea regardless of the cylinder axis of refraction. Single segment in the steep area was sufficient in early and moderate cases of KC. The new nomogram provided more topographic regularity with significant reduction of astigmatism and better improvement in uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) than the conventional nomogram. CONCLUSION The newly derived nomogram can produce better results than the conventional nomogram. Moreover, based on this concept, a new nomogram can be integrated into the femtosecond laser software to create topography-guided, customized, elliptical tunnels with modified focal asphericity that allows for customized focal flattening of the irregularly steepened ectatic cornea. PMID:28393023

  7. Refractive, Topographic, and Aberrometric Results at 2-Year Follow-Up for Accelerated Corneal Cross-Link for Progressive Keratoconus

    Science.gov (United States)

    Bozkurt, Ercüment; Akcay, Betul Ilkay Sezgin; Kurt, Tugba; Yildirim, Yusuf; Günaydin, Zehra Karaagaç; Demirok, Ahmet

    2017-01-01

    Purpose. To report the visual, refractive, and corneal topography and wavefront aberration results of accelerated corneal cross-linking (CXL) during a 24-month follow-up. Methods. Forty-seven eyes underwent riboflavin-ultraviolet A-induced accelerated CXL treatment (30 mW/cm2 with a total dose of 7.2 joules/cm2). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical and cylindrical values, keratometry (K) measurements (Ksteep, Kflat, Kavg, and Kapex), central corneal thickness, and anterior corneal aberrometric analyses including total wavefront error (WFE), total high order aberration (HOA), astigmatism, trefoil, coma, quadrafoil, secondary astigmatism, and spherical aberration were evaluated. Results. The mean UDVA and CDVA were significantly improved at 1 (p = 0.003 and p = 0.004, resp.) and 2 years after treatment (p = 0.001 and p = 0.001, resp.). The mean Ksteep, Kflat, Kaverage, and Kapex values were significantly lower than baseline at 12 months (p = 0.008, p = 0.024, p = 0.001, and p = 0.014, resp.) and 24 months (p = 0.014, p = 0.017, p = 0.001, and p = 0.012, resp.). Corneal thickness showed a significant decrease at 1 month. Total HOA and coma decreased significantly at the 12-month (p = 0.001 and p = 0.009, resp.) and 24-month visits (p = 0.001 and p = 0.007, resp.). Conclusion. Accelerated CXL (30 mW/cm2) was found to be effective in improving UDVA, CDVA, corneal topography readings, total HOA, and coma aberrations during the 24-month follow-up. PMID:28197339

  8. Outcome of Corneal Collagen Crosslinking for Progressive Keratoconus in Paediatric Patients

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    Deepa Viswanathan

    2014-01-01

    Full Text Available Purpose. To evaluate the efficacy of corneal collagen crosslinking for progressive keratoconus in paediatric patients. Methods. This prospective study included 25 eyes of 18 patients (aged 18 years or younger who underwent collagen crosslinking performed using riboflavin and ultraviolet-A irradiation (370 nm, 3 mW/cm2, 30 min. Results. The mean patient age was 14.3 ± 2.4 years (range 8–17 and mean followup duration was 20.1 ± 14.25 months (range 6–48. Crosslinked eyes demonstrated a significant reduction of keratometry values. The mean baseline simulated keratometry values were 46.34 dioptres (D in the flattest meridian and 50.06 D in the steepest meridian. At 20 months after crosslinking, the values were 45.67 D (P=0.03 and 49.34 D (P=0.005, respectively. The best spectacle corrected visual acuity (BSCVA and topometric astigmatism improved after crosslinking. Mean logarithm of the minimum angle of resolution (logMAR BSCVA decreased from 0.24 to 0.21 (P=0.89 and topometric astigmatism reduced from mean 3.50 D to 3.25 D (P=0.51. Conclusions. Collagen crosslinking using riboflavin and ultraviolet-A is an effective treatment option for progressive keratoconus in paediatric patients. Crosslinking stabilises the condition and, thus, reduces the need for corneal grafting in these young patients.

  9. Visual acuity and refraction by age for children of three different ethnic groups in Paraguay

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    Marissa Janine Carter

    2013-04-01

    Full Text Available PURPOSE: To characterize refractive errors in Paraguayan children aged 5-16 years and investigate effect of age, gender, and ethnicity. METHODS:The study was conducted at 3 schools that catered to Mennonite, indigenous, and mixed race children. Children were examined for presenting visual acuity, autorefraction with and without cycloplegia, and retinoscopy. Data were analyzed for myopia and hyperopia (SE ≤-1 D or -0.5 D and ≥2 D or ≥3 D and astigmatism (cylinder ≥1 D. Spherical equivalent (SE values were calculated from right eye cycloplegic autorefraction data and analyzed using general linear modelling. RESULTS: There were 190, 118, and 168 children of Mennonite, indigenous and mixed race ethnicity, respectively. SE values between right/left eyes were nonsignificant. Mean visual acuity (VA without correction was better for Mennonites compared to indigenous or mixed race children (right eyes: 0.031, 0.090, and 0.102 logMAR units, respectively; P<0.000001. There were 2 cases of myopia in the Mennonite group (1.2% and 2 cases in the mixed race group (1.4% (SE ≤-0.5 D. The prevalence of hyperopia (SE ≥2 D was 40.6%, 34.2%, and 46.3% for Mennonite, indigenous and mixed race children. Corresponding astigmatism rates were 3.2%, 9.5%, and 12.7%. Females were slightly more hyperopic than males, and the 9-11 years age group was the most hyperopic. Mennonite and mixed race children were more hyperopic than indigenous children. CONCLUSIONS: Paraguayan children were remarkably hyperopic and relatively free of myopia. Differences with regard to gender, age, and ethnicity were small.

  10. Compact three-dimensional head-mounted display system with Savart plate.

    Science.gov (United States)

    Lee, Chang-Kun; Moon, Seokil; Lee, Seungjae; Yoo, Dongheon; Hong, Jong-Young; Lee, Byoungho

    2016-08-22

    We propose three-dimensional (3D) head-mounted display (HMD) providing multi-focal and wearable functions by using polarization-dependent optical path switching in Savart plate. The multi-focal function is implemented as micro display with high pixel density of 1666 pixels per inches is optically duplicated in longitudinal direction according to the polarization state. The combination of micro display, fast switching polarization rotator and Savart plate retains small form factor suitable for wearable function. The optical aberrations of duplicated panels are investigated by ray tracing according to both wavelength and polarization state. Astigmatism and lateral chromatic aberration of extraordinary wave are compensated by modification of the Savart plate and sub-pixel shifting method, respectively. To verify the feasibility of the proposed system, a prototype of the HMD module for monocular eye is implemented. The module has the compact size of 40 mm by 90 mm by 40 mm and the weight of 131 g with wearable function. The micro display and polarization rotator are synchronized in real-time as 30 Hz and two focal planes are formed at 640 and 900 mm away from eye box, respectively. In experiments, the prototype also provides augmented reality function by combining the optically duplicated panels with a beam splitter. The multi-focal function of the optically duplicated panels without astigmatism and color dispersion compensation is verified. When light field optimization for two additive layers is performed, perspective images are observed, and the integration of real world scene and high quality 3D images is confirmed.

  11. The Evaluation of the Effects of Differently-Designed Toric Soft Contact Lenses on Visual Quality

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    Sevda Aydın Kurna

    2013-08-01

    Full Text Available Purpose: The purpose of this study was to evaluate the effects of aspheric Balafilcon A and spherical Senofilcon A toric soft contact lenses, which have two different stabilization systems, on visual quality. Material and Method: Forty eyes of 20 patients who were followed up in our contact lens section were included in this study. Refractive errors of the patients were between -0.50 and -6.0 diopters of myopia and >0.75 diopter of astigmatism. The patients were randomly assigned to wear Balafilcon A (Purevision Toric, Baush&Lomb with prism balast toric system or spherical designed Senofilcon A (Acuvue Oasys for astigmatism, Johnson&Johnson with accelerated stabilization toric system. We recorded and compared the visual acuity with Snellen chart, contrast sensitivity with Bailey-Lovie chart in letters, mean root mean square (RMS of corneal aberration with by Nidek Magellan Mapper for all eyes with and without glasses and while wearing Balafilcon A or Senofilcon A toric soft contact lenses. Results: We did not observe any difference in visual acuity between contact lenses. Contrast sensitivity was increased approximately 4.8-5.4 letters with contact lenses. Total higher order aberrations of mean RMS values were 0.42±0.14 µm without contact lens, 0.37±0.23 µm with Balafilcon A lens, 0.43±0.15 µm with Senofilcon A (p=0.507. Trefoil values were significantly higher with Senofilcon A lenses when compared to Balafilcon A lenses. There was no statistically significant difference for other measured higher order aberrations. Discussion: High and low contrast vision values were adequate in both contact lens groups. There was a non-significant decrease in total higher order aberration values with aspheric design contact lenses when compared to spherical designs. Although there were differences in aberrations related to lens designs, they did not have significant effect on visual quality. (Turk J Ophthalmol 2013; 43: 253-7

  12. [Polar and non polar notations of refraction].

    Science.gov (United States)

    Touzeau, O; Gaujoux, T; Costantini, E; Borderie, V; Laroche, L

    2010-01-01

    Refraction can be expressed by four polar notations which correspond to four different combinations of spherical or cylindrical lenses. Conventional expressions of refraction (plus and minus cylinder notation) are described by sphere, cylinder, and axis. In the plus cylinder notation, the axis visualizes the most powerful meridian. The axis usually corresponds to the bow tie axis in curvature maps. Plus cylinder notation is also valuable for all relaxing procedures (i.e., selective suture ablation, arcuate keratotomy, etc.). In the cross-cylinder notation, two orthogonal cylinders can describe (without the sphere component) the actual refraction of both the principal meridians. This notation must be made before performing the vertex calculation. Using an association of a Jackson cross-cylinder and a spherical equivalent, refraction can be broken down into two pure components: astigmatism and sphere. All polar notations of refraction may perfectly characterize a single refraction but are not suitable for statistical analysis, which requires nonpolar expression. After doubling the axis, a rectangular projection breaks down the Jackson cross-cylinder, which has a polar axis, into two Jackson cross-cylinders on the 0 degrees /90 degrees and 45 degrees /135 degrees axis. This procedure results in the loss of the directional nature of the data. Refraction can be written in a nonpolar notation by three rectangular coordinates (x,y,z), which can also represent the spherocylinder by one point in a dioptric space. These three independent (orthogonal) variables have a concrete optical significance: a spherical component, a direct/inverse (WTR/ATR) component, and an oblique component of the astigmatism. Finally, nonpolar notations are useful for statistical analysis and graphical representation of refraction.

  13. 硬性透气性角膜接触镜矫正圆锥角膜疗效分析%Clinical analysis of rigid gas permeable contact lens for keratoconus

    Institute of Scientific and Technical Information of China (English)

    张福生; 田晓丹; 徐艳春; 范春雷; 秦洁; 李艳; 巴秀凤

    2011-01-01

    Objective To evaluate the clinical efficacy and safety of RGP for keratoconus.Methods RGP corrected 63 cases of keratoconus in outpatient clinic from 2004 to 2010 were included in this study.Among them 41 males and 22 females,16-35 years old with mean aged (24.6± 7.81),Binoculus in 57 cases,ocellus in 6 cases.The patients who had significantly increased astigmatism and decreased visual acuity with glasses were detected with computer refractometer,corneal topographer and corneal endothelial microscopy for screening keratoconus.For the diagnosed or suspected keratoconus,based on the degree of corneal curvature,use a specially designed or seneral RGP to correct.The corrected visual acuity was measure with RGP and optometry with RGP.All the measured results were analyzed with correlation analysis with SPSS13.0 software,P <0.05 was significant differences.Results (1)The mean visual acuity with glasses:0.56+ 0.29,the mean visual acuity with RGP:0.93± 0.20,(t =-14.627,P =0.000).The corrected visual acuity with RGP was significantly better than with glasses.(2)The mean astigmatism before wearing RGP:(-4.16± 2.19)DC,the mean astigmatism with RGP:(-0.77+ 1.2)DC (t =-14.585,P =0.000).There was an obvious decrease of astigmatism with RGP.(3)In average 3.5 years' observation in 22 eyes,only 1 eye appeared corneal increased turbid,implemented lamellar corneal transplantation.There was a significant decreased astigmatism in the other 21 patients.Corneal thickness and corneal curvature were no significant difference.Conclusions RGP for irregular astigmatism of keratoconus can significantly improve the visual acuity to a certain extent and slow down the progress of keratoconus disease.%目的 探讨硬性透气性角膜接触镜(RGP)矫正圆锥角膜的临床疗效及安全性.方法 对2004~2010年视光门诊应用RGP矫正的63例圆锥角膜患者,男41例,女22例.年龄16-35岁,平均年龄(24.6±7.81)岁.双眼57例,单眼6例.对散光度明显增大,框架眼镜

  14. Change of corneal surface shapes in keratoconus corrected with RGPCL%圆锥角膜配戴硬性透气性角膜接触镜后角膜表面形态的改变

    Institute of Scientific and Technical Information of China (English)

    张立华; 贾丁; 王文平

    2011-01-01

    目的 评价圆锥角膜患者配戴硬性透气性角膜接触镜(RGP)后角膜前表面非球面形态(Q值)的改变以及SimK值的改变。方法 收集山西省眼科医院就诊的圆锥角膜患者25人43只眼,选配合适的RGP,分别于配戴前及配戴后1个月、3个月、6个月、12个月测定其矫正视力,并进行OPD-scan角膜地形图检查,采集角膜中央散光值、SimK值、Q值等参数,分析Q值及SimK值随配戴时间的变化,SimK值改变与角膜Q值改变有无相关性。结果 患者配戴RGP前,角膜散光值、Simk值、Q值分别为-6.03±2.66、50.12±5.65、-2.29±1.17。配戴RGP 3个月后角膜散光值、Simk值、Q值分别为-4.07±1.97、49.47±5.55、-1.62±0.95。角膜散光值、Simk值、Q值在配戴RGP前后差异有统计学意义。SimK值改变与角膜Q值改变有着显著的相关性,相关系数为0.698。配戴3个月、6个月及12个月后,角膜散光值,Simk值,Q值差异无统计学意义。结论 RGP为圆锥角膜患者提供了良好的视力矫正,并且可以在一定程度上改变角膜前表面的形态,从而控制圆锥角膜病情的发展。这种改变在配戴后3个月较为明显。随着配戴时间的延长,角膜散光值,Simk值,Q值趋于稳定。%Objective To investigate the changes of Q-value and simK-value in keratoconus corrected with RGPCL. Methods Twenty-five patients confirmed by corneal topography as keratoconus were correlated with RGPCL and followed by 1 month, 3, 6 and 12 months. Their corrected visual acuity (VA) and corneal topography were detected by OPD-scan. Cornea astigmatism, simK-value and Q-value were measured. Results Cornea astigmatism, simK-value and Q-value was -6.03 ± 2.66, 50.12± 5.65, and -2.29± 1.17 before wearing RGP respectively. With RGPCL for 3 months, cornea astigmatism, simK-value and Q-value was -4.07D± 1.97, 49.47± 5.55, and -1.62± 0.95 respectively.Corrected visual acuity (VA) was improved after

  15. Estudo prospectivo comparativo de duas técnicas cirúrgicas de extração extra-capsular planejada de catarata com implante de lente intra-ocular: incisão limbar e incisão escleral tunelizada Prospective comparative study of two techniques of planned extracapsular cataract extraction: limbal incision and scleral tunnel incision

    Directory of Open Access Journals (Sweden)

    Lincoln Lemes Freitas

    2001-06-01

    extraction (ECCE with posterior chamber intraocular lens implantation. This study aims to compare limbal incision and scleral tunnel incision in planned ECCE. Methods: Fifty-four consecutive patients (59 eyes with follow-up of 6 months were studied prospectively. ECCE with limbal incision was performed in 30 patients (Group I, and with scleral tunnel incision in 29 patients (Group II. Corrected visual acuity, intraocular inflammation (cells and flare, surgical time, specular microscopy, induced astigmatism and pachymetry were assessed. Results: Surgical time, endothelial cells loss and induced astigmatism were statistically greater in group I than in group II. No significant differences were found between groups when comparing the corrected visual acuity, intraocular inflammation and pachymetry. Conclusions: ECCE with scleral tunnel incision technique offers advantages regarding surgical time, endothelial cells loss and induced astigmatism if compared with limbal incision technique. Surgical steps used in this technique help in transition for phacoemulsification with low cost and a safer way.

  16. Prevalência das ametropias e oftalmopatias em crianças pré-escolares e escolares em favelas do Alto da Boa Vista, Rio de Janeiro, Brasil Prevalence of the ametropias and eye diseases in preschool and school children of Alto da Boa Vista favelas, Rio de Janeiro, Brazil

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    Abelardo de Souza Couto Júnior

    2007-10-01

    prevalence was 3.50% (hyperopia and astigmatism hyperopic were 1.78%, myopia and astigmatism myopic 1.06%, mixed astigmatism 0.67%.The eyes diseases prevalence was 3.50% (amblyopia was 2.00%, manifest strabismus was 1.72% and others causes was 1.11%. CONCLUSION: It was shown the prevalence of the main ophthalmologic children disorders. It also points out the need of ocular health campaigns thus achieve remarkably the development of the children visual acuity.

  17. Variable aberration correction technology based on axially shifting cylinder-Zernike correcting element%基于轴向移动柱面-泽尼克校正元件的动态像差校正技术

    Institute of Scientific and Technical Information of China (English)

    曲贺盟; 张新; 王灵杰

    2012-01-01

    The most significant feature of elliptical window optical system is dynamic aberration change which is dependent on the scanning field. Thus, astigmatism and coma become the main factors which influence imaging quality of the optical system and the effect of astigmatism is most prominent. In this paper, a new method for dynamic aberration correction was presented in order to solve this problem. And this so-called cylinder-Zernike element correcting method combines the characteristics of cylindrical lens and Zernike plate. The outer surfaces of cylinder-Zernike correcting element were a pair of cylindrical surfaces whose generating lines were mutual perpendicular and the corresponding internal surfaces were Zernike fringe sag surfaces. This method could adjust the distance between the two cylinder-Zernike correcting elements in real time according to the change of scanning field to realize the correcting of dynamic aberration induced by elliptical window. It breaks through the bottleneck that the fixed correcting elements cannot achieve super wide scanning field. The imaging optical system in the giving example achieves ±55° scanning field. The Zernike aberration coefficients of astigmatism and coma in each scanning field are corrected into ±0.8 wavelength and the imaging quality of the elliptical window optical system is greatly improved.%椭球形窗口光学系统最显著的特点在于其依赖扫描视场的动态像差变化特性,像散和彗差成为影响光学系统成像质量的主要因素,其中像散的影响最为突出.为解决这一难题,结合柱面透镜和泽尼克位相板的特点,提出了一种新颖的动态像差校正方法,即柱面-泽尼克元件校正方法,此元件的外表面为一对母线互相垂直的圆柱面,对应的两个内表面为泽尼克边缘矢高表面.该方法随扫描视场的变化实时地调整一对柱面-泽尼克校正元件间距以实现椭球形窗口引入像差的动态校正.突破了固定校

  18. Análise comparativa da refração automática objetiva e refração clínica Automatic objective refraction and clinical refraction - a comparative analysis

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    Ricardo Uras

    2001-02-01

    automated objective refraction was performed using the automatic keratorefractor TOPCON 3000. Results: 1,001 eyes of 504 patients were studied. 45.2% were male patients and the mean age was 36.6 years. There was an overall concordance between clinical refraction and the automated objective refraction in 66.7% of the patients. The concordance of a spherical value, not considering variations of -0.50 to +0.50 SD was, approximately 90%. In simple hyperopic/myopic astigmatic eyes the concordance was 27.6%, in eyes with compound hyperopic/myopic astigmatism the concordance was 97.7%. Cycloplegia did not significantly affect this concordance. There was no significant difference regarding the axis of astigmatic eyes when using both techniques. Conclusion: Automated objective refraction is an useful tool in clinical refraction but clinical data should also be considered and the final lens prescription should never be based solely on the automated examination.

  19. Comparison of automatic keratometry and corneal topography on children' corneal power%自动角膜曲率计与角膜地形图仪测量儿童角膜屈光力的比较研究

    Institute of Scientific and Technical Information of China (English)

    王延飒; 王利华; 马鲁新

    2008-01-01

    目的 比较KR-8100自动角膜曲率计与TMs-4角膜地形图仪测量屈光不正儿童角膜屈光力及散光轴向的差异,并对两种测量方法进行一致性评价.方法 采用KR-8100自动角膜曲率计及TMS-4角膜地形图仪对53例(106只眼)屈光不正儿童进行测量,应用配对t检验对两种方法测量的陡峭 子午线角膜屈光力(Ks)、平坦子午线角膜屈光力(Kf)、角膜散光Ks-Kf大小及轴向进行比较,并应用Bland-Altmann分析对两种测量方法进行一致性评价.结果 角膜地形图仪测量的Ks、Kf、Ks-Kf值均高于角膜曲率计的测量值(P<0.01);角膜地形图仪与角膜曲率计的散光轴向测量值差异有统计学意义(P<0.01).两种仪器测量Ks的差值的均数为1.72D,测量Kf的差值的均数为1.37D,这种测量差别临床上不能接受,说明两种仪器测量角膜屈光力的一致性较差.结论 KR-8100自动角膜曲率计与TMS-4角膜地形图两种测量方法在临床上不能替代使用.%Objective To evaluate the agreement of measuring corneal power and astigmatism axis between automatic keratometry and corneal topography on ametropia' children.Methods Keratometric reading with Topcon KR-8100 automatic keratometry and corneal topography with the TMS-4 on 53 ametropia' children, 106 eyes were compared.Difference in measurements of steep meridian power magnitude Ks, flat meridian power magnitude Kf, astigmatism magnitude Ks-Kf and location as well between the two methods were assessed using paired t test.Bland-Altmann method was used to evaluate the agreement of the two methods.Results The Ks,Kf,Ks-Kf of the corneal topography were higher than that of the keratometry' (P<0.01).The difference of the astigmatism axis between the corneal topography and the keratometry was significant (P<0.01).Of the two instruments,the mean difference of Ks was 1.72D,Kf was 1.37D,the difference of the measurement cannot be acceptable, so it showed incomparable results for them to

  20. Analysis of higher-order aberrations (HOAs) and related factors after small incision lenticule extraction (SMILE) surgery%SMILE术后全眼高阶像差变化及相关因素分析

    Institute of Scientific and Technical Information of China (English)

    梁刚; 查旭; 张丰菊

    2015-01-01

    目的 通过观察飞秒激光小切口基质透镜取出术(SMILE)治疗近视及近视散光眼术后全眼高阶像差的改变,探讨SMILE术后全眼高阶像差的变化特点及其相关因素.方法 回顾性研究.选择行SMILE手术治疗近视及近视散光患者共81例(162眼),随访时间3个月.术中眼球定位采用术前kappa角结合术中注视水印居中中心定位法.术前、术后3个月采用WASCA波前像差分析仪测量6 mm瞳孔直径下术眼的总高阶像差(HOA)及各单项HOA,同时采用Oculyzer眼前节分析系统测量kappa角及角膜Q值.手术前后数据比较应用配对t检验,运用Spearman秩相关分析法和Pearson相关分析总HOA及各项HOA的变化与术前等效球镜度(SE)、散光度及轴向、kappa角等参数的相关性.结果 手术前后总HOA(t=-12.24,P<0.01)、球差(C40)(t=16.60,P<0.01)、水平彗差(C31)(t=-11.06,P<0.01)、垂直彗差(C3-1)(t=-3.14,P<0.01)、垂直三叶草(C3-3)(t=-6.30,P<0.01)、四阶水平散光(C42)(t=5.84,P<0.01)的均方根(RMS)值差异均有统计学意义.手术前后Q值分别为-0.24±0.13和0.69±0.52,差异有统计学意义(t=-22.55,P<0.01).术后3个月总HOA与SE相关(r=-0.23,P<0.01),△总HOA主要与△C40、△C31相关(r=-0.40、0.26,P<0.01),与术前Q值、Kappa角、散光度均无相关性;术后C40、△C40与术前SE相关(r=0.35、0.29,P<0.01);C31与术前散光度和Q值相关(r=-0.24、-0.22,P<0.05),△C31与术前散光度相关(r=-0.29,P<0.01);术后C3-1和△C3-1与术前的SE、Q值、Kappa角、散光度均不相关.结论 近视及近视散光眼SMILE手术后总HOA增加,主要与术前SE有关,与散光度无关;手术前后C40变化量与术前SE有关,C31增加量与术前散光度有关.%Objective To investigate the changes in higher-order aberrations (HOAs) after small incision lenticule extraction (SMILE) surgery for myopia and myopic astigmatism, and to evaluate the association between the postoperative

  1. Results of Iris-Claw Intraocular Lens Implantation in Aphakia

    Directory of Open Access Journals (Sweden)

    Mehmet Tahir Şam

    2014-12-01

    Full Text Available Objectives: To evaluate the visual outcomes and complications of iris-claw intraocular lenses (ICIOL implanted in cases of aphakia or in cataract surgery with insufficient capsule support. Material and Method: In this retrospective study, we reviewed the medical records of 34 eyes of 34 patients who had undergone ICIOL implantation with a minimum follow-up of 12 months in Bucak State Hospital and in a private hospital between November 2007 and November 2012. Results: Twenty-one eyes with complicated cataract accompanied by zonular deficiency, 8 eyes with aphakia, and 5 eyes with dislocated IOL were operated and ICIOL implanted. Mean preoperative BCVA was 1.46±1.05 LogMAR and postoperative BCVA was 0.20±0.21 LogMAR. There was an improvement in visual acuity in 31 eyes of the 34 patients, and 29 of them had a visual acuity better than 6/12 postoperatively. Mean postoperative spherical equivalent (SE was -0.76±0.94 D, and deviation from estimated SE was -0.26±0.94 D. Mean preoperative astigmatism was -1.36±0.77 Cyl D and mean postoperative astigmatism was -0.98±0.82 Cyl D. In second postoperative month, one case had a pupillary block glaucoma due to the closure of peripheral iridotomy, and after ND-YAG laser treatment, intraocular pressure return to normal value. One eye had iris pigment precipitates on the ICIOL in early postoperative period, and in one case, there was a pupillary ovalization. Three months after a cataract surgery, retinal detachment developed in one eye of a patient who had a history of severe ocular trauma; anterior vitrectomy and ICIOL implantation were performed. Visual acuity remained unchanged after a successful pars plana vitrectomy operation. Conclusion: Iris-claw lenses provide fairly good visual outcomes in aphakic eyes without capsular support and in challenging cataract cases with zonular deficiency. They are safe regarding complications when compared to other alternative intraocular lens implantation methods

  2. Manifestações oculares em pacientes que tiveram desnutrição nos primeiros seis meses de vida Ocular manifestations in patients who had malnutrition in the first six months of life

    Directory of Open Access Journals (Sweden)

    Alessandra Pereira Dantas

    2005-12-01

    Full Text Available OBJETIVOS: Investigar possíveis alterações oftalmológicas em pacientes que tiveram desnutrição grave durante os primeiros seis meses de vida. MÉTODOS: Foram analisados 182 olhos de 91 crianças entre 2 e 11 anos que tiveram desnutrição grave durante os primeiros seis meses de vida (grupo estudo. Como grupo controle foram incluídas 88 crianças, selecionadas aleatoriamente segundo características similares de idade, gênero, condições econômicas e demográficas. RESULTADOS: Observou-se, de forma significante, no grupo estudo, maior freqüência de crianças com acuidade visual de 0,3 a 0,1 e menor que 0,1 (11,5% versus 0,7% - p PURPOSE: To investigate possible ophthalmologic alterations in patients who had severe malnutrition during the first six months of life. METHODS: 182 eyes of 91, 2 to 11-year-old, children who had had severe malnutrition during the first six months of life (study group were analyzed. As a control group 88 children selected according to similar characteristics of age, gender, demographic and economic conditions were included. RESULTS: In the study group, a higher frequency of children with visual acuity from 0.3 to 0.1 and less than 0.1 (11.5% versus 0.7% - p<0.0001 was observed. There was a higher frequency of astigmatism and myopia in the study group. A higher frequency of astigmatism of one diopter or more in the study group (p<0.0001 was also observed. The fundoscopic alterations were pale optic nerve (2.2%, increased disc cup (4.4%, increased vascular tortuosity (6.6%, alteration of retina color (13.2% and retinal pigment epithelium cell atrophy (12.0%. CONCLUSIONS: The present data support the concept that early malnutrition interferes in the individual's visual health. Further studies are necessary to establish a more precise cause-effect relationship.

  3. Optical quality of toric intraocular lens implantation in cataract surgery

    Institute of Scientific and Technical Information of China (English)

    Xian-Wen; Xiao; Jing; Hao; Hong; Zhang; Fang; Tian

    2015-01-01

    AIM: To analyze the optical quality after implantation of toric intraocular lens with optical quality analysis system.METHODS: Fifty-two eyes of forty-four patients with regular corneal astigmatism of at least 1.00 D underwent implantation of Acry Sof toric intraocular lens, including T3 group 19 eyes, T4 group 18 eyes, T5 group 10 eyes,T6 group 5 eyes. Main outcomes evaluated at 3mo of follow-up, included uncorrected distance visual acuity(UDVA), corrected distance visual acuity(CDVA), residual refractive cylinder and intraocular lens(IOL) axis rotation.Objective optical quality were measured using optical quality analysis system(OQAS Ⅱ, Visiometrics, Spain),included the cutoff frequency of modulation transfer function(MTFcutoff), objective scattering index(OSI),Strehl ratio, optical quality analysis system value(OV)100%, OV 20% and OV 9% [the optical quality analysis system(OQAS) values at contrasts of 100%, 20%, and 9%].RESULTS: At 3mo postoperative, the mean UDVA and CDVA was 0.18 ±0.11 and 0.07 ±0.08 log MAR; the mean residual refractive cylinder was 0.50 ±0.29 D; the mean toric IOL axis rotation was 3.62 ±1.76 degrees, the mean MTFcutoff, OSI, Strehl ratio, OV 100%, OV 20% and OV9% were 22.862 ±5.584, 1.80 ±0.84, 0.155 ±0.038, 0.76 ±0.18,0.77±0.19 and 0.78±0.21. The values of UDVA, CDVA, IOL axis rotation, MTFcutoff, OSI, Strehl ratio, OV100%,OV20% and OV9% depending on the power of the cylinder of the implantation were not significantly different(P >0.05), except the residual refractive cylinder(P <0.05).CONCLUSION: The optical quality analysis system was useful for characterizing the optical quality of Acry Sof toric IOL implantation. Implantation of an Acry Sof toric IOL is an effective and safe method to correct corneal astigmatism during cataract surgery.

  4. The efficiency of pneumatic retinopexy in the treatment of superior rhegmatogenous retinal detachment%充气视网膜固定术治疗上方视网膜脱离的疗效

    Institute of Scientific and Technical Information of China (English)

    刘炳乾; 邵毅; 丁亚梅; 熊杰; 张自平

    2014-01-01

    目的 观察充气视网膜固定术治疗上方孔源性视网膜脱离(RRD)的疗效.方法 回顾性分析21例(21眼)上方局限性RRD行充气视网膜固定术的临床资料.分析术后视网膜解剖复位率和手术并发症.随访时间6~9个月.结果 一次手术视网膜复位17眼,手术成功率为80.9%.术前术后散光比较差异无统计学意义,术后视力较术前好(t =3.53,P<0.05),其差异有统计学意义.结论 充气视网膜固定术治疗上方RRD一次手术复位率高,手术操作简便、并发症少,再次手术效果不受影响.可以作为部分RRD的首选治疗.%Objective To observe the efficacy of pneumatic retinopexy in the treatment of superior rhegmatogenous retinal detachment (RRD).Methods A retrospective analysis of 21 eyes of 21 patients with superior limited RRD treated by pneumatic retinopexy.Observational items included postoperative retinal reattachment rate,operational complications,postoperative visual acuity and retinal proliferation.The follow-up was 6-9 months.Results The retinal reattachment was achieved by one surgery in 17 eyes,the success rate of operation was 80.9%.Postoperative astigmatism was not statistically significantly different from preoperative astigmatism.The visual acuity of postoperation was improved compared with that of preoperation (t =3.53,P < 0.05).Conclusion The reattachment rate of pneumatic retinopexy is high in the treatment of superior RRD.The operation is simple with less complications,and less influence on prognosis of second operation.Pneumatic retinopexy can be used as the first choice for treatment of a part of RRD.

  5. Visual performance and aberration associated with contact lens wear in patients with keratoconus: a pilot study

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    Abdu M

    2014-08-01

    Full Text Available Mustafa Abdu, Norhani Mohidin, Bariah Mohd-Ali Optometry and Vision Science Program, School of Healthcare Sciences, Faculty of Health Science, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia Background: Rigid gas permeable (RGP and silicone hydrogel (SH contact lenses with specific designs are currently being used to improve visual function in patients with keratoconus. However, there are minimal data available comparing the effects of these lenses on visual function in patients with keratoconus. The objectives of this study were to compare visual acuity and contrast sensitivity using spectacles, RGP lenses, and SH lenses, and to evaluate the effects of RGP and SH lenses on higher-order aberrations and visual quality in eyes with keratoconus. The relationship between visual outcomes, aberration, and visual quality were also examined. Methods: This was a pilot study involving 13 eyes from nine subjects with keratoconus. Subjects were fitted with RGP and SH contact lenses. Visual acuity and contrast sensitivity were measured using Snellen and Pelli-Robson charts, respectively. Ocular aberrations and visual quality were measured using an OPD-Scan II device. All measurements were conducted before and after contact lens wear. Results: Significantly better visual acuity was obtained with RGP lenses than with spectacles or SH lenses (P<0.001. No significant difference in contrast sensitivity values was detected between RGP and SH lenses (P=0.06. Both SH and RGP lenses significantly reduced total ocular and higher-order aberrations (P<0.001 when compared with spectacles, but RGP lenses reduced trefoil, coma, and spherical aberrations more than SH lenses. No significant difference in astigmatic aberrations was found between RGP and SH lenses (P=0.12. Negative correlations were found between visual acuity and coma aberration and contrast sensitivity with higher-order aberrations and coma, trefoil, and astigmatic

  6. Outcomes of Penetrating Keratoplasty for Macular Corneal Dystrophy

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    Farid Karimian

    2009-01-01

    Full Text Available

    PURPOSE: To report the outcomes of penetrating keratoplasty (PKP in patients with macular corneal dystrophy (MCD. METHODS: This retrospective case series includes consecutive patients with MCD who underwent PKP from 1986 to 2006 with at least 6 months' follow-up. Main outcome measures included best spectacle-corrected visual acuity (BSCVA, postoperative astigmatism and graft survival. RESULTS: Sixty-two eyes of 39 patients with mean age of 34.0±10.5 (range 13-58 years at the time of keratoplasty were included for analysis. After a mean follow-up period of 52.0±47.3 (range 6-190 months, BSCVA improved from 1.4±0.4 logMAR (4/100 preoperatively to 0.2±0.3 logMAR (20/32 at final follow-up (P < 0.001. Mean postoperative BSCVA was 0.15±0.40 logMAR in patients (36 eyes aged less than 35 years at the time of surgery as compared to 0.26±0.25 logMAR in subjects (26 eyes older than 35 years (P=0.005. Final astigmatism was comparable with different suturing techniques including separate, continuous, and combined sutures (P=0.9. All grafts were clear at final follow-up except a single case of MCD with visually insignificant recurrence. Episodes of immunologic graft rejection occurred in 12 eyes (19.4% but none led to graft failure. CONCLUSION: PKP for MCD entails favorable outcomes in terms of graft survival and visual improvement

  7. Early wound healing and refractive response of different pocket configurations following presbyopic inlay implantation

    Science.gov (United States)

    Konstantopoulos, Aris; Liu, Yu-Chi; Teo, Ericia Pei Wen; Lwin, Nyein Chan; Yam, Gary Hin Fai; Mehta, Jodhbir S.

    2017-01-01

    Background Presbyopic inlays have mostly been implanted under a corneal flap. Implantation in a pocket has advantages including less postoperative dry eye and neurotrophic effect, and better biomechanical corneal stability. This study investigated the effect of different pocket and flocket dimensions on corneal stability and refractive power after Raindrop™ implantation, and the associated wound healing response. Methodology Ten New Zealand White rabbits had bilateral pocket Raindrop™ implantation. Eyes were allocated to 4 groups: pockets with 4mm, 6mm, and 8mm diameters, and 8mm flocket. They were examined pre-operatively, at day 1, weeks 1, 2, 3 and 4 post-surgery with anterior segment optical coherence tomography, corneal topography and in-vivo confocal microscopy. After euthanasia (week 4), CD11b, heat shock protein (HSP) 47 and fibronectin corneal immunohistochemistry was performed. Results Corneal thickness (mean±SD) increased from 360.0±16.2μm pre-operatively to 383.9±32.5, 409.4±79.3, 393.6±35.2, 396.4±50.7 and 405±20.3μm on day 1, weeks 1,2,3 and 4 respectively (pCorneal refractive power increased by 11.1±5.5, 7.5±2.5, 7.5±3.1, 7.0±3.6 and 6.3±2.9D (pCorneal astigmatism increased from 1.1±0.3D to 2.3±1.6, 1.7±0.7, 1.8±1.0, 1.6±0.9 and 1.6±0.9D respectively (p = 0.033). CT, refractive power change and astigmatism were not different between groups. The 8mm pocket and 8mm flocket groups had the least stromal keratocyte reflectivity. CD11b, fibronectin or HSP47 weren’t detected. Conclusions Anatomical and refractive stability was achieved by 1 week; the outcomes were not affected by pocket or flocket configuration. No scarring or inflammation was identified. The 8mm pocket and flocket showed the least keratocyte activation, suggesting they might be the preferred configuration. PMID:28235010

  8. The accuracy of corneal curvature measured by different types of keratometry%不同仪器测量角膜曲率的准确性研究

    Institute of Scientific and Technical Information of China (English)

    柏全豪; 苗雨晴; 扈月平; 张戈非

    2015-01-01

    Objective We compared and evaluated the accuracy of the four types of keratometry: manual keratometer, auto-refractometer, corneal topography and IOL-Master for measurement the corneal curvature. Methods Preoperative measurement of corneal curvature was prospectively obtained in 124 eyes of 86 subjects that underwent phacoemusification with intraocular lens implantation with four types of keratometry. Corneal refractive powers in mean values, corneal refractive powers in maximum axis, corneal refractive powers in minimum axis and the degree of axis were analysized by using SPSS 15.0 in one way ANOVA for statistics. Results There was no significant difference in measuring of the mean corneal refractive powers by using four different types of keratometry (P>0.05). There were also no significant differences in measuring degrees of the corneal refractive powers in maximum axis, corneal refractive powers in minimum axis and corneal astigmatism degree(P > 0.05). But there was significant difference in measuring of the axis values of corneal astigmatism (P < 0.01). Conclusion The accuracy of corneal curvature measured by different types of keratometry is perfect.%目的:研究比较手动角膜曲率计、电脑自动验光仪、角膜地形图和光学相干生物测量仪(IOL-Master)四种仪器测量角膜曲率的测量结果准确性。方法应用四种仪器分别测量拟施行白内障超声乳化摘除及人工晶体植入术的患者86例(124眼)的平均、最大及最小角膜屈光力、角膜散光度数及散光轴位,用SPSS15.0软件对测量参数进行统计学分析。结果这四种仪器测得的平均、最大及最小角膜屈光力、角膜散光度数无显著差异(P>0.05),角膜散光轴位测量结果有显著差异(P<0.01)。结论四种仪器测量角膜曲率的准确性较好。

  9. Effect of sutureless small incision cataract surgery plus intraocular lens implantation on Africans with cataract: a report of 1 730 cases%小切口无缝线白内障摘除加人工晶体植入术1730例临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    庞永明; 李辉

    2011-01-01

    Objective To investigate the effect of suture less small incision cataract surgery (SICS) plus intraocular lens (IOL) implantation for Africans with cataract. Methods Sutureless SICS plus IOL implantation was conducted on 1 730 African patients with cataract, a total of 2 207 eyes. The clinical effect was evaluated. Results One week after the surgery, 1 403 eyes were found with vision ≥0.5 (63.6%), and 112 were found with vision ≥1.0 (5.1%), with astigmatism of (1.96±0.72) D. Three months after the surgery, 2 094 eyes were found with vision ≥0.5 (94.9%), and 136 were found with vision ≥ 1.0 (6.2%), with astigmatism of (0.87±0.54) D. Conclusion Sutureless SICS plus IOL implantation leads to a smaller chance of injury and provides ideal vision recovery, which is worthy to be extended in African.%目的 探讨小切口无缝线白内障囊外摘除加人工晶体植入术治疗非洲黑人白内障的临床疗效.方法对1 730例(2 207眼)黑人白内障患者行小切口无缝线白内障囊外摘除及人工晶体植入术,评估疗效.结果术后1周视力≥0.5者占63.6%(1 403眼),视力≥1.0者占5.1%(112眼),散光为(1.96±0.72)D.3个月后视力≥0.5者占94.9%(2094眼).视力≥1.0 (136眼)占6.2%,散光为(0.87±0.54)D.结论小切口无缝线白内障囊外摘除及人工晶体植入术损伤小、术后视力恢复好,在非洲地区有推广运用价值.

  10. Accurate test of optical wave front for optical imaging system%光学成像系统光学波前的高精度测试

    Institute of Scientific and Technical Information of China (English)

    邵晶; 马冬梅; 聂真威

    2011-01-01

    Based on the Extended Nijboer-Zernike theory, the effect of different amplitudes for exit pupils on the image intensity in the focal plane was analyzed. A novel approach was applied to testing the wavefront according to the actual condition of the amplitude in the exit pupil, which can help eliminating the error caused by the nonuniformity illuminated pupil and the Fast Fourier Transform in the o-riginal phase retrieval algorithms. A testing experiment was performed on an imaging optical system, and obtained results show that the tested wave fronts in the exit pupil of a camera lens are 0. 196 5X in PV and 0. 022 4X in RMS (the testing wavelength X is 632. 8 nm). The aberrations in the wavefront are mainly astigmatism, coma and high order astigmatism. Furthermore, the approach can also be used to analyze the amplitude in the exit pupil of a camera lens and calculate the light intensity distribution on other focal planes. The experiment proves this approach available.%基于扩展奈波尔-泽尼克理论,分析了不同出瞳振幅分布情况对光学系统焦面处光强分布的影响.针对光学成像系统出瞳振幅实际分布状态,提出了一种新的测试光学波前的方法,解决了相位恢复算法中出瞳振幅分布不均匀和快速傅里叶变换引入计算误差的问题.通过测评实验,对一光学系统进行了测试,获得的光学系统出瞳波前(PV)值为0.196 5λ,RMS值为0.022 4λ(测试波长λ=632.8 nm),此波前中主要含有像散、彗差和高阶像散等像差.该方法亦可用于分析光学系统出瞳振幅分布,数值计算其他焦面处的光强分布.测评实验证明了此方法的有效性.

  11. Gendered Disparities in Quality of Cataract Surgery in a Marginalised Population in Pakistan: The Karachi Marine Fishing Communities Eye and General Health Survey.

    Directory of Open Access Journals (Sweden)

    Khabir Ahmad

    Full Text Available Marine fishing communities are among the most marginalised and hard-to-reach groups and have been largely neglected in health research. We examined the quality of cataract surgery and its determinants, with an emphasis on gender, in marine fishing communities in Karachi, Pakistan, using multiple indicators of performance.The Karachi Marine Fishing Communities Eye and General Health Survey was a door-to-door, cross-sectional study conducted between March 2009 and April 2010 in fishing communities living on 7 islands and in coastal areas in Keamari, Karachi, located on the Arabian Sea. A population-based sample of 638 adults, aged ≥ 50 years, was studied. A total of 145 eyes (of 97 persons had undergone cataract surgery in this sample. Cataract surgical outcomes assessed included vision (presenting and best-corrected with a reduced logMAR chart, satisfaction with surgery, astigmatism, and pupil shape. Overall, 65.5% of the operated eyes had some form of visual loss (presenting visual acuity [PVA] < 6/12. 55.2%, 29.0%, and 15.9% of these had good, borderline, and poor visual outcomes based on presenting vision; with best correction, these values were: 68.3 %, 18.6%, and 13.1%, respectively. Of 7 covariates evaluated in the multivariable generalized estimating equations (GEE analyses, gender was the only significant independent predictor of visual outcome. Women's eyes were nearly 4.38 times more likely to have suboptimal visual outcome (PVA<6/18 compared with men's eyes (adjusted odds ratio 4.38, 95% CI 1.96-9.79; P<0.001 after adjusting for the effect of household financial status. A higher proportion of women's than men's eyes had an irregular pupil (26.5% vs. 14.8% or severe/very severe astigmatism (27.5% vs. 18.2%. However, these differences did not reach statistical significance. Overall, more than one fourth (44/144 of cataract surgeries resulted in dissatisfaction. The only significant predictor of satisfaction was visual outcome (P <0

  12. One-site versus two-site phacotrabeculectomy: a prospective randomized study

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    Moschos MM

    2015-08-01

    Full Text Available Marilita M Moschos,1 Irini P Chatziralli,2 Michael Tsatsos3 1First Department of Ophthalmology, University of Athens, 2Second Department of Ophthalmology, Ophthalmiatrion Athinon, Athens, Greece; 3Department of Ophthalmology, Cambridge University Hospital NHS, Cambridge, UK Purpose: The purpose of this study is to compare the efficacy and safety of one-site and two-site combined phacotrabeculectomy with foldable posterior chamber intraocular lens implantation.Methods: Thirty-four patients (41 eyes with glaucoma and cataract were randomly assigned to undergo either a one-site (22 eyes or a two-site (19 eyes combined procedure. One-site approach consisted of a standard superior phacotrabeculectomy with a limbus-based conjunctival flap, while two-site approach consisted of a clear cornea phacoemulsification and a separate superior trabeculectomy with a limbus-based conjunctival flap.Results: Mean follow-up period was 54 months (standard deviation [SD] 2.3. Mean preoperative intraocular pressure (IOP in the one-site group was 21.3 mmHg (SD 2.8 and in the two-site group was 21.8 mmHg (SD 3.0 (P>0.1. Mean postoperative IOP significantly decreased in both groups compared to the preoperative level and was 15.6 mmHg (SD 3.5 in the one-site group and 14.9 mmHg (SD 2.7 in the two-site group. Three months later, the difference between the two groups was not statistically significant (P=0.058. The one-site group required significantly more medications than the two-site group (P=0.03. Best-corrected visual acuity (BCVA improved similarly in both groups, but there was less postoperative (induced astigmatism in the two-site group in a marginal statistical level (P=0.058. Intra- and postoperative complications were comparable in the two groups.Conclusion: Both techniques yielded similar results concerning final BCVA and IOP reduction. However, the two-site group had less induced astigmatism and a better postoperative IOP control with less required

  13. Microfocusing at the PG1 beamline at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Dziarzhytski, Siarhei, E-mail: siarhei.dziarzhytski@desy.de [DESY, Notkestrasse 85, 22067 Hamburg (Germany); Gerasimova, Natalia [European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); Goderich, Rene [University of South Florida (United States); Mey, Tobias [Laser Laboratorium Göttingen eV, Hans-Adolf-Krebs-Weg 1, 37077 Göttingen (Germany); Reininger, Ruben [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Rübhausen, Michael [University of Hamburg and Center for Free-Electron Laser Science, Notkestrasse 85, 22607 Hamburg (Germany); Siewert, Frank [Institute for Nanometre Optics and Technology at Helmholtz Zentrum Berlin/BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin (Germany); Weigelt, Holger; Brenner, Günter [DESY, Notkestrasse 85, 22067 Hamburg (Germany)

    2016-01-01

    The Kirkpatrick–Baez (KB) refocusing mirrors unit at the PG1 beamline at FLASH has been newly designed, developed and fully commissioned. The vertical focal size of the KB optics is measured to be 5.8 ± 1 µm FWHM and the horizontal 6 ± 2 µm FWHM; astigmatism has been minimized to below 1 mm between waist positions. Such a tight focus is essential for the VUV double Raman spectrometer as it serves as an entrance slit for the first monochromator and defines its resolution to a very large extent. The Raman spectrometer is a permanent end-station at the PG1 beamline, dedicated to inelastic soft X-ray scattering experiments. The Kirkpatrick–Baez (KB) refocusing mirror system installed at the PG1 branch of the plane-grating monochromator beamline at the soft X-ray/XUV free-electron laser in Hamburg (FLASH) is designed to provide tight aberration-free focusing down to 4 µm × 6 µm full width at half-maximum (FWHM) on the sample. Such a focal spot size is mandatory to achieve ultimate resolution and to guarantee best performance of the vacuum-ultraviolet (VUV) off-axis parabolic double-monochromator Raman spectrometer permanently installed at the PG1 beamline as an experimental end-station. The vertical beam size on the sample of the Raman spectrometer, which operates without entrance slit, defines and limits the energy resolution of the instrument which has an unprecedented design value of 2 meV for photon energies below 70 eV and about 15 meV for higher energies up to 200 eV. In order to reach the designed focal spot size of 4 µm FWHM (vertically) and to hold the highest spectrometer resolution, special fully motorized in-vacuum manipulators for the KB mirror holders have been developed and the optics have been aligned employing wavefront-sensing techniques as well as ablative imprints analysis. Aberrations like astigmatism were minimized. In this article the design and layout of the KB mirror manipulators, the alignment procedure as well as microfocus

  14. Visual outcome after correcting the refractive error of large pupil patients with wavefront-guided ablation

    Directory of Open Access Journals (Sweden)

    Khalifa MA

    2012-12-01

    Full Text Available Mounir A Khalifa,1,2 Waleed A Allam,1,2 Mohamed S Shaheen2,31Ophthalmology Department, Tanta University Eye Hospital, Tanta, Egypt; 2Horus Vision Correction Center, Alexandria, Egypt; 3Ophthalmology Department, Alexandria University, Alexandria, EgyptPurpose: To investigate the efficacy and predictability of wavefront-guided laser in situ keratomileusis (LASIK treatments using the iris registration (IR technology for the correction of refractive errors in patients with large pupils.Setting: Horus Vision Correction Center, Alexandria, Egypt.Methods: Prospective noncomparative study including a total of 52 eyes of 30 consecutive laser refractive correction candidates with large mesopic pupil diameters and myopia or myopic astigmatism. Wavefront-guided LASIK was performed in all cases using the VISX STAR S4 IR excimer laser platform. Visual, refractive, aberrometric and mesopic contrast sensitivity (CS outcomes were evaluated during a 6-month follow-up.Results: Mean mesopic pupil diameter ranged from 8.0 mm to 9.4 mm. A significant improvement in uncorrected distance visual acuity (UCDVA (P < 0.01 was found postoperatively, which was consistent with a significant refractive correction (P < 0.01. No significant change was detected in corrected distance visual acuity (CDVA (P = 0.11. Efficacy index (the ratio of postoperative UCDVA to preoperative CDVA and safety index (the ratio of postoperative CDVA to preoperative CDVA were calculated. Mean efficacy and safety indices were 1.06 ± 0.33 and 1.05 ± 0.18, respectively, and 92.31% of eyes had a postoperative spherical equivalent within ±0.50 diopters (D. Manifest refractive spherical equivalent improved significantly (P < 0.05 from a preoperative level of −3.1 ± 1.6 D (range −6.6 to 0 D to −0.1 ± 0.2 D (range −1.3 to 0.1 D at 6 months postoperative. No significant changes were found in mesopic CS (P ≥ 0.08, except CS for three cycles/degree, which improved significantly (P = 0

  15. Development of Miniaturized Difference Frequency Generation, Fiber Optic, and Quantum Cascade Laser Systems in Conjunction With Integrated Electronics for Global Studies of Atmospheric Tracers Using UAVs.

    Science.gov (United States)

    Witinski, M. F.; Lapson, L. B.; Anderson, J. G.

    2007-12-01

    In order to harness the power of UAVs (Unmanned Aerial Vehicles) for in situ atmospheric monitoring of tracers such as CO2, N2O, CH4, and H2O, we have developed small, lightweight, single mode laser systems with co- developed integrated electronics. The laser sources are of various types including newly developed cavity- enhanced difference frequency generation (CE DFG), distributed feedback quantum cascade lasers (DFB QCLs), and new types of commercially available DFB diode lasers. All are continuous wave (cw) and thermo-electrically cooled, ensuring a high instrument duty cycle in a compact, low maintenance package. The light sources are collimated with miniature aspherical lenses and coupled into a home-built astigmatic Herriott cell for detection of the various targets using direct absorption. In parallel with the optical components, we have developed integrated electrical systems for laser control, data processing, and acquisition. A prototype instrument suite is described that illustrates the importance of parallel development of optical and electrical components in achieving an apparatus that is compact, fully automated, and highly capable scientifically. Although the emphasis here is on atmospheric tracers, this technology could be applied to spectroscopic measurements of other atmospheric species such as isotopes, free radicals, and reactive intermediates.

  16. Refractive ocular conditions and reasons for spectacles renewal in a resource-limited economy

    Directory of Open Access Journals (Sweden)

    Folorunso Francisca N

    2010-05-01

    Full Text Available Abstract Background Although a leading cause of visual impairment and a treatable cause of blindness globally, the pattern of refractive errors in many populations is unknown. This study determined the pattern of refractive ocular conditions, reasons for spectacles renewal and the effect of correction on refractive errors in a resource-limited community. Methods A retrospective review of case records of 1,413 consecutive patients seen in a private optometry practice, Nigeria between January 2006 and July 2007. Results A total number of 1,216 (86.1% patients comprising of (486, 40% males and (730, 60% females with a mean age of 41.02 years SD 14.19 were analyzed. The age distribution peaked at peri-adolescent and the middle age years. The main ocular complaints were spectacles loss and discomfort (412, 33.9%, blurred near vision (399, 32.8% and asthenopia (255, 20.9%. The mean duration of ocular symptoms before consultation was 2.05 years SD 1.92. The most common refractive errors include presbyopia (431, 35.3%, hyperopic astigmatism (240, 19.7% and presbyopia with hyperopia (276, 22.7%. Only (59, 4.9% had myopia. Following correction, there were reductions in magnitudes of the blind (VA Conclusions Adequate correction of refractive errors reduces visual impairment and avoidable blindness and to achieve optimal control of refractive errors in the community, services should be targeted at individuals in the peri-adolescent and the middle age years.

  17. An off Axis Cavity Enhanced Absorption Spectrometer and a Rapid Scan Spectrometer with a Room-Temperature External Cavity Quantum Cascade Laser

    Science.gov (United States)

    Liu, Xunchen; Kang, Cheolhwa; Xu, Yunjie

    2009-06-01

    Quantum cascade laser (QCL) is a new type of mid-infrared tunable diode lasers with superior output power and mode quality. Recent developments, such as room temperature operation, wide frequency tunability, and narrow line width, make QCLs an ideal light source for high resolution spectroscopy. Two slit jet infrared spectrometers, namely an off-axis cavity enhanced absorption (CEA) spectrometer and a rapid scan spectrometer with an astigmatic multi-pass cell assembly, have been coupled with a newly purchased room temperature tunable mod-hop-free QCL with a frequency coverage from 1592 cm^{-1} to 1698 cm^{-1} and a scan rate of 0.1 cm^{-1}/ms. Our aim is to utilize these two sensitive spectrometers, that are equipped with a molecular jet expansion, to investigate the chiral molecules-(water)_n clusters. To demonstrate the resolution and sensitivity achieved, the rovibrational transitions of the static N_2O gas and the bending rovibrational transitions of the Ar-water complex, a test system, at 1634 cm^{-1} have been measured. D. Hofstetter and J. Faist in High performance quantum cascade lasers and their applications, Vol.89 Springer-Verlag Berlin & Heidelberg, 2003, pp. 61-98. Y. Xu, X. Liu, Z. Su, R. M. Kulkarni, W. S. Tam, C. Kang, I. Leonov and L. D'Agostino, Proc. Spie, 2009, 722208 (1-11). M. J. Weida and D. J. Nesbitt, J. Chem. Phys. 1997, 106, 3078-3089.

  18. [Soft contactlenses in general practice (author's transl)].

    Science.gov (United States)

    Miller, B

    1975-07-01

    In contrast to the hard lenses the soft lens has enough permeability for oxygen and water-soluble substances, whereas high molecular substances, bacteria and virus cannot penetrate the soft lenses, so long as their surfaces are intact. The two principal production methods, the spin cast method and the lathe-turned method are compared. The duration of wearing of the soft lens depends on the deposits of proteins from the tears on the surface of the lens and the desinfection method. The daily boiling of the lenses shortens their useful life, while chemical desinfection causes besides bacteriolysis, damage of the corneal cell protein. The new cleaners on the base of proteolytic plant enzymes promise good results. For the optical correction of astigmatism with more than 1 cyl, soft lenses with conic outer surface are used or combinations of a soft and a hard lens (Duosystem). The therapeutic use of soft lenses has as aim: protection of the cornea against mechanical irritation, release of pain, protracted administration output of medicaments. Further indications for use: aseptic corneal inflammation and corneal defects.

  19. Optimized SESAMs for kilowatt-level ultrafast lasers.

    Science.gov (United States)

    Diebold, A; Zengerle, T; Alfieri, C G E; Schriber, C; Emaury, F; Mangold, M; Hoffmann, M; Saraceno, C J; Golling, M; Follman, D; Cole, G D; Aspelmeyer, M; Südmeyer, T; Keller, U

    2016-05-16

    We present a thorough investigation of surface deformation and thermal properties of high-damage threshold large-area semiconductor saturable absorber mirrors (SESAMs) designed for kilowatt average power laser oscillators. We compare temperature rise, thermal lensing, and surface deformation of standard SESAM samples and substrate-removed SESAMs contacted using different techniques. We demonstrate that for all cases the thermal effects scale linearly with the absorbed power, but the contacting technique critically affects the strength of the temperature rise and the thermal lens of the SESAMs (i.e. the slope of the linear change). Our best SESAMs are fabricated using a novel substrate-transfer direct bonding technique and show excellent surface flatness (with non-measureable radii of curvature (ROC), compared to astigmatic ROCs of up to 10 m for standard SESAMs), order-of-magnitude improved heat removal, and negligible deformation with absorbed power. This is achieved without altering the saturation behavior or the recovery parameters of the samples. These SESAMs will be a key enabling component for the next generation of kilowatt-level ultrafast oscillators.

  20. Beam shaping characteristics of an unstable-waveguide hybrid resonator.

    Science.gov (United States)

    Xiao, Longsheng; Qin, Yingxiong; Tang, Xiahui; Wan, Chenhao; Li, Gen; Zhong, Lijing

    2014-04-01

    The unstable-waveguide hybrid resonator emits a rectangular, simple astigmatic beam with a large number of high-spatial-frequency oscillations in the unstable direction. To equalize the beam quality, in this paper, a beam shaping system with a spatial filter for the hybrid resonator was investigated by numerical simulation and experimental method. The high-frequency components and fundamental mode of the output beam of the hybrid resonator in the unstable direction are separated by a focus lens. The high-frequency components of the beam are eliminated by the following spatial filter. A nearly Gaussian-shaped beam with approximately equal beam propagation factor M² in the two orthogonal directions was obtained. The effects of the width of the spatial filter on the beam quality, power loss, and intensity distribution of the shaped beam were investigated. The M² factor in the unstable direction is changed from 1.6 to 1.1 by optimum design. The power loss is only 9.5%. The simulation results are in good agreement with the experimental results.