Método computadorizado para medida da acuidade visual A computerized method for visual acuity assessment

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Patrícia Katayama Kjaer Arippol

2006-12-01

Full Text Available OBJETIVO: Elaborar e validar teste computadorizado para medida da acuidade visual de escolares. MÉTODOS: Foi elaborado teste computadorizado para determinação da acuidade visual utilizando os padrões das tabelas logarítmicas impressas adotadas na clínica oftalmológica. Foram avaliados 90 alunos da primeira série do ensino básico, oito estudantes do curso de Tecnologia Oftálmica da UNIFESP-EPM e 10 pacientes do ambulatório de Estrabismo do Departamento de Oftalmologia da UNIFESP-EPM. Todos os sujeitos foram avaliados pelo mesmo examinador e submetidos ao exame de acuidade visual monocular, pela tabela logarítmica de optotipos E impressa e do novo teste computadorizado no mesmo momento. Os participantes forneceram os seus consentimentos após esclarecimento. RESULTADOS: As análises estatísticas revelaram correlação excelente (r>0,75 entre os dois métodos, apesar da leve tendência apresentada pelo teste computadorizado em superestimar a acuidade visual quando comparado com o padrão-ouro. O teste computadorizado apresentou sensibilidade de 100% e especificidade de 94%. CONCLUSÕES: Os resultados obtidos nos permitem dizer que o teste computadorizado pode ser utilizado como novo recurso para triagem da qualidade visual dos escolares, por ser método rápido, de fácil aplicação, barato, automático e atrativo para as crianças. A automatização desvincula o aplicador da interpretação das respostas dadas pelo aluno testado, garante padronização do procedimento, que favorece as análises de acompanhamento e pode ser realizado por diferentes examinadores. Para melhor compreensão da efetividade do teste como instrumento de triagem visual, seria interessante instituí-lo nas escolas do curso básico, após treinamento dos professores para sua aplicação.PURPOSE: To elaborate and to validate a computerized test for visual acuity screening of school-age children. METHODS: We have created a computerized test for visual acuity

Recognition versus Resolution: a Comparison of Visual Acuity Results Using Two Alternative Test Chart Optotype

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Pointer, Jonathan S.

2010-01-01

Purpose To quantify the difference between recognition (letter) and resolution (Landolt) visual acuity (VA) in a group of normally sighted subjects. Is it reasonable to assume that the two acuity measures are clinically equivalent? Methods A pair of 6 m acuity test charts was produced: one comprised letters and the other Landolt broken rings. Construction of both charts conformed to the logMAR design format. Monocular VA was determined for the dominant eye of 300 screened and normally sighted optometric patients aged 16 to 40, each wearing an optical refractive (spectacle) correction. Results Letter acuity was superior to Landolt acuity (P≤0.0001). The mean paired acuity difference was -0.041 logMAR (standard deviation 0.034): the 95% limits of agreement were ±0.067 logMAR units or ±3.3 chart optotype. Repeatability was high and similar for each chart type (±2.1 and ±2.4 optotype for letter and Landolt, respectively). Gender, test sequence, and laterality of the dominant eye (left or right) were each non-statistically significant variables. Conclusions For normally sighted subjects wearing an optimal refractive correction, a bias was recorded in favour of recognition over resolution acuity: the clinical difference amounted to approximately 40% of one logMAR chart line, with similar high repeatability for either chart optotype. We conclude that the assumption of clinical equivalence between letter and Landolt acuity is reasonable under optimum test conditions.

Evaluation of contrast visual acuity in patients with retinitis pigmentosa

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Oomachi, Kazumi; Ogata, Kazuha; Sugawara, Takeshi; Hagiwara, Akira; Hata, Akira; Yamamoto, Shuichi

2011-01-01

Background The purpose of this study was to determine visual acuity at different contrast levels under photopic and mesopic conditions in patients with retinitis pigmentosa. Methods Sixty eyes of 31 normal controls, 92 eyes of 52 patients with retinitis pigmentosa without other ocular disorders (RP-1 group), and 20 eyes of 14 patients with retinitis pigmentosa with cataracts and without other ocular disorders (RP-2 group) were studied. Conventional visual acuity was measured using a conventional Landolt ring chart with 100% contrast and luminance of 150 cd/m2. All of the patients with retinitis pigmentosa had a decimal visual acuity better than 1.0. Contrast visual acuity was measured with the same Landolt ring chart with contrasts of 100% and 10% and under photopic (200 cd/m2) and mesopic (10 cd/m2) conditions. Decimal visual acuities were converted to logMAR units for the analyses. Results The 100% contrast visual acuity and the 10% contrast visual acuity determined under both photopic and mesopic conditions were significantly poorer in both the RP-1 and RP-2 groups than in the controls. The differences between the conventional visual acuity and the 100% contrast visual acuity were significantly greater in the RP-1 and RP-2 groups than in the controls under both photopic and mesopic conditions. The differences between the 100% contrast visual acuity and the 10% contrast visual acuity were not significant among the three groups under photopic and mesopic conditions. Conclusion Contrast visual acuities were greatly reduced in patients with retinitis pigmentosa with relatively well preserved conventional visual acuity, and the contrast visual acuity was largely influenced by ambient light levels in patients with retinitis pigmentosa. Although a longitudinal study for confirmation has to be performed, our findings indicate that contrast visual acuity is a better test to follow changes in visual function in patients with retinitis pigmentosa. PMID:22069346

Visual acuity and stereoacuity among mentally retarded children.

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Letourneau, J E; Beaulne, C; Duplessis, L

1992-12-01

To evaluate the reliability and the validity of Landolt Rings and of the Frisby Test as measures of visual acuity and stereoacuity, respectively, the visual acuity of 30 mentally retarded children was measured with Landolt Rings shown as games, the Sjögren Test, the Dot Visual Acuity Test and stereoacuity with the Frisby Test. Subjects were tested 3 times over a period of 3 weeks to measure the reliability of the tests. No significant difference was observed among these tests. The validity of the Landolt Rings was measured by a correlation of .55 for the highest logMAR values of the Sjögren Test with the highest logMAR values of the Landolt Rings. Visual acuity was systematically lower on the Dot Visual Acuity Test. The Frisby Test was not reliable among a group of 16 normal children who improved systematically over 3 weeks.

21 CFR 886.1150 - Visual acuity chart.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Visual acuity chart. 886.1150 Section 886.1150 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1150 Visual acuity chart. (a) Identification...

Monocular Visual Deprivation Suppresses Excitability in Adult Human Visual Cortex

DEFF Research Database (Denmark)

Lou, Astrid Rosenstand; Madsen, Kristoffer Hougaard; Paulson, Olaf Bjarne

2011-01-01

The adult visual cortex maintains a substantial potential for plasticity in response to a change in visual input. For instance, transcranial magnetic stimulation (TMS) studies have shown that binocular deprivation (BD) increases the cortical excitability for inducing phosphenes with TMS. Here, we...... of visual deprivation has a substantial impact on experience-dependent plasticity of the human visual cortex.......The adult visual cortex maintains a substantial potential for plasticity in response to a change in visual input. For instance, transcranial magnetic stimulation (TMS) studies have shown that binocular deprivation (BD) increases the cortical excitability for inducing phosphenes with TMS. Here, we...... employed TMS to trace plastic changes in adult visual cortex before, during, and after 48 h of monocular deprivation (MD) of the right dominant eye. In healthy adult volunteers, MD-induced changes in visual cortex excitability were probed with paired-pulse TMS applied to the left and right occipital cortex...

Estimated Prevalence of Monocular Blindness and Monocular ...

African Journals Online (AJOL)

with MB/MSVI; among the 109 (51%) children with MB/MSVI that had a known etiology, trauma. Table 1: Major anatomical site of monocular blindness and monocular severe visual impairment in children. Anatomical cause. Total (%). Corneal scar. 89 (42). Whole globe. 43 (20). Lens. 42 (19). Amblyopia. 16 (8). Retina. 9 (4).

Should we add visual acuity ratios to referral criteria for potential cerebral visual impairment?

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van der Zee, Ymie J; Stiers, Peter; Evenhuis, Heleen M

To determine whether the assessment of visual acuity ratios might improve the referral of children with (sub)normal visual acuity but at risk of cerebral visual impairment. In an exploratory study, we assessed visual acuity, crowding ratio and the ratios between grating acuity (Teller Acuity Cards-II) and optotype acuity (Cambridge Crowding Cards) in 60 typically developing school children (mean age 5y8m±1y1m), 21 children with ocular abnormalities only (5y7m±1y9m) and 26 children with (suspected) brain damage (5y7m±1y11m). Sensitivities and specificities were calculated for targets and controls from the perspective of different groups of diagnosticians: youth health care professionals (target: children with any visual abnormalities), ophthalmologists and low vision experts (target: children at risk of cerebral visual impairment). For youth health care professionals subnormal visual acuity had the best sensitivity (76%) and specificity (70%). For ophthalmologists and low vision experts the crowding ratio had the best sensitivity (67%) and specificity (79 and 86%). Youth health care professionals best continue applying subnormal visual acuity for screening, whereas ophthalmologists and low vision experts best add the crowding ratio to their routine diagnostics, to distinguish children at risk of visual impairment in the context of brain damage from children with ocular pathology only. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

Effects of lighting and task parameters on visual acuity and performance

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Halonen, L.

1993-12-31

Lighting and task parameters and their effects on visual acuity and visual performance are dealt with. The parameters studied are target contrast, target size and subject`s age; and also adaptation luminance, luminance ratio between task and its surrounding and temporal change in luminances are studied. Experiments were carried out to examine the effects of luminance and light spectrum on visual acuity. Young normally sighted, older and low vision people participated in the measurements. In the young and older subject groups the visual acuity remained unchanged at contrasts 0.93 and 0.63 at the luminance range of 15-630 cd/m{sub 2}. The results show that at contrasts 0.03-0.93 young and older subjects` visual acuity remained unchanged in the luminance range of 105-630 cd/m{sub 2}. In the low vision group, the changes in luminances between 25-860 cd/m{sub 2} did not have significant effects on visual acuity measured at high contrast 0.93, at low contrast, slight individual changes were found. The colour temperature of the light sources was altered between 2900-9500 K in the experiment. In the groups of the older, young and low vision subjects the light spectrum did not have significant effects on visual acuity, except for two retinitis pigmentosa subjects. On the basis of the visual acuity experiments, a three dimensional visual acuity model (VA-HUT) has been developed. The model predicts visual acuity as a function of luminance, target contrast and observer age. On the basis of visual acuity experiments visual acuity reserve values have been calculated for different text sizes

Empiric determination of corrected visual acuity standards for train crews.

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Schwartz, Steven H; Swanson, William H

2005-08-01

Probably the most common visual standard for employment in the transportation industry is best-corrected, high-contrast visual acuity. Because such standards were often established absent empiric linkage to job performance, it is possible that a job applicant or employee who has visual acuity less than the standard may be able to satisfactorily perform the required job activities. For the transportation system that we examined, the train crew is required to inspect visually the length of the train before and during the time it leaves the station. The purpose of the inspection is to determine if an individual is in a hazardous position with respect to the train. In this article, we determine the extent to which high-contrast visual acuity can predict performance on a simulated task. Performance at discriminating hazardous from safe conditions, as depicted in projected photographic slides, was determined as a function of visual acuity. For different levels of visual acuity, which was varied through the use of optical defocus, a subject was required to label scenes as hazardous or safe. Task performance was highly correlated with visual acuity as measured under conditions normally used for vision screenings (high-illumination and high-contrast): as the acuity decreases, performance at discriminating hazardous from safe scenes worsens. This empirically based methodology can be used to establish a corrected high-contrast visual acuity standard for safety-sensitive work in transportation that is linked to the performance of a job-critical task.

Gender and environmental influences on visual acuity in Owerri ...

African Journals Online (AJOL)

This study assessed the gender and environmental influences on visual function among adults in Owerri, Nigeria. Visual acuity (V.A.) is a measure of visual function in health and disease. Visual disability together with other disabling conditions is a barrier to development, yet there is little known about the visual acuity and ...

Anisometropia and ptosis in patients with monocular elevation deficiency

International Nuclear Information System (INIS)

Zafar, S.N.; Islam, F.; Khan, A.M.

2016-01-01

Objective: To determine the effect of ptosis on the refractive error in eyes having monocular elevation deficiency Place and Duration of Study: Al-Shifa Trust Eye Hospital, Rawalpindi, from January 2011 to January 2014. Methodology: Visual acuity, refraction, orthoptic assessment and ptosis evaluation of all patients having monocular elevation deficiency (MED) were recorded. Shapiro-Wilk test was used for tests of normality. Median and interquartile range (IQR) was calculated for the data. Non-parametric variables were compared, using the Wilcoxon signed ranks test. P-values of <0.05 were considered significant. Results: A total of of 41 MED patients were assessed during the study period. Best corrected visual acuity (BCVA) and refractive error was compared between the eyes having MED and the unaffected eyes of the same patient. The refractive status of patients having ptosis with MED were also compared with those having MED without ptosis. Astigmatic correction and vision had significant difference between both the eyes of the patients. Vision was significantly different between the two eyes of patients in both the groups having either presence or absence of ptosis (p=0.04 and p < 0.001, respectively). Conclusion: Significant difference in vision and anisoastigmatism was noted between the two eyes of patients with MED in this study. The presence or absence of ptosis affected the vision but did not have a significant effect on the spherical equivalent (SE) and astigmatic correction between both the eyes. (author)

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

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

2010-06-01

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

[Schoolchildren's visual acuity in the dynamics of learning].

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Bezrukikh, M M; Voinov, V B; Kul'ba, S N; Shurygina, I P

2014-12-01

The results of the screening study of the acuity of schoolchildren between 7 and 17 years old living in Rostov Region of the Russian Federation are discussed in the article. The method of computer optometry was used to measure acuity. 93772 pupils, 48621 girls and 45151 boys, from 150 schools participated in this examination. It was found that there is sustained growth of those with low acuity (0,2 and less) among children of both sexes from junior group (7 years) to the senior (17). The signs of the decline in visual acuity among girls (14%) are manifested earlier than in boys (8%). The decline in visual acuity among 7-8-year-old children is about 3%. While comparing children from rural areas with those from big cities a true dependence of the parameter (acuity) on the factors (city and sex) was found.

[Dice test--a simple method for assessment of visual acuity in infants with visual deficits].

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Rohrschneider, K; Brill, B; Bayer, Y; Ahrens, P

2010-07-01

Determination of visual acuity in low vision infants or patients with additional cerebral retardation is difficult. In our low vision department we used dice of different sizes and colors as well as other defined objects to determine visual acuity (VA). In this study we compared the results of the dice test with conventional tests for measurement of visual acuity. A total of 88 children with different causes of visual impairment e.g. albinism, retinal scars, retinopathy of prematurity (ROP), achromatopsia and optic atrophy etc., were included in this longitudinal study. Median follow-up time was 8.7 years (range 2.9-18.9 years). The first reliable examination was performed between the ages of 4 and 24 months (median 11 months). We estimated VA depending on the edge length of the dice, which were recognized at a distance of 30 cm, while 4 mm complied with VA 20/200. Best corrected binocular visual acuity was compared between the dice test, measurement with the Lea symbols and with numbers or Landolt rings. Estimation of visual acuity using the dice test was possible at the end of the first year of life (median 11 months, range 4-27 months). Although observation is limited to visual acuity results in the low vision range between light reaction and 20/120 there was nearly complete agreement between all three VA measurements. Visual acuity ranged from light perception to 20/20 with a median of 20/100. In 39 patients visual acuity was 20/200 or less at the end of the observation period. Visual acuity estimation overestimated visual acuity only in 5 out of the 88 patients, while in all of the patients with later acuity measurements better than 20/200, our best value of 20/200 was achieved. Using simple visual objects, such as dice with different colors and size down to an edge length of 4 mm, it is possible to estimate visual acuity in low vision infants within the first year of life. This option is also very helpful in patients who are not able to perform other visual

A case-control study of visual acuity in onychocryptosis.

LENUS (Irish Health Repository)

Hogan, Aisling M

2012-02-01

BACKGROUND: There are many theories surrounding the etiology of ingrown toenails (IGTN). Few factors have been formally assessed, but it is widely accepted that a poor nail cutting technique has a causative role. AIM: To investigate the hypothesis that decreased visual acuity may lead to inadequate nail cutting and the formation of IGTN. METHODS: A prospective case-control study was performed. Near and distance visual acuity were tested on a population with IGTN (n = 19) and compared with that of an age- and sex-matched control cohort (n = 24) who underwent epidermal cyst excision in the same tertiary referral center. Comparisons of visual acuity were made between groups by Mann-Whitney U-test. Differences were taken to be significant if P < 0.05. Institutional Review Board approval was sought and granted. RESULTS: No significant difference in visual acuity (near or distance) was demonstrated between patients with IGTN and the control group (P = 0.33). CONCLUSION: Visual acuity does not appear to play a significant role in the development of IGTN.

The monocular visual imaging technology model applied in the airport surface surveillance

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Qin, Zhe; Wang, Jian; Huang, Chao

2013-08-01

At present, the civil aviation airports use the surface surveillance radar monitoring and positioning systems to monitor the aircrafts, vehicles and the other moving objects. Surface surveillance radars can cover most of the airport scenes, but because of the terminals, covered bridges and other buildings geometry, surface surveillance radar systems inevitably have some small segment blind spots. This paper presents a monocular vision imaging technology model for airport surface surveillance, achieving the perception of scenes of moving objects such as aircrafts, vehicles and personnel location. This new model provides an important complement for airport surface surveillance, which is different from the traditional surface surveillance radar techniques. Such technique not only provides clear objects activities screen for the ATC, but also provides image recognition and positioning of moving targets in this area. Thereby it can improve the work efficiency of the airport operations and avoid the conflict between the aircrafts and vehicles. This paper first introduces the monocular visual imaging technology model applied in the airport surface surveillance and then the monocular vision measurement accuracy analysis of the model. The monocular visual imaging technology model is simple, low cost, and highly efficient. It is an advanced monitoring technique which can make up blind spot area of the surface surveillance radar monitoring and positioning systems.

Analysis of relationship among visual evoked potential, oscillatory potential and visual acuity under stimulated weightlessness

Directory of Open Access Journals (Sweden)

Jun Zhao

2013-05-01

Full Text Available AIM: To observe the influence of head-down tilt simulated weightlessness on visual evoked potential(VEP, oscillatory potentials(OPsand visual acuity, and analyse the relationship among them. METHODS: Head-down tilt for -6° was adopted in 14 healthy volunteers. Distant visual acuity, near visual acuity, VEP and OPs were recorded before, two days and five days after trial. The record procedure of OPs followed the ISCEV standard for full-field clinical electroretinography(2008 update. RESULTS: Significant differences were detected in the amplitude of P100 waves and ∑OPs among various time points(P<0.05. But no relationship was observed among VEP, OPs and visual acuity. CONCLUSION: Head-down tilt simulated weightlessness induce the rearrange of blood of the whole body including eyes, which can make the change of visual electrophysiology but not visual acuity.

Development and clinical application of a color pediatric visual acuity chart

Directory of Open Access Journals (Sweden)

Shu-Guo Yin

2014-12-01

Full Text Available AIM: To introduce a new color pediatric visual acuity chart and its clinical application.METHODS:The color pediatric visual acuity chart was designed based on principle of visual angle. The optotype on the color chart had graphics. The progression rate of optotype size between 2 lines was 10(101/2 and 1.2589. A regular geometric progression of optotype sizes and distribution was employed to arrange 8 lines with 11 optotype on the color chart. The testing distance was 3m. The visual acuity score could be recorded as logarithm of the minimum angle of resolution notation or decimal notation. The reliability of naked distant measurements with this new chart was tested in one eye of 100 children(4 ～6 years oldtaking the Chinese national standard logarithm visual acuity chart standard. RESULTS: The color pediatric visual acuity chart and logarithmic chart controls, visual acuity test results that in the two groups had no significant difference(t=1.2671, P>0.05. Two sets of vision data existed positive correlation(r=0.924, PCONCLUSION:Children are easier to accept used new color pediatric visual acuity chart to inspect vision. New chart is reliability and apply to children's vision screening.

Monocular and binocular visual impairment in the UK Biobank study: prevalence, associations and diagnoses.

Science.gov (United States)

McKibbin, Martin; Farragher, Tracey M; Shickle, Darren

2018-01-01

To determine the prevalence of, associations with and diagnoses leading to mild visual impairment or worse (logMAR >0.3) in middle-aged adults in the UK Biobank study. Prevalence estimates for monocular and binocular visual impairment were determined for the UK Biobank participants with fundus photographs and spectral domain optical coherence tomography images. Associations with socioeconomic, biometric, lifestyle and medical variables were investigated for cases with visual impairment and matched controls, using multinomial logistic regression models. Self-reported eye history and image grading results were used to identify the primary diagnoses leading to visual impairment for a sample of 25% of cases. For the 65 033 UK Biobank participants, aged 40-69 years and with fundus images, 6682 (10.3%) and 1677 (2.6%) had mild visual impairment or worse in one or both eyes, respectively. Increasing deprivation, age and ethnicity were independently associated with both monocular and binocular visual impairment. No primary diagnosis for the recorded level of visual impairment could be identified for 49.8% of eyes. The most common identifiable diagnoses leading to visual impairment were cataract, amblyopia, uncorrected refractive error and vitreoretinal interface abnormalities. The prevalence of visual impairment in the UK Biobank study cohort is lower than for population-based studies from other industrialised countries. Monocular and binocular visual impairment are associated with increasing deprivation, age and ethnicity. The UK Biobank dataset does not allow confident identification of the causes of visual impairment, and the results may not be applicable to the wider UK population.

Monocular and binocular visual impairment in the UK Biobank study: prevalence, associations and diagnoses

Science.gov (United States)

Farragher, Tracey M; Shickle, Darren

2018-01-01

Objective To determine the prevalence of, associations with and diagnoses leading to mild visual impairment or worse (logMAR >0.3) in middle-aged adults in the UK Biobank study. Methods and analysis Prevalence estimates for monocular and binocular visual impairment were determined for the UK Biobank participants with fundus photographs and spectral domain optical coherence tomography images. Associations with socioeconomic, biometric, lifestyle and medical variables were investigated for cases with visual impairment and matched controls, using multinomial logistic regression models. Self-reported eye history and image grading results were used to identify the primary diagnoses leading to visual impairment for a sample of 25% of cases. Results For the 65 033 UK Biobank participants, aged 40–69 years and with fundus images, 6682 (10.3%) and 1677 (2.6%) had mild visual impairment or worse in one or both eyes, respectively. Increasing deprivation, age and ethnicity were independently associated with both monocular and binocular visual impairment. No primary diagnosis for the recorded level of visual impairment could be identified for 49.8% of eyes. The most common identifiable diagnoses leading to visual impairment were cataract, amblyopia, uncorrected refractive error and vitreoretinal interface abnormalities. Conclusions The prevalence of visual impairment in the UK Biobank study cohort is lower than for population-based studies from other industrialised countries. Monocular and binocular visual impairment are associated with increasing deprivation, age and ethnicity. The UK Biobank dataset does not allow confident identification of the causes of visual impairment, and the results may not be applicable to the wider UK population. PMID:29657974

Grating-acuity in children. Normal values of visual acuity in children up to 13 years as assessed by the acuity card procedure.

Science.gov (United States)

Schenk-Rootlieb, A J; van Nieuwenhuizen, O; van Zoggel, J; van der Graaf, Y; Willemse, J

1992-09-01

The acuity card procedure proved to be a useful method for assessing visual acuity in children. Normal values of visual acuity measured by this method had already been assessed in children up to four years. To enable application of the test in older children this study obtained values in a group of 396 normal children, aged three months to 13 years. The mean curve as well as the 10th centile was calculated in different age groups. A considerable variation of acuity values causing a 'dip' in the 10th centile was found in the ages 18 to 24 months. A smaller 'dip' was found in the ages 48 to 52 months. This has to be attributed to behavioural properties connected with age. The results obtained in the group of children under four years of age corresponded fairly well with other studies. In schoolchildren a fair agreement could also be found between the data obtained using the acuity card procedure and the data obtained with the Landolt-C rings. Obtaining normal values for the acuity card procedure in children covering a wide age range facilitates recognition of visual handicap in children who are difficult to assess.

[The influence of IOL implantation on visual acuity, contrast sensitivity and colour vision 2 and 4 months after cataract surgery].

Science.gov (United States)

Ventruba, J

2006-04-01

To assess the change in visual acuity, contrast sensitivity and colour vision in relation to the time after cataract surgery and to the type of implanted IOL, and to compare visual functions by patients with one and two pseudophakic eyes. 45 cataract patients were examined before and then 2 and 4 month after the cataract surgery. Visual acuity (VA) was tested on logMAR optotype chart with Landolt rings, contrast sensitivity (CS) was tested on the Pelli-Robson chart and the SWCT chart. For colour vision (CV) testing, the standard Farnsworth D-15 test and the desaturated Lanthony D-15 test were used. The patients were divided into two groups--a group with one pseudophakic eye and a group with two pseudophakic eyes, and also according to the type of IOL--PMMA or hydrophobic acrylate that had been implanted. Control group was composed of phakic subjects with no ocular pathology. After the cataract surgery, in both groups there was a significant improvement in monocular and binocular VA (p test (p test (p tested by means of psychophysical methods of VA, CS and CV significantly improve and are stable 2 month after the surgery. The second eye surgery improves binocular visual functions the level of which doesn't differ from that of normal phakic subjects. There was no influence of the type of IOL on final state of VA, CS or CV.

Perceptual Learning in Children With Visual Impairment Improves Near Visual Acuity

NARCIS (Netherlands)

Huurneman, Bianca; Boonstra, F. Nienke; Cox, Ralf F. A.; van Rens, Ger; Cillessen, Antonius H. N.

PURPOSE. This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four-to nine-year-old children with visual impairment. METHODS. Participants were 45 children with visual impairment and 29 children with normal vision. Children

Perceptual Learning in Children With Visual Impairment Improves Near Visual Acuity

NARCIS (Netherlands)

Huurneman, B.; Boonstra, F.N.; Cox, R.F.A.; van Rens, G.H.M.B.; Cillessen, A.H.N.

2013-01-01

Purpose. This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four- to nine-year-old children with visual impairment. Methods. Participants were 45 children with visual impairment and 29 children with normal vision. Children

Perceptual learning in children with visual impairment improves near visual acuity

NARCIS (Netherlands)

Huurneman, B.; Boonstra, F.N.; Cox, R.F.; Rens, G. van; Cillessen, A.H.

2013-01-01

PURPOSE: This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four- to nine-year-old children with visual impairment. METHODS: Participants were 45 children with visual impairment and 29 children with normal vision. Children

Perceptual Learning in Children With Visual Impairment Improves Near Visual Acuity

NARCIS (Netherlands)

Huurneman, B.; Boonstra, F.N.; Cox, R.F.A.; Rens, G.H.M.B. van; Cillessen, A.H.N.

2013-01-01

PURPOSE. This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four-to nine-year-old children with visual impairment. METHODS. Participants were 45 children with visual impairment and 29 children with normal vision. Children

Perceptual learning in children with visual impairment improves near visual acuity.

Science.gov (United States)

Huurneman, Bianca; Boonstra, F Nienke; Cox, Ralf F A; van Rens, Ger; Cillessen, Antonius H N

2013-09-17

This study investigated whether visual perceptual learning can improve near visual acuity and reduce foveal crowding effects in four- to nine-year-old children with visual impairment. Participants were 45 children with visual impairment and 29 children with normal vision. Children with visual impairment were divided into three groups: a magnifier group (n = 12), a crowded perceptual learning group (n = 18), and an uncrowded perceptual learning group (n = 15). Children with normal vision also were divided in three groups, but were measured only at baseline. Dependent variables were single near visual acuity (NVA), crowded NVA, LH line 50% crowding NVA, number of trials, accuracy, performance time, amount of small errors, and amount of large errors. Children with visual impairment trained during six weeks, two times per week, for 30 minutes (12 training sessions). After training, children showed significant improvement of NVA in addition to specific improvements on the training task. The crowded perceptual learning group showed the largest acuity improvements (1.7 logMAR lines on the crowded chart, P children in the crowded perceptual learning group showed improvements on all NVA charts. Children with visual impairment benefit from perceptual training. While task-specific improvements were observed in all training groups, transfer to crowded NVA was largest in the crowded perceptual learning group. To our knowledge, this is the first study to provide evidence for the improvement of NVA by perceptual learning in children with visual impairment. (http://www.trialregister.nl number, NTR2537.).

Diagnosing cerebral visual impairment in children with good visual acuity.

Science.gov (United States)

van Genderen, Maria; Dekker, Marjoke; Pilon, Florine; Bals, Irmgard

2012-06-01

To identify elements that could facilitate the diagnosis of cerebral visual impairment (CVI) in children with good visual acuity in the general ophthalmic clinic. We retrospectively investigated the clinical characteristics of 30 children with good visual acuity and CVI and compared them with those of 23 children who were referred with a suspicion of CVI, but proved to have a different diagnosis. Clinical characteristics included medical history, MRI findings, visual acuity, crowding ratio (CR), visual field assessment, and the results of ophthalmologic and orthoptic examination. We also evaluated the additional value of a short CVI questionnaire. Eighty-three percent of the children with an abnormal medical history (mainly prematurity and perinatal hypoxia) had CVI, in contrast with none of the children with a normal medical history. Cerebral palsy, visual field defects, and partial optic atrophy only occurred in the CVI group. 41% of the children with CVI had a CR ≥2.0, which may be related to dorsal stream dysfunction. All children with CVI, but also 91% of the children without CVI gave ≥3 affirmative answers on the CVI questionnaire. An abnormal pre- or perinatal medical history is the most important risk factor for CVI in children, and therefore in deciding which children should be referred for further multidisciplinary assessment. Additional symptoms of cerebral damage, i.e., cerebral palsy, visual field defects, partial optic atrophy, and a CR ≥2 may support the diagnosis. CVI questionnaires should not be used for screening purposes as they yield too many false positives.

Is theta burst stimulation applied to visual cortex able to modulate peripheral visual acuity?

Directory of Open Access Journals (Sweden)

Sabrina Brückner

Full Text Available Repetitive transcranial magnetic stimulation is usually applied to visual cortex to explore the effects on cortical excitability. Most researchers therefore concentrate on changes of phosphene threshold, rarely on consequences for visual performance. Thus, we investigated peripheral visual acuity in the four quadrants of the visual field using Landolt C optotypes before and after repetitive stimulation of the visual cortex. We applied continuous and intermittend theta burst stimulation with various stimulation intensities (60%, 80%, 100%, 120% of individual phosphene threshold as well as monophasic and biphasic 1 Hz stimulation, respectively. As an important result, no serious adverse effects were observed. In particular, no seizure was induced, even with theta burst stimulation applied with 120% of individual phosphene threshold. In only one case stimulation was ceased because the subject reported intolerable pain. Baseline visual acuity decreased over sessions, indicating a continuous training effect. Unexpectedly, none of the applied transcranial magnetic stimulation protocols had an effect on performance: no change in visual acuity was found in any of the four quadrants of the visual field. Binocular viewing as well as the use of peripheral instead of foveal presentation of the stimuli might have contributed to this result. Furthermore, intraindividual variability could have masked the TMS- induced effects on visual acuity.

Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices.

Science.gov (United States)

Livingstone, I A T; Tarbert, C M; Giardini, M E; Bastawrous, A; Middleton, D; Hamilton, R

2016-01-01

Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc.) and three ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off) exceeded the most stringent requirement for mean luminance (≥ 120 cd/m2) providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90%) regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (Lmin/Lmax ≥ 80%). Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off) had adequate mean luminance (≥ 120 cd/m2) and Weber contrast (≥ 90%), but all three charts failed to meet the luminance uniformity standard (Lmin/Lmax ≥ 80%). Two charts were operating beyond manufacturer's recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out

Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices.

Directory of Open Access Journals (Sweden)

I A T Livingstone

Full Text Available Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc. and three ETDRS (Early Treatment Diabetic Retinopathy Study visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off exceeded the most stringent requirement for mean luminance (≥ 120 cd/m2 providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90% regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (Lmin/Lmax ≥ 80%. Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off had adequate mean luminance (≥ 120 cd/m2 and Weber contrast (≥ 90%, but all three charts failed to meet the luminance uniformity standard (Lmin/Lmax ≥ 80%. Two charts were operating beyond manufacturer's recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out

Visual acuity and visual skills in Malaysian children with learning disabilities

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Muzaliha MN

2012-09-01

Full Text Available Mohd-Nor Muzaliha,1 Buang Nurhamiza,1 Adil Hussein,1 Abdul-Rani Norabibas,1 Jaafar Mohd-Hisham-Basrun,1 Abdullah Sarimah,2 Seo-Wei Leo,3 Ismail Shatriah11Department of Ophthalmology, 2Biostatistics and Research Methodology Unit, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia; 3Paediatric Ophthalmology and Strabismus Unit, Department of Ophthalmology, Tan Tock Seng Hospital, SingaporeBackground: There is limited data in the literature concerning the visual status and skills in children with learning disabilities, particularly within the Asian population. This study is aimed to determine visual acuity and visual skills in children with learning disabilities in primary schools within the suburban Kota Bharu district in Malaysia.Methods: We examined 1010 children with learning disabilities aged between 8–12 years from 40 primary schools in the Kota Bharu district, Malaysia from January 2009 to March 2010. These children were identified based on their performance in a screening test known as the Early Intervention Class for Reading and Writing Screening Test conducted by the Ministry of Education, Malaysia. Complete ocular examinations and visual skills assessment included near point of convergence, amplitude of accommodation, accommodative facility, convergence break and recovery, divergence break and recovery, and developmental eye movement tests for all subjects.Results: A total of 4.8% of students had visual acuity worse than 6/12 (20/40, 14.0% had convergence insufficiency, 28.3% displayed poor accommodative amplitude, and 26.0% showed signs of accommodative infacility. A total of 12.1% of the students had poor convergence break, 45.7% displayed poor convergence recovery, 37.4% showed poor divergence break, and 66.3% were noted to have poor divergence recovery. The mean horizontal developmental eye movement was significantly prolonged.Conclusion: Although their visual acuity was satisfactory, nearly 30% of the

Visual Acuity in Primary School Pupils in Lagos, Nigeria | Okoro ...

African Journals Online (AJOL)

... in visual acuity. Conclusion: Eye defects occur among school children with potential negative effects. Pre-school entry eye examinations and regular screening is advocated and glasses should be made available for children with refractive error. Keywords: Visual Acuity, Screening, School Children, School Health ...

Improvement of visual acuity by refraction in a low-vision population.

Science.gov (United States)

Sunness, Janet S; El Annan, Jaafar

2010-07-01

Refraction often may be overlooked in low-vision patients, because the main cause of vision decrease is not refractive, but rather is the result of underlying ocular disease. This retrospective study was carried out to determine how frequently and to what extent visual acuity is improved by refraction in a low-vision population. Cross-sectional study. Seven hundred thirty-nine low-vision patients seen for the first time. A database with all new low-vision patients seen from November 2005 through June 2008 recorded presenting visual acuity using an Early Treatment Diabetic Retinopathy Study chart; it also recorded the best-corrected visual acuity (BCVA) if it was 2 lines or more better than the presenting visual acuity. Retinoscopy was carried out on all patients, followed by manifest refraction. Improvement in visual acuity. Median presenting acuity was 20/80(-2) (interquartile range, 20/50-20/200). There was an improvement of 2 lines or more of visual acuity in 81 patients (11% of all patients), with 22 patients (3% of all patients) improving by 4 lines or more. There was no significant difference in age or in presenting visual acuity between the group that did not improve by refraction and the group that did improve. When stratified by diagnosis, the only 2 diagnoses with a significantly higher rate of improvement than the age-related macular degeneration group were myopic degeneration and progressive myopia (odds ratio, 4.8; 95% confidence interval [CI], 3.0-6.7) and status post-retinal detachment (odds ratio, 7.1; 95% CI, 5.2-9.0). For 5 patients (6% of those with improvement), the eye that was 1 line or more worse than the fellow eye at presentation became the eye that was 1 line or more better than the fellow eye after refraction. A significant improvement in visual acuity was attained by refraction in 11% of the new low-vision patients. Improvement was seen across diagnoses and the range of presenting visual acuity. The worse-seeing eye at presentation may

Vision in avian emberizid foragers: maximizing both binocular vision and fronto-lateral visual acuity.

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Moore, Bret A; Pita, Diana; Tyrrell, Luke P; Fernández-Juricic, Esteban

2015-05-01

Avian species vary in their visual system configuration, but previous studies have often compared single visual traits between two to three distantly related species. However, birds use different visual dimensions that cannot be maximized simultaneously to meet different perceptual demands, potentially leading to trade-offs between visual traits. We studied the degree of inter-specific variation in multiple visual traits related to foraging and anti-predator behaviors in nine species of closely related emberizid sparrows, controlling for phylogenetic effects. Emberizid sparrows maximize binocular vision, even seeing their bill tips in some eye positions, which may enhance the detection of prey and facilitate food handling. Sparrows have a single retinal center of acute vision (i.e. fovea) projecting fronto-laterally (but not into the binocular field). The foveal projection close to the edge of the binocular field may shorten the time to gather and process both monocular and binocular visual information from the foraging substrate. Contrary to previous work, we found that species with larger visual fields had higher visual acuity, which may compensate for larger blind spots (i.e. pectens) above the center of acute vision, enhancing predator detection. Finally, species with a steeper change in ganglion cell density across the retina had higher eye movement amplitude, probably due to a more pronounced reduction in visual resolution away from the fovea, which would need to be moved around more frequently. The visual configuration of emberizid passive prey foragers is substantially different from that of previously studied avian groups (e.g. sit-and-wait and tactile foragers). © 2015. Published by The Company of Biologists Ltd.

Visual Acuity does not Moderate Effect Sizes of Higher-Level Cognitive Tasks

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Houston, James R.; Bennett, Ilana J.; Allen, Philip A.; Madden, David J.

2016-01-01

Background Declining visual capacities in older adults have been posited as a driving force behind adult age differences in higher-order cognitive functions (e.g., the “common cause” hypothesis of Lindenberger & Baltes, 1994). McGowan, Patterson and Jordan (2013) also found that a surprisingly large number of published cognitive aging studies failed to include adequate measures of visual acuity. However, a recent meta-analysis of three studies (LaFleur & Salthouse, 2014) failed to find evidence that visual acuity moderated or mediated age differences in higher-level cognitive processes. In order to provide a more extensive test of whether visual acuity moderates age differences in higher-level cognitive processes, we conducted a more extensive meta-analysis of topic. Methods Using results from 456 studies, we calculated effect sizes for the main effect of age across four cognitive domains (attention, executive function, memory, and perception/language) separately for five levels of visual acuity criteria (no criteria, undisclosed criteria, self-reported acuity, 20/80-20/31, and 20/30 or better). Results As expected, age had a significant effect on each cognitive domain. However, these age effects did not further differ as a function of visual acuity criteria. Conclusion The current meta-analytic, cross-sectional results suggest that visual acuity is not significantly related to age group differences in higher-level cognitive performance—thereby replicating LaFleur and Salthouse (2014). Further efforts are needed to determine whether other measures of visual functioning (e.g. contrast sensitivity, luminance) affect age differences in cognitive functioning. PMID:27070044

A Case of Complete Recovery of Fluctuating Monocular Blindness Following Endovascular Treatment in Internal Carotid Artery Dissection.

Science.gov (United States)

Kim, Ki-Tae; Baik, Seung Guk; Park, Kyung-Pil; Park, Min-Gyu

2015-09-01

Monocular blindness may appear as the first symptom of internal carotid artery dissection (ICAD). However, there have been no reports that monocular visual loss repeatedly occurs and disappears in response to postural change in ICAD. A 33-year-old woman presented with transient monocular blindness (TMB) following acute-onset headache. TMB repeatedly occurred in response to postural change. Two days later, she experienced transient dysarthria and right hemiparesis in upright position. Pupil size and light reflex were normal, but a relative afferent pupillary defect was positive in the left eye. Diffusion-weighted imaging showed no acute lesion, but perfusion-weighted imaging showed perfusion delay in the left ICA territory. Digital subtraction angiography demonstrated a false lumen and an intraluminal filling defect in proximal segment of the left ICA. Carotid stenting was performed urgently. After carotid stenting, left relative afferent pupillary defect disappeared and TMB was not provoked anymore by upright posture. At discharge, left visual acuity was completely normalized. Because fluctuating visual symptoms in the ICAD may be associated with hemodynamically unstable status, assessment of the perfusion status should be done quickly. Carotid stenting may be helpful to improve the fluctuating visual symptoms and hemodynamically unstable status in selected patient with the ICAD. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Perceptual learning improves contrast sensitivity, visual acuity, and foveal crowding in amblyopia.

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Barollo, Michele; Contemori, Giulio; Battaglini, Luca; Pavan, Andrea; Casco, Clara

2017-01-01

Amblyopic observers present abnormal spatial interactions between a low-contrast sinusoidal target and high-contrast collinear flankers. It has been demonstrated that perceptual learning (PL) can modulate these low-level lateral interactions, resulting in improved visual acuity and contrast sensitivity. We measured the extent and duration of generalization effects to various spatial tasks (i.e., visual acuity, Vernier acuity, and foveal crowding) through PL on the target's contrast detection. Amblyopic observers were trained on a contrast-detection task for a central target (i.e., a Gabor patch) flanked above and below by two high-contrast Gabor patches. The pre- and post-learning tasks included lateral interactions at different target-to-flankers separations (i.e., 2, 3, 4, 8λ) and included a range of spatial frequencies and stimulus durations as well as visual acuity, Vernier acuity, contrast-sensitivity function, and foveal crowding. The results showed that perceptual training reduced the target's contrast-detection thresholds more for the longest target-to-flanker separation (i.e., 8λ). We also found generalization of PL to different stimuli and tasks: contrast sensitivity for both trained and untrained spatial frequencies, visual acuity for Sloan letters, and foveal crowding, and partially for Vernier acuity. Follow-ups after 5-7 months showed not only complete maintenance of PL effects on visual acuity and contrast sensitivity function but also further improvement in these tasks. These results suggest that PL improves facilitatory lateral interactions in amblyopic observers, which usually extend over larger separations than in typical foveal vision. The improvement in these basic visual spatial operations leads to a more efficient capability of performing spatial tasks involving high levels of visual processing, possibly due to the refinement of bottom-up and top-down networks of visual areas.

Visual acuity outcomes in eyes with flat corneas after PRK.

Science.gov (United States)

Varssano, David; Waisbourd, Michael; Minkev, Liza; Sela, Tzahi; Neudorfer, Meira; Binder, Perry S

2013-06-01

To evaluate the impact of corneal curvatures less than 35 diopters (D) after photorefractive keratectomy (PRK) on visual acuity outcomes. Visual acuity outcomes of 5,410 eyes that underwent PRK from January 2006 to November 2010 were retrospectively analyzed for the impact of postoperative corneal curvatures on visual outcomes. All procedures were performed on a single platform (Allegretto 200Hz excimer laser; Alcon Laboratories, Inc., Irvine, CA). Main outcome measures were postoperative corrected distance visual acuity (CDVA) and loss of CDVA. Corneas with a measured or a calculated postoperative flat meridian less than 35 D and those with a measured postoperative steep meridian less than 35 D had worse postoperative CDVA than corneas with meridians of either 35 D or more (P ≤ .021). However, the preoperative CDVA was worse in the flatter curvatures in all comparisons performed (P ≤ .024). Consequently, the measured or calculated meridian curvature had no effect on CDVA loss (P ≥ .074). Postoperative corneal keratometry values (flat and steep meridians) less than 35 D did not have a predictive effect on the risk of losing visual acuity following myopic PRK performed on the Allegretto 200Hz excimer laser. Copyright 2013, SLACK Incorporated.

Comparison of monochromatic aberrations in young adults with different visual acuity and refractive errors.

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Yazar, Seyhan; Hewitt, Alex W; Forward, Hannah; McKnight, Charlotte M; Tan, Alex; Mountain, Jenny A; Mackey, David A

2014-03-01

To compare the monochromatic aberrations in a large cohort of 20-year-old Australians with differing levels of visual acuity and explore the relationship between these aberrations and refractive error. Lions Eye Institute, Perth, Western Australia, Australia. Cross-sectional analysis of a population-based cohort. Monochromatic aberrations were measured using a Zywave II wavefront aberrometer with natural pupils in a dark room. The logMAR corrected distance visual acuity (CDVA) was measured monocularly under normal illumination. Cycloplegic autorefraction was also performed. The study enrolled 2039 eyes of 1040 participants. Data from 1007 right eyes were analyzed. The median CDVA and spherical equivalent were -0.06 logMAR (interquartile range [IQR], -0.10 to 0.00) and +0.25 diopters (D) (IQR, -0.38 to 0.63), respectively. The median 6.0 mm higher-order aberration (HOA) was 0.58 μm (IQR, 0.44 to 0.79). Coma-like aberrations and 3rd-, 4th-, and 5th-order HOAs were significantly different between subjects with a CDVA of -0.10 logMAR or better and those with a CDVA worse than -0.10 logMAR. Fourth-order aberrations Z(4,-4) (P=.024) and Z(4,-2) (P=.029) and 2nd-order aberration Z(2,0) (Peyes, emmetropic eyes, and hyperopic eyes. Subjects with higher myopia had slightly higher total HOAs. The HOAs in this population were marginally higher than previously reported values. The findings confirm there is a difference in monochromatic aberrations between different vision and refractive groups. Results in this study will benefit decision-making processes in the clinical setting. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Visual acuity in adults with Asperger's syndrome: no evidence for "eagle-eyed" vision.

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Falkmer, Marita; Stuart, Geoffrey W; Danielsson, Henrik; Bram, Staffan; Lönebrink, Mikael; Falkmer, Torbjörn

2011-11-01

Autism spectrum conditions (ASC) are defined by criteria comprising impairments in social interaction and communication. Altered visual perception is one possible and often discussed cause of difficulties in social interaction and social communication. Recently, Ashwin et al. suggested that enhanced ability in local visual processing in ASC was due to superior visual acuity, but that study has been the subject of methodological criticism, placing the findings in doubt. The present study investigated visual acuity thresholds in 24 adults with Asperger's syndrome and compared their results with 25 control subjects with the 2 Meter 2000 Series Revised ETDRS Chart. The distribution of visual acuities within the two groups was highly similar, and none of the participants had superior visual acuity. Superior visual acuity in individuals with Asperger's syndrome could not be established, suggesting that differences in visual perception in ASC are not explained by this factor. A continued search for explanations of superior ability in local visual processing in persons with ASC is therefore warranted. Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Improvements in clinical and functional vision and perceived visual disability after first and second eye cataract surgery

OpenAIRE

Elliott, D.; Patla, A.; Bullimore, M.

1997-01-01

AIMS—To determine the improvements in clinical and functional vision and perceived visual disability after first and second eye cataract surgery.
METHODS—Clinical vision (monocular and binocular high and low contrast visual acuity, contrast sensitivity, and disability glare), functional vision (face identity and expression recognition, reading speed, word acuity, and mobility orientation), and perceived visual disability (Activities of Daily Vision Scale) were measured in 25 subjects before a...

VEP-based acuity assessment in low vision.

Science.gov (United States)

Hoffmann, Michael B; Brands, Jan; Behrens-Baumann, Wolfgang; Bach, Michael

2017-12-01

Objective assessment of visual acuity (VA) is possible with VEP methodology, but established with sufficient precision only for vision better than about 1.0 logMAR. We here explore whether this can be extended down to 2.0 logMAR, highly desirable for low-vision evaluations. Based on the stepwise sweep algorithm (Bach et al. in Br J Ophthalmol 92:396-403, 2008) VEPs to monocular steady-state brief onset pattern stimulation (7.5-Hz checkerboards, 40% contrast, 40 ms on, 93 ms off) were recorded for eight different check sizes, from 0.5° to 9.0°, for two runs with three occipital electrodes in a Laplace-approximating montage. We examined 22 visually normal participants where acuity was reduced to ≈ 2.0 logMAR with frosted transparencies. With the established heuristic algorithm the "VEP acuity" was extracted and compared to psychophysical VA, both obtained at 57 cm distance. In 20 of the 22 participants with artificially reduced acuity the automatic analysis indicated a valid result (1.80 logMAR on average) in at least one of the two runs. 95% test-retest limits of agreement on average were ± 0.09 logMAR for psychophysical, and ± 0.21 logMAR for VEP-derived acuity. For 15 participants we obtained results in both runs and averaged them. In 12 of these 15 the low-acuity results stayed within the 95% confidence interval (± 0.3 logMAR) as established by Bach et al. (2008). The fully automated analysis yielded good agreement of psychophysical and electrophysiological VAs in 12 of 15 cases (80%) in the low-vision range down to 2.0 logMAR. This encourages us to further pursue this methodology and assess its value in patients.

Female carpet weavers' visual acuity and effective factors: Fordu rural area of Qom

Directory of Open Access Journals (Sweden)

Khajenasiri F.

2007-11-01

Full Text Available Background: Healthy vision of workers is one of the important elements in carpet weaving industry which has essential role in improving of the job quality and efficiency. Visual acuity is the primary outcome measure in most studies involving eye diseases. Ihe aim of this study was determination of visual acuity and its effective factors in women carpet weaver in fordu rural area of Qom has been investigated.  Methods: In a cross-sectional (descriptive-analytical study visual acuity of 177 women carpet weaver has been determined. Job hours per day, job history, age, literacy, trauma history, diabetes history, family history of eye diseases, eye diseases history and family size  of subjects were determined .Results: The results of study indicated that the right eyes visual acuity of 72.4 % of women were desirable (0 - 0.8 and 27.6 % were undesirable (0.9-1.2. These results for the left eyes were 69.5 % and 30.5 % respectively. In addition, the result showed that with increasing the job hours and history and age, percent of women with undesirable both eyes visual acuity were increased. With higher literacy levels, percent of women with undesirable both eyes visual acuity decreased. In subjects with truma history, the undesirable visual acuity was higher. In this study the relation between visual acuity and job history, age, literacy, truma history and eye diseases history were statistically significant (in all cases P<0.05.Conclusions: High percentage of women carpet weaver were in undesirable  visual acuity and in this study the relation between visual acuity and job history, age, literacy, trauma history and eye diseases history were statistically significant (in all cases P<0.05.

Out of sight, out of mind? Relations between visual acuity and cognition.

Science.gov (United States)

La Fleur, Claire G; Salthouse, Timothy A

2014-10-01

Prior research has established significant relations between measures of sensory ability and cognitive function in adults of different ages, and several explanations for this relation have been proposed. One explanation is that sensory abilities restrict cognitive processing, a second is that cognitive abilities influence assessments of sensory ability, and a third is that both sensory function and cognition are affected by a common, potentially age-based, third factor. These explanations were investigated using mediation and moderation analyses, with near visual acuity as the sensory measure and scores on visual speed tests and auditory memory tests as the cognitive measures. Measures of visual acuity, speed, and memory were obtained from three moderately large samples, two cross-sectional (N = 380, N = 4,779) and one longitudinal (N = 2,258), with participants ranging from 18 to 90 years of age. The visual acuity and cognitive measures had different age trajectories, and the visual acuity-cognition relations were similar in each 5-year age band. The results suggest that the age-related differences and changes in near visual acuity are unlikely to contribute to the age-related differences and changes in speed and memory measures.

Visual Servo Tracking Control of a Wheeled Mobile Robot with a Monocular Fixed Camera

National Research Council Canada - National Science Library

Chen, J; Dixon, W. E; Dawson, D. M; Chitrakaran, V. K

2004-01-01

In this paper, a visual servo tracking controller for a wheeled mobile robot (WMR) is developed that utilizes feedback from a monocular camera system that is mounted with a fixed position and orientation...

VISUAL ABILITY IN AMBLYOPIC CHILDREN COMPARED TO CHILDREN WITH NORMAL VISUAL ACUITY

Directory of Open Access Journals (Sweden)

Zorica Tončić

2016-03-01

Full Text Available Vision rehabilitation in adults with low vision, even in children, is achieved with special devices, called low vision aids, LVA. The aim of the study is to determine the degree of visual function in amblyopic children and daily activities that are best related to those of normally sighted peers with normal visual acuity. The subjects were divided into two groups, matched 1:1 by age and gender: the first group consisted of 19 amblyopic children, and the second one consisted of 19 children with normal visual acuity. The questionnaire used to assess visual ability was Cardiff Visual Ability Questionnaire for Children (CVAQC, a reliable instrument for measuring visual ability in children with low vision. The study was conducted in the only rehabilitation center for amblyopic children in this region, so this is also a pioneer study. The overall result of CVAQC in amblyopic children was 1.287 log vs.-2.956, representing statistically significantly poorer visual ability in comparison to peers without vision deficit (p˂0.005. Amblyopic children function best in entertainment activities, especially in listening music (-2.31 log; as for sport, these children report swimming to be their favourite activity (-0.99 log. In the field of education they show best results in language acquisition (-0.79 log and the worst in mathematics (3.13 log. The greatest problem is reading small print texts books (2.61 log. Low vision children have poorer result of visual function in comparison to their peers with normal visual acuity. A precise deficit assessment in the most important spheres of life can be determined by using the questionnaires, so the rehabilitation can be rightly chosen.

[Congenital lens subluxation: visual acuity outcomes and intraocular lens postoperative position].

Science.gov (United States)

Arraes, Caroline; Endriss, Daniela; Lobato, Francisco; Arraes, João; Ventura, Marcelo

2010-01-01

To evaluate the visual acuity outcomes and to investigate the intraocular lens (IOL) and endocapsular ring positions with ultrasound biomicroscopy in 17 eyes of 10 patients with congenital lens subluxation who underwent the same surgical technique, by the same surgeon. The study was performed in the ''Hospital de Olhos de Pernambuco'' and ''Fundação Altino Ventura''. The surgical technique consisted of phacoaspiration with implant of endocapsular ring and intraocular lens with one loop haptic amputated. The age varied from 7 to 22 years. Data on visual acuity (VA) before and after surgery, surgery follow-up period, and complications were analyzed. All patients underwent ultrasound biomicroscopy. The mean follow-up period was 2.8 years. There was a VA improvement in 17 (100%) eyes: in 12 eyes (70.6%) the visual acuity was better than 20/40; 4 (23.5%) ranged from 20/40 to 20/100, and 1 (5.9%) had visual acuity worse than 20/100, however better than the preoperative visual acuity. The posterior capsular opacification occurred in 10 eyes (58.9%). Ultrasound biomicroscopy showed that all IOL were partially decentralized, however without surpassing the pupil border limit. Endocapsular ring position was correct and there was a good capsular support in all cases. The evaluated surgical treatment provided good intraocular lens and endocapsular ring position, with VA improvement Thus, this technique is a viable, effective and safe option for the visual rehabilitation of patients with congenital lens subluxation.

Visual Acuity Improvement in Continuous vs Divided Occlusion in Anisometropic Amblyopia.

Science.gov (United States)

Irfani, Irawati; Feriyanto, Feri; Oktarima, Primawita; Kartasasmita, Arief

2018-01-01

To compare visual acuity improvement between continuous and split part-time occlusion for the treatment of moderate and severe anisometropic amblyopia. Randomised clinical trials in 6 - 13 y.o children with moderate and severe anisometropic amblyopia. Each patient was consecutively selected with continuous or split part-time occlusion. Best corrected visual acuity's improvement was followed up to six weeks and statistical data were analyzed using chi square and unpaired t-test. Best corrected visual acuity's improvement was comparable between continuous and split part-time occlusion (0.20±0.27 vs 0.21±0.25; p = 0.79). Split part-time occlusion may be considered as an alternative treatment for moderate and severe anisometropic amblyopia treatment.

Adaptive Monocular Visual-Inertial SLAM for Real-Time Augmented Reality Applications in Mobile Devices.

Science.gov (United States)

Piao, Jin-Chun; Kim, Shin-Dug

2017-11-07

Simultaneous localization and mapping (SLAM) is emerging as a prominent issue in computer vision and next-generation core technology for robots, autonomous navigation and augmented reality. In augmented reality applications, fast camera pose estimation and true scale are important. In this paper, we present an adaptive monocular visual-inertial SLAM method for real-time augmented reality applications in mobile devices. First, the SLAM system is implemented based on the visual-inertial odometry method that combines data from a mobile device camera and inertial measurement unit sensor. Second, we present an optical-flow-based fast visual odometry method for real-time camera pose estimation. Finally, an adaptive monocular visual-inertial SLAM is implemented by presenting an adaptive execution module that dynamically selects visual-inertial odometry or optical-flow-based fast visual odometry. Experimental results show that the average translation root-mean-square error of keyframe trajectory is approximately 0.0617 m with the EuRoC dataset. The average tracking time is reduced by 7.8%, 12.9%, and 18.8% when different level-set adaptive policies are applied. Moreover, we conducted experiments with real mobile device sensors, and the results demonstrate the effectiveness of performance improvement using the proposed method.

The Auckland Optotypes: An open-access pictogram set for measuring recognition acuity.

Science.gov (United States)

Hamm, Lisa M; Yeoman, Janice P; Anstice, Nicola; Dakin, Steven C

2018-03-01

When measuring recognition acuity in a research setting, the most widely used symbols are the Early Treatment of Diabetic Retinopathy Study (ETDRS) set of 10 Sloan letters. However, the symbols are not appropriate for patients unfamiliar with letters, and acuity for individual letters is variable. Alternative pictogram sets are available, but are generally comprised of fewer items. We set out to develop an open-access set of 10 pictograms that would elicit more consistent estimates of acuity across items than the ETDRS letters from visually normal adults. We measured monocular acuity for individual uncrowded optotypes within a newly designed set (The Auckland Optotype [TAO]), the ETDRS set, and Landolt Cs. Eleven visually normal adults were assessed on regular and vanishing formats of each set. Inter-optotype reliability and ability to detect subtle differences between participants were assessed using intraclass correlations (ICC) and fractional rank precision (FRP). The TAO vanishing set showed the strongest performance (ICC = 0.97, FRP = 0.90), followed by the other vanishing sets (Sloan ICC = 0.88, FRP = 0.74; Landolt ICC = 0.86, FRP = 0.80). Within the regular format, TAO again outperformed the existing sets (TAO ICC = 0.77, FRP = 0.75; Sloan ICC = 0.65, FRP = 0.64; Landolt ICC = 0.48, FRP = 0.63). For adults with normal visual acuity, the new optotypes (in both regular and vanishing formats) are more equally legible and sensitive to subtle individual differences than their Sloan counterparts. As this set does not require observers to be able to name Roman letters, and is freely available to use and modify, it may have wide application for measurement of acuity.

Measuring the Influence of Galilean Loupe System on Near Visual Acuity of Dentists under Simulated Clinical Conditions

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Iris Urlić

2016-01-01

Full Text Available Aim: The purpose of this study was to compare near visual acuity of dentists without optical aids (VSC with near visual acuity of those using the Galilean telescope system (VGA2 with magnification of x 2.5, and the distance of 350 mm in simulated clinical conditions. Methods: The study included 46 dentists (visual acuity 1.0 without correction. A visual acuity testing was carried out using a miniaturized Snellen visual acuity chart which was placed in the cavity of molar teeth mounted in a phantom head in simulated clinical conditions. Near visual acuity for the vicinity was examined: 1 without correction at a distance of 300-400 mm (VSC; 2 with Galilean loupes with magnification of x2.5, focal length of 350mm. Results: The distributions of near visual acuity recorded using VSC and VGA2, 5 systems were compared by the Wilcoxon Signed Rank test. The results obtained by Wilcoxon Signed Rank test pointed to a statistically significant difference in the distribution of recorded visual acuity between the VSC and VGA2 optical systems (W = - 403.5; p <0.001. Conclusion: If using the VGA2, 5 systems, higher values of the near visual acuity were recorded and subsequently compared to near visual acuity without magnifying aids (VSC.

How to measure distance visual acuity

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Janet Marsden

2014-04-01

Full Text Available Visual acuity (VA is a measure of the ability of the eye to distinguish shapes and the details of objects at a given distance. It is important to assess VA in a consistent way in order to detect any changes in vision. One eye is tested at a time.

Visual Suppression of Monocularly Presented Symbology Against a Fused Background in a Simulation and Training Environment

National Research Council Canada - National Science Library

Winterbottom, Marc D; Patterson, Robert; Pierce, Byron J; Taylor, Amanda

2006-01-01

.... This may create interocular differences in image characteristics that could disrupt binocular vision by provoking visual suppression, thus reducing visibility of the background scene, monocular symbology...

Gender and environmental influences on visual acuity in Owerri ...

African Journals Online (AJOL)

olayemitoyin

1Optometry Unit, Eye Clinic, Federal Medical Centre, Owerri, Imo State, 2Department of Physiology, College ... Visual acuity (V.A.) is a measure of visual function in health and disease. ..... environment especially during harmattan and dry.

Vernier But Not Grating Acuity Contributes to an Early Stage of Visual Word Processing.

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Tan, Yufei; Tong, Xiuhong; Chen, Wei; Weng, Xuchu; He, Sheng; Zhao, Jing

2018-03-28

The process of reading words depends heavily on efficient visual skills, including analyzing and decomposing basic visual features. Surprisingly, previous reading-related studies have almost exclusively focused on gross aspects of visual skills, while only very few have investigated the role of finer skills. The present study filled this gap and examined the relations of two finer visual skills measured by grating acuity (the ability to resolve periodic luminance variations across space) and Vernier acuity (the ability to detect/discriminate relative locations of features) to Chinese character-processing as measured by character form-matching and lexical decision tasks in skilled adult readers. The results showed that Vernier acuity was significantly correlated with performance in character form-matching but not visual symbol form-matching, while no correlation was found between grating acuity and character processing. Interestingly, we found no correlation of the two visual skills with lexical decision performance. These findings provide for the first time empirical evidence that the finer visual skills, particularly as reflected in Vernier acuity, may directly contribute to an early stage of hierarchical word processing.

Impact of Near Work Activity on Visual Acuity among Junior High School Students

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Raisha Pratiwi Indrawati

2016-03-01

Full Text Available Background: Uncorrected refractive error is experienced by at least 45 million productive-aged adults (aged 16–45 years old and 13 million children (aged 5–15 years old, and being the main cause of visual impairment in children worldwide and third cause of blindness in any age in Indonesia. Near work activity is estimated as one of environmental risk factor causing this refractive error, leading into decreased visual acuity. This study was conducted to analyse the impact of near work activity on visual acuity among junior high school students in Jatinangor Methods: This study was conducted in junior high school in Jatinangor, using cross sectional method. Total of 147 subjects were screened for visual impairment using Rapid Assessment of Avoidable Blindness (RAAB tumbling E chart and assesed for near work activity using questionnaire-guided interview method after informed consent had been obtained. Data were analysed using unpaired-T test and Mann-Whitney test. Results: Total diopter hours of near work activity among the group with visual acuity ≥6/18 and group with visual acuity <6/18 showed no significant difference (p=0.329, with latter group had less time-spent in near work activity. Similarly, each activity such as reading, watching TV, and using computer also showed no significant difference , except for playing games where the group with better visual acuity had shown significantly longer time spent than another group (p=0.018. Conclusions: Near work activity does not have impact on visual acuity among junior high school students, except for playing games

Visual Temporal Acuity Is Related to Auditory Speech Perception Abilities in Cochlear Implant Users.

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Jahn, Kelly N; Stevenson, Ryan A; Wallace, Mark T

Despite significant improvements in speech perception abilities following cochlear implantation, many prelingually deafened cochlear implant (CI) recipients continue to rely heavily on visual information to develop speech and language. Increased reliance on visual cues for understanding spoken language could lead to the development of unique audiovisual integration and visual-only processing abilities in these individuals. Brain imaging studies have demonstrated that good CI performers, as indexed by auditory-only speech perception abilities, have different patterns of visual cortex activation in response to visual and auditory stimuli as compared with poor CI performers. However, no studies have examined whether speech perception performance is related to any type of visual processing abilities following cochlear implantation. The purpose of the present study was to provide a preliminary examination of the relationship between clinical, auditory-only speech perception tests, and visual temporal acuity in prelingually deafened adult CI users. It was hypothesized that prelingually deafened CI users, who exhibit better (i.e., more acute) visual temporal processing abilities would demonstrate better auditory-only speech perception performance than those with poorer visual temporal acuity. Ten prelingually deafened adult CI users were recruited for this study. Participants completed a visual temporal order judgment task to quantify visual temporal acuity. To assess auditory-only speech perception abilities, participants completed the consonant-nucleus-consonant word recognition test and the AzBio sentence recognition test. Results were analyzed using two-tailed partial Pearson correlations, Spearman's rho correlations, and independent samples t tests. Visual temporal acuity was significantly correlated with auditory-only word and sentence recognition abilities. In addition, proficient CI users, as assessed via auditory-only speech perception performance, demonstrated

Eye size and visual acuity influence vestibular anatomy in mammals.

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Kemp, Addison D; Christopher Kirk, E

2014-04-01

The semicircular canals of the inner ear detect head rotations and trigger compensatory movements that stabilize gaze and help maintain visual fixation. Mammals with large eyes and high visual acuity require precise gaze stabilization mechanisms because they experience diminished visual functionality at low thresholds of uncompensated motion. Because semicircular canal radius of curvature is a primary determinant of canal sensitivity, species with large canal radii are expected to be capable of more precise gaze stabilization than species with small canal radii. Here, we examine the relationship between mean semicircular canal radius of curvature, eye size, and visual acuity in a large sample of mammals. Our results demonstrate that eye size and visual acuity both explain a significant proportion of the variance in mean canal radius of curvature after statistically controlling for the effects of body mass and phylogeny. These findings suggest that variation in mean semicircular canal radius of curvature among mammals is partly the result of selection for improved gaze stabilization in species with large eyes and acute vision. Our results also provide a possible functional explanation for the small semicircular canal radii of fossorial mammals and plesiadapiforms. Copyright © 2014 Wiley Periodicals, Inc.

Relationship between photoreceptor outer segment length and visual acuity in diabetic macular edema.

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Forooghian, Farzin; Stetson, Paul F; Meyer, Scott A; Chew, Emily Y; Wong, Wai T; Cukras, Catherine; Meyerle, Catherine B; Ferris, Frederick L

2010-01-01

The purpose of this study was to quantify photoreceptor outer segment (PROS) length in 27 consecutive patients (30 eyes) with diabetic macular edema using spectral domain optical coherence tomography and to describe the correlation between PROS length and visual acuity. Three spectral domain-optical coherence tomography scans were performed on all eyes during each session using Cirrus HD-OCT. A prototype algorithm was developed for quantitative assessment of PROS length. Retinal thicknesses and PROS lengths were calculated for 3 parameters: macular grid (6 x 6 mm), central subfield (1 mm), and center foveal point (0.33 mm). Intrasession repeatability was assessed using coefficient of variation and intraclass correlation coefficient. The association between retinal thickness and PROS length with visual acuity was assessed using linear regression and Pearson correlation analyses. The main outcome measures include intrasession repeatability of macular parameters and correlation of these parameters with visual acuity. Mean retinal thickness and PROS length were 298 mum to 381 microm and 30 microm to 32 mum, respectively, for macular parameters assessed in this study. Coefficient of variation values were 0.75% to 4.13% for retinal thickness and 1.97% to 14.01% for PROS length. Intraclass correlation coefficient values were 0.96 to 0.99 and 0.73 to 0.98 for retinal thickness and PROS length, respectively. Slopes from linear regression analyses assessing the association of retinal thickness and visual acuity were not significantly different from 0 (P > 0.20), whereas the slopes of PROS length and visual acuity were significantly different from 0 (P < 0.0005). Correlation coefficients for macular thickness and visual acuity ranged from 0.13 to 0.22, whereas coefficients for PROS length and visual acuity ranged from -0.61 to -0.81. Photoreceptor outer segment length can be quantitatively assessed using Cirrus HD-OCT. Although the intrasession repeatability of PROS

Contributing factors to VEP grating acuity deficit and inter-ocular acuity difference in children with cerebral visual impairment.

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Cavascan, Nívea Nunes; Salomão, Solange Rios; Sacai, Paula Yuri; Pereira, Josenilson Martins; Rocha, Daniel Martins; Berezovsky, Adriana

2014-04-01

To investigate contributing factors to visual evoked potential (VEP) grating acuity deficit (GAD) and inter-ocular acuity difference (IAD) measured by sweep-VEPs in children with cerebral visual impairment (CVI). VEP GAD was calculated for the better acuity eye by subtracting acuity thresholds from mean normal VEP grating acuity according to norms from our own laboratory. Deficits were categorized as mild (0.17 ≤ deficit children (66 males-57 %) with ages ranging from 1.2 to 166.5 months (median = 17.7) was examined. VEP GAD ranged from 0.17 to 1.28 log units (mean = 0.68 ± 0.27; median = 0.71), and it was mild in 23 (20 %) children, moderate in 32 (28 %) and severe in 60 (52 %). Severe deficit was significantly associated with older age and anti-seizure drug therapy. IAD ranged from 0 to 0.49 log units (mean = 0.06 ± 0.08; median = 0.04) and was acceptable in 96 (83 %) children. Children with strabismus and nystagmus had IAD significantly larger compared to children with orthoposition. In a large cohort of children with CVI, variable severity of VEP GAD was found, with more than half of the children with severe deficits. Older children and those under anti-seizure therapy were at higher risk for larger deficits. Strabismus and nystagmus provided larger IADs. These results should be taken into account on the clinical management of children with this leading cause of bilateral visual impairment.

Visual acuity and associated factors. The Central India Eye and Medical Study.

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Vinay Nangia

Full Text Available Visual acuity is a major parameter for quality of vision and quality of life. Information on visual acuity and its associated factors in rural societies almost untouched by any industrialization is mostly non-available. It was, therefore, the purpose of our study to determine the distribution of visual acuity and its associated factors in a rural population not marked influenced by modern lifestyle. The population-based Central India Eye and Medical Study included 4711 subjects (aged 30+ years, who underwent a detailed ophthalmologic examination including visual acuity measurement. Visual acuity measurements were available for 4706 subjects with a mean age of 49.5±13.4 years (range: 30-100 years. BCVA decreased significantly (P<0.001 from the moderately hyperopic group (0.08±0.15 logMAR to the emmetropic group (0.16±0.52 logMAR, the moderately myopic group (0.28±0.33 logMAR, the highly hyperopic group (0.66±0.62 logMAR and finally the highly myopic group (1.32±0.92 logMAR. In multivariate analysis, BCVA was significantly associated with the systemic parameters of lower age (P<0.001, higher level of education (P<0.001, higher body stature (P<0.001 and higher body mass index (P<0.001, and with the ophthalmic parameters of more hyperopic refractive error (spherical equivalent (P<0.001, shorter axial length (P<0.001, lower degree of nuclear cataract (P<0.001, and lower intraocular pressure (P = 0.006. The results suggest that in the rural population of Central India, major determinants of visual acuity were socioeconomic background, body stature and body mass index, age, refractive error, cataract and intraocular pressure.

VISUAL ACUITY AND CLINICAL REFRACTION FOLLOWING IMPLANTATION OF VARIOUS MULTIFOCAL INTRAOCULAR LENSES

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N. N. Temirov

2015-01-01

Full Text Available Aim. To analyze visual acuity, clinical refraction, and defocusing tolerance after the implantation of monofocal IOL with rotational asymmetric optic (Lentis Mplus 313 MF compared with Acrysof ReSTOR SN6AD1.Materials and methods. Phacoemulsification was performed in a total of 194 patients (288 eyes, i.e., 144 patients (188 eyes with cataract and 50 patients (100 eyes with presbyopia and high ametropia. The patients were divided into two groups. Study group included 132 patients (194 eyes implanted with Lentis Mplus while control group included 62 patients (94 eyes implanted with Acrysof ReSTOR. Uncorrected distance (5 m, intermediate (50‑70 cm, and near (20‑40 cm visual acuity under photopic (85 cd/m2 and mesopic (8 cd/m2 conditions were measured, objective and subjective refractometry were performed, and defocusing tolerance was evaluated.Results. Postoperatively, uncorrected distance and near visual acuity was high while intermediate visual acuity was moderately low. Lentis Mplus patients had better near and intermediate visual acuity under mesopic conditions as compared with Acrysof ReSTOR patients. Emmetropia (target refraction was achieved in 90.2% of study group patients and in 87.2% of control group patients. In patients implanted with Lentis Mplus, refraction was measured by subjective method. Optimal A-constant for Lentis Mplus and Acrysof ReSTOR was 118.0 and 118.6, respectively. Under defocusing, Lentis Mplus patients had better visual acuity than Acrysof ReSTOR patients. This indirectly confirms better intermediate vision.Conclusions. Lentis Mplus provides better vision at various distances that does not almost depend on light levels and induces minimal dysphotopsia. 

Visual acuity and quality of life in dry eye disease: Proceedings of the OCEAN group meeting.

Science.gov (United States)

Benítez-Del-Castillo, José; Labetoulle, Marc; Baudouin, Christophe; Rolando, Maurizio; Akova, Yonca A; Aragona, Pasquale; Geerling, Gerd; Merayo-Lloves, Jesús; Messmer, Elisabeth M; Boboridis, Kostas

2017-04-01

Dry eye disease (DED) results in tear film instability and hyperosmolarity, inflammation of the ocular surface and, ultimately, visual disturbance that can significantly impact a patient's quality of life. The effects on visual acuity result in difficulties with driving, reading and computer use and negatively impact psychological health. These effects also extend to the workplace, with a loss of productivity and quality of work causing substantial economic losses. The effects of DED and the impact on vision experienced by patients may not be given sufficient importance by ophthalmologists. Functional visual acuity (FVA) is a measure of visual acuity after sustained eye opening without blinking for at least 10 s and mimics the sustained visual acuity of daily life. Measuring dynamic FVA allows the detection of impaired visual function in patients with DED who may display normal conventional visual acuity. There are currently several tests and methods that can be used to measure dynamic visual function: the SSC-350 FVA measurement system, assessment of best-corrected visual acuity decay using the interblink visual acuity decay test, serial measurements of ocular and corneal higher order aberrations, and measurement of dynamic vision quality using the Optical Quality Analysis System. Although the equipment for these methods may be too large or unaffordable for use in clinical practice, FVA testing is an important assessment for DED. Copyright © 2016 Elsevier Inc. All rights reserved.

Presenting visual acuities in a new eye centre in Port Harcourt: initial ...

African Journals Online (AJOL)

Background: Visual acuity is a fundamental of an eye examination. It establishes in a quantitative way how well an eye can see. Apart from being a starting point in dealing with an eye, it is also a prognostic reference point and a medico-legal tool. Very few studies directly related to visual acuities are available as many ...

A Case of Recurrent Transient Monocular Visual Loss after Receiving Sildenafil

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Asaad Ghanem Ghanem

2011-01-01

Full Text Available A 53-year-old man was attended to the Clinic Ophthalmic Center, Mansoura University, Egypt, with recurrent transient monocular visual loss after receiving sildenafil citrate (Viagra for erectile dysfunction. Examination for possible risk factors revealed mild hypercholesterolemia. Family history showed that his father had suffered from bilateral nonarteritic anterior ischemic optic neuropathy (NAION. Physicians might look for arteriosclerotic risk factors and family history of NAION among predisposing risk factors before prescribing sildenafil erectile dysfunction drugs.

Relationship between Outer Retinal Layers Thickness and Visual Acuity in Diabetic Macular Edema

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Raymond L. M. Wong

2015-01-01

Full Text Available Purpose. To investigate the correlation of outer retinal layers (ORL thickness and visual acuity (VA in patients with diabetic macular edema (DME. Methods. Consecutive DME patients seen at the Retina Clinic of The University of Hong Kong were recruited for OCT assessment. The ORL thickness was defined as the distance between external limiting membrane (ELM and retinal pigment epithelium (RPE at the foveal center. The correlation between total retinal thickness, ORL thickness, and vision was calculated. Results. 78 patients with DME were recruited. The mean age was 58.1 years (±11.5 years and their mean visual acuity measured with Snellen chart was 0.51 (±0.18. The correlation coefficient between total retinal thickness and visual acuity was 0.34 (P < 0.001 whereas the correlation coefficient was 0.65 between ORL thickness and visual acuity (P < 0.001. Conclusion. ORL thickness correlates better with vision than the total retinal thickness. It is a novel OCT parameter in the assessment of DME. Moreover, it could be a potential long term visual prognostic factor for patients with DME.

[Measuring contrast sensitivity using visual acuity tests in retinal and optic nerve diseases].

Science.gov (United States)

Sommer, E; Marré, E; Mierdel, P

1990-01-01

The luminance contrast needed to discern various test types was measured with monochromatic and achromatic light to detect discrete functional deficiencies of the retina and optic nerve in cases of normal visual acuity. Landolt rings corresponding to visual acuity levels from 0.04 to 1.0 were used as test types. A significant increase in the necessary minimum contrast was detectable with blue test light on large Landolt rings in patients with diabetic retinopathy, ocular hypertension and glaucoma and with green or yellow test light on medium-sized and small Landolt rings in patients with central serous chorioidopathy and optic atrophy. The additional contrast needed to reach the maximum visual acuity amounts to 14-100% compared with normal visual acuity, depending on the color of the test light and the diagnosis. The amount of contrast needed is greatest in retinal diseases, and it is therefore possible to a certain extent to distinguish these from diseases of the optic nerve.

Impact of Target Distance, Target Size, and Visual Acuity on the Video Head Impulse Test.

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Judge, Paul D; Rodriguez, Amanda I; Barin, Kamran; Janky, Kristen L

2018-05-01

The video head impulse test (vHIT) assesses the vestibulo-ocular reflex. Few have evaluated whether environmental factors or visual acuity influence the vHIT. The purpose of this study was to evaluate the influence of target distance, target size, and visual acuity on vHIT outcomes. Thirty-eight normal controls and 8 subjects with vestibular loss (VL) participated. vHIT was completed at 3 distances and with 3 target sizes. Normal controls were subdivided on the basis of visual acuity. Corrective saccade frequency, corrective saccade amplitude, and gain were tabulated. In the normal control group, there were no significant effects of target size or visual acuity for any vHIT outcome parameters; however, gain increased as target distance decreased. The VL group demonstrated higher corrective saccade frequency and amplitude and lower gain as compared with controls. In conclusion, decreasing target distance increases gain for normal controls but not subjects with VL. Preliminarily, visual acuity does not affect vHIT outcomes.

Monocular Visual Odometry Based on Trifocal Tensor Constraint

Science.gov (United States)

Chen, Y. J.; Yang, G. L.; Jiang, Y. X.; Liu, X. Y.

2018-02-01

For the problem of real-time precise localization in the urban street, a monocular visual odometry based on Extend Kalman fusion of optical-flow tracking and trifocal tensor constraint is proposed. To diminish the influence of moving object, such as pedestrian, we estimate the motion of the camera by extracting the features on the ground, which improves the robustness of the system. The observation equation based on trifocal tensor constraint is derived, which can form the Kalman filter alone with the state transition equation. An Extend Kalman filter is employed to cope with the nonlinear system. Experimental results demonstrate that, compares with Yu’s 2-step EKF method, the algorithm is more accurate which meets the needs of real-time accurate localization in cities.

The validity of visual acuity assessment using mobile technology devices in the primary care setting.

Science.gov (United States)

O'Neill, Samuel; McAndrew, Darryl J

2016-04-01

The assessment of visual acuity is indicated in a number of clinical circumstances. It is commonly conducted through the use of a Snellen wall chart. Mobile technology developments and adoption rates by clinicians may potentially provide more convenient methods of assessing visual acuity. Limited data exist on the validity of these devices and applications. The objective of this study was to evaluate the assessment of distance visual acuity using mobile technology devices against the commonly used 3-metre Snellen chart in a primary care setting. A prospective quantitative comparative study was conducted at a regional medical practice. The visual acuity of 60 participants was assessed on a Snellen wall chart and two mobile technology devices (iPhone, iPad). Visual acuity intervals were converted to logarithm of minimum angle of resolution (logMAR) scores and subjected to intraclass correlation coefficient (ICC) assessment. The results show a high level of general agreement between testing modality (ICC 0.917 with a 95% confidence interval of 0.887-0.940). The high level of agreement of visual acuity results between the Snellen wall chart and both mobile technology devices suggests that clinicians can use this technology with confidence in the primary care setting.

Visual Acuity Testing: Feedback Affects Neither Outcome nor Reproducibility, but Leaves Participants Happier.

Science.gov (United States)

Bach, Michael; Schäfer, Kerstin

2016-01-01

Assessment of visual acuity is a well standardized procedure at least for expert opinions and clinical trials. It is often recommended not giving patients feedback on the correctness of their responses. As this viewpoint has not been quantitatively examined so far, we quantitatively assessed possible effects of feedback on visual acuity testing. In 40 normal participants we presented Landolt Cs in 8 orientations using the automated Freiburg Acuity Test (FrACT, feedback was provided in 2 x 4 conditions: (A) no feedback, (B) acoustic signals indicating correctness, (C)visual indication of correct orientation, and (D) a combination of (B) and (C). After each run the participants judged comfort. Main outcome measures were absolute visual acuity (logMAR), its test-retest agreement (limits of agreement) and participants' comfort estimates on a 5-step symmetric Likert scale. Feedback influenced acuity outcome significantly (p = 0.02), but with a tiny effect size: 0.02 logMAR poorer acuity for (D) compared to (A), even weaker effects for (B) and (C). Test-retest agreement was high (limits of agreement: ± 1.0 lines) and did not depend on feedback (p>0.5). The comfort ranking clearly differed, by 2 steps on the Likert scale: the condition (A)-no feedback-was on average "slightly uncomfortable", the other three conditions were "slightly comfortable" (pFeedback affected neither reproducibility nor the acuity outcome to any relevant extent. The participants, however, reported markedly greater comfort with any kind of feedback. We conclude that systematic feedback (as implemented in FrACT) offers nothing but advantages for routine use.

Relationship between socioeconomic deprivation 
or urban/rural residence and visual acuity before cataract surgery in Northern Scotland.

Science.gov (United States)

Chua, Paul Y; Mustafa, Mohammed S; Scott, Neil W; Kumarasamy, Manjula; Azuara-Blanco, Augusto

2013-01-01

To evaluate the influence of socioeconomic factors on visual acuity before cataract surgery. 
 The medical case notes of 240 consecutive patients listed for cataract surgery from January 1, 2010, at Grampian University Hospital, Aberdeen, were reviewed retrospectively. Patients with ocular comorbidity were excluded. Demographics, postal codes, and visual acuity were recorded. Scottish Index of Multiple Deprivation was used to determine the deprivation rank. Home location was classified as urban or rural. The effect of these parameters on preoperative visual acuity was investigated using chi-square tests or Fisher exact test as appropriate. 
 A total of 184 patients (mean 75 years) were included. A total of 127 (69%) patients had visual acuity of 6/12 or better. An association was found between affluence and preoperative visual acuity of 6/12 or better (χ2trend = 4.97, p = 0.03), with a significant rising trend across quintile of deprivation. There was no evidence to suggest association between geographical region and preoperative visual acuity (p = 0.63). 
 Affluence was associated with good visual acuity (6/12 or better) before cataract surgery. There was no difference in preoperative visual acuity between rural and urban populations.

Wavefront coherence area for predicting visual acuity of post-PRK and post-PARK refractive surgery patients

Science.gov (United States)

Garcia, Daniel D.; van de Pol, Corina; Barsky, Brian A.; Klein, Stanley A.

1999-06-01

Many current corneal topography instruments (called videokeratographs) provide an `acuity index' based on corneal smoothness to analyze expected visual acuity. However, post-refractive surgery patients often exhibit better acuity than is predicted by such indices. One reason for this is that visual acuity may not necessarily be determined by overall corneal smoothness but rather by having some part of the cornea able to focus light coherently onto the fovea. We present a new method of representing visual acuity by measuring the wavefront aberration, using principles from both ray and wave optics. For each point P on the cornea, we measure the size of the associated coherence area whose optical path length (OPL), from a reference plane to P's focus, is within a certain tolerance of the OPL for P. We measured the topographies and vision of 62 eyes of patients who had undergone the corneal refractive surgery procedures of photorefractive keratectomy (PRK) and photorefractive astigmatic keratectomy (PARK). In addition to high contrast visual acuity, our vision tests included low contrast and low luminance to test the contribution of the PRK transition zone. We found our metric for visual acuity to be better than all other metrics at predicting the acuity of low contrast and low luminance. However, high contrast visual acuity was poorly predicted by all of the indices we studied, including our own. The indices provided by current videokeratographs sometimes fail for corneas whose shape differs from simple ellipsoidal models. This is the case with post-PRK and post-PARK refractive surgery patients. Our alternative representation that displays the coherence area of the wavefront has considerable advantages, and promises to be a better predictor of low contrast and low luminance visual acuity than current shape measures.

Effect of neodymium:YAG laser capsulotomy on visual function in patients with posterior capsule opacification and good visual acuity.

Science.gov (United States)

Yotsukura, Erisa; Torii, Hidemasa; Saiki, Megumi; Negishi, Kazuno; Tsubota, Kazuo

2016-03-01

To evaluate the effect of neodymium:YAG (Nd:YAG) laser capsulotomy on the visual function in patients with posterior capsule opacification (PCO) and good visual acuity. Keio University Hospital, Tokyo, Japan. Observational case series. Eyes were evaluated that had previous cataract surgery with a clinical diagnosis of PCO requiring Nd:YAG laser capsulotomy regardless of a good corrected distance visual acuity (CDVA) (at least 20/20). The CDVA, 10% low contrast visual acuity (LCVA), wavefront aberrations from the 3rd to 6th order, and retinal straylight were measured before and after Nd:YAG laser capsulotomy. The study included 16 eyes of 16 patients (10 men, 6 women; mean age 69.5 years ± 9.3 [SD]). The mean CDVA, LCVA, and straylight after Nd:YAG laser capsulotomy improved significantly (P The root mean square (RMS) of the 3rd Zernike coefficients (S3) and the RMS of the total higher-order aberrations (HOAs) from the 3rd to 6th order decreased significantly after capsulotomy (P The straylight correlated significantly with the total HOAs (r = 0.727, P = .002) and S3 (r = 0.748, P = .001) before capsulotomy. Subjective symptoms resolved after capsulotomy in all cases. Neodymium:YAG laser capsulotomy enabled a significant improvement in visual function even in patients with PCO with good visual acuity. Straylight measurements might be useful to determine the indications for Nd:YAG laser capsulotomy when patients report visual disturbances without decreased visual acuity. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

The advanced glaucoma intervention study, 6: effect of cataract on visual field and visual acuity. The AGIS Investigators.

Science.gov (United States)

2000-12-01

To investigate the effect of cataract on visual function and the role of cataract in explaining a race-treatment interaction in outcomes of glaucoma surgery. The Advanced Glaucoma Intervention Study (AGIS) enrolled 332 black patients (451 eyes) and 249 white patients (325 eyes) with advanced glaucoma. Eyes were randomly assigned to an argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy sequence or a trabeculectomy-ALT-trabeculectomy sequence. From the AGIS experience with cataract surgery during follow-up, we estimated the expected change in visual function scores from before cataract surgery to after cataract surgery. Then, for eyes with cataract not removed, we used these estimates of expected change to adjust visual function scores for the presumed effects of cataract. In turn, we used the adjusted scores to obtain cataract-adjusted main outcome measures. Average percent of eyes with decrease of visual field (APDVF) and average percent of eyes with decrease of visual acuity (APDVA). Within the 2 months before cataract surgery, visual acuity was better in eyes of white patients than of black patients by an average of approximately 2 lines on the visual acuity test chart. Cataract surgery improved visual acuity and visual field defect scores, with the amounts of improvement greater when preoperative visual acuity was lower. Adjustments for cataract brought about the following relative reductions: for APDVF, a relative reduction of 5% to 11% in black patients and 9% to 11% in white patients; for APDVA, a relative reduction of 45% to 49% in black patients and 31% to 38% in white patients; and for the APDVF and APDVA race-treatment interactions, relative reductions of 25% and 45%, respectively. On average, visual function scores improved after cataract surgery. The findings of reduced race-treatment interactions after adjustment for cataract do not alter our earlier conclusion that the AGIS 7-year results support use of the ALT

Bevacizumab Injection in Patients with Age-Related Macular Degeneration Associated with Poor Initial Visual Acuity

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Leila El Matri

2012-01-01

Full Text Available Purpose. To evaluate functional and anatomic effects of intravitreal bevacizumab in patients with neovascular AMD and initial low visual acuity. Methods. Retrospective case series of 38 eyes with neovascular AMD and initial visual acuity of 20/200 or less, treated with intravitreal bevacizumab injection. Results. Mean followup was 14.1 months ±7.1 (range: 5 to 24 months. Mean logMAR vision at baseline was 1.38 logMAR ±0.33, at 6 months was 1.14 logMAR ±0.37 (=0.001 and at 12 months was 1.22 logMar ±0.33 (=0.004. Mean baseline central retinal thickness was 431 μm ±159.7 at 6 months was 293.43 μm  ±122.79 (=10−4 and at 12 months was 293.1 μm  ±130 (=0.004. Visual acuity improved in both patients with or without prior PDT treatment. Conclusions. Intravitreal bevacizumab injection may increase the chance of visual acuity gain in neovascular AMD even in cases with initial low visual acuity.

Recovery of neurofilament following early monocular deprivation

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Timothy P O'Leary

2012-04-01

Full Text Available A brief period of monocular deprivation in early postnatal life can alter the structure of neurons within deprived-eye-receiving layers of the dorsal lateral geniculate nucleus. The modification of structure is accompanied by a marked reduction in labeling for neurofilament, a protein that composes the stable cytoskeleton and that supports neuron structure. This study examined the extent of neurofilament recovery in monocularly deprived cats that either had their deprived eye opened (binocular recovery, or had the deprivation reversed to the fellow eye (reverse occlusion. The degree to which recovery was dependent on visually-driven activity was examined by placing monocularly deprived animals in complete darkness (dark rearing. The loss of neurofilament and the reduction of soma size caused by monocular deprivation were both ameliorated equally following either binocular recovery or reverse occlusion for 8 days. Though monocularly deprived animals placed in complete darkness showed recovery of soma size, there was a generalized loss of neurofilament labeling that extended to originally non-deprived layers. Overall, these results indicate that recovery of soma size is achieved by removal of the competitive disadvantage of the deprived eye, and occurred even in the absence of visually-driven activity. Recovery of neurofilament occurred when the competitive disadvantage of the deprived eye was removed, but unlike the recovery of soma size, was dependent upon visually-driven activity. The role of neurofilament in providing stable neural structure raises the intriguing possibility that dark rearing, which reduced overall neurofilament levels, could be used to reset the deprived visual system so as to make it more ameliorable with treatment by experiential manipulations.

Outcome of visual acuity after surgical removal of pituitary adenomas

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Grković Desanka

2013-01-01

Full Text Available Introduction. Pituitary adenomas with suprasellar extension may produce anterior visual pathway compression, resulting in characteristic visual deficit. Surgical decompression of these structures prevents further visual deterioration and its postop­ erative recovery. Objective. The aim of this study was to investigate pre­ and postoperative visual acuity (VA in patients with pituitary ad­ enomas, and to detect the influence of prognostic factors, such as symptoms duration, degree of visual acuity reduction and tumor size in the assessment of the prognosis of postoperative visual function. Methods. We analyzed 40 consecutive patients who fulfilled three criteria: evidence of preoperative visual dysfunction, transsphenoidal or transfrontal tumor resection and hystologically verified pituitary adenoma. A visual examination was performed under standard conditions, pre and postoperatively (10 days, one month and six months after surgery. A paired t­test was used to assess the differences of pre­ and postoperative characteristics values, and the Chisquare test of independence in the assessment of the influence of prognostic factors. Results. Postoperative improvement of VA was seen in 84.61% patients (68% eyes. Eyes with preoperative mild and moderate degree of VA reduction showed improvement in 89.65% eyes in contrast to 22.60% eyes with preoperative severe reduction of VA, which was all statistically significant. Eyes in patients with tumor smaller than 20 mm had improvement of VA in 91.66% eyes, while eyes with tumor larger than 40 mm had improvement of VA in 61.11% eyes, which was statistically significant. When symptoms duration was below two years the improvement of VA was detected in 65.38% eyes as related to 50% eyes with symptoms duration exceeding two years, which was not statistically significant. Conclusion. Pituitary adenomas commonly cause visual impairment. Postoperatively the majority of patients show a distinct improvement of

An assessment of the iPad as a testing platform for distance visual acuity in adults

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Black, J M; Jacobs, R J; Phillips, G; Chen, L; Tan, E; Tran, A; Thompson, B

2013-01-01

Objectives Visual acuity is a common measurement in general practice, and the advent of new technology such as tablet computers offers a change in the way in which these tests are delivered. The aim of this study was to assess whether measurements of distance visual acuity using LogMAR letter charts displayed on an iPad tablet computer were in agreement with standard clinical tests of visual acuity in adults with normal vision. Design Blinded, diagnostic test study. Setting Single centre (University) in Auckland, New Zealand. Participants University staff and students (n=85). Participants were required to have visual acuity better than 6/60 and wear habitual refractive correction during testing. Participants were excluded if there was any history of ocular pathology. Primary and secondary outcome measures Visual acuity measured under a number of conditions. Results The iPad tablet with its glossy screen was highly susceptible to glare resulting in acuity measurements that were significantly poorer (approximately 2 LogMAR lines) than those made using an ETDRS chart and a standard computerised testing system (n=56). However, fitting the iPad with an antiglare screen and positioning the device away from sources creating reflected (veiling) glare resulted in acuity measurements that were equivalent those made using gold standard charts (n=29). Conclusions Tablet computers are an attractive option for visual acuity measurement due to portability, the ability to randomise letters, automated scoring of acuity and the ability to select from a range of charts. However, these devices are only suitable for use in situations where sources of glare can be eliminated. PMID:23794568

Incorporating a Wheeled Vehicle Model in a New Monocular Visual Odometry Algorithm for Dynamic Outdoor Environments

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Jiang, Yanhua; Xiong, Guangming; Chen, Huiyan; Lee, Dah-Jye

2014-01-01

This paper presents a monocular visual odometry algorithm that incorporates a wheeled vehicle model for ground vehicles. The main innovation of this algorithm is to use the single-track bicycle model to interpret the relationship between the yaw rate and side slip angle, which are the two most important parameters that describe the motion of a wheeled vehicle. Additionally, the pitch angle is also considered since the planar-motion hypothesis often fails due to the dynamic characteristics of wheel suspensions and tires in real-world environments. Linearization is used to calculate a closed-form solution of the motion parameters that works as a hypothesis generator in a RAndom SAmple Consensus (RANSAC) scheme to reduce the complexity in solving equations involving trigonometric. All inliers found are used to refine the winner solution through minimizing the reprojection error. Finally, the algorithm is applied to real-time on-board visual localization applications. Its performance is evaluated by comparing against the state-of-the-art monocular visual odometry methods using both synthetic data and publicly available datasets over several kilometers in dynamic outdoor environments. PMID:25256109

Incorporating a Wheeled Vehicle Model in a New Monocular Visual Odometry Algorithm for Dynamic Outdoor Environments

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Yanhua Jiang

2014-09-01

Full Text Available This paper presents a monocular visual odometry algorithm that incorporates a wheeled vehicle model for ground vehicles. The main innovation of this algorithm is to use the single-track bicycle model to interpret the relationship between the yaw rate and side slip angle, which are the two most important parameters that describe the motion of a wheeled vehicle. Additionally, the pitch angle is also considered since the planar-motion hypothesis often fails due to the dynamic characteristics of wheel suspensions and tires in real-world environments. Linearization is used to calculate a closed-form solution of the motion parameters that works as a hypothesis generator in a RAndom SAmple Consensus (RANSAC scheme to reduce the complexity in solving equations involving trigonometric. All inliers found are used to refine the winner solution through minimizing the reprojection error. Finally, the algorithm is applied to real-time on-board visual localization applications. Its performance is evaluated by comparing against the state-of-the-art monocular visual odometry methods using both synthetic data and publicly available datasets over several kilometers in dynamic outdoor environments.

Creation of an Accurate Algorithm to Detect Snellen Best Documented Visual Acuity from Ophthalmology Electronic Health Record Notes.

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Mbagwu, Michael; French, Dustin D; Gill, Manjot; Mitchell, Christopher; Jackson, Kathryn; Kho, Abel; Bryar, Paul J

2016-05-04

Visual acuity is the primary measure used in ophthalmology to determine how well a patient can see. Visual acuity for a single eye may be recorded in multiple ways for a single patient visit (eg, Snellen vs. Jäger units vs. font print size), and be recorded for either distance or near vision. Capturing the best documented visual acuity (BDVA) of each eye in an individual patient visit is an important step for making electronic ophthalmology clinical notes useful in research. Currently, there is limited methodology for capturing BDVA in an efficient and accurate manner from electronic health record (EHR) notes. We developed an algorithm to detect BDVA for right and left eyes from defined fields within electronic ophthalmology clinical notes. We designed an algorithm to detect the BDVA from defined fields within 295,218 ophthalmology clinical notes with visual acuity data present. About 5668 unique responses were identified and an algorithm was developed to map all of the unique responses to a structured list of Snellen visual acuities. Visual acuity was captured from a total of 295,218 ophthalmology clinical notes during the study dates. The algorithm identified all visual acuities in the defined visual acuity section for each eye and returned a single BDVA for each eye. A clinician chart review of 100 random patient notes showed a 99% accuracy detecting BDVA from these records and 1% observed error. Our algorithm successfully captures best documented Snellen distance visual acuity from ophthalmology clinical notes and transforms a variety of inputs into a structured Snellen equivalent list. Our work, to the best of our knowledge, represents the first attempt at capturing visual acuity accurately from large numbers of electronic ophthalmology notes. Use of this algorithm can benefit research groups interested in assessing visual acuity for patient centered outcome. All codes used for this study are currently available, and will be made available online at https://phekb.org.

PATTERN ELECTRORETINOGRAPHY IN RELATION TO KINETIC AND STATIC PERIMETRY AND VISUAL ACUITY IN RETINITIS PIGMENTOSA

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Petra Popović

2002-12-01

Full Text Available Background. This study was conducted to assess whether pattern ERG is a sensitive test in evaluating the retinal function in patients with retinitis pigmentosa. We wanted to determine how pattern ERG, reflecting the activity of inner retinal layers, is related to other psychophysical tests such as perimetry and visual acuity.Methods. An analysis was performed on 50 eyes of 25 patients with typical rod-cone retinitis pigmentosa. The standard Snellen visual acuity was tested. Visual field sensitivity was measured with automated static perimetry (Octopus G2 program where mean defect was taken as an index of visual field loss. In kinetic perimetry (Goldmann the average radius of the visual field measured with target II/4 and V/4 was calculated. Transient pattern ERG and all five flash ERG responses were also measured according to ISCEV standards. Amplitudes of pattern ERG P50 and N95 waves were compared to results of visual acuity and visual field testing.Results. In our group of 25 RP patients with visual acuity ranging from 0.16 to 1.0, PERG responses were preserved much better than full field ERGs. 72% of them had still recordable PERG responses, while 48% had cone and only 32% maximal responses. Scotopic rod responses were extinguished in all eyes. The normalized amplitudes of the PERG responses were also much higher (43.5% than cone (22.5% or maximal responses (4.5%. A strong correlation of both P50 and N95 amplitudes with Octopus mean defect index was found. In kinetic perimetry the correlation with PERG amplitudes was also high, but it was better with II/4 than with V/4 target. Patients with high preserved ERG responses had good visual acuity. In all patients with visual acuity less than 0.4 both flash and pattern ERG responses were already absent.Conclusions. This study shows that pattern ERG is an objective and sensitive test in evaluating the functional visual loss in retinitis pigmentosa. Amplitudes of P50 and N95 responses are linearly

LASER PHOTOCOAGULATION IN DIABETIC MACULAR EDEMA: EFFECTS ON VISUAL ACUITY AND MACULAR EDEMA

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M.H. Dehghan

1999-06-01

Full Text Available Due to the importance of clinically significant macular edema in diabetic patients, this study is aimed to determine if laser photocoagulation is effective in the treatment of clinically significant diabetic macular edema. In addition, the effects of risk factors arc surveyed* This is an existing data study considering patients with clinically significant diabetic macular edema, treated with argon-green laser photocoagulation in Labbafinejad hospital, department of lasertherapy, from 1995 to 1997. in 60 (42.6% eyes the treatment method was focal, in 22 (15.6% eyes grid, and in 59 (41.84 modified grid laser photocoagulation was performed. The results are based upon deterioration of visual acuity, occurance of moderate visual loss and improvement or persistence of CSME. We studied 114 eyes from 87 patients. Two years after initial treatment, visual acuity improved in 19.1% of eyes, unchanged in 9.5% and worsened in 71.4% of eyes. After this period the rate of moderate visual loss was 28.6% and CSME was improved in 23.8% of eyes. According to our study, baseline visual acuity and retinopathy severity were two important intervening factors in response to lasertherapy. Comparing our results with natural course of diabetic macular edema, indicates that in assessing visual outcome laser photocoagulation is an effective modality in treatment of CSME, but it is not effective in maintaining or improving visual acuity, which is due to patients delay in visiting ophthalmologists and paying not enough attention to follow-up visits.

Lawn mower injuries as a cause of serious visual acuity impairment - Case reports.

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Jasielska, Monika; Winiarczyk, Mateusz; Bieliński, Paweł; Mackiewicz, Jerzy

2017-05-11

[b]Abstract Objective.[/b] The aim of the study is to present four cases of lawn mowers injuries as a cause of serious visual acuity impairment. [b]Materials and Method[/b]. A retrospective study of four patients admitted in 2013-2015 to the Department of Vitreoretinal Surgery in Lublin with severe open or closed globe injury, one with an intraocular foreign body (IOFB). The presence of eye protective equipment was assessed, as well as visual acuity, eye tissue condition before and after treatment, and applied therapy. In all cases an improvement was achieved in local conditions. The intraocular foreign body was removed, wounds sutured and damaged tissues placed in position. All eyeballs were saved. In three cases, visual acuity was improved to a usable level. Three patients underwent pars plana vitrectomy, one with IOFB removal from the vitreous cavity. [b]Conclusions[/b]. Lawn mower induced eye injuries are a significant cause of serious visual acuity impairment or blindness. The presented study shows that lawn mower eye injuries are still a therapeutic, social and economic problem, yet are very preventable with proper eye protection and patients' education. Current prevention strategies are inadequate, and therefore should be updated.

Contrast visual acuity after multifocal intraocular lens implantation:aspheric versus spherical design

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Jun-Hua Li

2014-02-01

Full Text Available AIM: To evaluate contrast visual acuity (CVA after implantation of an aspheric apodized diffractive intraocular lens (IOL or a spherical apodized diffractive IOL in cataract surgery.METHOD: This prospective randomized controlled study with a 12-month follow-up compared the results of cataract surgery with implantation of an aspheric AcrySof ReSTOR SN6AD3 IOL (30 eyes and a spherical AcrySof ReSTOR SN60D3 IOL (30 eyes. CVA with best distance correction was measured at 4 contrast levels (100%, 25%, 10% and 5% under 3 levels of chart luminance [250, 85 and 25 candelas per square meter (cd/m2] using a multi-functional visual acuity tester (MFVA-100．RESULTS:At 12 months after surgery, there were no statistically significant differences in 100% CVA and 25% CVA under 250cd/m2 (P100%=0.875 and P25%=0.057 and 85cd/m2 (P100%=0.198 and P25%=0.193 between the aspheric group and the spherical group. However, the 10% CVA and 5% CVA were significant better in aspheric group than spherical group under 250cd/m2 (P10%=0.042 and P5%=0.007 and 85cd/m2 (P10%=0.002 and P5%=0.039. Under the luminance level of 25cd/m2, no significant differences was found in the 100% CVA between the 2 group (P100%=0.245, while aspheric group had better visual acuity in the remaining 3 contracts (P25%=0.023, P10%=0.026 and P5%=0.002, respectively.CONCULSION:The aspheric AcrySof ReSTOR SN6AD3 IOL provided patients with better low-contrast visual acuity than the spherical AcrySof ReSTOR SN60D3 IOL.Keyword:cataract surgery; intraocular lens; contrast sensitivity; visual acuity

Relationships between luminance and visual acuity in the rhesus monkey

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Cavonius, C. R.; Robbins, D. O.

1973-01-01

1. The ability of rhesus monkeys to detect the gap in Landolt ring test-objects that were presented against background luminances between 5 × 10-5 cd/m2 and 5 × 103 cd/m2 was compared with similar human data. 2. At high luminance-levels the acuity of human observers is slightly better than that of rhesus, but rhesus have better acuity at scotopic luminance-levels. Both species have distinct photopic and scotopic acuity functions that cross at 6 × 10-3 cd/m2. 3. The threshold for light detection is estimated to be the same for both species when specified in quanta incident on the retina. 4. It is concluded that the receptor and neural mechanisms that mediate visual-acuity function similarly in rhesus and man, and that the differences in acuity that were measured in the two species may be attributed to optical rather than to physiological factors. PMID:4199366

Correlation between contrast sensitivity and visual acuity in retinitis pigmentosa patients.

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Akeo, Kiyoshi; Hiida, Yoshiki; Saga, Masamichi; Inoue, Rikako; Oguchi, Yoshihisa

2002-01-01

High-contrast figures such as Landolt rings are insufficient to evaluate the function of the foveal cones of retinitis pigmentosa (RP) patients. We investigated the correlation between visual function as determined with Landolt rings and with the Vistech Contrast Sensitivity Function Test (VCTS) at various spatial frequencies, in addition to the Cambridge Low Contrast Grating (CLCG). The study included 30 retinitis pigmentosa patients (53 eyes). All patients were assessed with Landolt rings, the Vistech method, and the CLCG. We estimated the relative contribution of contrast sensitivity to visual acuity by VCTS at each spatial frequency and by CLCG by simple linear regression analysis. The results of the regression analysis of VCTS at 1.5, 3.0, and 6.0 cycles/degree showed a significant correlation between Landolt rings and VCTS and between CLCG and VCTS that was strongest at 6.0 cycles/degree. There was no significant correlation between Landolt rings and VCTS or between CLCG and VCTS at 12.0 and 18.0 cycles/degree. Patients with a visual acuity of 20/25 and CLCG greater than 100 were divided into two groups according to their contrast sensitivity at 18.0 cycles/degree on VCTS. The VCTS at the highest frequency was useful for evaluating the foveal visual function in RP patients having good visual acuity with the Landolt rings. Thus, contrast sensitivity should be useful in detecting minute impairment or improvement of visual function in RP. Copyright 2002 S. Karger AG, Basel

A special role for binocular visual input during development and as a component of occlusion therapy for treatment of amblyopia.

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Mitchell, Donald E

2008-01-01

To review work on animal models of deprivation amblyopia that points to a special role for binocular visual input in the development of spatial vision and as a component of occlusion (patching) therapy for amblyopia. The studies reviewed employ behavioural methods to measure the effects of various early experiential manipulations on the development of the visual acuity of the two eyes. Short periods of concordant binocular input, if continuous, can offset much longer daily periods of monocular deprivation to allow the development of normal visual acuity in both eyes. It appears that the visual system does not weigh all visual input equally in terms of its ability to impact on the development of vision but instead places greater weight on concordant binocular exposure. Experimental models of patching therapy for amblyopia imposed on animals in which amblyopia had been induced by a prior period of early monocular deprivation, indicate that the benefits of patching therapy may be only temporary and decline rapidly after patching is discontinued. However, when combined with critical amounts of binocular visual input each day, the benefits of patching can be both heightened and made permanent. Taken together with demonstrations of retained binocular connections in the visual cortex of monocularly deprived animals, a strong argument is made for inclusion of specific training of stereoscopic vision for part of the daily periods of binocular exposure that should be incorporated as part of any patching protocol for amblyopia.

Visual acuity loss associated with excessive “dry macula” in exudative age-related macular degeneration

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Takahashi H

2018-02-01

Full Text Available Hidenori Takahashi,1–3 Yuji Inoue,1,2 Xue Tan,2,3 Satoru Inoda,1 Shinichi Sakamoto,1 Yusuke Arai,1 Yasuo Yanagi,4–6 Yujiro Fujino,2,3 Hidetoshi Kawashima1 1Department of Ophthalmology, Jichi Medical University, Shimotsuke, 2Department of Ophthalmology, The University of Tokyo, Bunkyo, 3Department of Ophthalmology, Japan Community Health Care Organization Tokyo Shinjuku Medical Center, Shinjuku, Japan; 4Medical Retina, Singapore National Eye Centre, 5Medical Retina, Singapore Eye Research Institute, 6Eye-ACP, Duke NUS Medical School, National University of Singapore, Singapore Purpose: To investigate the correlation between visual acuity and central macular thickness (CMT and choroidal thickness (CCT in patients with wet age-related macular degeneration (AMD. Methods: In this retrospective analysis, 14 eyes that received >10 ranibizumab injections (based on pro re nata [PRN] regimen and maintained initial visual acuity gain were analyzed. The following 5 parameters were measured at the foveal center: CMT (distance from the inner limiting membrane [ILM] to Bruch’s membrane; central retinal thickness (CRT; distance from the ILM to the inner limit of the retinal pigment epithelium or subretinal fluid [SRF]; SRF thickness (SRFT; pigment epithelium detachment thickness (PEDT; and CCT. The correlation between the logarithm of the minimum angle of resolution (logMAR best-corrected visual acuity (BCVA and the 5 parameters was examined with generalized estimating equations. Results: CMT, CRT, and CCT were negatively correlated with logMAR BCVA (P=0.031, 0.023, and 0.036, respectively when only CMT values less than the thickness that maximized visual acuity for each eye were used for the analysis. Each 100-µm reduction in CMT, CRT, or CCT improved logMAR BCVA by -0.1, -0.08, or -0.07, respectively. SRFT and PEDT were not correlated with BCVA. The median CMT that maximized the visual acuity was 230 µm. Conclusion: Dry macula with CMT <230 µm was

[Effect of acupuncture on pattern-visual evoked potential in rats with monocular visual deprivation].

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Yan, Xing-Ke; Dong, Li-Li; Liu, An-Guo; Wang, Jun-Yan; Ma, Chong-Bing; Zhu, Tian-Tian

2013-08-01

To explore electrophysiology mechanism of acupuncture for treatment and prevention of visual deprivation effect. Eighteen healthy 15-day Evans rats were randomly divided into a normal group, a model group and an acupuncture group, 6 rats in each one. Deprivation amblyopia model was established by monocular eyelid suture in the model group and acupuncture group. Acupuncture was applied at "Jingming" (BL 1), "Chengqi" (ST 1), "Qiuhou" (EX-HN 7) and "Cuanzhu" (BL 2) in the acupuncture group. The bilateral acupoints were selected alternately, one side for a day, and totally 14 days were required. The effect of acupuncture on visual evoked potential in different spatial frequencies was observed. Under three different kinds of spatial frequencies of 2 X 2, 4 X 4 and 8 X 8, compared with normal group, there was obvious visual deprivation effect in the model group where P1 peak latency was delayed (P0.05). Under spatial frequency of 4 X 4, N1-P1 amplitude value was maximum in the normal group and acupuncture group. With this spatial frequency the rat's eye had best resolving ability, indicating it could be the best spatial frequency for rat visual system. The visual system has obvious electrophysiology plasticity in sensitive period. Acupuncture treatment could adjust visual deprivation-induced suppression and slow of visual response in order to antagonism deprivation effect.

Visual outcome and optical quality after bilateral implantation of aspheric diffractive multifocal, aspheric monofocal and spherical monofocal intraocular lenses: a prospective comparison

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Ke Yao

2013-06-01

Full Text Available AIM: To evaluate the visual function after bilateral implantation of aspheric diffractive multifocal Tecnis ZMA00, aspheric monofocal ZA9003 versus spherical monofocal Akreos Adapt intraocular lenses (IOLs.METHODS: Tecnis ZMA00, Tecnis ZA9003 or Akreos Adapt IOLs were bilaterally implanted in 180 eyes from 90 patients. The following parameters were assessed 3 months postoperatively: monocular and binocular uncorrected visual acuity (UCVA and distance-corrected visual acuity (DCVA for distance, intermediate and near, spherical aberration (SA, contrast and glare sensitivity, near point refractive power, uncorrected and best-corrected near stereoscopic acuity (NSA. Patient satisfaction was assessed by a questionnaire.RESULTS: Three months postoperatively, the monocular and binocular UCVA and DCVA at near of Tecnis ZMA00 were significantly better than other two groups. The mean SA for 5.0mm optical zone in Tecnis ZMA00 and Tecnis ZA9003 was significantly lower than that in Akreos Adapt. Mean contrast sensitivity and glare sensitivity were better for Tecnis ZA9003 group than for other two groups. Patients with Tecnis ZMA00 had higher monocular and binocular near point refractive power and uncorrected NSA than monofocal groups. The patients in Tecnis ZMA00 had higher mean values for halo compared with other two groups.CONCLUSION: Tecnis ZMA00 provided better near VA and uncorrected NSA and higher near point refractive power than monofocal IOLs and patients were spectacle independent. The IOLs with Tecnis aspheric design improved contrast and glare sensitivity. Patients with Tecnis ZMA00 reported more disturbances on visual phenomena of halo.

Fluctuation in visual acuity during soft toric contact lens wear.

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Chamberlain, Paul; Morgan, Philip B; Moody, Kurt J; Maldonado-Codina, Carole

2011-04-01

To quantify changes in visual acuity (VA) with soft toric contact lenses as a result of lens movement and/or rotational instability caused by versional eye movements. A novel chart for vision assessment at near (40 cm) for soft toric contact lenses (VANT chart),consisting of a central, color-coded logMAR panel and eight peripheral letter targets set on a white background measuring 60 × 40 cm was constructed. In the developmental phase of the work, 10 subjects (20 eyes) wore 2 toric lenses in random order, and the impact of rapid and delayed eye versions in 8 directions of gaze on VANT acuity was investigated. In phase 2, 35 subjects (68 eyes) wore 4 toric lenses in random order, and a streamlined clinical protocol using the VANT chart was implemented. Standard assessments of toric lens fit and distance VA were also performed. Testing in the first phase showed no difference for change in VA for rapid vs. delayed version movements, (p = 0.17) but acuity reduction was greater for diagonal compared with horizontal/vertical versions (p = 0.06). As such, testing in phase 2 proceeded using rapid, diagonal versions only. In this second phase, there were differences for low-contrast distance VA measures between lens types (p = 0.02) and for both VANT baseline acuity (p = 0.03) and postversion acuity (p = 0.04), but no differences were found between lenses for magnitude of vision loss (p = 0.91), which was about one line. No relationship was established between the magnitude of vision loss and measured rotational stability (p = 0.75). This work has demonstrated that conventional approaches to measuring VA do not fully replicate the "real world" experience of soft toric lens wearers. The VANT chart has shown that VA is reduced immediately after versional eye movements and suggests that more dynamic methods of assessing visual performance should be considered for soft toric contact lens wearers, especially given the apparent inability of lens stability measurements to predict

Short-Term Monocular Deprivation Enhances Physiological Pupillary Oscillations

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Paola Binda

2017-01-01

Full Text Available Short-term monocular deprivation alters visual perception in adult humans, increasing the dominance of the deprived eye, for example, as measured with binocular rivalry. This form of plasticity may depend upon the inhibition/excitation balance in the visual cortex. Recent work suggests that cortical excitability is reliably tracked by dilations and constrictions of the pupils of the eyes. Here, we ask whether monocular deprivation produces a systematic change of pupil behavior, as measured at rest, that is independent of the change of visual perception. During periods of minimal sensory stimulation (in the dark and task requirements (minimizing body and gaze movements, slow pupil oscillations, “hippus,” spontaneously appear. We find that hippus amplitude increases after monocular deprivation, with larger hippus changes in participants showing larger ocular dominance changes (measured by binocular rivalry. This tight correlation suggests that a single latent variable explains both the change of ocular dominance and hippus. We speculate that the neurotransmitter norepinephrine may be implicated in this phenomenon, given its important role in both plasticity and pupil control. On the practical side, our results indicate that measuring the pupil hippus (a simple and short procedure provides a sensitive index of the change of ocular dominance induced by short-term monocular deprivation, hence a proxy for plasticity.

[Evaluation of visual acuity in a historical cohort of 137 patients treated for amblyopia by occlusion 30-35 years ago].

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Simonsz-Tóth, B; Loudon, S E; van Kempen-du Saar, H; van de Graaf, E S; Groenewoud, J H; Simonsz, H J

2007-01-01

Opinions differ on the course of the visual acuity in the amblyopic eye after cessation of occlusion therapy. This study evaluated visual acuity in a historical cohort treated for amblyopia with occlusion therapy 30-35 years ago. Between 1968 and 1975, 1250 patients had been treated by the orthoptist in the Waterland Hospital in Purmerend, The Netherlands. Of these, 471 received occlusion treatment for amblyopia (prevalence 5.0%, after comparison with the local birth rate). We were able to contact 203 of these patients, 137 were orthoptically re-examined in 2003. We correlated the current visual acuity with the cause of amblyopia, the age at start and end of treatment, the visual acuity at start and end of treatment, fixation, binocular vision and refractive errors. Mean age at the start of treatment was 5.4 +/- 1.9 years, 7.4 +/- 1.7 years at the end and 37 +/- 2.7 years at follow-up. Current visual acuity in the amblyopic eye was correlated with a low visual acuity at the start (p occlusion therapy, an eccentric fixation (p amblyopia (p = 0.005). At the end of the treatment, patients with a strabismic amblyopia (n = 98) had a visual acuity in the amblyopic eye of 0.29 logMAR +/- 0.3, and in 2003 0.27 +/- 0.3 logMAR. In patients with an anisometropic amblyopia (> 1 D, n = 16) visual acuity had decreased from 0.17 +/- 0.23 logMAR to 0.21 logMAR +/- 0.23. In patients with both strabismic and anisometropic amblyopia (n = 23), visual acuity had decreased from 0.52 logMAR +/- 0.54 to 0.65 logMAR +/- 0.54. Overall, acuity had decreased in 54 patients (39%) after cessation of treatment. Of these, 18 patients had an acuity decrease to less than 50% of their acuity at the end of treatment. In 15 of these 18 patients anisohypermetropia had increased. A decrease in visual acuity after cessation of occlusion therapy occurred in patients with a combined cause of amblyopia or with an increase in anisohypermetropia.

Effect of Target Location on Dynamic Visual Acuity During Passive Horizontal Rotation

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Appelbaum, Meghan; DeDios, Yiri; Kulecz, Walter; Peters, Brian; Wood, Scott

2010-01-01

The vestibulo-ocular reflex (VOR) generates eye rotation to compensate for potential retinal slip in the specific plane of head movement. Dynamic visual acuity (DVA) has been utilized as a functional measure of the VOR. The purpose of this study was to examine changes in accuracy and reaction time when performing a DVA task with targets offset from the plane of rotation, e.g. offset vertically during horizontal rotation. Visual acuity was measured in 12 healthy subjects as they moved a hand-held joystick to indicate the orientation of a computer-generated Landolt C "as quickly and accurately as possible." Acuity thresholds were established with optotypes presented centrally on a wall-mounted LCD screen at 1.3 m distance, first without motion (static condition) and then while oscillating at 0.8 Hz (DVA, peak velocity 60 deg/s). The effect of target location was then measured during horizontal rotation with the optotypes randomly presented in one of nine different locations on the screen (offset up to 10 deg). The optotype size (logMar 0, 0.2 or 0.4, corresponding to Snellen range 20/20 to 20/50) and presentation duration (150, 300 and 450 ms) were counter-balanced across five trials, each utilizing horizontal rotation at 0.8 Hz. Dynamic acuity was reduced relative to static acuity in 7 of 12 subjects by one step size. During the random target trials, both accuracy and reaction time improved proportional to optotype size. Accuracy and reaction time also improved between 150 ms and 300 ms presentation durations. The main finding was that both accuracy and reaction time varied as a function of target location, with greater performance decrements when acquiring vertical targets. We conclude that dynamic visual acuity varies with target location, with acuity optimized for targets in the plane of motion. Both reaction time and accuracy are functionally relevant DVA parameters of VOR function.

A new specialized visual acuity chart for amblyopic children aged 3-5 years old:development and its clinical applications

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Yang-Qing Huang

2013-12-01

Full Text Available AIM: To introduce a new specialized visual acuity chart for amblyopic children aged 3-5 years old and its clinical applications.METHODS:The new visual acuity chart and notations were designed based on Weber-Fechner law. The optotypes were red against a white background and were specially shaped four basic geometric symbols:circle, square, triangle，and cross. A regular geometric progression of the optotype sizes and distribution was employed to arrange in 14 lines. The progression rate of the optotype size between two lines was 1.2589 and the testing distance was 3m. Visual acuity score could be recorded as logMAR notation or decimal notation. Age-stratified diagnostic criteria for amblyopia established by consensus statement on diagnosis of amblyopia (2011 among members of the Strabismus and Pediatric Ophthalmology Group, Ophthalmology Society, Chinese Medical Association (SPOGOSCMA were illustrated in the new visual acuity chart.RESULTS: When assessing visual acuity in children aged 3-5 years old, this new visual acuity chart that consists of four symmetrical shapes (triangle, square, cross, and circle overcame an inability to recognize the letters of the alphabet and difficulties in designating the direction of black abstract symbols such as the tumbling ‘E’ or Landolt ‘C’, which the subjects were prone to lose interest in. The visual acuity score may be recorded in different notations:decimal acuity and logMAR. These two notations can be easily converted each other in the new eye chart. The measurements of this new chart not only showed a significant correlation and a good consistency with the international standard logarithmic visual acuity chart (r=0.932, P<0.01, but also indicated a high test-retest reliability (89% of retest scores were within 0.1logMAR units of the initial test score.CONCLUSION: The results of this study support the validity and reliability of distance visual acuity measurements using the new eye chart in

Evaluation of a Public Child Eye Health Tertiary Facility for Pediatric Cataract in Southern Nigeria I: Visual Acuity Outcome

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Duke, Roseline E.; Adio, Adedayo; Oparah, Sidney K.; Odey, Friday; Eyo, Okon A.

2016-01-01

Purpose: A retrospective study of the outcome of congenital and developmental cataract surgery was conducted in a public child eye health tertiary facility in children <16 years of age in Southern Nigeria, as part of an evaluation. Materials and Method: Manual Small Incision Cataract Surgery with or without anterior vitrectomy was performed. The outcome measures were visual acuity (VA) and change (gain) in visual acuity. The age of the child at onset, duration of delay in presentation, ocular co-morbidity, non ocular co-morbidity, gender, and pre operative visual acuity were matched with postoperative visual acuity. A total of 66 children were studied for a period of six weeks following surgery. Results: Forty eight (72.7%) children had bilateral congenital cataracts and 18 (27.3%) children had bilateral developmental cataracts. There were 38(57.6%) males and 28 (42.4%) females in the study. Thirty Five (53%) children had good visual outcome (normal vision range 6/6/ -6/18) post-operatively. The number of children with blindness (vision <3/60) decreased from 61 (92.4%) pre-operatively to 4 (6.1%) post-operatively. Post operative complication occurred in 6.8% of cases six week after surgery. Delayed presentation had an inverse relationship with change (gain) in visual acuity (r = - 0.342; p-value = 0.005). Pre-operative visual acuity had a positive relationship with post operative change (gain) in visual acuity (r = 0.618; p-value = 0.000). Conclusion: Predictors of change in visual acuity in our study were; delayed presentation and pre-operative VA. Cataract surgery in children showed clinical benefit. PMID:27347247

A comparison of behavioural (Landolt C) and anatomical estimates of visual acuity in archerfish (Toxotes chatareus).

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Temple, S E; Manietta, D; Collin, S P

2013-05-03

Archerfish forage by shooting jets of water at insects above the water's surface. The challenge of detecting small prey items against a complex background suggests that they have good visual acuity, but to date this has never been tested, despite archerfish becoming an increasingly important model species for vertebrate vision. We used a modified Landolt C test to measure visual acuity behaviourally, and compared the results to their predicted minimum separable angle based on both photoreceptor and ganglion cell spacing in the retina. Both measures yielded similar estimates of visual acuity; between 3.23 and 3.57 cycles per degree (0.155-0.140° of visual arc). Such a close match between behavioural and anatomical estimates of visual acuity in fishes is unusual and may be due to our use of an ecologically relevant task that measured the resolving power of the part of the retina that has the highest photoreceptor density and that is used in aligning their spitting angle with potential targets. Copyright © 2013 Elsevier Ltd. All rights reserved.

Visual acuity after trans-scleral sutured posterior chamber intraocular lens

International Nuclear Information System (INIS)

Mahmood, S.A.; Zafar, S.

2014-01-01

To determine the changes in visual acuity in patients undergoing Trans-Scleral Sutured Posterior Chamber Intra-Ocular Lens (TSSPCIOL) implantation at a tertiary care hospital in Karachi, Pakistan. Study Design: Case series. Place and Duration of Study: LRBT Tertiary Eye Hospital, Karachi, from January 2006 to December 2010. Methodology: Records of all patients undergoing implantation of TSSPCIOL were reviewed. Patients with diagnosed glaucoma, diabetic retinopathy, macular degeneration, history of recurrent uveitis, corneal haze or central corneal scars were excluded. For the final analysis, 70 eyes out of a total of 75 were selected. Main outcomes of interest were pre and postoperative visual acuities and surgical complications. SPSS 21 was used for data analysis. Results: Pre-operatively, the average Best Spectacle-Corrected Visual Acuity (BSCVA) was 6/36 on the Snellen chart. This improved to 6/12 postoperatively. The mean improvement seen was 2.4 lines on the Snellen chart (p < 0.05). Complications include transient intraocular pressure elevation in 25 eyes (36%), IOL tilt in 4 eyes (7.1%), Cystoid Macular Edema (CME) in 4 eyes (5.7%), vitreous haemorrhage in 2 eyes (2.9%), hyphema in 2 eyes (2.9%), uveitis in 1 eye (1.4%), and retinal detachment 1 eye (1.4%). No IOL subluxation, suture erosion, iris capture, choroidal effusion or endophthalmitis was encountered and no re-operations were needed. Conclusion: TSSPCIOLs are a good management option for patients with aphakia in whom PC IOLs cannot be placed. (author)

Distinct eye movement patterns enhance dynamic visual acuity

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Palidis, Dimitrios J.; Wyder-Hodge, Pearson A.; Fooken, Jolande; Spering, Miriam

2017-01-01

Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics—eye latency, acceleration, velocity gain, position error—and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns—minimizing eye position error, tracking smoothly, and inhibiting reverse saccades—were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA. PMID:28187157

Distinct eye movement patterns enhance dynamic visual acuity.

Science.gov (United States)

Palidis, Dimitrios J; Wyder-Hodge, Pearson A; Fooken, Jolande; Spering, Miriam

2017-01-01

Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics-eye latency, acceleration, velocity gain, position error-and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns-minimizing eye position error, tracking smoothly, and inhibiting reverse saccades-were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA.

The prevalence and causes of decreased visual acuity – a study based on vision screening conducted at Enukweni and Mzuzu Foundation Primary Schools, Malawi

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Thom L

2016-12-01

Full Text Available Leaveson Thom,1 Sanchia Jogessar,1,2 Sara L McGowan,1 Fiona Lawless,1,2 1Department of Optometry, Mzuzu University, Mzuzu, Malawi; 2Brienholden Vision Institute, Durban, South Africa Aim: To determine the prevalence and causes of decreased visual acuity (VA among pupils recruited in two primary schools in Mzimba district, northern region of Malawi.Materials and methods: The study was based on the vision screening which was conducted by optometrists at Enukweni and Mzuzu Foundation Primary Schools. The measurements during the screening included unaided distance monocular VA by using Low Vision Resource Center and Snellen chart, pinhole VA on any subject with VA of less than 6/6, refraction, pupil evaluations, ocular movements, ocular health, and shadow test.Results: The prevalence of decreased VA was found to be low in school-going population (4%, n=594. Even though Enukweni Primary School had few participants than Mzuzu Foundation Primary School, it had high prevalence of decreased VA (5.8%, n=275 than Mzuzu Foundation Primary School (1.8%, n=319. The principal causes of decreased VA in this study were found to be amblyopia and uncorrected refractive errors, with myopia being the main cause than hyperopia.Conclusion: Based on the low prevalence of decreased VA due to myopia or hyperopia, it should not be concluded that refractive errors are an insignificant contributor to visual disability in Malawi. More vision screenings are required at a large scale on school-aged population to reflect the real situation on the ground. Cost-effective strategies are needed to address this easily treatable cause of vision impairment. Keywords: vision screening, refractive errors, visual acuity, Enukweni, Mzuzu foundation

A comparison of Lea Symbol vs ETDRS letter distance visual acuity in a population of young children with a high prevalence of astigmatism.

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Dobson, Velma; Clifford-Donaldson, Candice E; Miller, Joseph M; Garvey, Katherine A; Harvey, Erin M

2009-06-01

To compare visual acuity results obtained by use of the Lea Symbols chart with results obtained with Early Treatment Diabetic Retinopathy Study (ETDRS) charts in young children who are members of a population with a high prevalence of astigmatism. Subjects were 438 children ages 5 through 7 years who were enrolled in kindergarten or first grade on the Tohono O'odham Reservation: 241 (55%) had astigmatism >or=1.00 D in one or both eyes (range, 0.00-6.75 D). While wearing best correction, each child had right eye visual acuity tested with the 62 cm by 65 cm Lea Symbols chart at 3 m and with the 62 cm by 65 cm ETDRS chart at 4 m. Visual acuity was scored as the smallest optotype size at which the child correctly identified 3 of a maximum of 5 optotypes. ETDRS visual acuity also was scored based on the total number of letters that the child correctly identified. Correlation between Lea Symbols visual acuity and ETDRS visual acuity was 0.78 (p < 0.001). Mean Lea Symbols visual acuity was one-half line (0.04-0.06 logMAR) better than mean ETDRS visual acuity (p < 0.001). The difference between Lea Symbols and ETDRS visual acuity was not correlated with the mean of the Lea Symbols and ETDRS visual acuity scores, which ranged from -0.3 logMAR (20/10) to 0.74 logMAR (20/110). In this population of young children, in whom the primary source of reduced visual acuity is astigmatism-related amblyopia, the Lea Symbols chart produced visual acuity scores that were about 0.5 line better than visual acuity scores obtained with ETDRS charts.

Influence of head posture on the visual acuity of children with nystagmus

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Ana Carla Ramos Vieira da Costa

2014-01-01

Full Text Available Purpose: Evaluate the relationship between the postural alignment of the head and possible interference in the view of children. Methods: We evaluated 11 children between 2 and 7 years of age of both sexes, with the visually impaired, who had nystagmus and head lock position. The test Lea Grating Acuity Test® was used to collect measurements of visual acuity. This applied on two occasions: with and without postural alignment of the head. For reliability of the postural alignment of the head, the slopes were measured by Fisiologic® software. Results: The children had a poorer performance after physiological postural alignment. This poor performance is possible due to loss of position lock nystagmus to gain postural alignment, said to be ideal. Postural compensations were observed, and sharply increased eyestrain. Conclusion: The pursuit of traditional postural alignment affect the visual response of children with visual impairments.

Visual acuity testing of radiographic inspectors in nondestructive inspection. Final report

International Nuclear Information System (INIS)

Yonemura, G.T.

1981-06-01

Visual acuity tests for radiographic inspectors should be correlated with the type of tasks encountered in real world radiography. The testing procedures should be capable of assessing differences in day to day performance of a given inspector as well as the performance of one inspector relative to other inspectors. Single line targets with specific parametric values for contrast, width, and blur are recommended to provide a means for testing a radiographic inspector for visual acuity. These targets may be used for periodic tests by the employing organization or for more frequent self testing by the inspector. Statistics from the National Health Survey, procedures recommended by the NAS-NRC Committee on Vision and real world radiographs have been utilized in arriving at recommended test configurations

Progressive improvement of impaired visual acuity during the first year after transsphenoidal surgery for non-functioning pituitary macroadenoma

NARCIS (Netherlands)

Dekkers, O. M.; de Keizer, R. J. W.; Roelfsema, F.; Vd Klaauw, A. A.; Honkoop, P. J.; van Dulken, H.; Smit, J. W. A.; Romijn, J. A.; Pereira, A. M.

2007-01-01

Improvement of visual field defects continues even years after the initial surgical treatment. Because this process of continuing improvement has not been documented for visual acuity, we audited our data to explore the pattern of recovery of visual acuity until 1 year after transsphenoidal surgery

Visual Acuity is Related to Parafoveal Retinal Thickness in Patients with Retinitis Pigmentosa and Macular Cysts

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Brockhurst, Robert J.; Gaudio, Alexander R.; Berson, Eliot L.

2008-01-01

Purpose To quantify the prevalence and effect on visual acuity of macular cysts in a large cohort of patients with retinitis pigmentosa. Methods In 316 patients with typical forms of retinitis pigmentosa, we measured visual acuities with Early Treatment Diabetic Retinopathy Study (ETDRS) charts, detected macular cysts with optical coherence tomography (OCT), and quantified retinal thicknesses by OCT. We used the FREQ, LOGISTIC, and GENMOD procedures of SAS to evaluate possible risk factors for cyst prevalence and the MIXED procedure to quantify the relationships of visual acuity to retinal thickness measured at different locations within the macula. Results We found macular cysts in 28% of the patients, 40% of whom had cysts in only one eye. Macular cysts were seen most often in patients with dominant disease and not at all in patients with X-linked disease (p = 0.006). In eyes with macular cysts, multiple regression analysis revealed that visual acuity was inversely and independently related to retinal thickness at the foveal center (p = 0.038) and within a ring spanning an eccentricity of 5° to 10° from the foveal center (p = 0.004). Conclusions Macular cysts are a common occurrence in retinitis pigmentosa, especially among patients with dominantly-inherited disease. Visual acuity is influenced by edema in the parafovea, as well as in the fovea. PMID:18552390

Visual abilities in two raptors with different ecology.

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Potier, Simon; Bonadonna, Francesco; Kelber, Almut; Martin, Graham R; Isard, Pierre-François; Dulaurent, Thomas; Duriez, Olivier

2016-09-01

Differences in visual capabilities are known to reflect differences in foraging behaviour even among closely related species. Among birds, the foraging of diurnal raptors is assumed to be guided mainly by vision but their foraging tactics include both scavenging upon immobile prey and the aerial pursuit of highly mobile prey. We studied how visual capabilities differ between two diurnal raptor species of similar size: Harris's hawks, Parabuteo unicinctus, which take mobile prey, and black kites, Milvus migrans, which are primarily carrion eaters. We measured visual acuity, foveal characteristics and visual fields in both species. Visual acuity was determined using a behavioural training technique; foveal characteristics were determined using ultra-high resolution spectral-domain optical coherence tomography (OCT); and visual field parameters were determined using an ophthalmoscopic reflex technique. We found that these two raptors differ in their visual capacities. Harris's hawks have a visual acuity slightly higher than that of black kites. Among the five Harris's hawks tested, individuals with higher estimated visual acuity made more horizontal head movements before making a decision. This may reflect an increase in the use of monocular vision. Harris's hawks have two foveas (one central and one temporal), while black kites have only one central fovea and a temporal area. Black kites have a wider visual field than Harris's hawks. This may facilitate the detection of conspecifics when they are scavenging. These differences in the visual capabilities of these two raptors may reflect differences in the perceptual demands of their foraging behaviours. © 2016. Published by The Company of Biologists Ltd.

Socio-Demographic Factors Associated With Loss Of Visual Acuity ...

African Journals Online (AJOL)

The study was designed to identify the sociodemographic factors, which significantly affect the visual acuity of glaucoma patients at presentation. It is a prospective study of 154 new patients with a diagnosis of primary open angle glaucoma seen over 1 year and 8 months at the eye clinic of the University of Benin Teaching ...

A new dynamic visual acuity test to assess peripheral vestibular function.

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Vital, Domenic; Hegemann, Stefan C A; Straumann, Dominik; Bergamin, Oliver; Bockisch, Christopher J; Angehrn, Dominik; Schmitt, Kai-Uwe; Probst, Rudolf

2010-07-01

To evaluate a novel test for dynamic visual acuity (DVA) that uses an adaptive algorithm for changing the size of Landolt rings presented during active or passive head impulses, and to compare the results with search-coil head impulse testing. Prospective study in healthy individuals and patients with peripheral vestibular deficits. Tertiary academic center. One hundred neuro-otologically healthy individuals (age range, 19-80 years) and 15 patients with bilateral (n = 5) or unilateral (n = 10) peripheral vestibular loss (age range, 27-72 years). Testing of static visual acuity (SVA), DVA during active and passive horizontal head rotations (optotype presentation at head velocities >100 degrees/s and >150 degrees/s), and quantitative horizontal head impulse testing with scleral search coils. Difference between SVA and DVA, that is, visual acuity loss (VA loss), gain of the high-acceleration vestibulo-ocular reflex. Passive head impulses and higher velocities were more effective than active impulses and lower velocities. Using passive head impulses and velocities higher than 150 degrees/s, the DVA test discriminated significantly (P test sensitivity was 100%, specificity was 94%, and accuracy was 95%, with search-coil head impulse testing used as a reference. In healthy individuals, VA loss increased significantly with age (P testing with Landolt rings that are adaptively changed in size enables detection of peripheral vestibular dysfunction in a fast and simple way.

Changes in brain morphology in albinism reflect reduced visual acuity.

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Bridge, Holly; von dem Hagen, Elisabeth A H; Davies, George; Chambers, Claire; Gouws, Andre; Hoffmann, Michael; Morland, Antony B

2014-07-01

Albinism, in humans and many animal species, has a major impact on the visual system, leading to reduced acuity, lack of binocular function and nystagmus. In addition to the lack of a foveal pit, there is a disruption to the routing of the nerve fibers crossing at the optic chiasm, resulting in excessive crossing of fibers to the contralateral hemisphere. However, very little is known about the effect of this misrouting on the structure of the post-chiasmatic visual pathway, and the occipital lobes in particular. Whole-brain analyses of cortical thickness in a large cohort of subjects with albinism showed an increase in cortical thickness, relative to control subjects, particularly in posterior V1, corresponding to the foveal representation. Furthermore, mean cortical thickness across entire V1 was significantly greater in these subjects compared to controls and negatively correlated with visual acuity in albinism. Additionally, the group with albinism showed decreased gyrification in the left ventral occipital lobe. While the increase in cortical thickness in V1, also found in congenitally blind subjects, has been interpreted to reflect a lack of pruning, the decreased gyrification in the ventral extrastriate cortex may reflect the reduced input to the foveal regions of the ventral visual stream. Copyright © 2012 Elsevier Ltd. All rights reserved.

Photovoltaic restoration of sight with high visual acuity

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Lorach, Henri; Goetz, Georges; Smith, Richard; Lei, Xin; Mandel, Yossi; Kamins, Theodore; Mathieson, Keith; Huie, Philip; Harris, James; Sher, Alexander; Palanker, Daniel

2015-01-01

Patients with retinal degeneration lose sight due to gradual demise of photoreceptors. Electrical stimulation of the surviving retinal neurons provides an alternative route for delivery of visual information. We demonstrate that subretinal arrays with 70 μm photovoltaic pixels provide highly localized stimulation, with electrical and visual receptive fields of comparable sizes in rat retinal ganglion cells. Similarly to normal vision, retinal response to prosthetic stimulation exhibits flicker fusion at high frequencies, adaptation to static images and non-linear spatial summation. In rats with retinal degeneration, these photovoltaic arrays provide spatial resolution of 64 ± 11 μm, corresponding to half of the normal visual acuity in pigmented rats. Ease of implantation of these wireless and modular arrays, combined with their high resolution opens the door to functional restoration of sight. PMID:25915832

[Amblyopia: reading speed in comparison with visual acuity for gratings, single Landolt Cs and series Landolt Cs].

Science.gov (United States)

Bach, M; Strahl, P; Waltenspiel, S; Kommerell, G

1990-01-01

In the treatment of amblyopia in preschool children, a means of predicting later reading ability would be helpful. This prediction might be possible using a test for visual acuity where the results correlate with reading ability in adult patients with amblyopia. We measured the following four parameters in 18 experienced readers with strabismic amblyopia: (1) time spent reading ten lines of a standard text in one of three magnifications, (2) visual acuity for gratings, (3) visual acuity for single Landolt Cs, and (4) visual acuity for crowded Landolt Cs (one Landolt C flanked by two full rings on each side each at a distance of 2.6 min of arc). The reading text was presented on paper at a distance of 40 cm; the subject had a choice of three magnifications. The acuity tests were generated by a computer on a VDU at 4.6 m. The relative impairment of the amblyopic eye was defined as the quotient between the performance of the amblyopic and the good eye. In addition, the difference between the times spent reading the ten lines with the amblyopic and with the good eye was calculated.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of pupil size on visual acuity in a laboratory model of pseudophakic monovision.

Science.gov (United States)

Kawamorita, Takushi; Uozato, Hiroshi; Handa, Tomoya; Ito, Misae; Shimizu, Kimiya

2010-05-01

To investigate the effect of pupil size on visual acuity in pseudophakic monovision. For the simulation, a modified Liou-Brennan model eye was used. The model eye was designed to include a centered optical system, corneal asphericity, an iris pupil, a Stiles-Crawford effect, an intraocular lens, and chromatic aberration. Calculation of the modulation transfer function (MTF) was performed with ZEMAX software. Visual acuity was estimated from the MTF and the retinal threshold curve. The sizes of the entrance pupil were 2.0, 2.5, 3.0, and 4.0 mm. Decreasing pupil diameter and increasing myopia progressively improved near visual acuity. For an entrance pupil size of 2.5 mm and a refractive error of -1.50 diopters, the logMAR value (Snellen; metric) in the non-dominant eye at 40 cm was 0.06 (20/23; 6/6.9). Knowledge of the patient's pupil diameter at near fixation can assist surgeons in determining the optimum degree of myopia for successful monovision.

Posterior staphyloma in oculocutaneous albinism: another possible cause of reduced visual acuity.

Science.gov (United States)

Lee, Susan; Schimmenti, Lisa A; King, Richard A; Brilliant, Murray; Anderson, Jennifer L; Schoonveld, Cheri; Summers, C Gail

2015-12-01

Posterior staphyloma is typically associated with myopic degeneration and has not been recognized as a cause of reduced visual acuity in albinism. We report 3 cases of posterior staphyloma, each with oculocutaneous albinism (OCA) defined by phenotype and genotype. Two cases are biological sisters with OCA type 2; one was myopic and the other was hyperopic. The third case involves a man with OCA associated with Hermansky-Pudlak syndrome (HPS-5). Staphyloma may be another cause of reduced visual acuity in albinism, particularly with increasing age. It may occur in association with myopia or hyperopia. Copyright © 2015 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

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

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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.

Short-term visual deprivation does not enhance passive tactile spatial acuity.

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Michael Wong

Full Text Available An important unresolved question in sensory neuroscience is whether, and if so with what time course, tactile perception is enhanced by visual deprivation. In three experiments involving 158 normally sighted human participants, we assessed whether tactile spatial acuity improves with short-term visual deprivation over periods ranging from under 10 to over 110 minutes. We used an automated, precisely controlled two-interval forced-choice grating orientation task to assess each participant's ability to discern the orientation of square-wave gratings pressed against the stationary index finger pad of the dominant hand. A two-down one-up staircase (Experiment 1 or a Bayesian adaptive procedure (Experiments 2 and 3 was used to determine the groove width of the grating whose orientation each participant could reliably discriminate. The experiments consistently showed that tactile grating orientation discrimination does not improve with short-term visual deprivation. In fact, we found that tactile performance degraded slightly but significantly upon a brief period of visual deprivation (Experiment 1 and did not improve over periods of up to 110 minutes of deprivation (Experiments 2 and 3. The results additionally showed that grating orientation discrimination tends to improve upon repeated testing, and confirmed that women significantly outperform men on the grating orientation task. We conclude that, contrary to two recent reports but consistent with an earlier literature, passive tactile spatial acuity is not enhanced by short-term visual deprivation. Our findings have important theoretical and practical implications. On the theoretical side, the findings set limits on the time course over which neural mechanisms such as crossmodal plasticity may operate to drive sensory changes; on the practical side, the findings suggest that researchers who compare tactile acuity of blind and sighted participants should not blindfold the sighted participants.

Dynamic Visual Acuity and Landing Sickness in Crewmembers Returning from Long-Duration Spaceflight

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Rosenberg, M.J.F; Peters, B.T.; Reschke, M. F.

2016-01-01

Long-term exposure to microgravity causes sensorimotor adaptations that result in functional deficits upon returning to a gravitational environment. At landing the vestibular system and the central nervous system, responsible for coordinating head and eye movements, are adapted to microgravity and must re-adapt to the gravitational environment. This re-adaptation causes decrements in gaze control and dynamic visual acuity, with astronauts reporting oscillopsia and blurred vision. Dynamic visual acuity (DVA) is assessed using an oscillating chair developed in the Neuroscience Laboratory at JSC. This chair is lightweight and easily portable for quick deployment in the field. The base of the chair is spring-loaded and allows for manual oscillation of the subject. Using a metronome, the chair is vertically oscillated plus or minus 2 cm at 2 Hz by an operator, to simulate walking. While the subject is being oscillated, they are asked to discern the direction of Landolt-C optotypes of varying sizes and record their direction using a gamepad. The visual acuity thresholds are determined using an algorithm that alters the size of the optotype based on the previous response of the subject using a forced-choice best parameter estimation that is able to rapidly converge on the threshold value. Visual acuity thresholds were determined both for static (seated) and dynamic (oscillating) conditions. Dynamic visual acuity is defined as the difference between the dynamic and static conditions. Dynamic visual acuity measures will be taken prior to flight (typically L-180, L-90, and L-60) and up to eight times after landing, including up to 3 times on R plus 0. Follow up measurements will be taken at R plus 1 (approximately 36 hours after landing). Long-duration International Space Station crewmembers will be tested once at the refueling stop in Europe and once again upon return to Johnson Space Center. In addition to DVA, subjective ratings of motion sickness will be recorded

Impact of colour in the assessment of potential visual acuity in patients with age-related macular degeneration.

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Dorrepaal, Stephen J; Markowitz, Samuel N

2013-06-01

To compare chromatic and achromatic potential visual acuity (PVA) in patients with bilateral low vision caused by age-related macular degeneration (AMD). Prospective, nonrandomized, observational case series. Fifty-five patients, representing a consecutive series of patients all presenting with bilateral AMD. Best-corrected visual acuity of each eye was measured using an Early Treatment in Diabetic Retinopathy Study (ETDRS) chart with appropriate near correction. Included were cases with visual acuity of 0.4 logMAR (20/50) or worse in both eyes. Achromatic and chromatic PVA were measured in each eye using white on black and red on yellow flooding E charts at 50 cm in controlled lighting conditions. One hundred and seven eyes from 55 patients were included in the analysis. Mean achromatic and chromatic PVA were 0.69 ± 0.26 and 0.65 ± 0.22 logMAR, respectively. Overall, patients had a significantly higher chromatic than achromatic PVA, with a median difference of 0.1 logMAR (p<0.05). Patients with ETDRS visual acuity worse than 0.9 logMAR also had a significantly higher chromatic than achromatic PVA, with a median difference of 0.1 logMAR (p<0.05). Patients with ETDRS visual acuity between 0.4 and 0.9 logMAR had a trend toward a higher chromatic than achromatic visual acuity that was not significant, with a median difference of 0.1 logMAR (p = 0.8539). Patients with low vision caused by AMD can discern smaller targets when a red on yellow colour scheme is used than when using achromatic white on black charts. Copyright © 2013 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

High visual acuity revealed in dogs.

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Lind, Olle; Milton, Ida; Andersson, Elin; Jensen, Per; Roth, Lina S V

2017-01-01

Humans have selectively bred and used dogs over a period of thousands of years, and more recently the dog has become an important model animal for studies in ethology, cognition and genetics. These broad interests warrant careful descriptions of the senses of dogs. Still there is little known about dog vision, especially what dogs can discriminate in different light conditions. We trained and tested whippets, pugs, and a Shetland sheepdog in a two-choice discrimination set-up and show that dogs can discriminate patterns with spatial frequencies between 5.5 and 19.5 cycle per degree (cpd) in the bright light condition (43 cd m-2). This is a higher spatial resolution than has been previously reported although the individual variation in our tests was large. Humans tested in the same set-up reached acuities corresponding to earlier studies, ranging between 32.1 and 44.2 cpd. In the dim light condition (0.0087 cd m-2) the acuity of dogs ranged between 1.8 and 3.5 cpd while in humans, between 5.9 and 9.9 cpd. Thus, humans make visual discrimination of objects from roughly a threefold distance compared to dogs in both bright and dim light.

High visual acuity revealed in dogs.

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Olle Lind

Full Text Available Humans have selectively bred and used dogs over a period of thousands of years, and more recently the dog has become an important model animal for studies in ethology, cognition and genetics. These broad interests warrant careful descriptions of the senses of dogs. Still there is little known about dog vision, especially what dogs can discriminate in different light conditions. We trained and tested whippets, pugs, and a Shetland sheepdog in a two-choice discrimination set-up and show that dogs can discriminate patterns with spatial frequencies between 5.5 and 19.5 cycle per degree (cpd in the bright light condition (43 cd m-2. This is a higher spatial resolution than has been previously reported although the individual variation in our tests was large. Humans tested in the same set-up reached acuities corresponding to earlier studies, ranging between 32.1 and 44.2 cpd. In the dim light condition (0.0087 cd m-2 the acuity of dogs ranged between 1.8 and 3.5 cpd while in humans, between 5.9 and 9.9 cpd. Thus, humans make visual discrimination of objects from roughly a threefold distance compared to dogs in both bright and dim light.

A Demonstration Project on Driving with Reduced Visual Acuity and a Bioptic Telescope System in the Netherlands

NARCIS (Netherlands)

Melis-Dankers, Bart J.M.; Kooijman, Aart C.; Brouwer, Wiebo H.; Busscher, Rens B.; Bredewoud, Ruud A.; Derksen, Peter H.; Amersfoort, Anoeska; IJsseldijk, Martin A.M.; Delden, Geert W. van; Grotenhuis, Thea H.P.A.; Witvliet, M.D.

2008-01-01

Background: In Europe, driving a passenger car is prohibited if binocular best corrected visual acuity (BCVA) is below 0.5 (20/40). Some US states allow people with reduced visual acuity to use a bioptic telescope system when driving. The aim of our study is to introduce a bioptic telescope system

Acuidade visual: Medidas e notações Visual acuity: Measurements and notations

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Harley E. A. Bicas

2002-06-01

Full Text Available Avaliações da função visual são muito complexas por dependerem de mecanismos aferentes, eferentes e cognitivos, além de fatores externos à pessoa examinada, como o tipo de estímulo e o de sua apresentação. O exame da acuidade visual é discutido em seus aspectos formais de definições, quantificações (critérios de medição de um ângulo e tamanho dos optotipos, notações (decimal ou fracionárias, escalas (representando relações angulares, lineares, logarítmicas e unidades em que os valores são expressos (recíproca do minuto de arco, número puro, freqüência espacial, decibéis e oitavas. Como conseqüência, referências numéricas sobre a acuidade visual e operações que as envolvem (p.ex., cálculo de valores médios, determinação de variações, relações entre elas podem levar a interpretações muito diferentes e até opostas num mesmo estudo, dependendo dos critérios nele empregados.Evaluations of the visual function are very intricate since they depend on afferent, efferent and cognitive mechanisms, besides external factors of the examined subject, such as the type of the stimulus and of its presentation. Testing the visual acuity is discussed in its formal aspects related to definitions, quantifications (criteria for the measurements of an angle, size of optotypes, notations (decimal or fractionary, scales (representing angular, linear or logarithmic relationships and units in which the values are expressed (reciprocal of minutes of arc, pure number, spacial frequency, decibels, octaves. As a consequence, numerical references about visual acuity and respective operations (e.g., calculations of average values, determinations of variations, relationships between them may lead to very different interpretations of a study, sometimes even opposite, according to the criteria which are used.

Vision-guided ocular growth in a mutant chicken model with diminished visual acuity.

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Ritchey, Eric R; Zelinka, Christopher; Tang, Junhua; Liu, Jun; Code, Kimberly A; Petersen-Jones, Simon; Fischer, Andy J

2012-09-01

Visual experience is known to guide ocular growth. We tested the hypothesis that vision-guided ocular growth is disrupted in a model system with diminished visual acuity. We examine whether ocular elongation is influenced by form-deprivation (FD) and lens-imposed defocus in the Retinopathy, Globe Enlarged (RGE) chicken. Young RGE chicks have poor visual acuity, without significant retinal pathology, resulting from a mutation in guanine nucleotide-binding protein β3 (GNB3), also known as transducin β3 or Gβ3. The mutation in GNB3 destabilizes the protein and causes a loss of Gβ3 from photoreceptors and ON-bipolar cells (Ritchey et al., 2010). FD increased ocular elongation in RGE eyes in a manner similar to that seen in wild-type (WT) eyes. By comparison, the excessive ocular elongation that results from hyperopic defocus was increased, whereas myopic defocus failed to significantly decrease ocular elongation in RGE eyes. Brief daily periods of unrestricted vision interrupting FD prevented ocular elongation in RGE chicks in a manner similar to that seen in WT chicks. Glucagonergic amacrine cells differentially expressed the immediate early gene Egr1 in response to growth-guiding stimuli in RGE retinas, but the defocus-dependent up-regulation of Egr1 was lesser in RGE retinas compared to that of WT retinas. We conclude that high visual acuity, and the retinal signaling mediated by Gβ3, is not required for emmetropization and the excessive ocular elongation caused by FD and hyperopic defocus. However, the loss of acuity and Gβ3 from RGE retinas causes enhanced responses to hyperopic defocus and diminished responses to myopic defocus. Copyright © 2012 Elsevier Ltd. All rights reserved.

Visual acuity in pelagic fishes and mollusks.

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Gagnon, Yakir L; Sutton, Tracey T; Johnsen, Sönke

2013-11-01

In the sea, visual scenes change dramatically with depth. At shallow and moderate depths (cephalopods, and a gastropod using a custom-built apparatus. The hatchetfishes (Argyropelecus aculeatus and Sternoptyx diaphana) and the barrel-eye (Opisthoproctus soleatus) were found to have the best lenses, which may allow them to break the counterillumination camouflage of their prey. The heteropod lens had unidirectional aberrations that matched its ribbon-shaped retina. We also found that lens angular resolution increased with depth. Due to a similar trend in the angular separation between adjacent ganglion cells in the retinas of fishes, the perceived visual contrast at the retinal cutoff frequency was constant with depth. The increase in acuity with depth allows the predators to focus all the available light bioluminescent prey animals emit and detect their next meal. Copyright © 2013 Elsevier B.V. All rights reserved.

Head Worn Display System for Equivalent Visual Operations

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Cupero, Frank; Valimont, Brian; Wise, John; Best. Carl; DeMers, Bob

2009-01-01

Head-Worn Displays or so-called, near-to-eye displays have potentially significant advantages in terms of cost, overcoming cockpit space constraints, and for the display of spatially-integrated information. However, many technical issues need to be overcome before these technologies can be successfully introduced into commercial aircraft cockpits. The results of three activities are reported. First, the near-to-eye display design, technological, and human factors issues are described and a literature review is presented. Second, the results of a fixed-base piloted simulation, investigating the impact of near to eye displays on both operational and visual performance is reported. Straight-in approaches were flown in simulated visual and instrument conditions while using either a biocular or a monocular display placed on either the dominant or non-dominant eye. The pilot's flight performance, visual acuity, and ability to detect unsafe conditions on the runway were tested. The data generally supports a monocular design with minimal impact due to eye dominance. Finally, a method for head tracker system latency measurement is developed and used to compare two different devices.

Visual training paired with electrical stimulation of the basal forebrain improves orientation-selective visual acuity in the rat.

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Kang, Jun Il; Groleau, Marianne; Dotigny, Florence; Giguère, Hugo; Vaucher, Elvire

2014-07-01

The cholinergic afferents from the basal forebrain to the primary visual cortex play a key role in visual attention and cortical plasticity. These afferent fibers modulate acute and long-term responses of visual neurons to specific stimuli. The present study evaluates whether this cholinergic modulation of visual neurons results in cortical activity and visual perception changes. Awake adult rats were exposed repeatedly for 2 weeks to an orientation-specific grating with or without coupling this visual stimulation to an electrical stimulation of the basal forebrain. The visual acuity, as measured using a visual water maze before and after the exposure to the orientation-specific grating, was increased in the group of trained rats with simultaneous basal forebrain/visual stimulation. The increase in visual acuity was not observed when visual training or basal forebrain stimulation was performed separately or when cholinergic fibers were selectively lesioned prior to the visual stimulation. The visual evoked potentials show a long-lasting increase in cortical reactivity of the primary visual cortex after coupled visual/cholinergic stimulation, as well as c-Fos immunoreactivity of both pyramidal and GABAergic interneuron. These findings demonstrate that when coupled with visual training, the cholinergic system improves visual performance for the trained orientation probably through enhancement of attentional processes and cortical plasticity in V1 related to the ratio of excitatory/inhibitory inputs. This study opens the possibility of establishing efficient rehabilitation strategies for facilitating visual capacity.

Visual Acuity Improvement of Amblyopia in an Adult With Levodopa/Carbidopa Treatment.

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Orge, Faruk H; Dar, Suhail A

2015-09-09

Amblyopia is the leading cause of visual loss in children, affecting 2% to 3% of the population. Occlusion of the dominant eye is the primary and best treatment, although efficacy decreases after 6 years of age. As a result, levodopa/carbidopa has been explored as an adjunct to conventional therapy and has been shown to have an immediate impact on visual acuity. Several studies to date have shown mixed results on the benefit of supplementing occlusion therapy with levodopa/carbidopa, although they have primarily studied children. The authors describe the oldest patient (46 years old) documented in the literature to have shown improvement in visual acuity using levodopa/carbidopa. He was given a 16-week course at a dose in line with previous studies while being effectively occluded full time due to a glaucomatous right eye with no light perception. On 3-month follow-up, his left eye improved two lines and stabilized at 6 months. Copyright 2015, SLACK Incorporated.

EXAMINATION OF THE VISUAL ACUITY ON THE LCD OPTOTYPE WITH WHOLE-LINE AND INTERPOLATION METHOD

OpenAIRE

Zajíček Tomáš; Veselý Petr; Veselý Petr; Synek Svatopluk; Synek Svatopluk

2012-01-01

The goal of this work is to show the possibility of us using the LCD optotype in common optometrist practice. Furthermore two commonly used methods for measuring visual acuity will be compared. 69 respondents were used for the measurements. The respondents were divided into two groups according to the measured LCD optotype. The visual acuity was measured using the whole-line method on modified Snellen charts as well as the interpolation method on ETDRS charts. Measurements were taken on the S...

Effect of magnetic resonance imaging on near visual acuity Efecto de la resonancia magnética sobre la agudeza visual cercana

OpenAIRE

José David Paulo Trujillo; Juan Carlos Vergara; Jorge Hernando Donado Gómez; Luz Marina Agudelo; Mercedes Cecilia Molina Betancur; Andrés Ignacio Arbeláez Medina; Carlos Andrés Molina Betancur

2007-01-01

Purpose: To determine the variation of near visual acuity, in patients exposed during short periods to intense magnetic fields in studies of magnetic resonance imaging. Methods: Descriptive study of a case series that included 40 healthy and literate individuals older than 40 years, nine of them men, submitted to a procedure of head and neck magnetic resonance imaging; all of them had near visual acuity better than 20/200 without glasses, and were not under the effects of ansiolytic medicatio...

Visual performance after the implantation of a new trifocal intraocular lens

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Vryghem JC

2013-10-01

Full Text Available Jérôme C Vryghem,1,2 Steven Heireman1,21Brussels Eye Doctors, Brussels, Belgium; 2Clinique Saint-Jean, Brussels, BelgiumPurpose: To evaluate the subjective and objective visual results after the implantation of a new trifocal diffractive intraocular lens.Methods: A new trifocal diffractive intraocular lens was designed combining two superimposed diffractive profiles: one with +1.75 diopters (D addition for intermediate vision and the other with +3.50 D addition for near vision. Fifty eyes of 25 patients that were operated on by one surgeon are included in this study. The uncorrected and best distance-corrected monocular and binocular, near, intermediate, and distance visual acuities, contrast sensitivity, and defocus curves were measured 6 months postoperatively. In addition to the standard clinical follow-up, a questionnaire evaluating individual satisfaction and quality of life was submitted to the patients.Results: The mean age of patients at the time of surgery was 70 ± 10 years. The mean uncorrected and corrected monocular distance visual acuity (VA were LogMAR 0.06 ± 0.10 and LogMAR 0.00 ± 0.08, respectively. The outcomes for the binocular uncorrected distance visual acuity were almost the same (LogMAR −0.04 ± 0.09. LogMAR −010 ± 0.15 and 0.02 ± 0.06 were measured for the binocular uncorrected intermediate and near VA, respectively. The distance-corrected visual acuity was maintained in mesopic conditions. The contrast sensitivity was similar to that obtained after implantation of a bifocal intraocular lens and did not decrease in mesopic conditions. The binocular defocus curve confirms good VA even in the intermediate distance range, with a moderate decrease of less than LogMAR 0.2 at −1.5 D, with respect to the best distance VA at 0 D defocus. Patient satisfaction was high. No discrepancy between the objective and subjective outcomes was evidenced.Conclusion: The introduction of a third focus in diffractive multifocal

Synaptic Mechanisms of Activity-Dependent Remodeling in Visual Cortex during Monocular Deprivation

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Cynthia D. Rittenhouse

2009-01-01

Full Text Available It has long been appreciated that in the visual cortex, particularly within a postnatal critical period for experience-dependent plasticity, the closure of one eye results in a shift in the responsiveness of cortical cells toward the experienced eye. While the functional aspects of this ocular dominance shift have been studied for many decades, their cortical substrates and synaptic mechanisms remain elusive. Nonetheless, it is becoming increasingly clear that ocular dominance plasticity is a complex phenomenon that appears to have an early and a late component. Early during monocular deprivation, deprived eye cortical synapses depress, while later during the deprivation open eye synapses potentiate. Here we review current literature on the cortical mechanisms of activity-dependent plasticity in the visual system during the critical period. These studies shed light on the role of activity in shaping neuronal structure and function in general and can lead to insights regarding how learning is acquired and maintained at the neuronal level during normal and pathological brain development.

RISK FOR LOW VISUAL ACUITY AFTER 1 AND 2 YEARS OF TREATMENT WITH RANIBIZUMAB OR BEVACIZUMAB FOR PATIENTS WITH NEOVASCULAR AGE-RELATED MACULAR DEGENERATION.

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Westborg, Inger; Albrecht, Susanne; Rosso, Aldana

2017-11-01

To investigate how patients with neovascular age-related macular degeneration treated with ranibizumab or bevacizumab respond to treatment in daily clinical practice. Data from the Swedish Macula Register on the treatment received by 3,912 patients during 2011 to 2014 is reported. Patients' characteristics at the first visit, visual acuity, number of injections, and reason for terminating the treatment if applicable are discussed. Furthermore, the risk of having poor vision (visual acuity under 60 Early Treatment Diabetes Retinopathy Study letters or approximately 20/60 Snellen) is calculated for the treated eye after 1 year and 2 years. The treatment outcome depends on the visual acuity at the first visit. For patients with visual acuity more than 60 letters, the risk of having a visual acuity lower than 60 letters after 1 year or 2 years of treatment is approximately 20%. However, for patients with low visual acuity at diagnosis (fewer than 60 letters), the risk is approximately 60%. The risk of having a visual acuity lower than 60 letters does not depend on the choice of treatment drug. Treatment with anti-vascular endothelial growth factor intravitreal injections mainly maintains the visual acuity level, and only approximately 20% and 40% of the patients required vision rehabilitation after 1 year and 2 years, respectively.

A randomised comparison between an inexpensive, general-purpose headlight and a purpose-built surgical headlight on users' visual acuity and colour vision.

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Street, I; Sayles, M; Nistor, M; McRae, A R

2014-02-01

To determine if there are any differences in near visual acuity and colour vision between an inexpensive general-purpose light emitting diode (LED) headlight and a purpose-built surgical LED headlight. A prospective study was conducted sequentially comparing near visual acuity and colour vision, the headlights being tested in random order, in a testing room with a constant minimal amount of background light. The participants were NHS employee volunteers, with self-declared normal (or corrected) vision, working in occupations requiring full literacy. For visual acuity, outcome was measured by recording the smallest font legible when using each headlight when the subject read a near visual acuity test card. For colour vision, the outcome was passing or failing the Ishihara test. There was no statistically significant difference between the general-purpose and the purpose-built headlights in users' near visual acuity or colour vision.

Monocular perceptual learning of contrast detection facilitates binocular combination in adults with anisometropic amblyopia.

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Chen, Zidong; Li, Jinrong; Liu, Jing; Cai, Xiaoxiao; Yuan, Junpeng; Deng, Daming; Yu, Minbin

2016-02-01

Perceptual learning in contrast detection improves monocular visual function in adults with anisometropic amblyopia; however, its effect on binocular combination remains unknown. Given that the amblyopic visual system suffers from pronounced binocular functional loss, it is important to address how the amblyopic visual system responds to such training strategies under binocular viewing conditions. Anisometropic amblyopes (n = 13) were asked to complete two psychophysical supra-threshold binocular summation tasks: (1) binocular phase combination and (2) dichoptic global motion coherence before and after monocular training to investigate this question. We showed that these participants benefited from monocular training in terms of binocular combination. More importantly, the improvements observed with the area under log CSF (AULCSF) were found to be correlated with the improvements in binocular phase combination.

A new Snellen's visual acuity chart with 'Indian' numerals.

OpenAIRE

Al-Salem, M

1987-01-01

'Indian' numerals, which are popular among the Arab population, were used to devise a new Snellen's visual acuity chart. The new chart has the advantages of a reading chart. It keeps the patient's interest, does not miss alexic patients, and is quicker to perform. It is also devoid of the many disadvantages of a kinetic response chart (the capital E letter or Landolt's broken rings), especially that of the limited option of test objects.

Efficacy of perceptual vision therapy in enhancing visual acuity and contrast sensitivity function in adult hypermetropic anisometropic amblyopia

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Yalcin E

2013-12-01

Full Text Available Elvan Yalcin, Ozlem BalciWorld Eye Hospital, Department of Pediatric Ophthalmology, Istanbul, TurkeyBackground: The purpose of this study was to evaluate the efficacy of neural vision therapy, also termed perceptual vision therapy, in enhancing best corrected visual acuity (BCVA and contrast sensitivity function in amblyopic patients.Methods: This prospective study enrolled 99 subjects previously diagnosed with unilateral hypermetropic amblyopia aged 9–50 years. The subjects were divided into two groups, with 53 subjects (53 eyes in the perceptual vision therapy group and 46 subjects (46 eyes in the control group. Because the nature of the treatment demands hard work and strict compliance, we enrolled the minimal number of subjects required to achieve statistically significant results. Informed consent was obtained from all subjects. Study phases included a baseline screening, a series of 45 training sessions with perceptual vision therapy, and an end-of-treatment examination. BCVA and contrast sensitivity function at 1.5, 3, 6, 12, and 18 cycles per degree spatial frequencies were obtained for statistical analysis in both groups. All subjects had follow-up examinations within 4–8 months. With the exception of one subject from the study group and two subjects from the control group, all subjects had occlusion during childhood. The study was not masked.Results: The results for the study group demonstrated a mean improvement of 2.6 logarithm of the minimum angle of resolution (logMAR lines in visual acuity (from 0.42 to 0.16 logMAR. Contrast sensitivity function improved at 1.5, 3, 6, 12, and 18 cycles per degree spatial frequencies. The control group did not show any significant change in visual acuity or contrast sensitivity function. None of the treated eyes showed a drop in visual acuity. Manifest refractions remained unchanged during the study.Conclusion: The results of our study demonstrate the efficacy of perceptual vision therapy in

Astronauts Cooper and Conrad prepare cameras during visual acuity tests

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1965-01-01

Astronauts L. Gordon Cooper Jr. (left), command pilot, and Charles Conrad Jr., pilot, the prime crew of the Gemini 5 space flight, prepare their cameras while aboard a C-130 aircraft flying near Laredo. The two astronauts are taking part in a series of visual acuity experiments to aid them in learning to identify known terrestrial features under controlled conditions.

The Prevalence of Visual Acuity Impairment among School Children at Arada Subcity Primary Schools in Addis Ababa, Ethiopia.

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Darge, Haile Fentahun; Shibru, Getahun; Mulugeta, Abiy; Dagnachew, Yinebeb Mezgebu

2017-01-01

Visual impairment and blindness are major public health problems in developing countries where there is no enough health-care service. To determine the prevalence of visual impairment among school children. A school-based cross-sectional study was conducted between 15 June 2015 and 30 November 2015 at Arada subcity primary schools, Addis Ababa, Ethiopia. Two schools were selected randomly, and 378 students were screened from grades 1 to 8 using systematic random sampling method. Snellen chart was used for visual acuity test. Students who had visual acuity of ≤6/12 were further examined by an ophthalmologist to diagnose the reason for low vision. Data was analyzed using SPSS version 20. A total of 378 students were screened, and 192 (50.8%) were females and the remaining 186 (49.2%) were males. The prevalence of visual impairment (VA) of ≤6/12 on either eye was 5.8%, VA visual acuity impairment. The prevalence of visual impairment among school children in the study area was 5.8% and school screening is recommended.

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

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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.

Low-level laser therapy improves visual acuity in adolescent and adult patients with amblyopia.

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Ivandic, Boris T; Ivandic, Tomislav

2012-03-01

The purpose of this study was to examine the effects of low-level laser therapy (LLLT) on visual acuity in adolescent and adult patients with amblyopia. Currently, amblyopia can be treated successfully only in children. In this single-blinded, placebo-controlled study, 178 patients (mean age 46.8 years) with amblyopia caused by ametropia (110 eyes) or strabismus (121 eyes) were included. For LLLT, the area of the macula was irradiated through the conjunctiva from 1 cm distance for 30 sec with laser light (780 nm, 292 Hz, 1:1 duty cycle; average power 7.5 mW; spot area 3 mm(2)). The treatment was repeated on average 3.5 times, resulting in a mean total dose of 0.77 J/cm(2). No occlusion was applied, and no additional medication was administered. Best corrected distant visual acuity was determined using Snellen projection optotypes. In 12 patients (12 eyes), the multifocal visual evoked potential (M-VEP) was recorded. A control group of 20 patients (20 eyes) received mock treatment. Visual acuity improved in ∼90% of the eyes treated with LLLT (pamblyopia caused by ametropia and strabismus, respectively. The treatment effect was maintained for at least 6 months. The mean M-VEP amplitude increased by 1207 nV (pamblyopia caused by ametropia or strabismus.

Motor skills of children with unilateral visual impairment in the Infant Aphakia Treatment Study.

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Celano, Marianne; Hartmann, E Eugenie; DuBois, Lindreth G; Drews-Botsch, Carolyn

2016-02-01

To assess motor functioning in children aged 4 years 6 months enrolled in the Infant Aphakia Treatment Study, and to determine contributions of visual acuity and stereopsis to measured motor skills. One hundred and four children (53% female) with unilateral aphakia randomized to intraocular lens or contact lens treatment were evaluated at 4 years 6 months (age range 4y 6mo-4y 11mo) for monocular recognition visual acuity, motor skills, and stereopsis by a traveling examiner masked to treatment condition. Motor skills were assessed with the Movement Assessment Battery for Children--Second Edition (MABC-2). Visual acuity was operationalized as log10 of the minimum angle of resolution (logMAR) value for treated eye, best logMAR value for either eye, and intraocular logMAR difference. Student's t-tests showed no significant differences in MABC-2 scores between the intraocular lens and contact lens groups. The mean total score was low (6.43; 18th centile) compared with the normative reference group. Motor functioning was not related to visual acuity in the treated eye or to intraocular logMAR difference, but was predicted in a regression model by the better visual acuity of either eye (usually the fellow eye), even after accounting for the influence of age at surgery, examiner, orthotropic ocular alignment, and stereopsis. Children with unilateral congenital cataract may have delayed motor functioning at 4 years 6 months, which may adversely affect their social and academic functioning. © 2015 Mac Keith Press.

Gains following perceptual learning are closely linked to the initial visual acuity.

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Yehezkel, Oren; Sterkin, Anna; Lev, Maria; Levi, Dennis M; Polat, Uri

2016-04-28

The goal of the present study was to evaluate the dependence of perceptual learning gains on initial visual acuity (VA), in a large sample of subjects with a wide range of VAs. A large sample of normally sighted and presbyopic subjects (N = 119; aged 40 to 63) with a wide range of uncorrected near visual acuities (VA, -0.12 to 0.8 LogMAR), underwent perceptual learning. Training consisted of detecting briefly presented Gabor stimuli under spatial and temporal masking conditions. Consistent with previous findings, perceptual learning induced a significant improvement in near VA and reading speed under conditions of limited exposure duration. Our results show that the improvements in VA and reading speed observed following perceptual learning are closely linked to the initial VA, with only a minor fraction of the observed improvement that may be attributed to the additional sessions performed by those with the worse VA.

Action Control: Independent Effects of Memory and Monocular Viewing on Reaching Accuracy

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Westwood, D.A.; Robertson, C.; Heath, M.

2005-01-01

Evidence suggests that perceptual networks in the ventral visual pathway are necessary for action control when targets are viewed with only one eye, or when the target must be stored in memory. We tested whether memory-linked (i.e., open-loop versus memory-guided actions) and monocular-linked effects (i.e., binocular versus monocular actions) on…

Longitudinal study of visual function in patients with relapsing-remitting multiple sclerosis with and without a history of optic neuritis.

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González Gómez, A; García-Ben, A; Soler García, A; García-Basterra, I; Padilla Parrado, F; García-Campos, J M

2017-03-15

The contrast sensitivity test determines the quality of visual function in patients with multiple sclerosis (MS). The purpose of this study is to analyse changes in visual function in patients with relapsing-remitting MS with and without a history of optic neuritis (ON). We conducted a longitudinal study including 61 patients classified into 3 groups as follows: a) disease-free patients (control group); b) patients with MS and no history of ON; and c) patients with MS and a history of unilateral ON. All patients underwent baseline and 6-year follow-up ophthalmologic examinations, which included visual acuity and monocular and binocular Pelli-Robson contrast sensitivity tests. Monocular contrast sensitivity was significantly lower in MS patients with and without a history of ON than in controls both at baseline (P=.00 and P=.01, respectively) and at 6 years (P=.01 and P=.02). Patients with MS and no history of ON remained stable throughout follow-up whereas those with a history of ON displayed a significant loss of contrast sensitivity (P=.01). Visual acuity and binocular contrast sensitivity at baseline and at 6 years was significantly lower in the group of patients with a history of ON than in the control group (P=.003 and P=.002 vs P=.006 and P=.005) and the group with no history of ON (P=.04 and P=.038 vs P=.008 and P=.01). However, no significant differences were found in follow-up results (P=.1 and P=.5). Monocular Pelli-Robson contrast sensitivity test may be used to detect changes in visual function in patients with ON. Copyright © 2017 The Author(s). Publicado por Elsevier España, S.L.U. All rights reserved.

Experimental validation of a Bayesian model of visual acuity.

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Dalimier, Eugénie

2009-01-01

Based on standard procedures used in optometry clinics, we compare measurements of visual acuity for 10 subjects (11 eyes tested) in the presence of natural ocular aberrations and different degrees of induced defocus, with the predictions given by a Bayesian model customized with aberrometric data of the eye. The absolute predictions of the model, without any adjustment, show good agreement with the experimental data, in terms of correlation and absolute error. The efficiency of the model is discussed in comparison with image quality metrics and other customized visual process models. An analysis of the importance and customization of each stage of the model is also given; it stresses the potential high predictive power from precise modeling of ocular and neural transfer functions.

Night-shift work and risk of compromised visual acuity among the workers in an electronics manufacturing company.

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Lin, Yu-Cheng; Ho, Kuo-Jung

2018-01-01

To evaluate the association between night-shift work exposure and visual health, this cross-sectional study utilized visual acuity, a surrogate measure for visual function, as a parameter, and performed an analysis comparing visual acuity between daytime and nighttime employees in an electronics manufacturing company. Data of personal histories, occupational records, physical examinations and blood tests was obtained from the electronic health records of workers. The total of 8280 workers including 3098 women and 5182 men, wearing their own daily used eyeglasses, were included in the final analysis. The mean age of the sample population was 34.7 years old (standard deviation = 5.4 years). All workers were divided into 3 work categories - consistent daytime worker (CDW), day-shift worker (DSW) and night-shift worker (NSW). The check-up results of glasses-corrected visual acuity (c-VA) were utilized to classify individuals as good (≥ 1.2, both eyes) and inadequate (electronics manufacturing company. Int J Occup Med Environ Health 2018;31(1):71-79. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Effect of occlusion amblyopia after prescribed full-time occlusion on long-term visual acuity outcomes.

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Longmuir, Susannah; Pfeifer, Wanda; Scott, William; Olson, Richard

2013-01-01

To investigate the incidence and characteristics of occlusion amblyopia with prescribed full-time patching and determine its effect on long-term visual acuity outcomes. The records of patients younger than 10 years diagnosed as having amblyopia between 1970 and 2000 were retrospectively reviewed. Patients were prescribed full-time occlusion and observed until completion of therapy. Of 597 patients treated for amblyopia by full-time patching, 115 were diagnosed as having occlusion amblyopia (19.3%). Seventy-five percent (86 of 115) developed occlusion amblyopia during the first episode of full-time patching. Occlusion amblyopia occurred more frequently in children prescribed full-time patching at an earlier age (P = .0002), with an odds ratio of 8.56 (95% confidence interval: 2.73, 26.84) in children younger than 36 months and 2.66 (95% confidence interval: 0.96, 7.37) in children between 36 and 59 months old. Seven of the patients with occlusion amblyopia did not reverse fixation and continued to fixate with the initially amblyopic eye after treatment. Final visual acuity in these eyes with occlusion amblyopia was 20/30 or better. After cessation of treatment, the final interocular difference in visual acuity was less in patients with a history of occlusion amblyopia (P = .003). Occlusion amblyopia occurred at all ages, but the incidence decreased with increasing age. Patients who developed occlusion amblyopia with prescribed full-time occlusion had less interocular visual acuity difference than patients who did not, suggesting that development of occlusion amblyopia can indicate the potential for the development of better vision in the originally amblyopic eye. Copyright 2013, SLACK Incorporated.

Desktop publishing and validation of custom near visual acuity charts.

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Marran, Lynn; Liu, Lei; Lau, George

2008-11-01

Customized visual acuity (VA) assessment is an important part of basic and clinical vision research. Desktop computer based distance VA measurements have been utilized, and shown to be accurate and reliable, but computer based near VA measurements have not been attempted, mainly due to the limited spatial resolution of computer monitors. In this paper, we demonstrate how to use desktop publishing to create printed custom near VA charts. We created a set of six near VA charts in a logarithmic progression, 20/20 through 20/63, with multiple lines of the same acuity level, different letter arrangements in each line and a random noise background. This design allowed repeated measures of subjective accommodative amplitude without the potential artifact of familiarity of the optotypes. The background maintained a constant and spatial frequency rich peripheral stimulus for accommodation across the six different acuity levels. The paper describes in detail how pixel-wise accurate black and white bitmaps of Sloan optotypes were used to create the printed custom VA charts. At all acuity levels, the physical sizes of the printed custom optotypes deviated no more than 0.034 log units from that of the standard, satisfying the 0.05 log unit ISO criterion we used to demonstrate physical equivalence. Also, at all acuity levels, log unit differences in the mean target distance for which reliable recognition of letters first occurred for the printed custom optotypes compared to the standard were found to be below 0.05, satisfying the 0.05 log unit ISO criterion we used to demonstrate functional equivalence. It is possible to use desktop publishing to create custom near VA charts that are physically and functionally equivalent to standard VA charts produced by a commercial printing process.

Evaluation of a visual acuity test using closed Landolt-Cs to determine malingering.

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Kröger, Nils; Jürgens, Clemens; Kohlmann, Thomas; Tost, Frank

2017-12-01

To evaluate a visual acuity test (VAT) with unexpected optotypes to detect malingering. We tested two groups. Group 1 consisted of 20 individuals with normal best corrected visual acuity (BCVA). Group 2 included participants with ocular diseases and reduced BCVA. All subjects underwent a VAT proposed by Gräf and Roesen to assess suspected malingering. This test used 36 charts with one Landolt-C per page. The first 20 optotypes were Landolt-Cs, while at positions 21, 26, 30, and 34 closed rings were presented. The testing distance was adapted to 50% of the test person's visual acuity. The test person was requested to name the gap direction of the Landolt-C within 3 s. The complete testing conversation was recorded digitally to determine response latency for each optotype from the audio tracks. The average response time was 0.46 s in group 1 and 0.45 s in group 2 for the first 20 Landolt-Cs. In both groups the response time was significantly extended (p ring compared to the mean of the first 20 Landolt-Cs, (group 1: 2.9 s; group 2: 2.3 s). The following three closed rings had also longer response times. However, these differences were not significant. Our results suggest that the proposed test may be helpful to evaluate ocular malingering. The testing procedure appeared to be feasible and showed good repeatability. The fast training effect may be a limitation for malingering detection.

3D display system using monocular multiview displays

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Sakamoto, Kunio; Saruta, Kazuki; Takeda, Kazutoki

2002-05-01

A 3D head mounted display (HMD) system is useful for constructing a virtual space. The authors have researched the virtual-reality systems connected with computer networks for real-time remote control and developed a low-priced real-time 3D display for building these systems. We developed a 3D HMD system using monocular multi-view displays. The 3D displaying technique of this monocular multi-view display is based on the concept of the super multi-view proposed by Kajiki at TAO (Telecommunications Advancement Organization of Japan) in 1996. Our 3D HMD has two monocular multi-view displays (used as a visual display unit) in order to display a picture to the left eye and the right eye. The left and right images are a pair of stereoscopic images for the left and right eyes, then stereoscopic 3D images are observed.

Comparison of visual acuity in reduced lumination and facility of ocular accommodation in table tennis champions and non- players.

Science.gov (United States)

Jafarzadehpur, Ebrahim; Yarigholi, Mohammad R

2004-03-01

A table tennis player should fixate at different distances; track the objects with different speed, and in different visual environment. Their visual skills must be well developed for these capabilities. Therefore, visual acuity in reduced lumination and facility of ocular accommodation those are two criteria for visual skills have been compared in table tennis players and normal non-players. Twenty-nine young table tennis champions and 29 normal matched non-players (did not take part in any racket sports game) were evaluated. Basic visual and eye examinations were done for both of them. Normal results in basic examination were fundamental requirement for all the subjects. +/-2.00 sphere lenses for accommodation facility are used. An electrical current regulator changed the output light intensity of a conventional chart projector (Topcon). Light intensity decreased to 10 cd·m(-2) and visual acuity tested. In comparison of visual acuity in reduced lumination and facility of ocular accommodation in table tennis champions and non-players there are significant differences (p reflecting a better perceptual system of experts to the constraints encountered during table tennis and its use in practical settings for evaluating athletes or detecting sport talents. However some visual and perceptual training that usually used in orthoptics can be used for novice table tennis player to improve their abilities. Key PointsThat the ability of a champion depends on many sensory, motor and perceptual factors.Visual factors such as facility of accommodation and visual acuity in reduced lumination should be considered in table tennis players.Visual training may be useful for novice and also for experts.

Baseline risk factors for incidence of blindness in a South Indian population: the chennai eye disease incidence study.

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Vijaya, Lingam; Asokan, Rashima; Panday, Manish; Choudhari, Nikhil S; Ramesh, Sathyamangalam Ve; Velumuri, Lokapavani; Boddupalli, Sachi Devi; Sunil, Govindan T; George, Ronnie

2014-08-07

To report the baseline risk factors and causes for incident blindness. Six years after the baseline study, 4419 subjects from the cohort underwent a detailed examination at the base hospital. Incident blindness was defined by World Health Organization criteria as visual acuity of less than 6/120 (3/60) and/or a visual field of less than 10° in the better-seeing eye at the 6-year follow-up, provided that the eye had a visual acuity of better than or equal to 6/120 (3/60) and visual field greater than 10° at baseline. For incident monocular blindness, both eyes should have visual acuity of more than 6/120 (3/60) at baseline and developed visual acuity of less than 6/120 (3/60) in one eye at 6-year follow-up. For incident blindness, 21 participants (0.48%, 95% confidence interval [CI], 0.3-0.7) became blind; significant baseline risk factors were increasing age (P = 0.001), smokeless tobacco use (P blindness was found in 132 participants (3.8%, 95% CI, 3.7-3.8); it was significantly more (P blindness and monocular blindness. No history of cataract surgery was a risk factor for blindness and a protective factor for monocular blindness. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

Switching from pro re nata to treat-and-extend regimen improves visual acuity in patients with neovascular age-related macular degeneration.

Science.gov (United States)

Kvannli, Line; Krohn, Jørgen

2017-11-01

To evaluate the visual outcome after transitioning from a pro re nata (PRN) intravitreal injection regimen to a treat-and-extend (TAE) regimen for patients with neovascular age-related macular degeneration (AMD). A retrospective review of patients who were switched from a PRN regimen with intravitreal injections of bevacizumab, ranibizumab or aflibercept to a TAE regimen. The best corrected visual acuity (BCVA), central retinal thickness (CRT) and type of medication used at baseline, at the time of changing treatment regimen and at the end of the study were analysed. Twenty-one eyes of 21 patients met the inclusion criteria. Prior to the switch, the patients received a mean of 13.8 injections (median, 10; range, 3-39 injections) with the PRN regimen for 44 months (range, 3-100 months), which improved the visual acuity in five patients (24%). After a mean of 6.1 injections (median, 5; range, 3-14 injections) with the TAE regimen over 8 months (range, 2-16 months), the visual acuity improved in 12 patients (57%). The improvement in visual acuity during treatment with the TAE regimen was statistically significant (p = 0.005). The proportion of patients with a visual acuity of 0.2 or better was significantly higher after treatment with the TAE regimen than after treatment with the PRN regimen (p = 0.048). No significant differences in CRT were found between the two treatment regimens. Even after prolonged treatment and a high number of intravitreal injections, switching AMD patients from a PRN regimen to a strict TAE regimen significantly improves visual acuity. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Macular Structures, Optical Components, and Visual Acuity in Preschool Children after Intravitreal Bevacizumab or Laser Treatment.

Science.gov (United States)

Lee, Yung-Sung; See, Lai-Chu; Chang, Shu-Hao; Wang, Nan-Kai; Hwang, Yih-Shiou; Lai, Chi-Chun; Chen, Kuan-Jen; Wu, Wei-Chi

2018-05-10

To investigate the macular structures, optical components, and visual acuity in preschool-aged children with a history of type I retinopathy of prematurity who underwent either intravitreal bevacizumab (IVB), laser, or a combination of treatments. Comparative interventional case series. A referred medical center in Taiwan. 80 eyes from 42 patients (33 IVB-treated eyes from 17 children, 24 laser-treated eyes from 13 children, and 23 laser + IVB-treated eyes from 12 children). Spectral-domain optical coherence tomography. The retinal thickness in the foveal area and the associated morphologic changes in foveal depression. Compared with the laser-treated and laser + IVB-treated eyes, the IVB-treated eyes had less myopia and deeper anterior chamber depths but presented similar axial lengths and corneal curvatures (P = .001, .002, .95 and .16, respectively). The IVB-treated eyes had significantly thinner foveal, parafoveal, and perifoveal retinal thicknesses (P < .01 for all) and a higher incidence of foveal depression than the laser- or laser + IVB-treated eyes. The macular and subfoveal choroidal thicknesses did not differ among the groups (P = .21 and .63, respectively). Moreover, compared with the eyes treated with laser or laser + IVB, the IVB-treated eyes had better uncorrected visual acuity, although a significant difference was not observed in best-corrected visual acuity (P = .008 and .29, respectively). Compared with laser therapy, IVB-treated eyes were associated with deeper anterior chamber depths and thinner foveal, parafoveal and perifoveal thicknesses. Moreover, these IVB-treated eyes had less refractive errors and better uncorrected visual acuity. Copyright © 2018. Published by Elsevier Inc.

Assessment of Grating Acuity in Infants and Toddlers Using an Electronic Acuity Card: The Dobson Card.

Science.gov (United States)

Mohan, Kathleen M; Miller, Joseph M; Harvey, Erin M; Gerhart, Kimberly D; Apple, Howard P; Apple, Deborah; Smith, Jordana M; Davis, Amy L; Leonard-Green, Tina; Campus, Irene; Dennis, Leslie K

2016-01-01

To determine if testing binocular visual acuity in infants and toddlers using the Acuity Card Procedure (ACP) with electronic grating stimuli yields clinically useful data. Participants were infants and toddlers ages 5 to 36.7 months referred by pediatricians due to failed automated vision screening. The ACP was used to test binocular grating acuity. Stimuli were presented on the Dobson Card. The Dobson Card consists of a handheld matte-black plexiglass frame with two flush-mounted tablet computers and is similar in size and form to commercially available printed grating acuity testing stimuli (Teller Acuity Cards II [TACII]; Stereo Optical, Inc., Chicago, IL). On each trial, one tablet displayed a square-wave grating and the other displayed a luminance-matched uniform gray patch. Stimuli were roughly equivalent to the stimuli available in the printed TACII stimuli. After acuity testing, each child received a cycloplegic eye examination. Based on cycloplegic retinoscopy, patients were categorized as having high or low refractive error per American Association for Pediatric Ophthalmology and Strabismus vision screening referral criteria. Mean acuities for high and low refractive error groups were compared using analysis of covariance, controlling for age. Mean visual acuity was significantly poorer in children with high refractive error than in those with low refractive error (P = .015). Electronic stimuli presented using the ACP can yield clinically useful measurements of grating acuity in infants and toddlers. Further research is needed to determine the optimal conditions and procedures for obtaining accurate and clinically useful automated measurements of visual acuity in infants and toddlers. Copyright 2016, SLACK Incorporated.

Improvement of visual acuity and VEP after optic nerve contusion by NGF and its safety analysis

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Ming Zhao

2018-02-01

Full Text Available AIM:To investigate the effect of neuropathic factor(NGFon visual acuity and visual evoked potential(VEPin patients with optic nerve contusion. METHODS:Totally 78 patients(78 eyeswith optic nerve contusion were selected. From January 2013 to June 2016, 39 cases(39 eyeswere divided into observation group and control group respectively according to the random number table method. Prednisone, vitamins and mecobalamin tablets treatment were given to both groups, based on that, the observation group was given NGF treatment, continuous treatment of 2 courses(21d for a course of treatment. RESULTS: There was no significant difference in visual field defect and visual field sensitivity between the observation group and the control group before treatment(P>0.05. After treatment, the visual field defect degree of the observation group was smaller, the visual field sensitivity was better than that of the control group(PP>0.05. After treatment, the P100 wave latency of the observation group was significantly shorter than that of the control group(PPPCONCLUSION: NGF treatment for optic nerve contusion can significantly improve the patient's visual acuity, VEP indicators, reduce visual field defects, improve visual field sensitivity.

Analysis of laser photocoagulation with cataract surgery for improvement of visual acuity and macular edema in patients with cataract and diabetic macular edema

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Chao-Yu Wang

2016-02-01

Full Text Available AIM:To explore laser photocoagulation with cataract surgery for improvement of visual acuity and macular edema in patients with cataract and diabetic macular edema.METHODS:A total of 60 patients(72 eyesfrom January 2014 to July 2015 in our hospital were selected, which all were diagnosed as cataract with diabetic macular edema. According to a random number table method, the patients were divided into observation group and control group, 30 cases(36 eyesin each group. The observation group was treated with combination therapy of laser photocoagulation before cataract surgeries, while the control group with the combination therapy of laser photocoagulation after cataract surgeries. At 2mo after surgeries, some routine examination, such as visual acuity, fundus examination after mydriasis, slit lamp examination, optical coherence tomography(OCTexamination, fluorescence angiography examination(FFAfor retinal blood vessels were applied in all the patients. RESULTS:The visual acuity of the observation group and the control group before treatments was not significantly different(P>0.05. At 2mo after treatments, the visual inspection showed that compared with the visual acuity before treatment, the visual acuity of the two groups were both significantly improved(PPP>0.05. At 2mo after treatments, compared with those before treatments, the macular thickness of two groups were both significantly improved(PPCONCLUSION:The laser photocoagulation before cataract surgery for patients with cataract and diabetic macular edema can significantly improve their visual acuity and macular thickness.

Color improves ‘visual’ acuity via sound

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Shelly eLevy-Tzedek

2014-11-01

Full Text Available Visual-to-auditory sensory substitution devices (SSDs convey visual information via sound, with the primary goal of making visual information accessible to blind and visually impaired individuals. We developed the EyeMusic SSD, which transforms shape, location and color information into musical notes. We tested the 'visual' acuity of 23 individuals (13 blind and 10 blindfolded sighted on the Snellen tumbling-E test, with the EyeMusic. Participants were asked to determine the orientation of the letter ‘E’. The test was repeated twice: in one test, the letter ‘E’ was drawn with a single color (white, and in the other test, with two colors (red and white. In the latter case, the vertical line in the letter, when upright, was drawn in red, with the three horizontal lines drawn in white. We found no significant differences in performance between the blind and the sighted groups. We found a significant effect of the added color on the ‘visual’ acuity. The highest acuity participants reached in the monochromatic test was 20/800, whereas with the added color, acuity doubled to 20/400. We conclude that color improves 'visual' acuity via sound.

Post-treatment visual acuity in patients treated with episcleral plaque therapy for choroidal melanoma: Dose and dose rate effects

International Nuclear Information System (INIS)

Jones, Robert; Gore, Elizabeth; Mieler, William; Gillin, Michael; Albano, Katherine; Erickson, Beth

1996-01-01

Purpose: To determine the relationship between the long-term visual function and the dose and dose rates delivered to critical ocular structures in patients with choroidal melanoma treated with 125 I episcleral plaque radiotherapy. Methods and Materials: From 1987 to 1993, 63 patients underwent 125 I episcleral plaque application for the treatment of choroidal melanoma. Mean tumor height was 4.6 mm (range 1.7-8.3 mm). Plaques utilized were of COMS design. Doses and dose rates at the tumor apex, macula, and optic disc were obtained. Visual acuity data prior to and after plaque application was available for 52 patients. 9 patients were excluded from analysis secondary to co-morbidities or disease progression. 43 records were scored to assess if a decrease in visual acuity of ≥ 2 lines on a standard Snellen eye chart had occurred. Statistical analysis was performed using chi-square tests of significance. Results: Of the 63 total patients, 59 (93.7%) were alive at a median follow-up of 36 months. Local progression occurred in (7(63)) (11.1%). Median dose and dose rate to the tumor apex were 90 Gy and 97.2 cGy/hr, respectively. Of the 43 patients with post-treatment visual acuity analysis, 28 (65.1%) experienced visual loss of ≥ 2 lines on a standard eye chart. Median time to altered visual acuity was 20 months. Median dose and dose rates to the macula in patients with a significant visual loss were 123.3 Gy and 122.5 cGy/hr, respectively, compared with 38 Gy and 51.9 cGy/hr in those without notable visual change. These differences reached statistical significance at a dose and dose rate to the macula of 82.0 Gy (p 125 I plaque brachytherapy for choroidal melanoma experienced favorable tumor control, but with a measurable incidence of decreased visual acuity. Both total dose and dose rates to the macula and optic disc correlated strongly with post-treatment visual outcome. This information may be valuable in decisions about the dose and dose rates used to treat

Post-treatment visual acuity in patients treated with episcleral plaque therapy for choroidal melanoma: dose and dose rate effects

International Nuclear Information System (INIS)

Jones, Robert; Gore, Elizabeth; Mieler, William; Murray, Kevin; Gillin, Michael; Albano, Katherine; Erickson, Beth

1996-01-01

Purpose: To determine the relationship between the long-term visual function and the dose and dose rates delivered to critical ocular structures in patients with choroidal melanoma treated with 125 I episcleral plaque radiotherapy. Methods and Materials: From 1987 to 1994, 63 patients underwent 125 I episcleral plaque application for the treatment of choroidal melanoma. Mean tumor height was 4.6 mm (range 1.7-8.3 mm). Plaques utilized were of COMS design. Doses and dose rates at the tumor apex, macula, and optic disc were obtained. Visual acuity data prior to and after plaque application was available for 52 patients. Nine patients were excluded from analysis secondary to co-morbidities or disease progression. Forty-three records were scored to assess if a decrease in visual acuity of ≥ 2 lines on a standard Snellen eye chart had occurred. Statistical analysis was performed using chi-square tests of significance. Results: Of the 63 total patients, 59 (93.7%) were alive at a median follow-up of 36 months. Local progression occurred in 7/63 (11.1%). Median dose and dose rate to the tumor apex were 90 Gy and 97.2 cGy/hr, respectively. Of the 43 patients with post-treatment visual acuity analysis, 28 (65.1%) experienced visual loss of ≥ 2 lines on a standard eye chart. Median time to altered visual acuity was 20 months. Median dose and dose rates to the macula in patients with a significant visual loss were 123.3 Gy and 122.5 cGy/hr, respectively, compared with 38 Gy and 51.9 cGy/hr in those without notable visual change. These differences reached statistical significance at a dose and dose rate to the macula of 82.0 Gy (p 125 I plaque brachytherapy for choroidal melanoma experienced favorable tumor control, but with a measurable incidence of decreased visual acuity. Both total dose and dose rates to the macula and optic disc correlated strongly with post-treatment visual outcome. This information may be valuable in decisions about the dose and dose rates used to

Sudden visual loss after cardiac resynchronization therapy device implantation.

Science.gov (United States)

De Vitis, Luigi A; Marchese, Alessandro; Giuffrè, Chiara; Carnevali, Adriano; Querques, Lea; Tomasso, Livia; Baldin, Giovanni; Maestranzi, Gisella; Lattanzio, Rosangela; Querques, Giuseppe; Bandello, Francesco

2017-03-10

To report a case of sudden decrease in visual acuity possibly due to a cardiogenic embolism in a patient who underwent cardiac resynchronization therapy (CRT) device implantation. A 62-year-old man with severe left ventricular systolic dysfunction and a left bundle branch block was referred to our department because of a sudden decrease in visual acuity. Nine days earlier, he had undergone cardiac transapical implantation of a CRT device, which was followed, 2 days later, by an inflammatory reaction. The patient underwent several general and ophthalmologic examinations, including multimodal imaging. At presentation, right eye (RE) best-corrected visual acuity (BCVA) was counting fingers and RE pupil was hyporeactive. Fundus examination revealed white-centered hemorrhagic dots suggestive of Roth spots. Fluorescein angiography showed delay in vascular perfusion during early stage, late hyperfluorescence of the macula and optic disk, and peripheral perivascular leakage. The first visual field test showed complete loss of vision RE and a normal left eye. Due to suspected giant cell arteritis, temporal artery biopsy was performed. Thirty minutes after the procedure, an ischemic stroke with right hemisyndrome and aphasia occurred. The RE BCVA worsened to hands motion. Four months later, RE BCVA did not improve, despite improvement in fluorescein angiography inflammatory sign. We report a possible cardiogenic embolism secondary to undiagnosed infective endocarditis causing monocular visual loss after CRT device implantation. It remains unclear how the embolus caused severe functional damage without altering the retinal anatomical structure.

Cirurgia monocular para esotropias de grande ângulo: um novo paradigma Monocular surgery for large-angle esotropias: a new paradigm

Directory of Open Access Journals (Sweden)

Edmilson Gigante

2009-02-01

anesthesia and received no adjustable sutures. The methods used for refractometry, measurement of visual acuity and angle of deviation were those traditionally used in strabismology. Postoperatively, measurements in primary position (and side gaze were carried out, along with assessments of limitations to adduction or abduction of the operated eye. RESULTS: Four groups comprised the study according to four periods of time: one week, six months, two years and four to seven years. The results for the postoperative angle of deviation were compatible with those reported in the literature, and remained stable in the folllowup. The motility of the operated eye presented a slight limitation in adduction and no limitation in abduction, contradicting the findings presented in the strabologic literature. No statistically significant differences were detected in the comparison between adults and children, neither regarding amblyopes and non-amblyopes. CONCLUSION: Monocular recession-resection surgery seems to be a valid option in the treatment of large-angle esotropias, both for adults and children, as well as for amblyopes and non-amblyopes.

Tactile acuity charts: a reliable measure of spatial acuity.

Science.gov (United States)

Bruns, Patrick; Camargo, Carlos J; Campanella, Humberto; Esteve, Jaume; Dinse, Hubert R; Röder, Brigitte

2014-01-01

For assessing tactile spatial resolution it has recently been recommended to use tactile acuity charts which follow the design principles of the Snellen letter charts for visual acuity and involve active touch. However, it is currently unknown whether acuity thresholds obtained with this newly developed psychophysical procedure are in accordance with established measures of tactile acuity that involve passive contact with fixed duration and control of contact force. Here we directly compared tactile acuity thresholds obtained with the acuity charts to traditional two-point and grating orientation thresholds in a group of young healthy adults. For this purpose, two types of charts, using either Braille-like dot patterns or embossed Landolt rings with different orientations, were adapted from previous studies. Measurements with the two types of charts were equivalent, but generally more reliable with the dot pattern chart. A comparison with the two-point and grating orientation task data showed that the test-retest reliability of the acuity chart measurements after one week was superior to that of the passive methods. Individual thresholds obtained with the acuity charts agreed reasonably with the grating orientation threshold, but less so with the two-point threshold that yielded relatively distinct acuity estimates compared to the other methods. This potentially considerable amount of mismatch between different measures of tactile acuity suggests that tactile spatial resolution is a complex entity that should ideally be measured with different methods in parallel. The simple test procedure and high reliability of the acuity charts makes them a promising complement and alternative to the traditional two-point and grating orientation thresholds.

The Prevalence of Visual Acuity Impairment among School Children at Arada Subcity Primary Schools in Addis Ababa, Ethiopia

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Haile Fentahun Darge

2017-01-01

Full Text Available Background. Visual impairment and blindness are major public health problems in developing countries where there is no enough health-care service. Objective. To determine the prevalence of visual impairment among school children. Materials and Methods. A school-based cross-sectional study was conducted between 15 June 2015 and 30 November 2015 at Arada subcity primary schools, Addis Ababa, Ethiopia. Two schools were selected randomly, and 378 students were screened from grades 1 to 8 using systematic random sampling method. Snellen chart was used for visual acuity test. Students who had visual acuity of ≤6/12 were further examined by an ophthalmologist to diagnose the reason for low vision. Data was analyzed using SPSS version 20. Results. A total of 378 students were screened, and 192 (50.8% were females and the remaining 186 (49.2% were males. The prevalence of visual impairment (VA of ≤6/12 on either eye was 5.8%, VA < 6/18 on either eye was 1.1%, and VA < 6/18 on the better eye was 0.53%. In this study, color blindness [OR: 19.65, 95% CI (6.01–64.33] was significantly associated with visual acuity impairment. Conclusion. The prevalence of visual impairment among school children in the study area was 5.8% and school screening is recommended.

Monocular zones in stereoscopic scenes: A useful source of information for human binocular vision?

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Harris, Julie M.

2010-02-01

When an object is closer to an observer than the background, the small differences between right and left eye views are interpreted by the human brain as depth. This basic ability of the human visual system, called stereopsis, lies at the core of all binocular three-dimensional (3-D) perception and related technological display development. To achieve stereopsis, it is traditionally assumed that corresponding locations in the right and left eye's views must first be matched, then the relative differences between right and left eye locations are used to calculate depth. But this is not the whole story. At every object-background boundary, there are regions of the background that only one eye can see because, in the other eye's view, the foreground object occludes that region of background. Such monocular zones do not have a corresponding match in the other eye's view and can thus cause problems for depth extraction algorithms. In this paper I will discuss evidence, from our knowledge of human visual perception, illustrating that monocular zones do not pose problems for our human visual systems, rather, our visual systems can extract depth from such zones. I review the relevant human perception literature in this area, and show some recent data aimed at quantifying the perception of depth from monocular zones. The paper finishes with a discussion of the potential importance of considering monocular zones, for stereo display technology and depth compression algorithms.

Acuidade visual em implantes bilaterais de lentes intra-oculares monofocais e multifocais Visual acuity of bilateral implants of monofocal and multifocal intraocular lenses

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Leonardo Akaishi

2003-01-01

Full Text Available OBJETIVO: Comparar a acuidade visual de longe e perto de pacientes submetidos à facoemulsificação binocular não simultânea com implante de lentes multifocais ou monofocais. MÉTODOS: Foram selecionados 20 pacientes com lentes multifocais bilaterais e outros 20 pacientes com lentes monofocais também bilaterais, com acuidade visual sem correção melhor ou igual a 0,63 (20/30, medidos separadamente, nos três primeiros meses de pós-operatório. Foi medida a acuidade visual para longe e perto com e sem correção e testes de sensibilidade ao contraste e ofuscamento. RESULTADOS: A acuidade visual sem correção para longe no grupo das monofocais teve média de 0,82 (DP± 0,16 e no grupo das multifocais, 0,94 (DP±0,12, valor de p 0,001. Os dois grupos de lentes tiveram visão com correção para longe igual a 1. No grupo das multifocais, 75% tiveram J1 e 100% tiveram J3 ou melhor sem correção. No grupo das lentes monofocais, 10% tiveram J1 e 70% tiveram J3 ou melhor sem correção. Não houve diferença significante na avaliação com o teste de sensibilidade ao contraste entre os grupos pesquisados. No teste de ofuscamento, os dois grupos tiveram redução da visão, que foi mais acentuada no grupo dos pacientes com lentes multifocais. CONCLUSÃO: A acuidade visual para longe com correção nos pacientes com implante multifocal foi semelhante a dos pacientes com implantes monofocais, embora a acuidade visual para perto no grupo em que foi implantado lente multifocal foi bastante superior ao grupo da lente monofocal. A sensibilidade ao contraste manteve-se semelhante nos dois grupos, já o ofuscamento ("glare test" no grupo multifocal foi maior que no grupo monofocal.PURPOSE: To compare distant and near visual acuity between patients submitted to bilateral nonsimultaneous facoemulsification and implantation of multifocal or monofocal intraocular lenses (IOL. METHODS: Twenty patients with bilateral multifocal IOL and 20 patients with

Outcomes of visual acuity in carbon ion radiotherapy: Analysis of dose-volume histograms and prognostic factors

International Nuclear Information System (INIS)

Hasegawa, Azusa; Mizoe, Jun-etsu; Mizota, Atsushi; Tsujii, Hirohiko

2006-01-01

Purpose: To analyze the tolerance dose for retention of visual acuity in patients with head-and-neck tumors treated with carbon ion radiotherapy. Methods and Materials: From June 1994 to March 2000, 163 patients with tumors in the head and neck or skull base region were treated with carbon ion radiotherapy. Analysis was performed on 54 optic nerves (ONs) corresponding to 30 patients whose ONs had been included in the irradiated volume. These patients showed no evidence of visual impairment due to other factors and had a follow-up period of >4 years. All patients had been informed of the possibility of visual impairment before treatment. We evaluated the dose-complication probability and the prognostic factors for the retention of visual acuity in carbon ion radiotherapy, using dose-volume histograms and multivariate analysis. Results: The median age of 30 patients (14 men, 16 women) was 57.2 years. Median prescribed total dose was 56.0 gray equivalents (GyE) at 3.0-4.0 GyE per fraction per day (range, 48-64 GyE; 16-18 fractions; 4-6 weeks). Of 54 ONs that were analyzed, 35 had been irradiated with max ]) resulting in no visual loss. Conversely, 11 of the 19 ONs (58%) irradiated with >57 GyE (D max ) suffered a decrease of visual acuity. In all of these cases, the ONs had been involved in the tumor before carbon ion radiotherapy. In the multivariate analysis, a dose of 20% of the volume of the ON (D 2 ) was significantly associated with visual loss. Conclusions: The occurrence of visual loss seems to be correlated with a delivery of >60 GyE to 20% of the volume of the ON

A study of static, kinetic, and dynamic visual acuity in 102 Japanese professional baseball players

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Hoshina K

2013-03-01

Full Text Available Kohji Hoshina,1 Yuichi Tagami,2 Osamu Mimura,3 Hiroshi Edagawa,4 Masao Matsubara,5 Teiichi Nakayama6 1Hoshina Eye Clinic, Nishinomiya, Japan; 2Department of Ophthalmology, Kobe Century Memorial Hospital, Kobe, Japan; 3Department of Ophthalmology, Hyogo College of Medicine, Nishinomiya, Japan; 4Edagawa Eye Clinic, Tokyo, Japan; 5Department of Ophthalmology, Tokyo Women's Medical University Medical Center East, Tokyo, Japan; 6Ritsumeikan University, Kyoto, Japan Background: It seemed that visual functions might have some effects on the performance of baseball players. We measured static, kinetic, and dynamic visual acuity (SVA, KVA, and DVA, respectively of Japanese professional baseball players to ascertain whether there would be any difference in SVA, KVA, and DVA among player groups stratified according to their performance level. Methods: The subjects were 102 male professional baseball players with a mean age of 26 years who were members of a Japanese professional baseball club from 2000 to 2009. They were stratified into three groups according to their performance level: A (players who were on the roster of the top-level team all the time throughout the study period, B (players who were on the roster of the top-level team sometimes but not all the time, and C (players who were never on the roster of the top-level team. They were interviewed for the use of corrective visual aids, and examined for SVA, KVA, and DVA. The measurements of these parameters were compared among groups A, B, and C. We also investigated and analyzed the association of KVA or DVA with player position (pitchers or fielders and with hand dominance for batting. KVA was compared between the pitchers and the fielders because they each require different playing skills. DVA was compared between the right-handed and the left-handed batters. Results: There was no statistically significant difference among groups A, B, and C. There was a statistically significant difference in

Possible role for fundus autofluorescence as a predictive factor for visual acuity recovery after epiretinal membrane surgery.

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Brito, Pedro N; Gomes, Nuno L; Vieira, Marco P; Faria, Pedro A; Fernandes, Augusto V; Rocha-Sousa, Amândio; Falcão-Reis, Fernando

2014-02-01

To study the potential association between fundus autofluorescence, spectral-domain optical coherence tomography, and visual acuity in patients undergoing surgery because of epiretinal membranes. Prospective, interventional case series including 26 patients submitted to vitrectomy because of symptomatic epiretinal membranes. Preoperative evaluation consisted of a complete ophthalmologic examination, autofluorescence, and spectral-domain optical coherence tomography. Studied variables included foveal autofluorescence (fov.AF), photoreceptor inner segment/outer segment (IS/OS) junction line integrity, external limiting membrane integrity, central foveal thickness, and foveal morphology. All examinations were repeated at the first, third, and sixth postoperative months. The main outcome measures were logarithm of minimal angle resolution visual acuity, fov.AF integrity, and IS/OS integrity. All cases showing a continuous IS/OS line had an intact fov.AF, whereas patients with IS/OS disruption could have either an increased area of foveal hypoautofluorescence or an intact fov.AF, with the latter being associated with IS/OS integrity recovery in follow-up spectral-domain optical coherence tomography imaging. The only preoperative variables presenting a significant correlation with final visual acuity were baseline visual acuity (P = 0.047) and fov.AF grade (P = 0.023). Recovery of IS/OS line integrity after surgery, in patients with preoperative IS/OS disruption and normal fov.AF, can be explained by the presence of a functional retinal pigment epithelium-photoreceptor complex, supporting normal photoreceptor activity. Autofluorescence imaging provides a functional component to the study of epiretinal membranes, complementing the structural information obtained with optical coherence tomography.

Tactile acuity charts: a reliable measure of spatial acuity.

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Patrick Bruns

Full Text Available For assessing tactile spatial resolution it has recently been recommended to use tactile acuity charts which follow the design principles of the Snellen letter charts for visual acuity and involve active touch. However, it is currently unknown whether acuity thresholds obtained with this newly developed psychophysical procedure are in accordance with established measures of tactile acuity that involve passive contact with fixed duration and control of contact force. Here we directly compared tactile acuity thresholds obtained with the acuity charts to traditional two-point and grating orientation thresholds in a group of young healthy adults. For this purpose, two types of charts, using either Braille-like dot patterns or embossed Landolt rings with different orientations, were adapted from previous studies. Measurements with the two types of charts were equivalent, but generally more reliable with the dot pattern chart. A comparison with the two-point and grating orientation task data showed that the test-retest reliability of the acuity chart measurements after one week was superior to that of the passive methods. Individual thresholds obtained with the acuity charts agreed reasonably with the grating orientation threshold, but less so with the two-point threshold that yielded relatively distinct acuity estimates compared to the other methods. This potentially considerable amount of mismatch between different measures of tactile acuity suggests that tactile spatial resolution is a complex entity that should ideally be measured with different methods in parallel. The simple test procedure and high reliability of the acuity charts makes them a promising complement and alternative to the traditional two-point and grating orientation thresholds.

Prism therapy and visual rehabilitation in homonymous visual field loss.

LENUS (Irish Health Repository)

O'Neill, Evelyn C

2012-02-01

PURPOSE: Homonymous visual field defects (HVFD) are common and frequently occur after cerebrovascular accidents. They significantly impair visual function and cause disability particularly with regard to visual exploration. The purpose of this study was to assess a novel interventional treatment of monocular prism therapy on visual functioning in patients with HVFD of varied etiology using vision targeted, health-related quality of life (QOL) questionnaires. Our secondary aim was to confirm monocular and binocular visual field expansion pre- and posttreatment. METHODS: Twelve patients with acquired, documented HVFD were eligible to be included. All patients underwent specific vision-targeted, health-related QOL questionnaire and monocular and binocular Goldmann perimetry before commencing prism therapy. Patients were fitted with monocular prisms on the side of the HVFD with the base-in the direction of the field defect creating a peripheral optical exotropia and field expansion. After the treatment period, QOL questionnaires and perimetry were repeated. RESULTS: Twelve patients were included in the treatment group, 10 of whom were included in data analysis. Overall, there was significant improvement within multiple vision-related, QOL functioning parameters, specifically within the domains of general health (p < 0.01), general vision (p < 0.05), distance vision (p < 0.01), peripheral vision (p < 0.05), role difficulties (p < 0.05), dependency (p < 0.05), and social functioning (p < 0.05). Visual field expansion was shown when measured monocularly and binocularly during the study period in comparison with pretreatment baselines. CONCLUSIONS: Patients with HVFD demonstrate decreased QOL. Monocular sector prisms can improve the QOL and expand the visual field in these patients.

The Advanced Glaucoma Intervention Study (AGIS): 12. Baseline risk factors for sustained loss of visual field and visual acuity in patients with advanced glaucoma.

Science.gov (United States)

2002-10-01

To examine the relationships between baseline risk factors and sustained decrease of visual field (SDVF) and sustained decrease of visual acuity (SDVA). Cohort study of participants in the Advanced Glaucoma Intervention Study (AGIS). This multicenter study enrolled patients between 1988 and 1992 and followed them until 2001; 789 eyes of 591 patients with advanced glaucoma were randomly assigned to one of two surgical sequences, argon laser trabeculoplasty (ALT)-trabeculectomy-trabeculectomy (ATT) or trabeculectomy-ALT-trabeculectomy (TAT). This report is based on data from 747 eyes. Eyes were offered the next intervention in the sequence upon failure of the previous intervention. Failure was based on recurrent intraocular pressure elevation, visual field defect, and disk rim criteria. Study visits occurred every 6 months; potential follow-up ranged from 8 to 13 years. For each intervention sequence, Cox multiple regression analyses were used to examine the baseline characteristics for association with two vision outcomes: SDVF and SDVA. The magnitude of the association is measured by the hazard ratio (HR), where HR for binary variables is the relative change in the hazard (or risk) of the outcome in eyes with the factor divided by the hazard in eyes without the factor, and HR for continuous variables is the relative change in the hazard (or risk) of the outcome in eyes with a unit increase in the factor. Characteristics associated with increased SDVF risk in the ATT sequence are: less baseline visual field defect (hazard ratio [HR] = 0.86, P <.001, 95% CI = 0.82-0.90), male gender (HR = 2.23, P <.001, 1.54-3.23), and worse baseline visual acuity (HR = 0.96, P =.001, 0.94-0.98); in the TAT sequence: less baseline visual field defect (HR = 0.93, P =.001, 0.89-0.97) and diabetes (HR = 1.87, P =.007, 1.18-2.97). Characteristics associated with increased SDVA risk in both treatment sequences are better baseline acuity (ATT: HR = 1.05, P <.001, 1.02-1.09; TAT: HR = 1

Visual system plasticity in mammals: the story of monocular enucleation-induced vision loss

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Nys, Julie; Scheyltjens, Isabelle; Arckens, Lutgarde

2015-01-01

The groundbreaking work of Hubel and Wiesel in the 1960’s on ocular dominance plasticity instigated many studies of the visual system of mammals, enriching our understanding of how the development of its structure and function depends on high quality visual input through both eyes. These studies have mainly employed lid suturing, dark rearing and eye patching applied to different species to reduce or impair visual input, and have created extensive knowledge on binocular vision. However, not all aspects and types of plasticity in the visual cortex have been covered in full detail. In that regard, a more drastic deprivation method like enucleation, leading to complete vision loss appears useful as it has more widespread effects on the afferent visual pathway and even on non-visual brain regions. One-eyed vision due to monocular enucleation (ME) profoundly affects the contralateral retinorecipient subcortical and cortical structures thereby creating a powerful means to investigate cortical plasticity phenomena in which binocular competition has no vote.In this review, we will present current knowledge about the specific application of ME as an experimental tool to study visual and cross-modal brain plasticity and compare early postnatal stages up into adulthood. The structural and physiological consequences of this type of extensive sensory loss as documented and studied in several animal species and human patients will be discussed. We will summarize how ME studies have been instrumental to our current understanding of the differentiation of sensory systems and how the structure and function of cortical circuits in mammals are shaped in response to such an extensive alteration in experience. In conclusion, we will highlight future perspectives and the clinical relevance of adding ME to the list of more longstanding deprivation models in visual system research. PMID:25972788

High-Acuity Information Is Retained through the Cortical Visual Hierarchy of Primates.

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Chelazzi, Leonardo; Santandrea, Elisa

2018-04-18

Vision requires perception of both coarse layout and fine details of objects. In this issue of Neuron, Lu et al. (2018) describe a possible basis for the latter: neuronal clusters in area V4 coding high-acuity information, despite the tendency along the visual hierarchy to generate global representations of objects. Copyright © 2018 Elsevier Inc. All rights reserved.

Retrospective Comparison of Visual Outcomes After KAMRA Corneal Inlay Implantation With Simultaneous PRK or LASIK.

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Moshirfar, Majid; Bean, Andrew E; Albarracin, Julio C; Rebenitsch, Ronald L; Wallace, Ryan T; Birdsong, Orry C

2018-05-01

To report a retrospective study of simultaneous LASIK versus photorefractive keratectomy (PRK) with accompanying small-aperture cornea inlay implantation (KAMRA; AcuFocus, Inc., Irvine, CA) in treating presbyopia. Simultaneous LASIK/inlay and simultaneous PRK/inlay was performed on 79 and 47 patients, respectively. Follow-up examinations were conducted at 1, 3, and 6 months postoperatively. The main outcome measures were safety, efficacy, predictability, and stability with primary emphasis on monocular uncorrected near visual acuity (UNVA). Both groups met U.S. Food and Drug Administration criteria for efficacy with 95% and 55% of the LASIK/inlay group and 83% and 52% of the PRK/inlay group having a monocular UNVA of 20/40 (J5) and 20/25 (J2), respectively, at 6-month follow-up. Ninety-two percent of the LASIK/inlay group and 95% of the PRK/inlay group had a UDVA of 20/40 or better at 6 months. Two eyes lost one line of corrected distance visual acuity (CDVA). Mild hyperopic shift was noted in both groups at 6 months. Simultaneous PRK/inlay and LASIK/inlay meet the U.S. Food and Drug Administration standards for efficacy and safety based on 6-month preliminary results and have similar outcomes to emmetropic eyes. [J Refract Surg. 2018;34(5):310-315.]. Copyright 2018, SLACK Incorporated.

Monocular channels have a functional role in endogenous orienting.

Science.gov (United States)

Saban, William; Sekely, Liora; Klein, Raymond M; Gabay, Shai

2018-03-01

The literature has long emphasized the role of higher cortical structures in endogenous orienting. Based on evolutionary explanation and previous data, we explored the possibility that lower monocular channels may also have a functional role in endogenous orienting of attention. Sensitive behavioral manipulation was used to probe the contribution of monocularly segregated regions in a simple cue - target detection task. A central spatially informative cue, and its ensuing target, were presented to the same or different eyes at varying cue-target intervals. Results indicated that the onset of endogenous orienting was apparent earlier when the cue and target were presented to the same eye. The data provides converging evidence for the notion that endogenous facilitation is modulated by monocular portions of the visual stream. This, in turn, suggests that higher cortical mechanisms are not exclusively responsible for endogenous orienting, and that a dynamic interaction between higher and lower neural levels, might be involved. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparação entre acuidade visual e photoscreening como métodos de triagem visual para crianças em idade escolar Comparison between visual acuity and photoscreening used like visual screening methods for scholar aged children

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Roberta Lílian Fernandes de Sousa

2012-12-01

Full Text Available OBJETIVO: Avaliar a sensibilidade do aparelho photoscreener na detecção de alterações oculares em crianças informantes, comparando os dados à acuidade visual obtida pela tabela E de Snellen. MÉTODOS: Foram avaliadas 500 crianças de idades entre 5 e 12 anos, de escola do município de Botucatu, estado de São Paulo. As crianças foram submetidas ao teste de acuidade visual pela tabela E de Snellen e foram fotografadas utilizando-se o aparelho photoscreenerTM system model MTI-PS100, seguindo-se a análise das fotos obtidas. RESULTADOS: Houve concordância negativa (criança com boa acuidade visual e teste negativo com o photoscreener em 81,0%; concordância positiva (acuidade visual alterada e teste positivo em 7,6% e não houve concordância de resultados em 11,0% dos casos. CONCLUSÃO: A avaliação comparativa entre o método da acuidade visual pela tabela E de Snellen e o photocreener para detecção de problemas visuais mostrou alta concordância. Os autores sugerem entretanto, a triagem usando tabelas de acuidade visual quando se trata de crianças informantes, devido aos custos com o aparelho.PURPOSE: To evaluate the sensitivity of the photoscreener equipment to detect ocular changes in informative children comparing with the data obtained by the E Snellen´s table. METHODS: We evaluated 500 children between 5 and 12 years old, from a school of Botucatu city, São Paulo state. The children were submitted to a visual acuity test using the Snellen´s E Table and were photographed with the photoscreenerTM system model MTI-PS100, following the photos' analyze. RESULTS: There were negative agreement (children with a good visual acuity and a negative test with the Photoscreener in 81.0%; positive agreement (children without a good visual acuity and a positive test in 7.6% and there was no agreement of the results in 11.0% (9 of the cases. CONCLUSION: The comparative analysis between the visual acuity test using the Snellen's E table and

Comparison of the Lea Symbols and HOTV charts for preschool vision screening from age 3 to 4.5 years old

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Ya-Hui Zhang

2014-12-01

Full Text Available AIM: To evaluate the applicability and the development of the normal visual acuity from age 3 to 3.5 years using Lea Symbols and HOTV charts.METHODS: It was a survey research study. Totally, 133 preschoolers(266 eyesbetween 3 to 4.5 years old recruited from two kid-gardens in Guangzhou were tested with both the Lea Symbols chart and the HOTV chart. Outcome measures were monocular logarithm of the minimum angle of resolution(logMARvisual acuity and inter-eye acuity difference in logMAR units for each test. RESULTS: The testability rates of the two charts were high(96.24% vs 92.48%, respectively, but difference was not statistically significant(P>0.05. The difference between the two kind of monocular vision was not statistically significant(the right eye: t=0.517, P=0.606; the left eye: t=-0.618, P=0.538. There was no significant difference between different eye(Lea Symbols chart: t=0.638, P=0.525; HOTV chart: t=-0.897, P=0.372. The visual acuities of the boys were better than those of the girls, but the difference was not statistically significant(P>0.05. The results which came from visual acuities with the two charts for the corresponding age groups(3-year-old group, 3.5-year-old group, 4-year-old group, 4.5-year-old groupindicated that the visual acuities of the preschoolers were improving with increasing age, but the difference among the visual acuities with the Lea Symbols chart was not statistically significant(the right eye: F=2.662, P=0.052; the left eye: F=1.850, P=0.143. However the difference among the visual acuities with the HOTV chart was statistically significant(the right eye: F=4.518, P=0.005; the left eye: F=3.893, P=0.011.CONCLUSION: Both Lea Symbols and HOTV chars are accepted and appropriate for preschool vision screening from 3 to 4.5 years old. The monocular visual acuity of preschoolers from age 3 to 4.5 years could be assessed was similar using the two charts. There is no correlation between visual acuity and different eye

Near-field visual acuity of pigeons: effects of head location and stimulus luminance.

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Hodos, W; Leibowitz, R W; Bonbright, J C

1976-03-01

Two pigeons were trained to discriminate a grating stimulus from a blank stimulus of equivalent luminance in a three-key chamber. The stimuli and blanks were presented behind a transparent center key. The procedure was a conditional discrimination in which pecks on the left key were reinforced if the blank had been present behind the center key and pecks on the right key were reinforced if the grating had been present behind the center key. The spatial frequency of the stimuli was varied in each session from four to 29.5 lines per millimeter in accordance with a variation of the method of constant stimuli. The number of lines per millimeter that the subjects could discriminate at threshold was determined from psychometric functions. Data were collected at five values of stimulus luminance ranging from--0.07 to 3.29 log cd/m2. The distance from the stimulus to the anterior nodal point of the eye, which was determined from measurements taken from high-speed motion-picture photographs of three additional pigeons and published intraocular measurements, was 62.0 mm. This distance and the grating detection thresholds were used to calculate the visual acuity of the birds at each level of luminance. Acuity improved with increasing luminance to a peak value of 0.52, which corresponds to a visual angle of 1.92 min, at a luminance of 2.33 log cd/m2. Further increase in luminance produced a small decline in acuity.

Clinical profile and visual outcome of ocular injuries in a rural area of western India.

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Misra, Somen; Nandwani, Rupali; Gogri, Pratik; Misra, Neeta

2013-01-01

Ocular trauma is a major cause of visual impairment and morbidity worldwide. To identify the various type of ocular injury in a rural area, determine the presence of any associated visual damage and assess the final visual outcome after treatment. Hospital-based, prospective study conducted over a period of two years. A total of 60 patients of ocular trauma were included. Ocular injuries were more commonly seen in adult (55 per cent) patients who were associated with agricultural work (43.33 per cent). They were more common in male patients (71.67 per cent). Closed globe injury (68.33 per cent) was more common than open globe injury (31.67 per cent). Both in open and closed globe injuries, the commonest object causing injury was a wooden stick. Just 26.7 per cent of the patients had a visual acuity better than 6/60 at presentation; while after completed treatment at two months follow-up, 68.3 per cent had best corrected visual acuity better than 6/60. Agricultural trauma is an important cause of monocular blindness in rural India. The visual outcome depends upon the site and size of the injury and the extent of the ocular damage.

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

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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

How well do you see what you hear? The acuity of visual-to-auditory sensory substitution

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Alastair eHaigh

2013-06-01

Full Text Available Sensory substitution devices (SSDs aim to compensate for the loss of a sensory modality, typically vision, by converting information from the lost modality into stimuli in a remaining modality. The vOICe is a visual-to-auditory SSD which encodes images taken by a camera worn by the user into soundscapes such that an experienced user can extract information about their surroundings. Here we investigated how much detail was resolvable during the early induction stages by testing the acuity of blindfolded sighted, naïve vOICe users. Initial performance was well above chance. Participants who took the test twice as a form of minimal training showed a marked improvement on the second test. Acuity was slightly but not significantly impaired when participants wore a camera and judged letter orientations live. A positive correlation was found between participants’ musical training and their acuity. The relationship between auditory expertise via musical training and the lack of a relationship with visual imagery, suggests that early use of a sensory substitution device draws primarily on the mechanisms of the sensory modality being used rather than the one being substituted. If vision is lost, audition represents the sensory channel of highest bandwidth of those remaining. The level of acuity found here, and the fact it was achieved with very little experience in sensory substitution by naïve users is promising.

Prism therapy and visual rehabilitation in homonymous visual field loss.

LENUS (Irish Health Repository)

O'Neill, Evelyn C

2011-02-01

Homonymous visual field defects (HVFD) are common and frequently occur after cerebrovascular accidents. They significantly impair visual function and cause disability particularly with regard to visual exploration. The purpose of this study was to assess a novel interventional treatment of monocular prism therapy on visual functioning in patients with HVFD of varied etiology using vision targeted, health-related quality of life (QOL) questionnaires. Our secondary aim was to confirm monocular and binocular visual field expansion pre- and posttreatment.

Monocular Elevation Deficiency - Double Elevator Palsy

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... Español Condiciones Chinese Conditions Monocular Elevation Deficiency/ Double Elevator Palsy En Español Read in Chinese What is monocular elevation deficiency (Double Elevator Palsy)? Monocular Elevation Deficiency, also known by the ...

Macular edema in Asian Indian premature infants with retinopathy of prematurity: Impact on visual acuity and refractive status after 1-year

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Anand Vinekar

2015-01-01

Full Text Available Purpose: To report the impact of transient, self-resolving, untreated "macular edema" detected on spectral domain optical coherence tomography in Asian Indian premature infants with retinopathy of prematurity (ROP on visual acuity (VA and refraction at 1-year of corrected age. Materials and Methods: Visual acuity and refraction of 11 infants with bilateral macular edema (Group A was compared with gestational age-matched 16 infants with ROP without edema (Group B and 17 preterms infants without ROP and without edema (Group C at 3, 6, 9 and 12 months of corrected age using Teller Acuity Cards and cycloplegic retinoscopy. Sub-group analysis of the previously described pattern A and B macular edema was performed. Results: Visual acuity was lower in infants with macular edema compared with the other two control groups throughout the study period, but statistically significant only at 3 months. Visual improvement in these infants was highest between the 3 rd and 6 th month and plateaued by the end of the 1 st year with acuity comparable to the other two groups. The edema cohort was more hyperopic compared to the other two groups between 3 and 12 months of age. Pattern A edema had worse VA compared to pattern B, although not statistically significant. Conclusion: Macular edema, although transient, caused reduced VA as early as 3 months of corrected age in Asian Indian premature infants weighing <2000 g at birth. The higher hyperopia in these infants is possibly due to visual disturbances caused at a critical time of fovealization. We hypothesize a recovery and feedback mechanism based on the principles of active emmetropization to explain our findings.

Cooperative Monocular-Based SLAM for Multi-UAV Systems in GPS-Denied Environments.

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Trujillo, Juan-Carlos; Munguia, Rodrigo; Guerra, Edmundo; Grau, Antoni

2018-04-26

This work presents a cooperative monocular-based SLAM approach for multi-UAV systems that can operate in GPS-denied environments. The main contribution of the work is to show that, using visual information obtained from monocular cameras mounted onboard aerial vehicles flying in formation, the observability properties of the whole system are improved. This fact is especially notorious when compared with other related visual SLAM configurations. In order to improve the observability properties, some measurements of the relative distance between the UAVs are included in the system. These relative distances are also obtained from visual information. The proposed approach is theoretically validated by means of a nonlinear observability analysis. Furthermore, an extensive set of computer simulations is presented in order to validate the proposed approach. The numerical simulation results show that the proposed system is able to provide a good position and orientation estimation of the aerial vehicles flying in formation.

Examination of factors affecting gait properties in healthy older adults: focusing on knee extension strength, visual acuity, and knee joint pain.

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Demura, Tomohiro; Demura, Shin-ichi; Uchiyama, Masanobu; Sugiura, Hiroki

2014-01-01

Gait properties change with age because of a decrease in lower limb strength and visual acuity or knee joint disorders. Gait changes commonly result from these combined factors. This study aimed to examine the effects of knee extension strength, visual acuity, and knee joint pain on gait properties of for 181 healthy female older adults (age: 76.1 (5.7) years). Walking speed, cadence, stance time, swing time, double support time, step length, step width, walking angle, and toe angle were selected as gait parameters. Knee extension strength was measured by isometric dynamometry; and decreased visual acuity and knee joint pain were evaluated by subjective judgment whether or not such factors created a hindrance during walking. Among older adults without vision problems and knee joint pain that affected walking, those with superior knee extension strength had significantly greater walking speed and step length than those with inferior knee extension strength (P pain in both knees showed slower walking speed and longer stance time and double support time. A decrease of knee extension strength and visual acuity and knee joint pain are factors affecting gait in the female older adults. Decreased knee extension strength and knee joint pain mainly affect respective distance and time parameters of the gait.

Visual impairment secondary to congenital glaucoma in children: visual responses, optical correction and use of low vision AIDS

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Maria Aparecida Onuki Haddad

2009-01-01

Full Text Available INTRODUCTION: Congenital glaucoma is frequently associated with visual impairment due to optic nerve damage, corneal opacities, cataracts and amblyopia. Poor vision in childhood is related to global developmental problems, and referral to vision habilitation/rehabilitation services should be without delay to promote efficient management of the impaired vision. OBJECTIVE: To analyze data concerning visual response, the use of optical correction and prescribed low vision aids in a population of children with congenital glaucoma. METHOD: The authors analyzed data from 100 children with congenital glaucoma to assess best corrected visual acuity, prescribed optical correction and low vision aids. RESULTS: Fifty-five percent of the sample were male, 43% female. The mean age was 6.3 years. Two percent presented normal visual acuity levels, 29% mild visual impairment, 28% moderate visual impairment, 15% severe visual impairment, 11% profound visual impairment, and 15% near blindness. Sixty-eight percent received optical correction for refractive errors. Optical low vision aids were adopted for distance vision in 34% of the patients and for near vision in 6%. A manual monocular telescopic system with 2.8 × magnification was the most frequently prescribed low vision aid for distance, and for near vision a +38 diopter illuminated stand magnifier was most frequently prescribed. DISCUSSION AND CONCLUSION: Careful low vision assessment and the appropriate prescription of optical corrections and low vision aids are mandatory in children with congenital glaucoma, since this will assist their global development, improving efficiency in daily life activities and promoting social and educational inclusion.

Temporary marked impairment of visual acuity in a case of intraocular malignant lymphoma during radiation therapy

International Nuclear Information System (INIS)

Miyao, Yoko; Tada, Rei; Koizumi, Noriko; Yamada, Hideaki; Kinoshita, Shigeru; Ikeda, Tsunehiko

2000-01-01

A 56-year-old female was referred to us for blurring of both eyes since 2 years before. She had been diagnosed as chronic uveitis and responded poorly to systemic and topical corticosteroid. Her corrected visual acuity was 0.8 right and 0.5 left. Systemic studies, including magnetic resonance imaging and gadolinium scintigraphy, were negative. Vitreous biopsy led to the diagnosis of malignant lymphoma originating from the eye. Seven days after initiation of radiation at the daily doses of 2 Gy, massive subretinal infiltration developed in her right eye forming a niveau. Systemic prednisolone induced resolution of exudate with improved visual acuity to 1.0 13 days later. This cases illustrates that radiation may induce temporary aggravation of intraocular malignant lymphoma and that it may undergo resolution following systemic corticosteroid. (author)

Monocular Perceptual Deprivation from Interocular Suppression Temporarily Imbalances Ocular Dominance.

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Kim, Hyun-Woong; Kim, Chai-Youn; Blake, Randolph

2017-03-20

Early visual experience sculpts neural mechanisms that regulate the balance of influence exerted by the two eyes on cortical mechanisms underlying binocular vision [1, 2], and experience's impact on this neural balancing act continues into adulthood [3-5]. One recently described, compelling example of adult neural plasticity is the effect of patching one eye for a relatively short period of time: contrary to intuition, monocular visual deprivation actually improves the deprived eye's competitive advantage during a subsequent period of binocular rivalry [6-8], the robust form of visual competition prompted by dissimilar stimulation of the two eyes [9, 10]. Neural concomitants of this improvement in monocular dominance are reflected in measurements of brain responsiveness following eye patching [11, 12]. Here we report that patching an eye is unnecessary for producing this paradoxical deprivation effect: interocular suppression of an ordinarily visible stimulus being viewed by one eye is sufficient to produce shifts in subsequent predominance of that eye to an extent comparable to that produced by patching the eye. Moreover, this imbalance in eye dominance can also be induced by prior, extended viewing of two monocular images differing only in contrast. Regardless of how shifts in eye dominance are induced, the effect decays once the two eyes view stimuli equal in strength. These novel findings implicate the operation of interocular neural gain control that dynamically adjusts the relative balance of activity between the two eyes [13, 14]. Copyright © 2017 Elsevier Ltd. All rights reserved.

SLAMM: Visual monocular SLAM with continuous mapping using multiple maps.

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Hayyan Afeef Daoud

Full Text Available This paper presents the concept of Simultaneous Localization and Multi-Mapping (SLAMM. It is a system that ensures continuous mapping and information preservation despite failures in tracking due to corrupted frames or sensor's malfunction; making it suitable for real-world applications. It works with single or multiple robots. In a single robot scenario the algorithm generates a new map at the time of tracking failure, and later it merges maps at the event of loop closure. Similarly, maps generated from multiple robots are merged without prior knowledge of their relative poses; which makes this algorithm flexible. The system works in real time at frame-rate speed. The proposed approach was tested on the KITTI and TUM RGB-D public datasets and it showed superior results compared to the state-of-the-arts in calibrated visual monocular keyframe-based SLAM. The mean tracking time is around 22 milliseconds. The initialization is twice as fast as it is in ORB-SLAM, and the retrieved map can reach up to 90 percent more in terms of information preservation depending on tracking loss and loop closure events. For the benefit of the community, the source code along with a framework to be run with Bebop drone are made available at https://github.com/hdaoud/ORBSLAMM.

Comparison between OPD-Scan results and visual outcomes of monofocal and multifocal intraocular lenses Comparação dos resultados do OPD-Scan e performance visual das lentes intraoculares monofocal e multifocal

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Wilson Takashi Hida

2009-08-01

Full Text Available PURPOSE: To compare the visual outcome, contrast sensitivity and wavefront analysis of patients that underwent cataract surgery and implantation of AcrySof SN60D3 multifocal intraocular lens with those who received the AcrySof SN60AT monofocal IOL. METHODS: This was a prospective clinical trial of forty eyes that received the multifocal IOL and thirty-two eyes that received the monofocal IOL after phacoemulsification. RESULTS: Values for total and spherical aberrations in the multifocal group were statistically lower than in the monofocal group. In the monofocal group, 75% achieved uncorrected intermediate visual acuities between Jaeger 1 and 6. In the multifocal group, 75% of the eyes achieved more than Jaeger 6. At least 87.5% of the multifocal group and 6.3% of the monofocal group achieved monocular uncorrected near acuity of 20/30 (J2, N5 or better. And 90.0% of the eyes in the multifocal group and 37.5% in the monofocal group achieved an uncorrected near acuity of 20/40 (J3, N6 or better. The mean spherical error was 0.11 D in the multifocal group and -0.18 D in the monofocal group (p=0.0379. The SN60D3 group compared to SN60AT group had low contrast sensitivity (log units with statistically significant differences in 6.0 cpd in photopic conditions (p=0.014 and the SN60D3 group compared to SN60AT group had higher contrast sensitivity (log units under mesopic conditions (p=0.044. CONCLUSION: The multifocal IOLs induced less spherical aberration than monofocal IOLs and predictably good uncorrected distance and uncorrected near acuities. However, contrast sensitivity was lower in the multifocal group.OBJETIVO: Comparar a performance visual, sensibilidade ao contraste e de wavefront com OPD-Scan em pacientes submetidos a cirurgia de facoemulsificação com implante de lente intraocular AcrySof SN60D3 multifocal e AcrySof SA60AT monofocal. MÉTODOS: Quarenta olhos com a lente intraocular multifocal e trinta e dois olhos com a lente intraocular

Effects of Milk vs Dark Chocolate Consumption on Visual Acuity and Contrast Sensitivity Within 2 Hours: A Randomized Clinical Trial.

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Rabin, Jeff C; Karunathilake, Nirmani; Patrizi, Korey

2018-04-26

Consumption of dark chocolate can improve blood flow, mood, and cognition in the short term, but little is known about the possible effects of dark chocolate on visual performance. To compare the short-term effects of consumption of dark chocolate with those of milk chocolate on visual acuity and large- and small-letter contrast sensitivity. A randomized, single-masked crossover design was used to assess short-term visual performance after consumption of a dark or a milk chocolate bar. Thirty participants without pathologic eye disease each consumed dark and milk chocolate in separate sessions, and within-participant paired comparisons were used to assess outcomes. Testing was conducted at the Rosenberg School of Optometry from June 25 to August 15, 2017. Visual acuity (in logMAR units) and large- and small-letter contrast sensitivity (in the log of the inverse of the minimum detectable contrast [logCS units]) were measured 1.75 hours after consumption of dark and milk chocolate bars. Among the 30 participants (9 men and 21 women; mean [SD] age, 26 [5] years), small-letter contrast sensitivity was significantly higher after consumption of dark chocolate (mean [SE], 1.45 [0.04] logCS) vs milk chocolate (mean [SE], 1.30 [0.05] logCS; mean improvement, 0.15 logCS [95% CI, 0.08-0.22 logCS]; P chocolate (mean [SE], 2.05 [0.02] logCS) vs milk chocolate (mean [SE], 2.00 [0.02] logCS; mean improvement, 0.05 logCS [95% CI, 0.00-0.10 logCS]; P = .07). Visual acuity improved slightly after consumption of dark chocolate (mean [SE], -0.22 [0.01] logMAR; visual acuity, approximately 20/12) and milk chocolate (mean [SE], -0.18 [0.01] logMAR; visual acuity, approximately 20/15; mean improvement, 0.04 logMAR [95% CI, 0.02-0.06 logMAR]; P = .05). Composite scores combining results from all tests showed significant improvement after consumption of dark compared with milk chocolate (mean improvement, 0.20 log U [95% CI, 0.10-0.30 log U]; P chocolate bar compared with a

The Joint Effects of Spatial Cueing and Transcranial Direct Current Stimulation on Visual Acuity

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Taly Bonder

2018-02-01

Full Text Available The present study examined the mutual influence of cortical neuroenhancement and allocation of spatial attention on perception. Specifically, it explored the effects of transcranial Direct Current Stimulation (tDCS on visual acuity measured with a Landolt gap task and attentional precues. The exogenous cues were used to draw attention either to the location of the target or away from it, generating significant performance benefits and costs. Anodal tDCS applied to posterior occipital area for 15 min improved performance during stimulation, reflecting heightened visual acuity. Reaction times were lower, and accuracy was higher in the tDCS group, compared to a sham control group. Additionally, in post-stimulation trials tDCS significantly interacted with the effect of precuing. Reaction times were lower in valid cued trials (benefit and higher in invalid trials (cost compared to neutrally cued trials, the effect which was pronounced stronger in tDCS group than in sham control group. The increase of cost and benefit effects in the tDCS group was of a similar magnitude, suggesting that anodal tDCS influenced the overall process of attention orienting. The observed interaction between the stimulation of the visual cortex and precueing indicates a magnification of attention modulation.

Amblyopia after unilateral infantile cataract extraction after six weeks of age Ambliopia no pós-operatório de catarata congênita unilateral operada após seis semanas de vida

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Fábio Ejzenbaum

2009-10-01

Full Text Available PURPOSE: To determine interocular grating acuity difference in children treated for unilateral infantile cataract. METHODS: A group of 27 children previously treated for unilateral infantile cataract, had their monocular visual acuity measured by sweep visual evoked potentials. Interocular grating acuity difference was calculated as the absolute subtraction of monocular acuity scores. Lens status, opacity severity and eye alignment were considered for analysis. RESULTS: Mean interocular grating acuity difference obtained from unilateral cataract patients was 0.58 ± 0.20 logMAR. This result was significantly larger than 0.10 logMAR used as normative data. Children with severe opacities had a more pronounced amblyopia than the moderate ones. No significant correlation between amblyopia and strabismus or aphakia was found. CONCLUSIONS: Interocular acuity difference in this group of unilateral congenital cataract was more pronounced than previous reports, mainly because of delay in diagnosis, surgery and optical correction.OBJETIVOS: Determinar a diferença interocular da acuidade visual de resolução de grades em crianças operadas de catarata congênita unilateral. MÉTODOS: Um grupo de 27 pacientes operados de catarata congênita unilateral tiveram mensurada sua acuidade visual monocular pelo potencial visual evocado de varredura. A diferença interocular foi calculada pela subtração absoluta das acuidades monoculares. A intensidade da opacificação, implante ou não de lente intraocular e presença de estrabismo foram consideradas para análise. RESULTADOS: A média da diferença interocular foi de 0,58 ± 0,20 logMAR. Esse resultado foi significantemente maior que 0,10 logMAR, valor considerado como média normal nos estudos normativos. Crianças com opacidades intensas tiveram ambliopia mais pronunciada que os casos moderados. Não houve correlação significante entre a intensidade da ambliopia com estrabismo e afacia. CONCLUSÕES: A

Lawn mower injuries as a cause of serious visual acuity impairment – Case reports

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Monika Jasielska

2017-05-01

Lawn mower induced eye injuries are a significant cause of serious visual acuity impairment or blindness. The presented study shows that lawn mower eye injuries are still a therapeutic, social and economic problem, yet are very preventable with proper eye protection and patients’ education. Current prevention strategies are inadequate, and therefore should be updated.

PROSPECTIVE EVALUATION OF VISUAL ACUITY AGREEMENT BETWEEN STANDARD EARLY TREATMENT DIABETIC RETINOPATHY STUDY CHART AND A HANDHELD EQUIVALENT IN EYES WITH RETINAL PATHOLOGY.

Science.gov (United States)

Rahimy, Ehsan; Reddy, Sahitya; DeCroos, Francis Char; Khan, M Ali; Boyer, David S; Gupta, Omesh P; Regillo, Carl D; Haller, Julia A

2015-08-01

To evaluate the visual acuity agreement between a standard back-illuminated Early Treatment Diabetic Retinopathy Study (ETDRS) chart and a handheld internally illuminated ETDRS chart. Two-center prospective study. Seventy patients (134 eyes) with retinal pathology were enrolled between October 2012 and August 2013. Visual acuity was measured using both the ETDRS chart and the handheld device by masked independent examiners after best protocol refraction. Examination was performed in the same room under identical illumination and testing conditions. The mean number of letters seen was 63.0 (standard deviation: 19.8 letters) and 61.2 letters (standard deviation: 19.1 letters) for the ETDRS chart and handheld device, respectively. Mean difference per eye between the ETDRS and handheld device was 1.8 letters. A correlation coefficient (r) of 0.95 demonstrated a positive linear correlation between ETDRS chart and handheld device measured acuities. Intraclass correlation coefficient was performed to assess the reproducibility of the measurements made by different observers measuring the same quantity and was calculated to be 0.95 (95% confidence interval: 0.93-0.96). Agreement was independent of retinal disease. The strong correlation between measured visual acuity using the ETDRS and handheld equivalent suggests that they may be used interchangeably, with accurate measurements. Potential benefits of this device include convenience and portability, as well as the ability to assess ETDRS visual acuity without a dedicated testing lane.

The role of visual acuity and segmentation cues in compound word identification

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Jukka eHyönä

2012-06-01

Full Text Available Studies are reviewed that demonstrate how the foveal area of the eye constrains how compound words are identified during reading. When compound words are short, their letters can be identified during a single fixation, leading to the whole-word route dominating word recognition from early on. Hence, visually marking morpheme boundaries by hyphens slows down processing by encouraging morphological decomposition when holistic processing is a feasible option. In contrast, the decomposition route dominates the early stages of identifying long compound words. Thus, visual marking of morpheme boundaries facilitates processing of long compound words, unless the initial fixation made on the word lands very close to the morpheme boundary. The reviewed pattern of results is explained by the visual acuity principle (Bertram & Hyönä, 2003 and the dual-route framework of morphological processing.

A contralateral eye study comparing apodized diffrative and full diffrative lenses: wavefront analysis and distance and near uncorrected visual acuity

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Marcony Rodrigues de Santhiago

2009-01-01

Full Text Available PURPOSE: To evaluate intraindividual visual acuity, wavefront errors and modulation transfer functions in patients implanted with two diffractive multifocal intraocular lenses. METHODS: This prospective study examined 40 eyes of 20 cataract patients who underwent phacoemulsification and implantation of a spherical multifocal ReSTOR intraocular lens in one eye and an aspheric Tecnis ZM900 multifocal intraocular lens in the other eye. The main outcome measures, over a 3-month follow-up period, were the uncorrected photopic distance and near visual acuity and the defocus curve. The visual acuity was converted to logMAR for statistical analysis and is presented in decimal scale. The wavefront error and modulation transfer function were also evaluated in both groups. RESULTS: At the 3-month postoperative visit, the mean photopic distance uncorrected visual acuity (UCVA was 0.74 ± 0.20 in the ReSTOR group and 0.76 ± 0.22 in the Tecnis group (p=0.286. The mean near UCVA was 0.96 ± 0.10 in the ReSTOR group and 0.93 ± 0.14 in the Tecnis group (p=0.963. The binocular defocus curve showed measurements between the peaks better than 0.2 logMAR. The total aberration, higher-order aberration and coma aberration were not significantly different between the groups. The spherical aberration was significantly lower in the Tecnis group than in the ReSTOR group. (p=0.004. Both groups performed similarly for the modulation transfer function. CONCLUSION: The ReSTOR SN60D3 and Tecnis ZM 900 intraocular lenses provided similar photopic visual acuity at distance and near. The diffractive intraocular lenses studied provided a low value of coma and spherical aberrations, with the Tecnis intraocular lens having a statistically lower spherical aberration compared to the ReSTOR intraocular lens. In the 5 mm pupil diameter analyses, both intraocular lens groups showed similar modulation transfer functions.

COMPARISON OF VISUAL ACUITY IN REDUCED LUMINATION AND FACILITY OF OCULAR ACCOMMODATION IN TABLE TENNIS CHAMPIONS AND NON- PLAYERS

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Ebrahim Jafarzadehpur

2004-03-01

Full Text Available A table tennis player should fixate at different distances; track the objects with different speed, and in different visual environment. Their visual skills must be well developed for these capabilities. Therefore, visual acuity in reduced lumination and facility of ocular accommodation those are two criteria for visual skills have been compared in table tennis players and normal non-players. Twenty-nine young table tennis champions and 29 normal matched non-players (did not take part in any racket sports game were evaluated. Basic visual and eye examinations were done for both of them. Normal results in basic examination were fundamental requirement for all the subjects. +/-2.00 sphere lenses for accommodation facility are used. An electrical current regulator changed the output light intensity of a conventional chart projector (Topcon. Light intensity decreased to 10 cd·m-2 and visual acuity tested. In comparison of visual acuity in reduced lumination and facility of ocular accommodation in table tennis champions and non-players there are significant differences (p < 0.001. In the preliminary visual tests there was not any significant different in the two groups but the results in the top level table tennis player was very uniform and in every test and the standard deviation was lesser in tennis player group than non-players. These results show that motor and sensorial functions of expert players are well developed. That is consistent with other researchers. This result was interpreted as reflecting a better perceptual system of experts to the constraints encountered during table tennis and its use in practical settings for evaluating athletes or detecting sport talents. However some visual and perceptual training that usually used in orthoptics can be used for novice table tennis player to improve their abilities

Long-Term Visual Training Increases Visual Acuity and Long-Term Monocular Deprivation Promotes Ocular Dominance Plasticity in Adult Standard Cage-Raised Mice

OpenAIRE

Hosang, Leon; Yusifov, Rashad; Löwel, Siegrid

2018-01-01

Abstract For routine behavioral tasks, mice predominantly rely on olfactory cues and tactile information. In contrast, their visual capabilities appear rather restricted, raising the question whether they can improve if vision gets more behaviorally relevant. We therefore performed long-term training using the visual water task (VWT): adult standard cage (SC)-raised mice were trained to swim toward a rewarded grating stimulus so that using visual information avoided excessive swimming toward ...

CLINICAL PRESENTATION OF LENS INDUCED GLAUCOMA: STUDY OF EPIDEMIOLOGY, DURATION OF SYMPTOMS, INTRAOCULAR PRESSURE AND VISUAL ACUITY

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Venkataratnam

2015-10-01

Full Text Available BACKGROUND: Lens Induced Glaucoma is a common cause of ocular morbidity. OBJECTIVES: Our study was to know the Epidemiological factors, Duration of Symptoms, Visual Acuity and Intraocular Pressure in the clinical Presentation of Lens Induced Glaucoma. MATERIALS AND METHODS : This w as a tertiary hospital based prospective study in the department of Glaucoma, Sarojini Devi Eye Hospital and Regional Institute of Ophthalmology (RIO, Osmania Medical College, Hyderabad over a period from March 2015 to August 2015. 50 Patients clinically diagnosed as Lens Induced Glaucoma (LIG were studied with the data of Age, Sex, literacy, Laterality and Rural / Urban status with the duration of symptoms, Intraocular pressure and Visual Acuity. The data was analyzed by simple statistical methods. RESULT S: 50 patients, clinically diagnosed as Lens Induced Glaucoma (LIG were studied. Age group distribution was 1(2.0% in 40 - 50yrs, 13 ( 26.0% in >50 - 60yrs, 26(52.0% in >60 - 70yrs and 10(20.0% in > 70 yrs. Sex distribution was 23(46.0% of Males and 27(54.0% of Females. Urban / Rural status was 15(30.0% of Urban and 35(70.0% of Rural. Literacy status was 7(14.0% of Literate and 43(86.0% of Illiterate. Laterality was RE in 24(48.0% and LE in 26(52.0%. Duration of the presenting symptoms before re porting to the Hospital was 12.0% in 2wks. Intraocular pressure (IOP in mm of Hg showed no case (0.0% in 20 – 40, 27(54.0% in >40 - 60 and 5(10.0% >60 wit h the Mean IOP of 42.12 mm of Hg. Visual Acuity (VA was PL +ve in 24(48.0 and HM - 3/60. CONCLUSIONS: Increasing age, female gender, rural, illiterate, and delayed reporting to the hospital after the pre senting symptoms were the common risk factors with increased Intraocular pressure and poor visual acuity in the clinical presentation of Lens induced Glaucoma.

Amblyopia and Binocular Vision

OpenAIRE

Birch, Eileen E.

2012-01-01

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3% to 3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of bin...

Localisation accuracy of semi-dense monocular SLAM

Science.gov (United States)

Schreve, Kristiaan; du Plessies, Pieter G.; Rätsch, Matthias

2017-06-01

Understanding the factors that influence the accuracy of visual SLAM algorithms is very important for the future development of these algorithms. So far very few studies have done this. In this paper, a simulation model is presented and used to investigate the effect of the number of scene points tracked, the effect of the baseline length in triangulation and the influence of image point location uncertainty. It is shown that the latter is very critical, while the other all play important roles. Experiments with a well known semi-dense visual SLAM approach are also presented, when used in a monocular visual odometry mode. The experiments shows that not including sensor bias and scale factor uncertainty is very detrimental to the accuracy of the simulation results.

Monocular deprivation of Fourier phase information boosts the deprived eye's dominance during interocular competition but not interocular phase combination.

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Bai, Jianying; Dong, Xue; He, Sheng; Bao, Min

2017-06-03

Ocular dominance has been extensively studied, often with the goal to understand neuroplasticity, which is a key characteristic within the critical period. Recent work on monocular deprivation, however, demonstrates residual neuroplasticity in the adult visual cortex. After deprivation of patterned inputs by monocular patching, the patched eye becomes more dominant. Since patching blocks both the Fourier amplitude and phase information of the input image, it remains unclear whether deprivation of the Fourier phase information alone is able to reshape eye dominance. Here, for the first time, we show that removing of the phase regularity without changing the amplitude spectra of the input image induced a shift of eye dominance toward the deprived eye, but only if the eye dominance was measured with a binocular rivalry task rather than an interocular phase combination task. These different results indicate that the two measurements are supported by different mechanisms. Phase integration requires the fusion of monocular images. The fused percept highly relies on the weights of the phase-sensitive monocular neurons that respond to the two monocular images. However, binocular rivalry reflects the result of direct interocular competition that strongly weights the contour information transmitted along each monocular pathway. Monocular phase deprivation may not change the weights in the integration (fusion) mechanism much, but alters the balance in the rivalry (competition) mechanism. Our work suggests that ocular dominance plasticity may occur at different stages of visual processing, and that homeostatic compensation also occurs for the lack of phase regularity in natural scenes. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Distributed Monocular SLAM for Indoor Map Building

OpenAIRE

Ruwan Egodagamage; Mihran Tuceryan

2017-01-01

Utilization and generation of indoor maps are critical elements in accurate indoor tracking. Simultaneous Localization and Mapping (SLAM) is one of the main techniques for such map generation. In SLAM an agent generates a map of an unknown environment while estimating its location in it. Ubiquitous cameras lead to monocular visual SLAM, where a camera is the only sensing device for the SLAM process. In modern applications, multiple mobile agents may be involved in the generation of such maps,...

Comparison on testability of visual acuity, stereo acuity and colour vision tests between children with learning disabilities and children without learning disabilities in government primary schools.

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Abu Bakar, Nurul Farhana; Chen, Ai-Hong

2014-02-01

Children with learning disabilities might have difficulties to communicate effectively and give reliable responses as required in various visual function testing procedures. The purpose of this study was to compare the testability of visual acuity using the modified Early Treatment Diabetic Retinopathy Study (ETDRS) and Cambridge Crowding Cards, stereo acuity using Lang Stereo test II and Butterfly stereo tests and colour perception using Colour Vision Test Made Easy (CVTME) and Ishihara's Test for Colour Deficiency (Ishihara Test) between children in mainstream classes and children with learning disabilities in special education classes in government primary schools. A total of 100 primary school children (50 children from mainstream classes and 50 children from special education classes) matched in age were recruited in this cross-sectional comparative study. The testability was determined by the percentage of children who were able to give reliable respond as required by the respective tests. 'Unable to test' was defined as inappropriate response or uncooperative despite best efforts of the screener. The testability of the modified ETDRS, Butterfly stereo test and Ishihara test for respective visual function tests were found lower among children in special education classes ( P learning disabilities. Modifications of vision testing procedures are essential for children with learning disabilities.

The (lack of) relation between straylight and visual acuity. Two domains of the point-spread-function

NARCIS (Netherlands)

van den Berg, Thomas J T P

2017-01-01

PURPOSE: The effect of cataract and other media opacities on functional vision is typically assessed clinically using visual acuity. In both clinical and basic research, straylight (the functional result of light scattering in the eye) is commonly measured. The purpose of the present study was to

Parafoveal magnification: visual acuity does not modulate the perceptual span in reading.

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Miellet, Sébastien; O'Donnell, Patrick J; Sereno, Sara C

2009-06-01

Models of eye guidance in reading rely on the concept of the perceptual span-the amount of information perceived during a single eye fixation, which is considered to be a consequence of visual and attentional constraints. To directly investigate attentional mechanisms underlying the perceptual span, we implemented a new reading paradigm-parafoveal magnification (PM)-that compensates for how visual acuity drops off as a function of retinal eccentricity. On each fixation and in real time, parafoveal text is magnified to equalize its perceptual impact with that of concurrent foveal text. Experiment 1 demonstrated that PM does not increase the amount of text that is processed, supporting an attentional-based account of eye movements in reading. Experiment 2 explored a contentious issue that differentiates competing models of eye movement control and showed that, even when parafoveal information is enlarged, visual attention in reading is allocated in a serial fashion from word to word.

Visual acuity, self-reported vision and falls in the EPIC-Norfolk Eye study

OpenAIRE

Yip, Jennifer L Y; Khawaja, Anthony P; Broadway, David; Luben, Robert; Hayat, Shabina; Dalzell, Nichola; Bhaniani, Amit; Wareham, Nicholas; Khaw, Kay-Tee; Foster, Paul J

2013-01-01

Purpose To examine the relationship between visual acuity (VA) and self-reported vision (SRV) in relation to falls in 8317 participants of the European Prospective Investigation into Cancer-Norfolk Eye study. Methods All participants completed a health questionnaire that included a question regarding SRV and questions regarding the number of falls in the past year. Distance VA was measured using a logMAR chart for each eye. Poor SRV was defined as those reporting fair or poor distance vision....

Monocular perceptual learning of contrast detection facilitates binocular combination in adults with anisometropic amblyopia

OpenAIRE

Chen, Zidong; Li, Jinrong; Liu, Jing; Cai, Xiaoxiao; Yuan, Junpeng; Deng, Daming; Yu, Minbin

2016-01-01

Perceptual learning in contrast detection improves monocular visual function in adults with anisometropic amblyopia; however, its effect on binocular combination remains unknown. Given that the amblyopic visual system suffers from pronounced binocular functional loss, it is important to address how the amblyopic visual system responds to such training strategies under binocular viewing conditions. Anisometropic amblyopes (n?=?13) were asked to complete two psychophysical supra-threshold binoc...

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

Science.gov (United States)

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

2016-11-01

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

Dysfunction in the fellow eyes of strabismic and anisometropic amblyopic children assessed by visually evoked potentials

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Eric Pinheiro Andrade

Full Text Available ABSTRACT Purpose: To evaluate visual acuity and transient pattern reversal (PR visual evoked potentials (VEPs in the fellow eyes of children with strabismic and/or anisometropic amblyopia. Methods: Children diagnosed with strabismic and/or anisometropic amblyopia were recruited for electrophysiological assessment by VEPs. Monocular grating and optotype acuity were measured using sweep-VEPs and an Early Treatment Diabetic Retinopathy Study chart, respectively. During the same visit, transient PR-VEPs of each eye were recorded using stimuli subtending with a visual angle of 60', 15', and 7.5'. Parameters of amplitude (in μV and latency (in ms were determined from VEP recordings. Results: A group of 40 strabismic and/or anisometropic amblyopic children (22 females: 55%, mean age= 8.7 ± 2.2 years, median= 8 years was examined. A control group of 19 healthy children (13 females: 68.4%, mean age= 8.2 ± 2.6 years, median= 8 years was also included. The fellow eyes of all amblyopes had significantly worse optotype acuity (p=0.021 than the control group, regardless of whether they were strabismic (p=0.040 or anisometropic (p=0.048. Overall, grating acuity was significantly worse in the fellow eyes of amblyopes (p=0.016 than in healthy controls. Statistically prolonged latency for visual angles of 15' and 7.5' (p=0.018 and 0.002, respectively was found in the strabismic group when compared with the control group. For the smaller visual stimulus (7.5', statistically prolonged latency was found among all fellow eyes of amblyopic children (p<0.001. Conclusions: The fellow eyes of amblyopic children showed worse optotype and grating acuity, with subtle abnormalities in the PR-VEP detected as prolonged latencies for smaller size stimuli when compared with eyes of healthy children. These findings show the deleterious effects of amblyopia in several distinct visual functions, mainly those related to spatial vision.

LASIK monocular en pacientes adultos con ambliopía por anisometropía

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Alejandro Tamez-Peña

2017-09-01

Conclusiones: La cirugía refractiva monocular en pacientes con ambliopía por anisometropía es una opción terapéutica segura y efectiva que ofrece resultados visuales satisfactorios, preservando o incluso mejorando la AVMC preoperatoria.

Refractive lens exchange with a multifocal diffractive aspheric intraocular lens

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Teresa Ferrer-Blasco

2012-06-01

Full Text Available PURPOSE: To evaluate the safety, efficacy and predictability after refractive lens exchange with multifocal diffractive aspheric intraocular lens implantation. METHODS: Sixty eyes of 30 patients underwent bilateral implantation with AcrySof® ReSTOR® SN6AD3 intraocular lens with +4.00 D near addition. Patients were divided into myopic and hyperopic groups. Monocular best corrected visual acuity at distance and near and monocular uncorrected visual acuity at distance and near were measured before and 6 months postoperatively. RESULTS: After surgery, uncorrected visual acuity was 0.08 ± 0.15 and 0.11 ± 0.14 logMAR for the myopic and hyperopic groups, respectively (50% and 46.67% of patients had an uncorrected visual acuity of 20/20 or better in the myopic and hyperopic groups, respectively. The safety and efficacy indexes were 1.05 and 0.88 for the myopic and 1.01 and 0.86 for the hyperopic groups at distance vision. Within the myopic group, 20 eyes remained unchanged after the surgery, and 3 gained >2 lines of best corrected visual acuity. For the hyperopic group, 2 eyes lost 2 lines of best corrected visual acuity, 21 did not change, and 3 eyes gained 2 lines. At near vision, the safety and efficacy indexes were 1.23 and 1.17 for the myopic and 1.16 and 1.13 for the hyperopic groups. Best corrected near visual acuity improved after surgery in both groups (from 0.10 logMAR to 0.01 logMAR in the myopic group, and from 0.10 logMAR to 0.04 logMAR in the hyperopic group. CONCLUSIONS: The ReSTOR® SN6AD3 intraocular lens in refractive lens exchange demonstrated good safety, efficacy, and predictability in correcting high ametropia and presbyopia.

A New Visual Stimulation Program for Improving Visual Acuity in Children with Visual Impairment: A Pilot Study

Science.gov (United States)

Tsai, Li-Ting; Hsu, Jung-Lung; Wu, Chien-Te; Chen, Chia-Ching; Su, Yu-Chin

2016-01-01

The purpose of this study was to investigate the effectiveness of visual rehabilitation of a computer-based visual stimulation (VS) program combining checkerboard pattern reversal (passive stimulation) with oddball stimuli (attentional modulation) for improving the visual acuity (VA) of visually impaired (VI) children and children with amblyopia and additional developmental problems. Six children (three females, three males; mean age = 3.9 ± 2.3 years) with impaired VA caused by deficits along the anterior and/or posterior visual pathways were recruited. Participants received eight rounds of VS training (two rounds per week) of at least eight sessions per round. Each session consisted of stimulation with 200 or 300 pattern reversals. Assessments of VA (assessed with the Lea symbol VA test or Teller VA cards), visual evoked potential (VEP), and functional vision (assessed with the Chinese-version Functional Vision Questionnaire, FVQ) were carried out before and after the VS program. Significant gains in VA were found after the VS training [VA = 1.05 logMAR ± 0.80 to 0.61 logMAR ± 0.53, Z = –2.20, asymptotic significance (2-tailed) = 0.028]. No significant changes were observed in the FVQ assessment [92.8 ± 12.6 to 100.8 ±SD = 15.4, Z = –1.46, asymptotic significance (2-tailed) = 0.144]. VEP measurement showed improvement in P100 latency and amplitude or integration of the waveform in two participants. Our results indicate that a computer-based VS program with passive checkerboard stimulation, oddball stimulus design, and interesting auditory feedback could be considered as a potential intervention option to improve the VA of a wide age range of VI children and children with impaired VA combined with other neurological disorders. PMID:27148014

A New Visual Stimulation Program for Improving Visual Acuity in Children with Visual Impairment: A Pilot Study.

Science.gov (United States)

Tsai, Li-Ting; Hsu, Jung-Lung; Wu, Chien-Te; Chen, Chia-Ching; Su, Yu-Chin

2016-01-01

The purpose of this study was to investigate the effectiveness of visual rehabilitation of a computer-based visual stimulation (VS) program combining checkerboard pattern reversal (passive stimulation) with oddball stimuli (attentional modulation) for improving the visual acuity (VA) of visually impaired (VI) children and children with amblyopia and additional developmental problems. Six children (three females, three males; mean age = 3.9 ± 2.3 years) with impaired VA caused by deficits along the anterior and/or posterior visual pathways were recruited. Participants received eight rounds of VS training (two rounds per week) of at least eight sessions per round. Each session consisted of stimulation with 200 or 300 pattern reversals. Assessments of VA (assessed with the Lea symbol VA test or Teller VA cards), visual evoked potential (VEP), and functional vision (assessed with the Chinese-version Functional Vision Questionnaire, FVQ) were carried out before and after the VS program. Significant gains in VA were found after the VS training [VA = 1.05 logMAR ± 0.80 to 0.61 logMAR ± 0.53, Z = -2.20, asymptotic significance (2-tailed) = 0.028]. No significant changes were observed in the FVQ assessment [92.8 ± 12.6 to 100.8 ±SD = 15.4, Z = -1.46, asymptotic significance (2-tailed) = 0.144]. VEP measurement showed improvement in P100 latency and amplitude or integration of the waveform in two participants. Our results indicate that a computer-based VS program with passive checkerboard stimulation, oddball stimulus design, and interesting auditory feedback could be considered as a potential intervention option to improve the VA of a wide age range of VI children and children with impaired VA combined with other neurological disorders.

A new visual stimulation program for improving visual acuity in children with visual impairment: a pilot study

Directory of Open Access Journals (Sweden)

Li-Ting eTsai

2016-04-01

Full Text Available The purpose of this study was to investigate the effectiveness of visual rehabilitation of a computer-based visual stimulation (VS program combining checkerboard pattern reversal (passive stimulation with oddball stimuli (attentional modulation for improving the visual acuity (VA of visually impaired (VI children and children with amblyopia and additional developmental problems. Six children (3 females, 3 males; mean age = 3.9 ± 2.3 years with impaired VA caused by deficits along the anterior and/or posterior visual pathways were recruited. Participants received eight rounds of VS training (two rounds per week of at least 8 sessions per round. Each session consisted of stimulation with 200 or 300 pattern reversals. Assessments of VA (assessed with the Lea symbol VA test or Teller VA cards, visual evoked potential (VEP, and functional vision (assessed with the Chinese-version Functional Vision Questionnaire, FVQ were carried out before and after the VS program. Significant gains in VA were found after the VS training (VA=1.05 logMAR ± 0.80 to 0.61 logMAR ± 0.53, Z=-2.20, asymptotic significance (2-tailed =0.028. No significant changes were observed in the FVQ assessment (92.8 ± 12.6 to 100.8 ± SD=15.4, Z=-1.46, asymptotic significance (2-tailed = 0.144. VEP measurement showed improvement in P100 latency and amplitude or integration of the waveform in two participants. Our results indicate that a computer-based VS program with passive checkerboard stimulation, oddball stimulus design, and interesting auditory feedback could be considered as a potential intervention option to improve the VA of a wide age range of VI children and children with impaired VA combined with other neurological disorders.

Assessment of visual disability using visual evoked potentials.

Science.gov (United States)

Jeon, Jihoon; Oh, Seiyul; Kyung, Sungeun

2012-08-06

The purpose of this study is to validate the use of visual evoked potential (VEP) to objectively quantify visual acuity in normal and amblyopic patients, and determine if it is possible to predict visual acuity in disability assessment to register visual pathway lesions. A retrospective chart review was conducted of patients diagnosed with normal vision, unilateral amblyopia, optic neuritis, and visual disability who visited the university medical center for registration from March 2007 to October 2009. The study included 20 normal subjects (20 right eyes: 10 females, 10 males, ages 9-42 years), 18 unilateral amblyopic patients (18 amblyopic eyes, ages 19-36 years), 19 optic neuritis patients (19 eyes: ages 9-71 years), and 10 patients with visual disability having visual pathway lesions. Amplitude and latencies were analyzed and correlations with visual acuity (logMAR) were derived from 20 normal and 18 amblyopic subjects. Correlation of VEP amplitude and visual acuity (logMAR) of 19 optic neuritis patients confirmed relationships between visual acuity and amplitude. We calculated the objective visual acuity (logMAR) of 16 eyes from 10 patients to diagnose the presence or absence of visual disability using relations derived from 20 normal and 18 amblyopic eyes. Linear regression analyses between amplitude of pattern visual evoked potentials and visual acuity (logMAR) of 38 eyes from normal (right eyes) and amblyopic (amblyopic eyes) subjects were significant [y = -0.072x + 1.22, x: VEP amplitude, y: visual acuity (logMAR)]. There were no significant differences between visual acuity prediction values, which substituted amplitude values of 19 eyes with optic neuritis into function. We calculated the objective visual acuity of 16 eyes of 10 patients to diagnose the presence or absence of visual disability using relations of y = -0.072x + 1.22 (-0.072). This resulted in a prediction reference of visual acuity associated with malingering vs. real

Effect of ruboxistaurin (RBX) On visual acuity decline over a 6-year period with cessation and reinstitution of therapy

DEFF Research Database (Denmark)

Sheetz, Matthew J; Aiello, Lloyd Paul; Shahri, Nazila

2011-01-01

reduced the occurrence of sustained moderate visual loss (SMVL; ≥15-letter decline in visual acuity sustained for the last 6 months of study participation) from 9.1% in the PBO group (N = 340) to 5.5% in the RBX group (N = 345, P = 0.034). This study evaluates the primary end point of SMVL in a 2-year...

SMARTPHONE-BASED DILATED FUNDUS PHOTOGRAPHY AND NEAR VISUAL ACUITY TESTING AS INEXPENSIVE SCREENING TOOLS TO DETECT REFERRAL WARRANTED DIABETIC EYE DISEASE.

Science.gov (United States)

Toy, Brian C; Myung, David J; He, Lingmin; Pan, Carolyn K; Chang, Robert T; Polkinhorne, Alison; Merrell, Douglas; Foster, Doug; Blumenkranz, Mark S

2016-05-01

To compare clinical assessment of diabetic eye disease by standard dilated examination with data gathered using a smartphone-based store-and-forward teleophthalmology platform. 100 eyes of 50 adult patients with diabetes from a health care safety-net ophthalmology clinic. All patients underwent comprehensive ophthalmic examination. Concurrently, a smartphone was used to estimate near visual acuity and capture anterior and dilated posterior segment photographs, which underwent masked, standardized review. Quantitative comparison of clinic and smartphone-based data using descriptive, kappa, Bland-Altman, and receiver operating characteristic analyses was performed. Smartphone visual acuity was successfully measured in all eyes. Anterior and posterior segment photography was of sufficient quality to grade in 96 and 98 eyes, respectively. There was good correlation between clinical Snellen and smartphone visual acuity measurements (rho = 0.91). Smartphone-acquired fundus photographs demonstrated 91% sensitivity and 99% specificity to detect moderate nonproliferative and worse diabetic retinopathy, with good agreement between clinic and photograph grades (kappa = 0.91 ± 0.1, P smartphone-based telemedicine system that demonstrated sensitivity and specificity to detect referral-warranted diabetic eye disease as a proof-of-concept. Additional studies are warranted to evaluate this approach to expanding screening for diabetic retinopathy.

Higher-order aberrations and visual acuity after LASEK.

Science.gov (United States)

Urgancioglu, Berrak; Bilgihan, Kamil; Ozturk, Sertac

2008-08-01

To determine ocular higher-order aberrations (HOAs) in eyes with supernormal vision after myopic astigmatic laser subepithelial keratomileusis (LASEK) and to compare the findings with those in eyes with natural supernormal vision. Ocular HOAs were measured after LASEK in 20 eyes of 12 myopic astigmatic patients with postoperative uncorrected visual acuity (UCVA) of >20/16 (group 1). Patients who were included in the study had no visual symptoms like glare, halo or double vision. The measurements were taken 8.3 +/- 3 months after LASEK surgery. In group 2 ocular HOAs were examined in 20 eyes of 10 subjects with natural UCVA of >20/16 as a control. Measurements were taken across a pupil with a diameter of 4.0 mm and 6.0 mm. Root-mean-square (RMS) values of HOAs, Z(3)-1, Z(3)1, Z(4)0, Z(5)-1, Z(5)1 and Z(6)0 were analyzed. The mean RMS values for each order were higher in group 1 when compared with group 2 at 4.0 mm and 6.0 mm pupil diameters. There was no statistically significant difference between groups in spherical and coma aberrations (P > 0.05). Mean RMS values for total HOAs were 0.187 +/- 0.09 microm at 4.0 mm and 0.438 +/- 0.178 microm at 6.0 mm pupil in group 1 and 0.120 +/- 0.049 microm at 4.0 mm and 0.344 +/- 0.083 microm at 6.0 mm pupil in group 2. The difference between groups in total HOAs was statistically significant at 4.0 mm and 6.0 mm pupil diameters (P < 0.05). Ocular HOAs exist in eyes with supernormal vision. After LASEK, the amount of HOAs of the eye increases under both mesopic and photopic conditions. However the amount of HOA increase does not seem to be consistent with visual symptoms.

Visual acuity with simulated and real astigmatic defocus.

Science.gov (United States)

Ohlendorf, Arne; Tabernero, Juan; Schaeffel, Frank

2011-05-01

To compare the effects of "simulated" and "real" spherical and astigmatic defocus on visual acuity (VA). VA was determined with letter charts that were blurred by calculated spherical or astigmatic defocus (simulated defocus) or were seen through spherical or astigmatic trial lenses (real defocus). Defocus was simulated using ZEMAX and the Liou-Brennan eye model. Nine subjects participated [mean age, 27.2 ± 1.8 years; logarithm of the minimum angle of resolution (logMAR), -0.1]. Three different experiments were conducted in which VA was reduced by 20% (logMAR 0.0), 50% (logMAR 0.2), or 75% (logMAR 0.5) by either (1) imposing positive spherical defocus, (2) imposing positive and negative astigmatic defocus in three axes (0, 45, and 90°), and (3) imposing cross-cylinder defocus in the same three axes as in (2). Experiment (1): there were only minor differences in VA with simulated and real positive spherical defocus. Experiment (2): simulated astigmatic defocus reduced VA twice as much as real astigmatic defocus in all tested axes (p < 0.01 in all cases). Experiment (3): simulated cross-cylinder defocus reduced VA much more than real cross-cylinder defocus (p < 0.01 in all cases), similarly for all three tested axes. The visual system appears more tolerant against "real" spherical, astigmatic, and cross-cylinder defocus than against "simulated" blur. Possible reasons could be (1) limitations in the modeling procedures to simulate defocus, (2) higher ocular aberrations, and (3) fluctuations of accommodation. However, the two optical explanations (2) and (3) cannot account for the magnitude of the effect, and (1) was carefully analyzed. It is proposed that something may be special about the visual processing of real astigmatic and cross-cylinder defocus-because they have less effect on VA than simulations predict.

The Cost-effectiveness of Welcome to Medicare Visual Acuity Screening and a Possible Alternative Welcome to Medicare Eye Evaluation Among Persons Without Diagnosed Diabetes Mellitus

Science.gov (United States)

Rein, David B.; Wittenborn, John S.; Zhang, Xinzhi; Hoerger, Thomas J.; Zhang, Ping; Klein, Barbara Eden Kobrin; Lee, Kris E.; Klein, Ronald; Saaddine, Jinan B.

2013-01-01

Objective To estimate the cost-effectiveness of visual acuity screening performed in primary care settings and of dilated eye evaluations performed by an eye care professional among new Medicare enrollees with no diagnosed eye disorders. Medicare currently reimburses visual acuity screening for new enrollees during their initial preventive primary care health check, but dilated eye evaluations may be a more cost-effective policy. Design Monte Carlo cost-effectiveness simulation model with a total of 50 000 simulated patients with demographic characteristics matched to persons 65 years of age in the US population. Results Compared with no screening policy, dilated eye evaluations increased quality-adjusted life-years (QALYs) by 0.008 (95% credible interval [CrI], 0.005–0.011) and increased costs by $94 (95% CrI, −$35 to $222). A visual acuity screening increased QALYs in less than 95% of the simulations (0.001 [95% CrI, −0.002 to 0.004) and increased total costs by $32 (95% CrI, −$97 to $159) per person. The incremental cost-effectiveness ratio of a visual acuity screening and an eye examination compared with no screening were $29 000 and $12 000 per QALY gained, respectively. At a willingness-to-pay value of $15 000 or more per QALY gained, a dilated eye evaluation was the policy option most likely to be cost-effective. Conclusions The currently recommended visual acuity screening showed limited efficacy and cost-effectiveness compared with no screening. In contrast, a new policy of reimbursement for Welcome to Medicare dilated eye evaluations was highly cost-effective. PMID:22232367

Monocular and binocular development in children with albinism, infantile nystagmus syndrome, and normal vision.

Science.gov (United States)

Huurneman, Bianca; Boonstra, F Nienke

2013-12-01

To compare interocular acuity differences, crowding ratios, and binocular summation ratios in 4- to 8-year-old children with albinism (n = 16), children with infantile nystagmus syndrome (n = 10), and children with normal vision (n = 72). Interocular acuity differences and binocular summation ratios were compared between groups. Crowding ratios were calculated by dividing the single Landolt C decimal acuity with the crowded Landolt C decimal acuity mono- and binocularly. A linear regression analysis was conducted to investigate the contribution of 5 predictors to the monocular and binocular crowding ratio: nystagmus amplitude, nystagmus frequency, strabismus, astigmatism, and anisometropia. Crowding ratios were higher under mono- and binocular viewing conditions for children with infantile nystagmus syndrome than for children with normal vision. Children with albinism showed higher crowding ratios in their poorer eye and under binocular viewing conditions than children with normal vision. Children with albinism and children with infantile nystagmus syndrome showed larger interocular acuity differences than children with normal vision (0.1 logMAR in our clinical groups and 0.0 logMAR in children with normal vision). Binocular summation ratios did not differ between groups. Strabismus and nystagmus amplitude predicted the crowding ratio in the poorer eye (p = 0.015 and p = 0.005, respectively). The crowding ratio in the better eye showed a marginally significant relation with nystagmus frequency and depth of anisometropia (p = 0.082 and p = 0.070, respectively). The binocular crowding ratio was not predicted by any of the variables. Children with albinism and children with infantile nystagmus syndrome show larger interocular acuity differences than children with normal vision. Strabismus and nystagmus amplitude are significant predictors of the crowding ratio in the poorer eye.

Could visual neglect induce amblyopia?

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Bier, J C; Vokaer, M; Fery, P; Garbusinski, J; Van Campenhoudt, G; Blecic, S A; Bartholomé, E J

2004-12-01

Oculomotor nerve disease is a common cause of diplopia. When strabismus is present, absence of diplopia has to induce the research of either uncovering of visual fields or monocular suppression, amblyopia or blindness. We describe the case of a 41-year-old woman presenting with right oculomotor paresis and left object-centred visual neglect due to a right fronto-parietal haemorrhage expanding to the right peri-mesencephalic cisterna caused by the rupture of a right middle cerebral artery aneurysm. She never complained of diplopia despite binocular vision and progressive recovery of strabismus, excluding uncovering of visual fields. Since all other causes were excluded in this case, we hypothesise that the absence of diplopia was due to the object-centred visual neglect. Partial internal right oculomotor paresis causes an ocular deviation in abduction; the image being perceived deviated contralaterally to the left. Thus, in our case, the neglect of the left image is equivalent to a right monocular functional blindness. However, bell cancellation test clearly worsened when assessed in left monocular vision confirming that eye patching can worsen attentional visual neglect. In conclusion, our case argues for the possibility of a functional monocular blindness induced by visual neglect. We think that in presence of strabismus, absence of diplopia should induce the search for hemispatial visual neglect when supratentorial lesions are suspected.

Refraction and visual acuity in a national Danish cohort of 4-year-old children of extremely preterm delivery

DEFF Research Database (Denmark)

Fledelius, Hans C; Bangsgaard, Regitze; Slidsborg, Carina

2015-01-01

PURPOSE: A recent threefold increase in laser treatment for advanced retinopathy of prematurity (ROP) triggered a nationwide preschool ophthalmic and developmental status among extremely preterm survivors. Here, we discuss refraction and visual acuity. METHODS: Survivors (n = 178) from a national...... was 0.1 in FT and 0.2 in PT, in Snellen equivalents 0.8 and 0.63. Snellen acuity ≤0.5 occurred across the ROP subgroups, but mainly in those with at least ROP stage 3. Two children had low vision. CONCLUSIONS: The overall fair outcome for refraction and function is in accordance with other recent...

Layer 2/3 synapses in monocular and binocular regions of tree shrew visual cortex express mAChR-dependent long-term depression and long-term potentiation.

Science.gov (United States)

McCoy, Portia; Norton, Thomas T; McMahon, Lori L

2008-07-01

Acetylcholine is an important modulator of synaptic efficacy and is required for learning and memory tasks involving the visual cortex. In rodent visual cortex, activation of muscarinic acetylcholine receptors (mAChRs) induces a persistent long-term depression (LTD) of transmission at synapses recorded in layer 2/3 of acute slices. Although the rodent studies expand our knowledge of how the cholinergic system modulates synaptic function underlying learning and memory, they are not easily extrapolated to more complex visual systems. Here we used tree shrews for their similarities to primates, including a visual cortex with separate, defined regions of monocular and binocular innervation, to determine whether mAChR activation induces long-term plasticity. We find that the cholinergic agonist carbachol (CCh) not only induces long-term plasticity, but the direction of the plasticity depends on the subregion. In the monocular region, CCh application induces LTD of the postsynaptic potential recorded in layer 2/3 that requires activation of m3 mAChRs and a signaling cascade that includes activation of extracellular signal-regulated kinase (ERK) 1/2. In contrast, layer 2/3 postsynaptic potentials recorded in the binocular region express long-term potentiation (LTP) following CCh application that requires activation of m1 mAChRs and phospholipase C. Our results show that activation of mAChRs induces long-term plasticity at excitatory synapses in tree shrew visual cortex. However, depending on the ocular inputs to that region, variation exists as to the direction of plasticity, as well as to the specific mAChR and signaling mechanisms that are required.

Prevalence and risk factors of undercorrected refractive errors among Singaporean Malay adults: the Singapore Malay Eye Study.

Science.gov (United States)

Rosman, Mohamad; Wong, Tien Y; Tay, Wan-Ting; Tong, Louis; Saw, Seang-Mei

2009-08-01

To describe the prevalence and the risk factors of undercorrected refractive error in an adult urban Malay population. This population-based, cross-sectional study was conducted in Singapore in 3280 Malay adults, aged 40 to 80 years. All individuals were examined at a centralized clinic and underwent standardized interviews and assessment of refractive errors and presenting and best corrected visual acuities. Distance presenting visual acuity was monocularly measured by using a logarithm of the minimum angle of resolution (logMAR) number chart at a distance of 4 m, with the participants wearing their "walk-in" optical corrections (spectacles or contact lenses), if any. Refraction was determined by subjective refraction by trained, certified study optometrists. Best corrected visual acuity was monocularly assessed and recorded in logMAR scores using the same test protocol as was used for presenting visual acuity. Undercorrected refractive error was defined as an improvement of at least 0.2 logMAR (2 lines equivalent) in the best corrected visual acuity compared with the presenting visual acuity in the better eye. The mean age of the subjects included in our study was 58 +/- 11 years, and 52% of the subjects were women. The prevalence rate of undercorrected refractive error among Singaporean Malay adults in our study (n = 3115) was 20.4% (age-standardized prevalence rate, 18.3%). More of the women had undercorrected refractive error than the men (21.8% vs. 18.8%, P = 0.04). Undercorrected refractive error was also more common in subjects older than 50 years than in subjects aged 40 to 49 years (22.6% vs. 14.3%, P Malay adults with refractive errors was higher than that of the Singaporean Chinese adults with refractive errors. Undercorrected refractive error is a significant cause of correctable visual impairment among Singaporean Malay adults, affecting one in five persons.

Distributed Monocular SLAM for Indoor Map Building

Directory of Open Access Journals (Sweden)

Ruwan Egodagamage

2017-01-01

Full Text Available Utilization and generation of indoor maps are critical elements in accurate indoor tracking. Simultaneous Localization and Mapping (SLAM is one of the main techniques for such map generation. In SLAM an agent generates a map of an unknown environment while estimating its location in it. Ubiquitous cameras lead to monocular visual SLAM, where a camera is the only sensing device for the SLAM process. In modern applications, multiple mobile agents may be involved in the generation of such maps, thus requiring a distributed computational framework. Each agent can generate its own local map, which can then be combined into a map covering a larger area. By doing so, they can cover a given environment faster than a single agent. Furthermore, they can interact with each other in the same environment, making this framework more practical, especially for collaborative applications such as augmented reality. One of the main challenges of distributed SLAM is identifying overlapping maps, especially when relative starting positions of agents are unknown. In this paper, we are proposing a system having multiple monocular agents, with unknown relative starting positions, which generates a semidense global map of the environment.

Use of the Dynamic Visual Acuity Test as a screener for community-dwelling older adults who fall.

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Honaker, Julie A; Shepard, Neil T

2011-01-01

Adequate function of the peripheral vestibular system, specifically the vestibulo-ocular reflex (VOR; a network of neural connections between the peripheral vestibular system and the extraocular muscles) is essential for maintaining stable vision during head movements. Decreased visual acuity resulting from an impaired peripheral vestibular system may impede balance and postural control and place an individual at risk of falling. Therefore, sensitive measures of the vestibular system are warranted to screen for the tendency to fall, alerting clinicians to recommend further risk of falling assessment and referral to a falling risk reduction program. Dynamic Visual Acuity (DVA) testing is a computerized VOR assessment method to evaluate the peripheral vestibular system during head movements; reduced visual acuity as documented with DVA testing may be sensitive to screen for falling risk. This study examined the sensitivity and specificity of the computerized DVA test with yaw plane head movements for identifying community-dwelling adults (58-78 years) who are prone to falling. A total of 16 older adults with a history of two or more unexplained falls in the previous twelve months and 16 age and gender matched controls without a history of falls in the previous twelve months participated. Computerized DVA with horizontal head movements at a fixed velocity of 120 deg/sec was measured and compared with the Dynamic Gait Index (DGI) a gold standard gait assessment measurement for identifying falling risk. Receiver operating characteristics (ROC) curve analysis and area under the ROC curve (AUC) were used to assess the sensitivity and specificity of the computerized DVA as a screening measure for falling risk as determined by the DGI. Results suggested a link between computerized DVA and the propensity to fall; DVA in the yaw plane was found to be a sensitive (92%) and accurate screening measure when using a cutoff logMAR value of >0.25.

Lrit1, a Retinal Transmembrane Protein, Regulates Selective Synapse Formation in Cone Photoreceptor Cells and Visual Acuity

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Akiko Ueno

2018-03-01

Full Text Available Summary: In the vertebrate retina, cone photoreceptors play crucial roles in photopic vision by transmitting light-evoked signals to ON- and/or OFF-bipolar cells. However, the mechanisms underlying selective synapse formation in the cone photoreceptor pathway remain poorly understood. Here, we found that Lrit1, a leucine-rich transmembrane protein, localizes to the photoreceptor synaptic terminal and regulates the synaptic connection between cone photoreceptors and cone ON-bipolar cells. Lrit1-deficient retinas exhibit an aberrant morphology of cone photoreceptor pedicles, as well as an impairment of signal transmission from cone photoreceptors to cone ON-bipolar cells. Furthermore, we demonstrated that Lrit1 interacts with Frmpd2, a photoreceptor scaffold protein, and with mGluR6, an ON-bipolar cell-specific glutamate receptor. Additionally, Lrit1-null mice showed visual acuity impairments in their optokinetic responses. These results suggest that the Frmpd2-Lrit1-mGluR6 axis regulates selective synapse formation in cone photoreceptors and is essential for normal visual function. : Ueno et al. finds that Lrit1 plays an important role in regulating the synaptic connection between cone photoreceptors and cone ON-bipolar cells. The Frmpd2-Lrit1-mGluR6 axis is crucial for selective synapse formation in cone photoreceptors and for development of normal visual function. Keywords: retina, circuit, synapse formation, cone photoreceptor cell, ON-bipolar cell, visual acuity

Lateralized visual behavior in bottlenose dolphins (Tursiops truncatus) performing audio-visual tasks: the right visual field advantage.

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Delfour, F; Marten, K

2006-01-10

Analyzing cerebral asymmetries in various species helps in understanding brain organization. The left and right sides of the brain (lateralization) are involved in different cognitive and sensory functions. This study focuses on dolphin visual lateralization as expressed by spontaneous eye preference when performing a complex cognitive task; we examine lateralization when processing different visual stimuli displayed on an underwater touch-screen (two-dimensional figures, three-dimensional figures and dolphin/human video sequences). Three female bottlenose dolphins (Tursiops truncatus) were submitted to a 2-, 3- or 4-, choice visual/auditory discrimination problem, without any food reward: the subjects had to correctly match visual and acoustic stimuli together. In order to visualize and to touch the underwater target, the dolphins had to come close to the touch-screen and to position themselves using monocular vision (left or right eye) and/or binocular naso-ventral vision. The results showed an ability to associate simple visual forms and auditory information using an underwater touch-screen. Moreover, the subjects showed a spontaneous tendency to use monocular vision. Contrary to previous findings, our results did not clearly demonstrate right eye preference in spontaneous choice. However, the individuals' scores of correct answers were correlated with right eye vision, demonstrating the advantage of this visual field in visual information processing and suggesting a left hemispheric dominance. We also demonstrated that the nature of the presented visual stimulus does not seem to have any influence on the animals' monocular vision choice.

Using the Freiburg Acuity and Contrast Test to measure visual performance in USAF personnel after PRK.

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Dennis, Richard J; Beer, Jeremy M A; Baldwin, J Bruce; Ivan, Douglas J; Lorusso, Frank J; Thompson, William T

2004-07-01

Photorefractive keratectomy (PRK) may be an alternative to spectacle and contact lens wear for United States Air Force (USAF) aircrew and may offer some distinct advantages in operational situations. However, any residual corneal haze or scar formation from PRK could exacerbate the disabling effects of a bright glare source on a complex visual task. The USAF recently completed a longitudinal clinical evaluation of the long-term effects of PRK on visual performance, including the experiment described herein. After baseline data were collected, 20 nonflying active duty USAF personnel underwent PRK. Visual performance was then measured at 6, 12, and 24 months after PRK. Visual acuity (VA) and contrast sensitivity (CS) data were collected by using the Freiburg Acuity and Contrast Test (FrACT), with the subject viewing half of the runs through a polycarbonate windscreen. Experimental runs were completed under 3 glare conditions: no glare source and with either a broadband or a green laser (532-nm) glare annulus (luminance approximately 6090 cd/m) surrounding the Landolt C stimulus. Systematic effects of PRK on VA relative to baseline were not identified. However, VA was almost 2 full Snellen lines worse with the laser glare source in place versus the broadband glare source. A significant drop-off was observed in CS performance after PRK under conditions of no glare and broadband glare; this was the case both with and without the windscreen. As with VA, laser glare disrupted CS performance significantly and more than broadband glare did. PRK does not appear to have affected VA, but the changes in CS might represent a true decline in visual performance. The greater disruptive effects from laser versus broadband glare may be a result of increased masking from coherent spatial noise (speckle) surrounding the laser stimulus.

CORRELATION OF CLINICAL AND STRUCTURAL PROGRESSION WITH VISUAL ACUITY LOSS IN MACULAR TELANGIECTASIA TYPE 2: MacTel Project Report No. 6-The MacTel Research Group.

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Peto, Tunde; Heeren, Tjebo F C; Clemons, Traci E; Sallo, Ferenc B; Leung, Irene; Chew, Emily Y; Bird, Alan C

2018-01-01

To evaluate progression of macular telangiectasia Type 2 lesions and their correlation with visual acuity. An international multicenter prospective study with annual examinations including best-corrected visual acuity (BCVA), fundus photography, fluorescein angiography, and optical coherence tomography images graded centrally. Mixed models were used to estimate progression rates, and a generalized linear model to compute the relative risk of BCVA loss, loss of ellipsoid zone (EZ) reflectivity, development of pigment plaques, or neovascularization. One thousand and fourteen eyes of 507 participants were followed for 4.2 ± 1.6 years. Best-corrected visual acuity decreased 1.07 ± 0.05 letters (mean ± SE) per year. Of all eyes, 15% lost ≥15 letters after 5 years. Of the eyes without EZ loss, 76% developed a noncentral loss. Of the eyes with noncentral loss, 45% progressed to central EZ loss. The rate of BCVA loss in eyes with noncentral EZ loss at baseline was similar to eyes without EZ loss. The rate of BCVA loss was significantly higher in eyes with central EZ loss at baseline (-1.40 ± 0.14 letters, P structural component reflecting visual function. Its presence in the fovea significantly correlates with worse visual prognosis.

A cross-sectional examination of visual acuity by specific type of albinism.

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Winsor, Caitlin Nosanov; Holleschau, Ann M; Connett, John E; Summers, C Gail

2016-10-01

Reports of best-corrected visual acuity (BCVA) in albinism are often based on overlapping clinical phenotypes. BCVA in albinism has been shown to improve with age. This study reports a large cross-sectional investigation to determine whether BCVA differs by specific type of albinism when age-corrected. This retrospective review identified 170 individuals with a specific type of albinism identified by mutation(s) in a gene known to cause albinism (for OCA1, OCA2, and Hermansky-Pudlak syndrome ([HPS]) or a specific phenotype (white hair and no melanin pigment in OCA1A; pigmentary mosaicism in the obligate carriers for males with OA1). We recorded optotype binocular BCVA at final follow-up. Patients were age-grouped (2-5 years, 6-14 years, and ≥15 years) for comparison. The greatest visual acuity deficit was found for OCA1A in all age groups. At age ≥15 years (n = 79), mean BCVA was 20/128 for OCA1A, 20/37 for OCA1B, 20/59 for OCA2, 20/63 for OA1, and 20/121 for HPS. Significant differences between BCVA at ≥15 years were found in the following: OCA1A vs OCA1B, OCA1A vs OCA2, OCA1A vs OA1, OCA1B vs HPS, OCA2 vs HPS, and OA1 vs HPS (P ≤ 0.02). This study provides a large sample size and includes only those with a specific type of albinism. BCVA varies by albinism type, and there is overlap in BCVA, particularly in the younger age groups. For ages ≥15 years, there are significant differences in BCVA between several types of albinism. Copyright © 2016 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Optic disc boundary segmentation from diffeomorphic demons registration of monocular fundus image sequences versus 3D visualization of stereo fundus image pairs for automated early stage glaucoma assessment

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Gatti, Vijay; Hill, Jason; Mitra, Sunanda; Nutter, Brian

2014-03-01

Despite the current availability in resource-rich regions of advanced technologies in scanning and 3-D imaging in current ophthalmology practice, world-wide screening tests for early detection and progression of glaucoma still consist of a variety of simple tools, including fundus image-based parameters such as CDR (cup to disc diameter ratio) and CAR (cup to disc area ratio), especially in resource -poor regions. Reliable automated computation of the relevant parameters from fundus image sequences requires robust non-rigid registration and segmentation techniques. Recent research work demonstrated that proper non-rigid registration of multi-view monocular fundus image sequences could result in acceptable segmentation of cup boundaries for automated computation of CAR and CDR. This research work introduces a composite diffeomorphic demons registration algorithm for segmentation of cup boundaries from a sequence of monocular images and compares the resulting CAR and CDR values with those computed manually by experts and from 3-D visualization of stereo pairs. Our preliminary results show that the automated computation of CDR and CAR from composite diffeomorphic segmentation of monocular image sequences yield values comparable with those from the other two techniques and thus may provide global healthcare with a cost-effective yet accurate tool for management of glaucoma in its early stage.

A new binocular approach to the treatment of amblyopia in adults well beyond the critical period of visual development.

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Hess, R F; Mansouri, B; Thompson, B

2010-01-01

The present treatments for amblyopia are predominantly monocular aiming to improve the vision in the amblyopic eye through either patching of the fellow fixing eye or visual training of the amblyopic eye. This approach is problematic, not least of which because it rarely results in establishment of binocular function. Recently it has shown that amblyopes possess binocular cortical mechanisms for both threshold and suprathreshold stimuli. We outline a novel procedure for measuring the extent to which the fixing eye suppresses the fellow amblyopic eye, rendering what is a structurally binocular system, functionally monocular. Here we show that prolonged periods of viewing (under the artificial conditions of stimuli of different contrast in each eye) during which information from the two eyes is combined leads to a strengthening of binocular vision in strabismic amblyopes and eventual combination of binocular information under natural viewing conditions (stimuli of the same contrast in each eye). Concomitant improvement in monocular acuity of the amblyopic eye occurs with this reduction in suppression and strengthening of binocular fusion. Furthermore, in a majority of patients tested, stereoscopic function is established. This provides the basis for a new treatment of amblyopia, one that is purely binocular and aimed at reducing suppression as a first step.

The Use of Dynamic Visual Acuity as a Functional Test of Gaze Stabilization Following Space Flight

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Peters, B. T.; Mulavara, A. P.; Brady, R.; Miller, C. A.; Richards, J. T.; Warren, L. E.; Cohen, H. S.; Bloomberg, J. J.

2006-01-01

After prolonged exposure to a given gravitational environment the transition to another is accompanied by adaptations in the sensorimotor subsystems, including the vestibular system. Variation in the adaptation time course of these subsystems, and the functional redundancies that exist between them make it difficult to accurately assess the functional capacity and physical limitations of astro/cosmonauts using tests on individual subsystems. While isolated tests of subsystem performance may be the only means to address where interventions are required, direct measures of performance may be more suitable for assessing the operational consequences of incomplete adaptation to changes in the gravitational environment. A test of dynamic visual acuity (DVA) is currently being used in the JSC Neurosciences Laboratory as part of a series of measures to assess the efficacy of a countermeasure to mitigate postflight locomotor dysfunction. In the current protocol, subjects visual acuity is determined using Landolt ring optotypes presented sequentially on a computer display. Visual acuity assessments are made both while standing and while walking at 1.8 m/s on a motorized treadmill. The use of a psychophysical threshold detection algorithm reduces the required number of optotype presentations and the results can be presented immediately after the test. The difference between the walking and standing acuity measures provides a metric of the change in the subject s ability to maintain gaze fixation on the visual target while walking. This functional consequence is observable regardless of the underlying subsystem most responsible for the change. Data from 15 cosmo/astronauts have been collected following long-duration (approx. 6 months) stays in space using a visual target viewing distance of 4.0 meters. An investigation of the group mean shows a change in DVA soon after the flight that asymptotes back to baseline approximately one week following their return to earth. The

Acuidade visual e eletrorretinografia de campo total em pacientes com síndrome de Usher Visual acuity and full-field electroretinography in patients with Usher's syndrome

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Luana Mendieta

2005-04-01

and visual acuity (VA among patients with type I and II Usher's syndrome. METHODS: Electroretinography responses and visual acuity were studied in 22 patients (mean age at test = 26.8±16.8 years. Seventeen patients had SU type I and 5 patients were diagnosed as Usher's syndrome type II. RESULTS: Mean visual acuity was 0.9 logMAR (20/160, Snellen equivalent for patients with Usher's syndrome type I and 0.4 logMAR (20/50, Snellen equivalent for patients with Usher's syndrome type II. Scotopic rod and maximal responses were non-detectable in both groups. Mean amplitude for oscillatory potentials was 14.5 µV ±6.1 in Usher's syndrome type I and 12.6 µV±5.2 in Usher's syndrome type II. Cone responses were non-detectable in 95% of the patients with Usher's syndrome I and in 100% of patients with Usher's syndrome II. Mean amplitude for 30 Hz flicker photopic cone response was 3.1 µV±4.1 for Usher's syndrome type I and 1.0 µV±0.6 for type II with mean implicit time of 34.0 ms±6.2 (US I and 35.8 ms±3.1 (type II. CONCLUSIONS: Visual acuity was relatively preserved in both groups, however Usher's syndrome II group showed better visual acuity results. Electroretinography findings were severely reduced in both groups, with most patients showing non-detectable rod and cone responses.

Quality of life and visual acuity outcomes in the Registry in Glaucoma Outcomes Research study.

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Coleman, Anne L; Lum, Flora C; Gliklich, Richard E; Velentgas, Priscilla; Su, Zhaohui

2016-01-01

The RiGOR study evaluated the association of treatment and patient-reported outcomes for open-angle glaucoma patients. The Glaucoma Symptom Scale (National Eye Institute-Visual Function Questionnaire (NEI-VFQ) and visual acuity (VA) were collected as quality of life measures. The proportion of patients with improvement of at least two lines of vision was highest in the incisional surgery group (14.2% compared with 9.9% for laser surgery and 10.9% for additional medication). No clinically relevant differences were seen in benefit for the laser surgery or incisional surgery groups compared with additional medications for the Glaucoma Symptom Scale or NEI-VFQ measures or subscales. Differences in quality of life by race need to be explored in further studies.

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

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

2017-08-01

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

Changes in visual acuity in patients with wet age-related macular degeneration treated with intravitreal ranibizumab in daily clinical practice: the LUMIERE study.

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Cohen, Salomon Y; Mimoun, Gerard; Oubraham, Hassiba; Zourdani, Alain; Malbrel, Christian; Queré, Stephane; Schneider, Véronique

2013-03-01

To survey compliance with recommended intravitreal ranibizumab treatment protocols in daily clinical practice in France, with reference to outcomes. A retrospective, descriptive, observational study in patients with subfoveal wet age-related macular degeneration treated with ranibizumab. All historical data for the study period, including demographic, treatment, and disease details and visual acuity measurements (baseline, Month 3, and Month 12), were recorded retrospectively at least 12 months after the beginning of treatment. In 551 patients followed by 16 ophthalmologists, 12 months of intravitreal ranibizumab treatment induced a mean visual acuity gain of 3.2 ± 14.8 Early Treatment Diabetic Retinopathy Study-equivalent letters. Fewer than 40% of patients received the recommended treatment of initial 3 monthly injections. More than 50% had to wait >8 days between diagnosis and treatment. At Month 3, visual acuity gain was greater in patients who had received recommended induction and in whom treatment was initiated quickly. At Month 12, the induction-related effect had largely disappeared but the time-to-treatment effect persisted. Patients had an average of 5.1 injections (2.6 during induction period). No patients were monitored monthly as stipulated in the guidelines. Although poor compliance with recommendations has been reflected in mediocre outcomes, there is evidence that practice is improving.

Contrast sensitivity measured by two different test methods in healthy, young adults with normal visual acuity.

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Koefoed, Vilhelm F; Baste, Valborg; Roumes, Corinne; Høvding, Gunnar

2015-03-01

This study reports contrast sensitivity (CS) reference values obtained by two different test methods in a strictly selected population of healthy, young adults with normal uncorrected visual acuity. Based on these results, the index of contrast sensitivity (ICS) is calculated, aiming to establish ICS reference values for this population and to evaluate the possible usefulness of ICS as a tool to compare the degree of agreement between different CS test methods. Military recruits with best eye uncorrected visual acuity 0.00 LogMAR or better, normal colour vision and age 18-25 years were included in a study to record contrast sensitivity using Optec 6500 (FACT) at spatial frequencies of 1.5, 3, 6, 12 and 18 cpd in photopic and mesopic light and CSV-1000E at spatial frequencies of 3, 6, 12 and 18 cpd in photopic light. Index of contrast sensitivity was calculated based on data from the three tests, and the Bland-Altman technique was used to analyse the agreement between ICS obtained by the different test methods. A total of 180 recruits were included. Contrast sensitivity frequency data for all tests were highly skewed with a marked ceiling effect for the photopic tests. The median ICS for Optec 6500 at 85 cd/m2 was -0.15 (95% percentile 0.45), compared with -0.00 (95% percentile 1.62) for Optec at 3 cd/m2 and 0.30 (95% percentile 1.20) FOR CSV-1000E. The mean difference between ICSFACT 85 and ICSCSV was -0.43 (95% CI -0.56 to -0.30, p<0.00) with limits of agreement (LoA) within -2.10 and 1.22. The regression line on the difference of average was near to zero (R2=0.03). The results provide reference CS and ICS values in a young, adult population with normal visual acuity. The agreement between the photopic tests indicated that they may be used interchangeably. There was little agreement between the mesopic and photopic tests. The mesopic test seemed best suited to differentiate between candidates and may therefore possibly be useful for medical selection purposes. �

Effects of brief daily periods of unrestricted vision during early monocular form deprivation on development of visual area 2.

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Zhang, Bin; Tao, Xiaofeng; Wensveen, Janice M; Harwerth, Ronald S; Smith, Earl L; Chino, Yuzo M

2011-09-14

Providing brief daily periods of unrestricted vision during early monocular form deprivation reduces the depth of amblyopia. To gain insights into the neural basis of the beneficial effects of this treatment, the binocular and monocular response properties of neurons were quantitatively analyzed in visual area 2 (V2) of form-deprived macaque monkeys. Beginning at 3 weeks of age, infant monkeys were deprived of clear vision in one eye for 12 hours every day until 21 weeks of age. They received daily periods of unrestricted vision for 0, 1, 2, or 4 hours during the form-deprivation period. After behavioral testing to measure the depth of the resulting amblyopia, microelectrode-recording experiments were conducted in V2. The ocular dominance imbalance away from the affected eye was reduced in the experimental monkeys and was generally proportional to the reduction in the depth of amblyopia in individual monkeys. There were no interocular differences in the spatial properties of V2 neurons in any subject group. However, the binocular disparity sensitivity of V2 neurons was significantly higher and binocular suppression was lower in monkeys that had unrestricted vision. The decrease in ocular dominance imbalance in V2 was the neuronal change most closely associated with the observed reduction in the depth of amblyopia. The results suggest that the degree to which extrastriate neurons can maintain functional connections with the deprived eye (i.e., reducing undersampling for the affected eye) is the most significant factor associated with the beneficial effects of brief periods of unrestricted vision.

Variação da acuidade visual em pacientes jovens com ectopia lentis submetidos à cirurgia Variation of visual acuity in young patients with ectopia lentis submitted to surgery

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Mauro Waiswol

2005-08-01

Full Text Available OBJETIVOS:Avaliar os resultados quanto à acuidade visual, de dois procedimentos cirúrgicos para a ectopia lentis. MÉTODOS: Foram operados 51 olhos de 28 pacientes (16 do sexo masculino e 12 do feminino, com média de idade de 16,00±8,5 anos com ectopia lentis simples (19 casos, ou associada à síndrome de Marfan (nove casos, com diferentes graus de subluxação cristaliniana. Em 21 casos a técnica empregada foi a facectomia com implante de lente intra-ocular (LIO por fixação escleral e em 30 casos foi utilizada a facectomia com implante da lente intra-ocular no saco capsular, previamente expandido por anel endocapsular (ANEL. Os resultados enfatizaram a acuidade visual pré e pós-operatória em seguimento de seis meses. RESULTADOS:Em ambas as técnicas, a acuidade visual pós-operatória sem e com correção teve aumento significante, que foi maior nos casos operados com fixação escleral da lente intra-ocular. Mais do que a técnica empregada, os graus de subluxação pré-operatórios foram determinantes para os resultados. CONCLUSÕES: Mediante as técnicas operatórias apresentadas, a correção cirúrgica da ectopia lentis simples ou associada à síndrome de Marfan é segura e eficaz, com recuperação significante da acuidade visual, embora os resultados operatórios dependam, intrinsecamente, dos graus pré-operatórios de subluxação do cristalino.PURPOSE: To assess the results as to visual acuity of two different surgical procedures for ectopia lentis. METHODS: Fifty-one eyes of 28 patients (16 males and 12 females, mean age 16.00± 8.5 with simple (19 cases or Marfan syndrome-associated (9 cases ectopia lentis with different levels of subluxation underwent lens extraction with implantation of intraocular lenses (IOL with scleral fixation (21 cases or by lens extraction with implantation of the intraocular lenses in the capsular bag expanded by endocapsular ring (RING (30 cases. Result analysis emphasized pre- and

Visual acuity after Ruthenium106 brachytherapy of choroidal melanomas

International Nuclear Information System (INIS)

Damato, Bertil; Patel, Imran M.; Campbell, Ian R.; Mayles, Helen M.; Errington, R. Douglas

2005-01-01

Purpose: To report on conservation of visual acuity after Ruthenium 106 (Ru-106) brachytherapy of choroidal melanoma. Methods and materials: This study was a noncomparative interventional case series of 458 patients with choroidal melanoma treated at a single center between January 1993 and December 2001. The intervention consisted of Ru-106 brachytherapy delivering minimum scleral and apex doses of 300 Gy and 80 Gy, respectively, using a 15-mm or 20-mm plaque. For discrete, posterior tumors, the plaque was positioned eccentrically with its posterior edge aligned with the posterior tumor margin. To ensure correct plaque positioning, any overlying extraocular muscles were dis-inserted, and the locations of both tumor and plaque edges were confirmed by transillumination and indentation. The main outcome measures were conservation of vision of 20/40 or better, 20/200 or better, and Counting Fingers or better, according to baseline variables. Results: The actuarial rate of conservation of 20/40 or better was 55% at 9 years, loss of such vision correlating with posterior tumor extension (p 106 brachytherapy of posterior choroidal melanoma achieves good conservation of vision if the tumor does not extend close to the optic nerve or fovea

Color improves “visual” acuity via sound

OpenAIRE

Levy-Tzedek, Shelly; Riemer, Dar; Amedi, Amir

2014-01-01

Visual-to-auditory sensory substitution devices (SSDs) convey visual information via sound, with the primary goal of making visual information accessible to blind and visually impaired individuals. We developed the EyeMusic SSD, which transforms shape, location, and color information into musical notes. We tested the “visual” acuity of 23 individuals (13 blind and 10 blindfolded sighted) on the Snellen tumbling-E test, with the EyeMusic. Participants were asked to determine the orientation of...

Amblyopia and binocular vision.

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Birch, Eileen E

2013-03-01

Amblyopia is the most common cause of monocular visual loss in children, affecting 1.3%-3.6% of children. Current treatments are effective in reducing the visual acuity deficit but many amblyopic individuals are left with residual visual acuity deficits, ocular motor abnormalities, deficient fine motor skills, and risk for recurrent amblyopia. Using a combination of psychophysical, electrophysiological, imaging, risk factor analysis, and fine motor skill assessment, the primary role of binocular dysfunction in the genesis of amblyopia and the constellation of visual and motor deficits that accompany the visual acuity deficit has been identified. These findings motivated us to evaluate a new, binocular approach to amblyopia treatment with the goals of reducing or eliminating residual and recurrent amblyopia and of improving the deficient ocular motor function and fine motor skills that accompany amblyopia. Copyright © 2012 Elsevier Ltd. All rights reserved.

Experience-independent development of the hamster circadian visual system.

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August Kampf-Lassin

2011-04-01

Full Text Available Experience-dependent functional plasticity is a hallmark of the primary visual system, but it is not known if analogous mechanisms govern development of the circadian visual system. Here we investigated molecular, anatomical, and behavioral consequences of complete monocular light deprivation during extended intervals of postnatal development in Syrian hamsters. Hamsters were raised in constant darkness and opaque contact lenses were applied shortly after eye opening and prior to the introduction of a light-dark cycle. In adulthood, previously-occluded eyes were challenged with visual stimuli. Whereas image-formation and motion-detection were markedly impaired by monocular occlusion, neither entrainment to a light-dark cycle, nor phase-resetting responses to shifts in the light-dark cycle were affected by prior monocular deprivation. Cholera toxin-b subunit fluorescent tract-tracing revealed that in monocularly-deprived hamsters the density of fibers projecting from the retina to the suprachiasmatic nucleus (SCN was comparable regardless of whether such fibers originated from occluded or exposed eyes. In addition, long-term monocular deprivation did not attenuate light-induced c-Fos expression in the SCN. Thus, in contrast to the thalamocortical projections of the primary visual system, retinohypothalamic projections terminating in the SCN develop into normal adult patterns and mediate circadian responses to light largely independent of light experience during development. The data identify a categorical difference in the requirement for light input during postnatal development between circadian and non-circadian visual systems.

Origins of Superior Dynamic Visual Acuity in Baseball Players: Superior Eye Movements or Superior Image Processing

OpenAIRE

Uchida, Yusuke; Kudoh, Daisuke; Murakami, Akira; Honda, Masaaki; Kitazawa, Shigeru

2012-01-01

Dynamic visual acuity (DVA) is defined as the ability to discriminate the fine parts of a moving object. DVA is generally better in athletes than in non-athletes, and the better DVA of athletes has been attributed to a better ability to track moving objects. In the present study, we hypothesized that the better DVA of athletes is partly derived from better perception of moving images on the retina through some kind of perceptual learning. To test this hypothesis, we quantitatively measured DV...

Medida da acuidade visual em um shopping center metropolitano Visual acuity measurement in a metropolitan shopping mall population

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Giovanni M. Travi

2000-04-01

Full Text Available Objetivo: Determinar a prevalência de baixa acuidade visual (AV em uma amostra populacional, com um padrão socioeconômico diferenciado. Métodos: Realizou-se estudo de prevalência, sendo verificada a AV de 213 voluntários examinados em um posto no interior de um shopping center em Porto Alegre, por meio do aparelho Ortho-Rater, da Bausch & Lomb. Foi medida a AV para longe em todos os indivíduos e naqueles com 40 anos ou mais, a AV para perto, ambos sem e com correção. Determinou-se como baixa AV, aquela inferior a 10 (equivalente a 20/20 na Tabela de Snellen. Resultados: A idade variou de 6 a 75 anos, com uma média ± desvio-padrão de 27,8 ± 15,16 anos, pertencendo a maioria dos examinados à faixa entre 10 e 40 anos. Encontrou-se uma prevalência de 38,7% (IC 95%: 32,1-45,7 de baixa AV para longe nos dois olhos. 24,9% (IC 95%: 19,2-31,3 apresentavam déficit visual binocular e não faziam uso de correção. Para perto, observou-se que 70,8% (IC 95%: 55,9-83 dos indivíduos testados apresentaram déficit visual binocular sem correção e 41,7% (IC 95%: 27,6-56,8 apresentaram baixa AV independente do uso de correção. Conclusão: Este estudo demonstrou que existe considerável parcela da população com déficit visual, necessitando de avaliação e manejo adequados. Conclui-se que programas de medida da AV e orientação sobre saúde ocular são importantes em qualquer ambiente e atingindo diferentes classes socioeconômicas.Purpose: To determine the prevalence of low visual acuity (VA in a populational sample, with a differentiated social pattern. Methods: This was a prevalence study, in which the 213 volunteers' VA, examined in a shopping mall in Porto Alegre, was verified through the Ortho-Rater device, from Bausch & Lomb. Far sight VA was measured in all the individuals and in those who were 40 years old or older, near sight VA, both of them without and with correction. VA was considered low when it was less than 10 (equivalent

An Audit of Visual Acuity using a Snellen chart for Residents in a Care home, aged 65years or over

OpenAIRE

Ward, Hannah

2012-01-01

Background: Visual impairment (VI) is highly prevalent, but currently remains untreated and preventable in Britain‟s older population (Evans, Fletcher, Wormald et al. 2002). Eighty percent of all VI can be avoided or treated (WHO, 2011). People in residential or nursing homes are at a higher risk of having their eye problems overlooked (Pols, Bates, McGraw et al. 2000). Aim: To conduct an audit of visual acuity (VA), a measure of VI against a national standard, the British Geriatric Societ...

Correlation between observation task performance and visual acuity, contrast sensitivity and environmental light in a simulated maritime study.

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Koefoed, Vilhelm F; Assmuss, Jörg; Høvding, Gunnar

2018-03-25

To examine the relevance of visual acuity (VA) and index of contrast sensitivity (ICS) as predictors for visual observation task performance in a maritime environment. Sixty naval cadets were recruited to a study on observation tasks in a simulated maritime environment under three different light settings. Their ICS were computed based on contrast sensitivity (CS) data recorded by Optec 6500 and CSV-1000E CS tests. The correlation between object identification distance and VA/ICS was examined by stepwise linear regression. The object detection distance was significantly correlated to the level of environmental light (p maritime environment may presumably be ascribed to the normal and uniform visual capacity in all our study subjects. © 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Can perceptual learning be used to treat amblyopia beyond the critical period of visual development?

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Astle, Andrew T; Webb, Ben S; McGraw, Paul V

2011-11-01

Amblyopia presents early in childhood and affects approximately 3% of western populations. The monocular visual acuity loss is conventionally treated during the 'critical periods' of visual development by occluding or penalising the fellow eye to encourage use of the amblyopic eye. Despite the measurable success of this approach in many children, substantial numbers of people still suffer with amblyopia later in life because either they were never diagnosed in childhood, did not respond to the original treatment, the amblyopia was only partially remediated, or their acuity loss returned after cessation of treatment. In this review, we consider whether the visual deficits of this largely overlooked amblyopic group are amenable to conventional and innovative therapeutic interventions later in life, well beyond the age at which treatment is thought to be effective. There is a considerable body of evidence that residual plasticity is present in the adult visual brain and this can be harnessed to improve function in adults with amblyopia. Perceptual training protocols have been developed to optimise visual gains in this clinical population. Results thus far are extremely encouraging; marked visual improvements have been demonstrated, the perceptual benefits transfer to new visual tasks and appear to be relatively enduring. The essential ingredients of perceptual training protocols are being incorporated into video game formats, facilitating home-based interventions. Many studies support perceptual training as a tool for improving vision in amblyopes beyond the critical period. Should this novel form of treatment stand up to the scrutiny of a randomised controlled trial, clinicians may need to re-evaluate their therapeutic approach to adults with amblyopia. Ophthalmic & Physiological Optics © 2011 The College of Optometrists.

Can perceptual learning be used to treat amblyopia beyond the critical period of visual development?

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Astle, Andrew T.; Webb, Ben S.; McGraw, Paul V.

2012-01-01

Background Amblyopia presents early in childhood and affects approximately 3% of western populations. The monocular visual acuity loss is conventionally treated during the “critical periods” of visual development by occluding or penalising the fellow eye to encourage use of the amblyopic eye. Despite the measurable success of this approach in many children, substantial numbers of people still suffer with amblyopia later in life because either they were never diagnosed in childhood, did not respond to the original treatment, the amblyopia was only partially remediated, or their acuity loss returned after cessation of treatment. Purpose In this review, we consider whether the visual deficits of this largely overlooked amblyopic group are amenable to conventional and innovative therapeutic interventions later in life, well beyond the age at which treatment is thought to be effective. Recent findings There is a considerable body of evidence that residual plasticity is present in the adult visual brain and this can be harnessed to improve function in adults with amblyopia. Perceptual training protocols have been developed to optimise visual gains in this clinical population. Results thus far are extremely encouraging: marked visual improvements have been demonstrated, the perceptual benefits transfer to new visual tasks and appear to be relatively enduring. The essential ingredients of perceptual training protocols are being incorporated into video game formats, facilitating home-based interventions. Summary Many studies support perceptual training as a tool for improving vision in amblyopes beyond the critical period. Should this novel form of treatment stand up to the scrutiny of a randomised controlled trial, clinicians may need to re-evaluate their therapeutic approach to adults with amblyopia. PMID:21981034

Higher-order aberrations and best-corrected visual acuity in Native American children with a high prevalence of astigmatism.

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Miller, Joseph M; Harvey, Erin M; Schwiegerling, Jim

2015-08-01

To determine whether higher-order aberrations (HOAs) in children from a highly astigmatic population differ from population norms and whether HOAs are associated with astigmatism and reduced best-corrected visual acuity. Subjects were 218 Tohono O'odham Native American children 5-9 years of age. Noncycloplegic HOA measurements were obtained with a handheld Shack-Hartmann sensor (SHS). Signed (z06s to z14s) and unsigned (z06u to z14u) wavefront aberration Zernike coefficients Z(3,-3) to Z(4,4) were rescaled for a 4 mm diameter pupil and compared to adult population norms. Cycloplegic refraction and best-corrected logMAR letter visual acuity (BCVA) were also measured. Regression analyses assessed the contribution of astigmatism (J0) and HOAs to BCVA. The mean root-mean-square (RMS) HOA of 0.191 ± 0.072 μm was significantly greater than population norms (0.100 ± 0.044 μm). All unsigned HOA coefficients (z06u to z14u) and all signed coefficients except z09s, z10s, and z11s were significantly larger than population norms. Decreased BCVA was associated with astigmatism (J0) and spherical aberration (z12u) but not RMS coma, with the effect of J0 about 4 times as great as z12u. Tohono O'odham children show elevated HOAs compared to population norms. Astigmatism and unsigned spherical aberration are associated with decreased acuity, but the effects of spherical aberration are minimal and not clinically significant. Copyright © 2015 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Contrast sensitivity after refractive lens exchange with a multifocal diffractive aspheric intraocular lens

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Teresa Ferrer-Blasco

2013-04-01

Full Text Available PURPOSE: To evaluate distance and near contrast sensitivity (CS under photopic and mesopic conditions before and after refractive lens exchange (RLE and implantation of the aspheric AcrySof®ReSTOR® (SN6AD3 model intraocular lens (IOL. METHODS:Seventy-four eyes of 37 patients after RLE underwent bilateral implantation with the aspheric AcrySof ReSTOR IOL. The patient sample was divided into myopic and hyperopic groups. Monocular uncorrected visual acuity at distance and near (UCVA and UCNVA, respectively and monocular best corrected visual acuity at distance and near (BCVA and BCNVA, respectively were measured before and 6 months postoperatively. Monocular CS function was measured at three different luminance levels (85, 5 and 2.5 cd/m² before and after RLE. Post-implantation results at 6 months were compared with those found before surgery. RESULTS: Our results revealed that patients in both groups obtained good UCVA and BCVA after RLE at distance and near vision in relation to pre-surgery values. No statistically significant differences were found between the values of CS pre and post-RLE at distance and near, at any lighting condition and spatial frequency (p>0.002. CONCLUSIONS: Refractive lens exchange with aspheric AcrySof ReSTOR IOL in myopic and hyperopic population provided good visual function and yield good distance and near CS under photopic and mesopic conditions.

Amblyopia treatment strategies and new drug therapies.

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Pescosolido, Nicola; Stefanucci, Alessio; Buomprisco, Giuseppe; Fazio, Stefano

2014-01-01

Amblyopia is a unilateral or bilateral reduction of visual acuity secondary to abnormal visual experience during early childhood. It is one of the most common causes of vision loss and monocular blindness and is commonly associated with strabismus, anisometropia, and visual deprivation (in particular congenital cataract and ptosis). It is clinically defined as a two-line difference of best-corrected visual acuity between the eyes. The purpose of this study was to understand the neural mechanisms of amblyopia and summarize the current therapeutic strategies. In particular, the authors focused on the concept of brain plasticity and its implication for new treatment strategies for children and adults with amblyopia. Copyright 2014, SLACK Incorporated.

Avaliação da acuidade visual Snellen Snellen visual acuity evaluation

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Marcio Zapparoli

2009-12-01

âncias diversas, mantém a razão de proporcionalidade dos optotipos baseada no ângulo visual e se aproxima em muito ao padrão teórico preconizado por Herman Snellen em 1862.PURPOSE: To evaluate the visual acuity (VA measurement by Snellen chart at three main Ophthalmology centers in Curitiba, compare these measurements with a computerized method for calibrating VA and also with the standard theory developed by Hermann Snellen. METHODS: Descriptive study including 15 Ophthalmology clinics and a computerized method to measure the VA. Using a tape measure and a caliper, measurement of the distance was obtained from the sitting patients' eye to VA optotypes projection on the wall. At the same time, measurement of the size of the letters of 4 lines of the VA projection on the wall was performed. RESULTS: To analyze the results, it was opted to compare the angles presented by each clinic for each measurement. It was not surprising that no clinic presented an exact angle of 5 arch minutes. Comparing clinics results with computerized method, we observed that only 2 clinics obtained better results if compared with the angles obtained from optotypes projection, but the data is very similar and with no statistical significance. In relation to the other clinics, the superiority of the computerized method is very relevant. All had differences in comparison to the gold standard. Individually, comparing computerized method to standard Snellen theory, it was observed that a condition very close to the ideal was obtained, in other words, results very similar to 5 arch minutes were noted in all the visual acuities analyzed. CONCLUSIONS: It can be concluded that there is a great heterogeneity in the evaluation of VA in different Ophthalmology centers. Also, the same patient, evaluated in different clinics, can obtain different VA measurements. The computerized method is practical, portable, adjustable for different distances, and maintains optotypes proportionality ratio based on visual angle

A pilot trial of the iPad tablet computer as a portable device for visual acuity testing.

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Zhang, Zhao-tian; Zhang, Shao-chong; Huang, Xiong-gao; Liang, Ling-yi

2013-01-01

We evaluated the accuracy of an app for the iPad tablet computer (Eye Chart Pro) as a portable method of visual acuity (VA) testing. A total of 120 consecutive patients (240 eyes) underwent visual acuity test with an iPad 2 and a conventional light-box chart. The logMAR VA results from the iPad were significantly higher than those from the light-box (P iPad chart and the light-box chart, with 95% limits of agreement of -0.14 to 0.19. Two groups of patients were defined: in Group 1 there were 182 eyes with VA better than 0.1 according to the light-box VA test. The median logMAR VA by the iPad was 0.54 and by the light-box chart it was 0.52; there was no significant difference between them (P = 0.69). In Group 2 there were 58 eyes with VA equal to or worse than 0.1 according to the light-box VA test. The median logMAR VA by the iPad was 1.26 and was 1.10 by the light box; the result from the iPad was significantly lower (P iPad is reliable for VA testing only when the Snellen VA is better than 0.1 (20/200).

Fusion and rivalry are dependent on the perceptual meaning of visual stimuli.

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Andrews, Timothy J; Lotto, R Beau

2004-03-09

We view the world with two eyes and yet are typically only aware of a single, coherent image. Arguably the simplest explanation for this is that the visual system unites the two monocular stimuli into a common stream that eventually leads to a single coherent sensation. However, this notion is inconsistent with the well-known phenomenon of rivalry; when physically different stimuli project to the same retinal location, the ensuing perception alternates between the two monocular views in space and time. Although fundamental for understanding the principles of binocular vision and visual awareness, the mechanisms under-lying binocular rivalry remain controversial. Specifically, there is uncertainty about what determines whether monocular images undergo fusion or rivalry. By taking advantage of the perceptual phenomenon of color contrast, we show that physically identical monocular stimuli tend to rival-not fuse-when they signify different objects at the same location in visual space. Conversely, when physically different monocular stimuli are likely to represent the same object at the same location in space, fusion is more likely to result. The data suggest that what competes for visual awareness in the two eyes is not the physical similarity between images but the similarity in their perceptual/empirical meaning.

Interocular Shift of Visual Attention Enhances Stereopsis and Visual Acuities of Anisometropic Amblyopes beyond the Critical Period of Visual Development: A Novel Approach

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Liwen Huang

2014-01-01

Full Text Available Aims. Increasing evidence shows that imbalanced suppressive drive prior to binocular combination may be the key factor in amblyopia. We described a novel binocular approach, interocular shift of visual attention (ISVA, for treatment of amblyopia in adult patients. Methods. Visual stimuli were presented anaglyphically on a computer screen. A square target resembling Landolt C had 2 openings, one in red and one in cyan color. Through blue-red goggles, each eye could only see one of the two openings. The patient was required to report the location of the opening presented to the amblyopic eye. It started at an opening size of 800 sec of arc, went up and down in 160 sec of arc step, and stopped when reaching the 5th reversals. Ten patients with anisometropic amblyopia older than age 14 (average age: 26.7 were recruited and received ISVA treatment for 6 weeks, with 2 training sessions per day. Results. Both Titmus stereopsis (z=-2.809, P=0.005 and Random-dot stereopsis (z=-2.317, P=0.018 were significantly improved. Average improvement in best corrected visual acuity (BCVA was 0.74 line (t=5.842, P<0.001. Conclusions. The ISVA treatment may be effective in treating amblyopia and restoring stereoscopic function.

Anatomic features and function of the macula and outcome of surgical tenotomy and reattachment in achiasma.

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Weiss, Avery H; Phillips, James O; Kelly, John P

2013-07-01

To examine the anatomic features and function of the macula in achiasma and to compare visual acuity, eye movements, foveation, and eye velocity before and after tenotomy and reattachment (T&R) surgery. Case series. Two children with isolated achiasma. Ophthalmologic examinations, brain magnetic resonance imaging, full-field and multifocal electroretinography (ERG), visual evoked potentials (VEPs), spectral-domain optical coherence tomography (OCT), eye-movement recordings, and unilateral T&R in 1 patient. Visual acuity before and after surgery, macular anatomic features and function, and eye velocity before and after T&R surgery in 1 patient. Magnetic resonance imaging and VEP confirmed absence of decussation of retinofugal fibers in both patients. Visual acuity was 20/100 and 20/200. The anatomic features and function of the fovea and macula were normal by OCT and multifocal ERG. After T&R, there was a marked reduction in horizontal eye velocity and monocular visual acuity improved to 20/80. The finding that the macula is normal in achiasma suggests that reduced acuity is the result of retinal image motion from nystagmus. Two-muscle T&R reduces horizontal retinal image motion and can improve visual acuity in achiasma or patients with infantile nystagmus. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Ergonomic evaluation of ubiquitous computing with monocular head-mounted display

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Kawai, Takashi; Häkkinen, Jukka; Yamazoe, Takashi; Saito, Hiroko; Kishi, Shinsuke; Morikawa, Hiroyuki; Mustonen, Terhi; Kaistinen, Jyrki; Nyman, Göte

2010-01-01

In this paper, the authors conducted an experiment to evaluate the UX in an actual outdoor environment, assuming the casual use of monocular HMD to view video content while short walking. In conducting the experiment, eight subjects were asked to view news videos on a monocular HMD while walking through a large shopping mall. Two types of monocular HMDs and a hand-held media player were used, and the psycho-physiological responses of the subjects were measured before, during, and after the experiment. The VSQ, SSQ and NASA-TLX were used to assess the subjective workloads and symptoms. The objective indexes were heart rate and stride and a video recording of the environment in front of the subject's face. The results revealed differences between the two types of monocular HMDs as well as between the monocular HMDs and other conditions. Differences between the types of monocular HMDs may have been due to screen vibration during walking, and it was considered as a major factor in the UX in terms of the workload. Future experiments to be conducted in other locations will have higher cognitive loads in order to study the performance and the situation awareness to actual and media environments.

History of falling and visual ability among independently living elderly in Sweden.

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Källstrand-Eriksson, Jeanette; Hildingh, Cathrine; Bengtsson, Boel

2016-01-01

The aim of this study was to assess the performance-based visual ability among independently living elderly subjects and to investigate whether there was any association between visual ability and falls. A total of 298 randomly selected subjects aged 70-85 years were invited for an examination including monocular and binocular visual acuity (VA), contrast sensitivity (CS), stereoscopic vision, and monocular visual fields (VFs), which were integrated to estimate the binocular VFs. Type of lenses used in their habitual correction was noted. Out of the 212 subjects who were examined, 38% reported at least one fall and 48% of these reported at least two falls during the last 2 years. Most subjects had normal results; 90% had normal binocular VA, 85% had normal binocular CS, and ~80% had positive stereopsis. Twenty-nine subjects had VF defects in the lower quadrants of the binocular VF, and 14 of these reported at least one fall. A significant association was seen between one fall or more and VA better eye, the odds ratio (OR) was 2.26, P=0.013, and between recurrent falls and lack of stereoscopic vision, the OR was 3.23, P=0.002; no other functional test showed any significant association with recurrent falls. The ORs were 1.58 for worse binocular VA, 0.60 for worse binocular CS, and 0.71 for non-normal stereoscopic vision for at least one fall, but wide confidence intervals made it difficult to draw firm conclusions about any association. Bifocal or progressive spectacles were worn by 71% with no significant difference between fallers and nonfallers (P=0.078). Even though ~40% of the total sample had experienced one or more falls, the only visual function test significantly associated with falls were VA better eye, lack of stereoscopic vision, and recurrent falls. Our results suggest that there may be more powerful predictors of falling than decreased visual ability.

Visual stimulus parameters seriously compromise the measurement of approximate number system acuity and comparative effects between adults and children

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Denes eSzucs

2013-07-01

Full Text Available It has been suggested that a simple non-symbolic magnitude comparison task is sufficient to measure the acuity of a putative Approximate Number System (ANS. A proposed measure of the ANS, the so-called 'internal Weber fraction' (w, would provide a clear measure of ANS acuity. However, ANS studies have never presented adequate evidence that the visual stimulus parameters did not compromise measurements of w to such extent that w is actually driven by visual instead of numerical processes. We therefore investigated this question by testing non-symbolic magnitude discrimination in seven-year-old children and adults. We controlled for visual parameters in a more stringent manner than usual. As a consequence of these controls, in some trials numerical cues correlated positively with number while in others they correlated negatively with number. This congruency effect strongly correlated with w, which means that congruency effects were probably driving effects in w. Consequently, in both adults and children congruency had a major impact on the fit of the model underlying the computation of w. Furthermore, children showed larger congruency effects than adults. This suggests that ANS tasks are seriously compromised by the visual stimulus parameters, which cannot be controlled. Hence, they are not pure measures of the ANS and some putative w or ratio effect differences between children and adults in previous ANS studies may be due to the differential influence of the visual stimulus parameters in children and adults. In addition, because the resolution of congruency effects relies on inhibitory (interference suppression function, some previous ANS findings were probably influenced by the developmental state of inhibitory processes especially when comparing children with developmental dyscalculia and typically developing children.

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.

Reading strategies in mild to moderate strabismic amblyopia: an eye movement investigation.

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Kanonidou, Evgenia; Proudlock, Frank A; Gottlob, Irene

2010-07-01

PURPOSE. To investigate oculomotor strategies in strabismic amblyopia and evaluate abnormalities during monocular and binocular reading. METHODS. Eye movements were recorded with a head-mounted infrared video eye-tracker (250 Hz, amblyopia, reading is impaired, not only during monocular viewing with the amblyopic eye, but also with the nonamblyopic eye and binocularly, even though normal visual acuity pertains to the latter two conditions. The impaired reading performance is associated with differences in both the saccadic and fixational patterns, most likely as adaptation strategies to abnormal sensory experiences such as crowding and suppression.

Monocular tool control, eye dominance, and laterality in New Caledonian crows.

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Martinho, Antone; Burns, Zackory T; von Bayern, Auguste M P; Kacelnik, Alex

2014-12-15

Tool use, though rare, is taxonomically widespread, but morphological adaptations for tool use are virtually unknown. We focus on the New Caledonian crow (NCC, Corvus moneduloides), which displays some of the most innovative tool-related behavior among nonhumans. One of their major food sources is larvae extracted from burrows with sticks held diagonally in the bill, oriented with individual, but not species-wide, laterality. Among possible behavioral and anatomical adaptations for tool use, NCCs possess unusually wide binocular visual fields (up to 60°), suggesting that extreme binocular vision may facilitate tool use. Here, we establish that during natural extractions, tool tips can only be viewed by the contralateral eye. Thus, maintaining binocular view of tool tips is unlikely to have selected for wide binocular fields; the selective factor is more likely to have been to allow each eye to see far enough across the midsagittal line to view the tool's tip monocularly. Consequently, we tested the hypothesis that tool side preference follows eye preference and found that eye dominance does predict tool laterality across individuals. This contrasts with humans' species-wide motor laterality and uncorrelated motor-visual laterality, possibly because bill-held tools are viewed monocularly and move in concert with eyes, whereas hand-held tools are visible to both eyes and allow independent combinations of eye preference and handedness. This difference may affect other models of coordination between vision and mechanical control, not necessarily involving tools. Copyright © 2014 Elsevier Ltd. All rights reserved.

Grey and white matter changes in children with monocular amblyopia: voxel-based morphometry and diffusion tensor imaging study.

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Li, Qian; Jiang, Qinying; Guo, Mingxia; Li, Qingji; Cai, Chunquan; Yin, Xiaohui

2013-04-01

To investigate the potential morphological alterations of grey and white matter in monocular amblyopic children using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). A total of 20 monocular amblyopic children and 20 age-matched controls were recruited. Whole-brain MRI scans were performed after a series of ophthalmologic exams. The imaging data were processed and two-sample t-tests were employed to identify group differences in grey matter volume (GMV), white matter volume (WMV) and fractional anisotropy (FA). After image screening, there were 12 amblyopic participants and 15 normal controls qualified for the VBM analyses. For DTI analysis, 14 amblyopes and 14 controls were included. Compared to the normal controls, reduced GMVs were observed in the left inferior occipital gyrus, the bilateral parahippocampal gyrus and the left supramarginal/postcentral gyrus in the monocular amblyopic group, with the lingual gyrus presenting augmented GMV. Meanwhile, WMVs reduced in the left calcarine, the bilateral inferior frontal and the right precuneus areas, and growth in the WMVs was seen in the right cuneus, right middle occipital and left orbital frontal areas. Diminished FA values in optic radiation and increased FA in the left middle occipital area and right precuneus were detected in amblyopic patients. In monocular amblyopia, cortices related to spatial vision underwent volume loss, which provided neuroanatomical evidence of stereoscopic defects. Additionally, white matter development was also hindered due to visual defects in amblyopes. Growth in the GMVs, WMVs and FA in the occipital lobe and precuneus may reflect a compensation effect by the unaffected eye in monocular amblyopia.

Visual field structure in the Empress Leilia, Asterocampa leilia (Lepidoptera, Nymphalidae): dimensions and regional variation in acuity.

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Rutowski, Ronald L; Warrant, Eric J

2002-02-01

Male Empress Leilia butterflies ( Asterocampa leilia) use a sit-and-wait tactic to locate mates. To see how vision might influence male behavior, we studied the morphology, optics, and receptor physiology of their eyes and found the following. (1) Each eye's visual field is approximately hemispherical with at most a 10 degrees overlap in the fields of the eyes. There are no large sexual differences in visual field dimensions. (2) In both sexes, rhabdoms in the frontal and dorsal ommatidia are longer than those in other eye regions. (3) Interommatidial angles are smallest frontally and around the equator of the eye. Minimum interommatidial angles are 0.9-1 degrees in males and 1.3-1.4 degrees in females. (4) Acceptance angles of ommatidia closely match interommatidial angles in the frontal region of the eye. We conclude that vision in these butterflies is mostly monocular and that males have more acute vision than females, especially in the frontal region (large facets, small interommatidial angles, small acceptance angles, long rhabdoms, and a close match between interommatidial angles and acceptance angles). This study also suggests that perched males direct their most acute vision where females are likely to appear but show no eye modifications that appear clearly related to a mate-locating tactic.

Suppression of metabolic activity caused by infantile strabismus and strabismic amblyopia in striate visual cortex of macaque monkeys.

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Wong, Agnes M F; Burkhalter, Andreas; Tychsen, Lawrence

2005-02-01

Suppression is a major sensorial abnormality in humans and monkeys with infantile strabismus. We previously reported evidence of metabolic suppression in the visual cortex of strabismic macaques, using the mitochondrial enzyme cytochrome oxidase as an anatomic label. The purpose of this study was to further elucidate alterations in cortical metabolic activity, with or without amblyopia. Six macaque monkeys were used in the experiments (four strabismic and two control). Three of the strabismic monkeys had naturally occurring, infantile strabismus (two esotropic, one exotropic). The fourth strabismic monkey had infantile microesotropia induced by alternating monocular occlusion in the first months of life. Ocular motor behaviors and visual acuity were tested after infancy in each animal, and development of stereopsis was recorded during infancy in one strabismic and one control monkey. Ocular dominance columns (ODCs) of the striate visual cortex (area V1) were labeled using cytochrome oxidase (CO) histochemistry alone, or CO in conjunction with an anterograde tracer ([H 3 ]proline or WGA-HRP) injected into one eye. Each of the strabismic monkeys showed inequalities of metabolic activity in ODCs of opposite ocularity, visible as rows of lighter CO staining, corresponding to ODCs of lower metabolic activity, alternating with rows of darker CO staining, corresponding to ODCs of higher metabolic activity. In monkeys who had infantile strabismus and unilateral amblyopia, lower metabolic activity was found in (suppressed) ODCs driven by the nondominant eye in each hemisphere. In monkeys who had infantile esotropia and alternating fixation (no amblyopia), metabolic activity was lower in ODCs driven by the ipsilateral eye in each hemisphere. The suppression included a monocular core zone at the center of ODCs and binocular border zones at the boundaries of ODCs. This suppression was not evident in the monocular lamina of the LGN, indicating an intracortical rather than

A novel visual-inertial monocular SLAM

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Yue, Xiaofeng; Zhang, Wenjuan; Xu, Li; Liu, JiangGuo

2018-02-01

With the development of sensors and computer vision research community, cameras, which are accurate, compact, wellunderstood and most importantly cheap and ubiquitous today, have gradually been at the center of robot location. Simultaneous localization and mapping (SLAM) using visual features, which is a system getting motion information from image acquisition equipment and rebuild the structure in unknown environment. We provide an analysis of bioinspired flights in insects, employing a novel technique based on SLAM. Then combining visual and inertial measurements to get high accuracy and robustness. we present a novel tightly-coupled Visual-Inertial Simultaneous Localization and Mapping system which get a new attempt to address two challenges which are the initialization problem and the calibration problem. experimental results and analysis show the proposed approach has a more accurate quantitative simulation of insect navigation, which can reach the positioning accuracy of centimeter level.

Correlation of visual acuity and central macular morphology in different types of diabetic macular edema

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Qiu-Ju Wu

2016-02-01

Full Text Available AIM:To observe the correlation of visual acuity and central macular morphology in patients with different types of diabetic macular edema(DME. METHODS: Presented study was single-center, uncontrolled retrospective clinical study. Sixty-two patients(103 eyeswith DME were included. Best corrected visual acuity(BCVAwas evaluated using early treatment diabetic retinopathy study(ETDRSvision test chart. All patients were examined by non-contact tonometer, slit lamp, indirect ophthalmoscope, and fundus fluorescein angiography(FFA. Central subfield mean thickness(CSMTin the macular area of diameter 1mm was measured by optical coherence tomography(OCT.And in the same time the integrity of inner segments/ outer segments(IS/OSand external limiting membrane(ELMreflecting light strip of 350μm center horizontal scanning line was investigated by OCT. BCVA and CSMT in different types of DME patients were analyzed using Kruskal- Wallis test. BCVA and CSMT between the two-two groups in different types of DME patients were analyzed using Nemenyi test, and multiple regression analysis was used to analyze the relative factors of BCVA. RESULTS: In the 103 eyes, 47 eyes(45.6%were focal DME, 35 eyes(34.0%were diffuse DME, 6 eyes(5.8%were ischemic DME and 15 eyes(14.6%were proliferative DME. The difference of mean BCVA(H=69.167, PH=57.113, Pχ2=14.982,Pχ2=14.537,Pχ2=15.596,Pχ2=15.393,Pχ2=16.567,Pχ2=15.687,Pχ2=12.974、P=0.008; CSMT:χ2=13.999,Pr=-0.064,-0.207,-0.082 and -0.160, respectively, Pr=-0.885, -2.522, -1.504, and-0.595, respectively, P>0.05. CONCLUSION: There are statistically significant differences on macular morphology and vision function among different types of DME patients.

Adaptive Monocular Visual–Inertial SLAM for Real-Time Augmented Reality Applications in Mobile Devices

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Jin-Chun Piao

2017-11-01

Full Text Available Simultaneous localization and mapping (SLAM is emerging as a prominent issue in computer vision and next-generation core technology for robots, autonomous navigation and augmented reality. In augmented reality applications, fast camera pose estimation and true scale are important. In this paper, we present an adaptive monocular visual–inertial SLAM method for real-time augmented reality applications in mobile devices. First, the SLAM system is implemented based on the visual–inertial odometry method that combines data from a mobile device camera and inertial measurement unit sensor. Second, we present an optical-flow-based fast visual odometry method for real-time camera pose estimation. Finally, an adaptive monocular visual–inertial SLAM is implemented by presenting an adaptive execution module that dynamically selects visual–inertial odometry or optical-flow-based fast visual odometry. Experimental results show that the average translation root-mean-square error of keyframe trajectory is approximately 0.0617 m with the EuRoC dataset. The average tracking time is reduced by 7.8%, 12.9%, and 18.8% when different level-set adaptive policies are applied. Moreover, we conducted experiments with real mobile device sensors, and the results demonstrate the effectiveness of performance improvement using the proposed method.

Adaptive Monocular Visual–Inertial SLAM for Real-Time Augmented Reality Applications in Mobile Devices

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Piao, Jin-Chun; Kim, Shin-Dug

2017-01-01

Simultaneous localization and mapping (SLAM) is emerging as a prominent issue in computer vision and next-generation core technology for robots, autonomous navigation and augmented reality. In augmented reality applications, fast camera pose estimation and true scale are important. In this paper, we present an adaptive monocular visual–inertial SLAM method for real-time augmented reality applications in mobile devices. First, the SLAM system is implemented based on the visual–inertial odometry method that combines data from a mobile device camera and inertial measurement unit sensor. Second, we present an optical-flow-based fast visual odometry method for real-time camera pose estimation. Finally, an adaptive monocular visual–inertial SLAM is implemented by presenting an adaptive execution module that dynamically selects visual–inertial odometry or optical-flow-based fast visual odometry. Experimental results show that the average translation root-mean-square error of keyframe trajectory is approximately 0.0617 m with the EuRoC dataset. The average tracking time is reduced by 7.8%, 12.9%, and 18.8% when different level-set adaptive policies are applied. Moreover, we conducted experiments with real mobile device sensors, and the results demonstrate the effectiveness of performance improvement using the proposed method. PMID:29112143

Diamond burr superficial keratectomy in the treatment of visually-significant anterior corneal lesions Ceratectomia superficial com broca de diamante no tratamento de lesões anteriores da córnea

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João Baptista Nigro Santiago Malta

2008-06-01

Full Text Available PURPOSE: To evaluate the efficacy and safety of diamond burr superficial keratectomy in the treatment of visually-significant anterior corneal lesions. METHODS: A retrospective review of 23 eyes (23 patients. Pre- and postoperative visual acuities and refractions, slit-lamp biomicroscopic findings, and the incidence of recurrence of disease after keratectomy were studied. RESULTS: Nineteen eyes had map-dot-fingerprint basement membrane dystrophy and 4 had Salzmann's nodular degeneration. All patients presented with decreased vision, as well as varying degrees of glare, halos, and monocular diplopia. Postoperative follow-up ranged from 3 to 39 months (mean 10.6 months, and no recurrence of the original disease occurred within this period. This procedure improved the best-corrected visual acuity from 20/36 (LogMar 0.250 to 20/24 (LogMar 0.076 by LogMar statistical evaluation (pOBJETIVO: Avaliar a eficácia e segurança da ceratectomia superficial com broca de diamante no tratamento das lesões anteriores da córnea. MÉTODOS: Foi realizado estudo retrospectivo de 23 olhos de 23 pacientes. Foram avaliados acuidade visual e refração pré e pós-operatório, biomicroscopia e incidência de recorrência da doença após ceratectomia. RESULTADOS: Dos 23 olhos avaliados, 19 olhos apresentavam distrofia da membrana basal (map-dot-fingerprint e 4 degeneração nodular de Salzmann. Todos os pacientes apresentavam diminuição da acuidade visual, assim como graus variados de ofuscamento, halos e diplopia monocular. O seguimento pós-operatório variou entre 3 e 39 meses (média de 10,6 meses e não houve recorrência da doença original nesse período. O procedimento melhorou a acuidade visual com melhor correção de 20/36 (LogMar 0,250 para 20/24 (LogMar 0,076 com p<0,001. Em relação as mudanças refracionais não houve significância (p=0,232 sendo o equivalente esférico pré-operatório de - 0,36 ± 2,28DE e pós-operatório de -0,71 ± 2,26DE. As

Higher order optical aberrations and visual acuity in a randomized controlled trial comparing transepithelial versus epithelium-off corneal crosslinking for progressive keratoconus

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Godefrooij DA

2017-10-01

Full Text Available Daniel A Godefrooij, Mustapha El Kandoussi, Nienke Soeters, Robert PL Wisse Utrecht Cornea Research Group, Department of Ophthalmology, University Medical Center Utrecht, Utrecht, the Netherlands Purpose: The purpose of this study was to compare the effects of transepithelial crosslinking (trans-CXL versus epithelium-off crosslinking (epi-off CXL for progressive keratoconus with respect to the development of higher order aberrations (HOAs and their effects on visual acuity.Materials and methods: A total of 61 patients were randomized and examined preoperatively and 1, 3, 6, and 12 months postoperatively in an academic referral center. Total corneal HOAs were compared between the two treatment groups using mixed linear modeling. Types of HOAs (coma, trefoil, and spherical aberration that differed between groups were entered in a multivariable analysis to test their effect on uncorrected distance visual acuity (UDVA and corrected distance visual acuity (CDVA.Results: The epi-off CXL group had more flattening in maximal keratometry compared to the trans-CXL group (P=0.02. UDVA did not differ significantly between the groups (P=0.59; however, CDVA was significantly more improved in the trans-CXL group (P=0.02. Horizontal trefoil improved more in the epi-off group compared to the trans-CXL group (P=0.04, whereas the other HOAs were virtually unchanged in both groups. Differences in changes in HOAs between the two groups had no effect on either UCVA (P=0.76 or CDVA (P=0.96.Conclusion: Although HOAs are clinically relevant determinants of vision quality in keratoconus patients, the change in total HOAs post treatment did not differ between the trans-CXL and epi-off CXL groups. Only horizontal trefoil differed significantly post treatment between the trans-CXL and epi-off CXL groups. However, this difference did not independently affect either UDVA or CDVA. Trans-CXL provides no benefit over epi-off CXL regarding visual relevant HOAs. Keywords

Functional vision loss: a diagnosis of exclusion.

Science.gov (United States)

Villegas, Rex B; Ilsen, Pauline F

2007-10-01

Most cases of visual acuity or visual field loss can be attributed to ocular pathology or ocular manifestations of systemic pathology. They can also occasionally be attributed to nonpathologic processes or malingering. Functional vision loss is any decrease in vision the origin of which cannot be attributed to a pathologic or structural abnormality. Two cases of functional vision loss are described. In the first, a 58-year-old man presented for a baseline eye examination for enrollment in a vision rehabilitation program. He reported bilateral blindness since a motor vehicle accident with head trauma 4 years prior. Entering visual acuity was "no light perception" in each eye. Ocular health examination was normal and the patient made frequent eye contact with the examiners. He was referred for neuroimaging and electrophysiologic testing. The second case was a 49-year-old man who presented with a long history of intermittent monocular diplopia. His medical history was significant for psycho-medical evaluations and a diagnosis of factitious disorder. Entering uncorrected visual acuities were 20/20 in each eye, but visual field testing found constriction. No abnormalities were found that could account for the monocular diplopia or visual field deficit. A diagnosis of functional vision loss secondary to factitious disorder was made. Functional vision loss is a diagnosis of exclusion. In the event of reduced vision in the context of a normal ocular health examination, all other pathology must be ruled out before making the diagnosis of functional vision loss. Evaluation must include auxiliary ophthalmologic testing, neuroimaging of the visual pathway, review of the medical history and lifestyle, and psychiatric evaluation. Comanagement with a psychiatrist is essential for patients with functional vision loss.

Simulating Visibility Under Reduced Acuity and Contrast Sensitivity

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Thompson, William B.; Legge, Gordon E.; Kersten, Daniel J.; Shakespeare, Robert A.; Lei, Quan

2017-01-01

Architects and lighting designers have difficulty designing spaces that are accessible to those with low vision, since the complex nature of most architectural spaces requires a site-specific analysis of the visibility of mobility hazards and key landmarks needed for navigation. We describe a method that can be utilized in the architectural design process for simulating the effects of reduced acuity and contrast on visibility. The key contribution is the development of a way to parameterize the simulation using standard clinical measures of acuity and contrast sensitivity. While these measures are known to be imperfect predictors of visual function, they provide a way of characterizing general levels of visual performance that is familiar to both those working in low vision and our target end-users in the architectural and lighting design communities. We validate the simulation using a letter recognition task. PMID:28375328

A variação da acuidade visual durante esforços físicos em atletas com baixa visão, participantes de seleção brasileira de atletismo The visual acuity variability during physical efforts in low vision athletes from the athletics Brazilian team

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Ciro Winckler de Oliveira Filho

2007-08-01

Full Text Available INTRODUÇÃO E OBJETIVO: Esta pesquisa teve como objetivo avaliar o comportamento da acuidade visual em atletas com baixa visão, durante um protocolo de esforço contínuo. Pesquisas apontam que a acuidade visual apresenta variações de rendimento quando submetida a esforços físicos em sujeitos sem deficiência visual. MÉTODO: A população estudada foi composta por seis pessoas, praticantes de atletismo e integrantes da seleção brasileira em provas de pista. No primeiro dia aplicou-se o teste de esforço físico progressivo, realizado em esteira. No segundo dia realizou-se o teste de esforço contínuo, o qual foi dividido em três níveis, cada um com 15 minutos de duração e 30 minutos de intervalo entre eles. Como delimitador das intensidades aplicadas utilizaram-se os resultados obtidos no teste de físico progressivo (60% do VE pico, limiar de VE e 90% do VE pico. A aferição da acuidade visual aconteceu antes, durante e após cada nível de intensidade no protocolo de esforço contínuo. O teste t de Student foi utilizado para a análise estatística (p INTRODUCTION AND OBJECTIVE: This study had as an objective to evaluate the visual acuity behavior in athletes with low vision, during a continuous effort protocol. Researches point out that visual acuity presents performance varieties when submitted to physical efforts in subjects without visual impairment. METHOD: The studied population was composed by six peoples, who practiced athletics and were part of the Brazilian team in track events. The progressive physical effort test was applied on the first day in a treadmill. On the second day the continuous effort test was applied, which was divided in three levels, each one had a 15 and 30 minutes break between them. To determine the intensities, the results obtained in the progressive physical effort test (60% of VE peak, limiar VE and 90% VE peak were used. The visual acuity was measured before, during and after each level of

A Novel Metric Online Monocular SLAM Approach for Indoor Applications

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Yongfei Li

2016-01-01

Full Text Available Monocular SLAM has attracted more attention recently due to its flexibility and being economic. In this paper, a novel metric online direct monocular SLAM approach is proposed, which can obtain the metric reconstruction of the scene. In the proposed approach, a chessboard is utilized to provide initial depth map and scale correction information during the SLAM process. The involved chessboard provides the absolute scale of scene, and it is seen as a bridge between the camera visual coordinate and the world coordinate. The scene is reconstructed as a series of key frames with their poses and correlative semidense depth maps, using a highly accurate pose estimation achieved by direct grid point-based alignment. The estimated pose is coupled with depth map estimation calculated by filtering over a large number of pixelwise small-baseline stereo comparisons. In addition, this paper formulates the scale-drift model among key frames and the calibration chessboard is used to correct the accumulated pose error. At the end of this paper, several indoor experiments are conducted. The results suggest that the proposed approach is able to achieve higher reconstruction accuracy when compared with the traditional LSD-SLAM approach. And the approach can also run in real time on a commonly used computer.

Metformin Impairs Spatial Memory and Visual Acuity in Old Male Mice.

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Thangthaeng, Nopporn; Rutledge, Margaret; Wong, Jessica M; Vann, Philip H; Forster, Michael J; Sumien, Nathalie

2017-02-01

Metformin is an oral anti-diabetic used as first-line therapy for type 2 diabetes. Because benefits of metformin extend beyond diabetes to other age-related pathology, and because its effect on gene expression profiles resembles that of caloric restriction, metformin has a potential as an anti-aging intervention and may soon be assessed as an intervention to extend healthspan. However, beneficial actions of metformin in the central nervous system have not been clearly established. The current study examined the effect of chronic oral metformin treatment on motor and cognitive function when initiated in young, middle-aged, or old male mice. C57BL/6 mice aged 4, 11, or 22 months were randomly assigned to either a metformin group (2 mg/ml in drinking water) or a control group. The mice were monitored weekly for body weight, as well as food and water intake and a battery of behavioral tests for motor, cognitive and visual function was initiated after the first month of treatment. Liver, hippocampus and cortex were collected at the end of the study to assess redox homeostasis. Overall, metformin supplementation in male mice failed to affect blood glucose, body weights and redox homeostasis at any age. It also had no beneficial effect on age-related declines in psychomotor, cognitive or sensory functions. However, metformin treatment had a deleterious effect on spatial memory and visual acuity, and reduced SOD activity in brain regions. These data confirm that metformin treatment may be associated with deleterious effect resulting from the action of metformin on the central nervous system.

Distinct Circuits for Recovery of Eye Dominance and Acuity in Murine Amblyopia.

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Stephany, Céleste-Élise; Ma, Xiaokuang; Dorton, Hilary M; Wu, Jie; Solomon, Alexander M; Frantz, Michael G; Qiu, Shenfeng; McGee, Aaron W

2018-05-24

Degrading vision by one eye during a developmental critical period yields enduring deficits in both eye dominance and visual acuity. A predominant model is that "reactivating" ocular dominance (OD) plasticity after the critical period is required to improve acuity in amblyopic adults. However, here we demonstrate that plasticity of eye dominance and acuity are independent and restricted by the nogo-66 receptor (ngr1) in distinct neuronal populations. Ngr1 mutant mice display greater excitatory synaptic input onto both inhibitory and excitatory neurons with restoration of normal vision. Deleting ngr1 in excitatory cortical neurons permits recovery of eye dominance but not acuity. Reciprocally, deleting ngr1 in thalamus is insufficient to rectify eye dominance but yields improvement of acuity to normal. Abolishing ngr1 expression in adult mice also promotes recovery of acuity. Together, these findings challenge the notion that mechanisms for OD plasticity contribute to the alterations in circuitry that restore acuity in amblyopia. Copyright © 2018 Elsevier Ltd. All rights reserved.

To Further the Near-Vision Visual Acuity Tests (3): For a Test Which Saves Time, Labor, and Expenses

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高橋, ひとみ; 川端, 秀仁; 衞藤, 隆

2014-01-01

The Ministry of Education, Culture, Sports, Science and Technology of Japan has its advisory board to review the list of medical checkup for school children every ten years. In August 2013 the board found that there was a considerable number of school children who had poor near vision and thus learn in the class less efficiently. The board recommended that the Ministry consider whether to include a near-vision visual acuity test in a regular medical examination at school. It may not be known ...

Individual Differences in Scotopic Visual Acuity and Contrast Sensitivity: Genetic and Non-Genetic Influences.

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Alex J Bartholomew

Full Text Available Despite the large amount of variation found in the night (scotopic vision capabilities of healthy volunteers, little effort has been made to characterize this variation and factors, genetic and non-genetic, that influence it. In the largest population of healthy observers measured for scotopic visual acuity (VA and contrast sensitivity (CS to date, we quantified the effect of a range of variables on visual performance. We found that young volunteers with excellent photopic vision exhibit great variation in their scotopic VA and CS, and this variation is reliable from one testing session to the next. We additionally identified that factors such as Circadian preference, iris color, astigmatism, depression, sex and education have no significant impact on scotopic visual function. We confirmed previous work showing that the amount of time spent on the vision test influences performance and that laser eye surgery results in worse scotopic vision. We also showed a significant effect of intelligence and photopic visual performance on scotopic VA and CS, but all of these variables collectively explain <30% of the variation in scotopic vision. The wide variation seen in young healthy volunteers with excellent photopic vision, the high test-retest agreement, and the vast majority of the variation in scotopic vision remaining unexplained by obvious non-genetic factors suggests a strong genetic component. Our preliminary genome-wide association study (GWAS of 106 participants ruled out any common genetic variants of very large effect and paves the way for future, larger genetic studies of scotopic vision.

History of falling and visual ability among independently living elderly in Sweden

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Källstrand-Eriksson J

2016-07-01

Full Text Available Jeanette Källstrand-Eriksson,1 Cathrine Hildingh,1 Boel Bengtsson2 1School of Health and Welfare, Halmstad University, Halmstad, 2Department of Clinical Sciences in Malmö, Ophthalmology, Lund University, Malmö, Sweden Purpose: The aim of this study was to assess the performance-based visual ability among independently living elderly subjects and to investigate whether there was any association between visual ability and falls.Subjects and methods: A total of 298 randomly selected subjects aged 70–85 years were invited for an examination including monocular and binocular visual acuity (VA, contrast sensitivity (CS, stereoscopic vision, and monocular visual fields (VFs, which were integrated to estimate the binocular VFs. Type of lenses used in their habitual correction was noted.Results: Out of the 212 subjects who were examined, 38% reported at least one fall and 48% of these reported at least two falls during the last 2 years. Most subjects had normal results; 90% had normal binocular VA, 85% had normal binocular CS, and ~80% had positive stereopsis. Twenty-nine subjects had VF defects in the lower quadrants of the binocular VF, and 14 of these reported at least one fall. A significant association was seen between one fall or more and VA better eye, the odds ratio (OR was 2.26, P=0.013, and between recurrent falls and lack of stereoscopic vision, the OR was 3.23, P=0.002; no other functional test showed any significant association with recurrent falls. The ORs were 1.58 for worse binocular VA, 0.60 for worse binocular CS, and 0.71 for non-normal stereoscopic vision for at least one fall, but wide confidence intervals made it difficult to draw firm conclusions about any association. Bifocal or progressive spectacles were worn by 71% with no significant difference between fallers and nonfallers (P=0.078.Conclusion: Even though ~40% of the total sample had experienced one or more falls, the only visual function test significantly associated

Local and non-local deficits in amblyopia: acuity and spatial interactions.

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Bonneh, Yoram S; Sagi, Dov; Polat, Uri

2004-12-01

Amblyopic vision is thought to be limited by abnormal long-range spatial interactions, but their exact mode of action and relationship to the main amblyopic deficit in visual acuity is largely unknown. We studied this relationship in a group (N=59) of anisometropic (N=21) and strabismic (or combined, N=38) subjects, using (1) a single and multi-pattern (crowded) computerized static Tumbling-E test with scaled spacing of two pattern widths (TeVA), in addition to an optotype (ETDRS chart) acuity test (VA) and (2) contrast detection of Gabor patches with lateral flankers (lateral masking) along the horizontal and vertical axes as well as in collinear and parallel configurations. By correlating the different measures of visual acuity and contrast suppression, we found that (1) the VA of the strabismic subjects could be decomposed into two uncorrelated components measured in TeVA: acuity for isolated patterns and acuity reduction due to flanking patterns. The latter comprised over 60% of the VA magnitude, on the average and accounted for over 50% of its variance. In contrast, a slight reduction in acuity was found in the anisometropic subjects, and the acuity for a single pattern could account for 70% of the VA variance. (2) The lateral suppression (contrast threshold elevation) in a parallel configuration along the horizontal axis was correlated with the VA (R2=0.7), as well as with the crowding effect (TeVA elevation, R2=0.5) for the strabismic group. Some correlation with the VA was also found for the collinear configuration in the anisometropic group, but less suppression and no correlation were found for all the vertical configurations in all the groups. The results indicate the existence of a specific non-local component of the strabismic deficit, in addition to the local acuity deficit in all amblyopia types. This deficit might reflect long-range lateral inhibition, or alternatively, an inaccurate and scattered top-down attentional selection mechanism.

Correlation Between Near-Vision Acuity and the Incidence of Peritoneal Dialysis-Related Infections.

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Kojima, Shigeki; Sakurada, Tsutomu; Koitabashi, Kenichiro; Kojima, Kaori; Watanabe, Shiika; Uchida, Daisuke; Kaneshiro, Nagayuki; Konno, Yusuke; Shibagaki, Yugo

Peritoneal dialysis (PD)-related infections (PDIs) such as peritonitis, exit-site infection, and tunnel infection are serious complications affecting patients on PD. Because patients with diabetes (DM) and of older age have increased in number in Japan, the number of patients with visual impairment is estimated also to have increased. Near vision is necessary for performing proper PD daily care. However, no studies have reported whether visual impairment is likely to increase the risk of PDIs.Our study included 31 PD patients (16 men, 15 women; mean age: 61.5 ± 11.8 years; mean PD duration: 27.3 ± 20.3 months; 38.7% with DM; 54.8% wearing glasses) who performed their own PD care. At our facility and related facilities, we used a standard near-vision test chart, which classifies vision into 12 grades, from 0.1 (poor) to 1.5 (clear), to assess near-vision binocular visual acuity in those patients between March 2015 and September 2015. In addition, we retrospectively examined the medical records of the patients to determine their history of PDIs. We then evaluated the correlation between near-vision acuity and the incidence of PDIs.Mean measured near-vision acuity was 0.61 ± 0.29, and we observed no significant difference in the visual acuity of patients with and without DM (0.55 ± 0.31 vs. 0.63 ± 0.26 respectively, p = 0.477). In addition, we observed no significant difference in the incidence of PDIs between patients with and without DM (1.298 ± 1.609 per year vs. 1.164 ± 0.908 per year respectively, p = 0.804). We did not find a correlation between near-vision acuity and the incidence of PDIs (r = -0.071, p = 0.795).

Uncorrected visual acuity in the immediate postoperative period following uncomplicated cataract surgery: bimanual microincision cataract surgery versus standard coaxial phacoemulsification.

LENUS (Irish Health Repository)

Saeed, Ayman

2012-02-01

AIM: We compared bimanual microincision cataract surgery (MICS) and standard coaxial phacoemulsification (CAP) in terms of uncorrected visual acuity (UCVA) recorded 1 h and 2 weeks postoperatively. METHODS: This was a prospective, nonrandomised comparative study. All MICS procedures were performed by one surgeon (MGM), and all CAP procedures were performed by another surgeon (SB). Eyes with visually consequential ocular morbidity were excluded. The primary outcome measure was UCVA recorded 1 h postoperatively. RESULTS: One hundred eyes underwent MICS and CAP (50 eyes in each group). The treatment groups did not differ significantly in terms of preoperative mean best corrected visual acuity (6\\/24 +\\/- 4.3 lines and 6\\/20 +\\/- 4.4 lines in the MICS and the CAP groups, respectively; P = 0.65). Also, there was no significant difference in terms of postoperative UCVA at 1 h or at 2 weeks (mean +\\/- standard deviation UCVA 1 h postoperatively: MICS: 6\\/36 +\\/- 5.7 lines; CAP: 6\\/30 +\\/- 4.7 lines; P = 0.80; UCVA 2 weeks postoperatively: MICS: 6\\/10 +\\/- 1.9 lines; CAP: 6\\/10 +\\/- 2.2 lines; P = 0.90). However, nine eyes (18%) and one eye (2%) achieved a UCVA of C6\\/12 at 1 h following MICS and CAP, respectively, and this difference was statistically significant (P = 0.02). CONCLUSION: Mean UCVA at 1 h and at 2 weeks following cataract surgery was not significantly different between eyes undergoing MICS and CAP. However, a greater proportion of patients achieved a UCVA of C6\\/12 following MICS when compared with CAP.

Quantitative measurement of interocular suppression in anisometropic amblyopia: a case-control study.

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Li, Jinrong; Hess, Robert F; Chan, Lily Y L; Deng, Daming; Yang, Xiao; Chen, Xiang; Yu, Minbin; Thompson, Benjamin

2013-08-01

The aims of this study were to assess (1) the relationship between interocular suppression and visual function in patients with anisometropic amblyopia, (2) whether suppression can be simulated in matched controls using monocular defocus or neutral density filters, (3) the effects of spectacle or rigid gas-permeable contact lens correction on suppression in patients with anisometropic amblyopia, and (4) the relationship between interocular suppression and outcomes of occlusion therapy. Case-control study (aims 1-3) and cohort study (aim 4). Forty-five participants with anisometropic amblyopia and 45 matched controls (mean age, 8.8 years for both groups). Interocular suppression was assessed using Bagolini striated lenses, neutral density filters, and an objective psychophysical technique that measures the amount of contrast imbalance between the 2 eyes that is required to overcome suppression (dichoptic motion coherence thresholds). Visual acuity was assessed using a logarithm minimum angle of resolution tumbling E chart and stereopsis using the Randot preschool test. Interocular suppression assessed using dichoptic motion coherence thresholds. Patients exhibited significantly stronger suppression than controls, and stronger suppression was correlated significantly with poorer visual acuity in amblyopic eyes. Reducing monocular acuity in controls to match that of cases using neutral density filters (luminance reduction) resulted in levels of interocular suppression comparable with that in patients. This was not the case for monocular defocus (optical blur). Rigid gas-permeable contact lens correction resulted in less suppression than spectacle correction, and stronger suppression was associated with poorer outcomes after occlusion therapy. Interocular suppression plays a key role in the visual deficits associated with anisometropic amblyopia and can be simulated in controls by inducing a luminance difference between the eyes. Accurate quantification of suppression

Bilateral symmetry in vision and influence of ocular surgical procedures on binocular vision: A topical review

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Samuel Arba Mosquera

2016-10-01

Full Text Available We analyze the role of bilateral symmetry in enhancing binocular visual ability in human eyes, and further explore how efficiently bilateral symmetry is preserved in different ocular surgical procedures. The inclusion criterion for this review was strict relevance to the clinical questions under research. Enantiomorphism has been reported in lower order aberrations, higher order aberrations and cone directionality. When contrast differs in the two eyes, binocular acuity is better than monocular acuity of the eye that receives higher contrast. Anisometropia has an uncommon occurrence in large populations. Anisometropia seen in infancy and childhood is transitory and of little consequence for the visual acuity. Binocular summation of contrast signals declines with age, independent of inter-ocular differences. The symmetric associations between the right and left eye could be explained by the symmetry in pupil offset and visual axis which is always nasal in both eyes. Binocular summation mitigates poor visual performance under low luminance conditions and strong inter-ocular disparity detrimentally affects binocular summation. Considerable symmetry of response exists in fellow eyes of patients undergoing myopic PRK and LASIK, however the method to determine whether or not symmetry is maintained consist of comparing individual terms in a variety of ad hoc ways both before and after the refractive surgery, ignoring the fact that retinal image quality for any individual is based on the sum of all terms. The analysis of bilateral symmetry should be related to the patients’ binocular vision status. The role of aberrations in monocular and binocular vision needs further investigation.

A monocular, unconscious form of visual attention

NARCIS (Netherlands)

Self, M.W.; Roelfsema, P.R.

2010-01-01

Sudden changes in our visual field capture our attention so that we are faster and more accurate in our responses to that region of space. The underlying mechanisms by which these behavioral improvements occur are unknown. Here we investigate the level of the visual system at which attentional

On so-called paradoxical monocular stereoscopy.

Science.gov (United States)

Koenderink, J J; van Doorn, A J; Kappers, A M

1994-01-01

Human observers are apparently well able to judge properties of 'three-dimensional objects' on the basis of flat pictures such as photographs of physical objects. They obtain this 'pictorial relief' without much conscious effort and with little interference from the (flat) picture surface. Methods for 'magnifying' pictorial relief from single pictures include viewing instructions as well as a variety of monocular and binocular 'viewboxes'. Such devices are reputed to yield highly increased pictorial depth, though no methodologies for the objective verification of such claims exist. A binocular viewbox has been reconstructed and pictorial relief under monocular, 'synoptic', and natural binocular viewing is described. The results corroborate and go beyond early introspective reports and turn out to pose intriguing problems for modern research.

Analysis the macular ganglion cell complex thickness in monocular strabismic amblyopia patients by Fourier-domain OCT

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Hong-Wei Deng

2014-11-01

Full Text Available AIM: To detect the macular ganglion cell complex thickness in monocular strabismus amblyopia patients, in order to explore the relationship between the degree of amblyopia and retinal ganglion cell complex thickness, and found out whether there is abnormal macular ganglion cell structure in strabismic amblyopia. METHODS: Using a fourier-domain optical coherence tomography(FD-OCTinstrument iVue®(Optovue Inc, Fremont, CA, Macular ganglion cell complex(mGCCthickness was measured and statistical the relation rate with the best vision acuity correction was compared Gman among 26 patients(52 eyesincluded in this study. RESULTS: The mean thickness of the mGCC in macular was investigated into three parts: centrial, inner circle(3mmand outer circle(6mm. The mean thicknesses of mGCC in central, inner and outer circle was 50.74±21.51μm, 101.4±8.51μm, 114.2±9.455μm in the strabismic amblyopia eyes(SAE, and 43.79±11.92μm,92.47±25.01μm, 113.3±12.88μm in the contralateral sound eyes(CSErespectively. There was no statistically significant difference among the eyes(P>0.05. But the best corrected vision acuity had a good correlation rate between mGcc thicknesses, which was better relative for the lower part than the upper part.CONCLUSION:There is a relationship between the amblyopia vision acuity and the mGCC thickness. Although there has not statistically significant difference of the mGCC thickness compared with the SAE and CSE. To measure the macular center mGCC thickness in clinic may understand the degree of amblyopia.

When the Wheels Touch Earth and the Flight is Through, Pilots Find One Eye is Better Than Two?

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Valimont, Brian; Wise, John A.; Nichols, Troy; Best, Carl; Suddreth, John; Cupero, Frank

2009-01-01

This study investigated the impact of near to eye displays on both operational and visual performance by employing a human-in-the-loop simulation of straight-in ILS approaches while using a near to eye (NTE) display. The approaches were flown in simulated visual and instrument conditions while using either a biocular NTE or a monocular NTE display on either the dominant or non dominant eye. The pilot s flight performance, visual acuity, and ability to detect unsafe conditions on the runway were tested.

Efficacy and safety of multifocal intraocular lenses following cataract and refractive lens exchange: Metaanalysis of peer-reviewed publications.

Science.gov (United States)

Rosen, Emanuel; Alió, Jorge L; Dick, H Burkhard; Dell, Steven; Slade, Stephen

2016-02-01

We performed a metaanaysis of peer-reviewed studies involving implantation of a multifocal intraocular lens (IOL) in presbyopic patients with cataract or having refractive lens exchange (RLE). Previous reviews have considered the use of multifocal IOLs after cataract surgery but not after RLE, whereas greater insight might be gained from examining the full range of studies. Selected studies were examined to collate outcomes with monocular and binocular uncorrected distance, intermediate, and near visual acuity; spectacle independence; contrast sensitivity; visual symptoms; adverse events; and patient satisfaction. In 8797 eyes, the mean postoperative monocular uncorrected distance visual acuity (UDVA) was 0.05 logMAR ± 0.006 (SD) (Snellen equivalent 20/20(-3)). In 6334 patients, the mean binocular UDVA was 0.04 ± 0.00 logMAR (Snellen equivalent 20/20(-2)), with a mean spectacle independence of 80.1%. Monocular mean UDVA did not differ significantly between those who had a cataract procedure and those who had an RLE procedure. Neural adaptation to multifocality may vary among patients. Dr. Alió is a clinical research investigator for Hanita Lenses, Carl Zeiss Meditec AG, Topcon Medical Systems, Inc., Oculentis GmbH, and Akkolens International BV. Dr. Dell is a consultant to Bausch & Lomb and Abbott Medical Optics, Inc. Dr. Slade is a consultant to Alcon Surgical, Inc., Carl Zeiss Meditec AG, and Bausch & Lomb. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Monocular SLAM for autonomous robots with enhanced features initialization.

Science.gov (United States)

Guerra, Edmundo; Munguia, Rodrigo; Grau, Antoni

2014-04-02

This work presents a variant approach to the monocular SLAM problem focused in exploiting the advantages of a human-robot interaction (HRI) framework. Based upon the delayed inverse-depth feature initialization SLAM (DI-D SLAM), a known monocular technique, several but crucial modifications are introduced taking advantage of data from a secondary monocular sensor, assuming that this second camera is worn by a human. The human explores an unknown environment with the robot, and when their fields of view coincide, the cameras are considered a pseudo-calibrated stereo rig to produce estimations for depth through parallax. These depth estimations are used to solve a related problem with DI-D monocular SLAM, namely, the requirement of a metric scale initialization through known artificial landmarks. The same process is used to improve the performance of the technique when introducing new landmarks into the map. The convenience of the approach taken to the stereo estimation, based on SURF features matching, is discussed. Experimental validation is provided through results from real data with results showing the improvements in terms of more features correctly initialized, with reduced uncertainty, thus reducing scale and orientation drift. Additional discussion in terms of how a real-time implementation could take advantage of this approach is provided.

Decrease in monocular sleep after sleep deprivation in the domestic chicken

NARCIS (Netherlands)

Boerema, AS; Riedstra, B; Strijkstra, AM

2003-01-01

We investigated the trade-off between sleep need and alertness, by challenging chickens to modify their monocular sleep. We sleep deprived domestic chickens (Gallus domesticus) to increase their sleep need. We found that in response to sleep deprivation the fraction of monocular sleep within sleep

Revealing Detail along the Visual Hierarchy: Neural Clustering Preserves Acuity from V1 to V4.

Science.gov (United States)

Lu, Yiliang; Yin, Jiapeng; Chen, Zheyuan; Gong, Hongliang; Liu, Ye; Qian, Liling; Li, Xiaohong; Liu, Rui; Andolina, Ian Max; Wang, Wei

2018-04-18

How primates perceive objects along with their detailed features remains a mystery. This ability to make fine visual discriminations depends upon a high-acuity analysis of spatial frequency (SF) along the visual hierarchy from V1 to inferotemporal cortex. By studying the transformation of SF across macaque parafoveal V1, V2, and V4, we discovered SF-selective functional domains in V4 encoding higher SFs up to 12 cycles/°. These intermittent higher-SF-selective domains, surrounded by domains encoding lower SFs, violate the inverse relationship between SF preference and retinal eccentricity. The neural activities of higher- and lower-SF domains correspond to local and global features, respectively, of the same stimuli. Neural response latencies in high-SF domains are around 10 ms later than in low-SF domains, consistent with the coarse-to-fine nature of perception. Thus, our finding of preserved resolution from V1 into V4, separated both spatially and temporally, may serve as a connecting link for detailed object representation. Copyright © 2018 Elsevier Inc. All rights reserved.

Audiovisual plasticity following early abnormal visual experience: Reduced McGurk effect in people with one eye.

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Moro, Stefania S; Steeves, Jennifer K E

2018-04-13

Previously, we have shown that people who have had one eye surgically removed early in life during visual development have enhanced sound localization [1] and lack visual dominance, commonly observed in binocular and monocular (eye-patched) viewing controls [2]. Despite these changes, people with one eye integrate auditory and visual components of multisensory events optimally [3]. The current study investigates how people with one eye perceive the McGurk effect, an audiovisual illusion where a new syllable is perceived when visual lip movements do not match the corresponding sound [4]. We compared individuals with one eye to binocular and monocular viewing controls and found that they have a significantly smaller McGurk effect compared to binocular controls. Additionally, monocular controls tended to perceive the McGurk effect less often than binocular controls suggesting a small transient modulation of the McGurk effect. These results suggest altered weighting of the auditory and visual modalities with both short and long-term monocular viewing. These results indicate the presence of permanent adaptive perceptual accommodations in people who have lost one eye early in life that may serve to mitigate the loss of binocularity during early brain development. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

[DIN-compatible vision assessment of increased reproducibility using staircase measurement and maximum likelihood analysis].

Science.gov (United States)

Weigmann, U; Petersen, J

1996-08-01

Visual acuity determination according to DIN 58,220 does not make full use of the information received about the patient, in contrast to the staircase method. Thus, testing the same number of optotypes, the staircase method should yield more reproducible acuity results. On the other hand, the staircase method gives systematically higher acuity values because it converges on the 48% point of the psychometric function (for Landolt rings in eight positions) and not on the 65% probability, as DIN 58,220 with criterion 3/5 does. This bias can be avoided by means of a modified evaluation. Using the staircase data we performed a maximum likelihood estimate of the psychometric function as a whole and computed the acuity value for 65% probability of correct answers. We determined monocular visual acuity in 102 persons with widely differing visual performance. Each subject underwent four tests in random order, two according to DIN 58,220 and two using the modified staircase method (Landolt rings in eight positions scaled by a factor 1.26; PC monitor with 1024 x 768 pixels; distance 4.5 m). Each test was performed with 25 optotypes. The two procedures provide the same mean visual acuity values (difference less than 0.02 acuity steps). The test-retest results match in 30.4% of DIN repetitions but in 50% of the staircases. The standard deviation of the test-retest difference is 1.41 (DIN) and 1.06 (modified staircase) acuity steps. Thus the standard deviation of the single test is 1.0 (DIN) and 0.75 (modified staircase) acuity steps. The new method provides visual acuity values identical to DIN 58,220 but is superior with respect to reproducibility.

Visual function of cataract with high myopia

Directory of Open Access Journals (Sweden)

Jian-Tao Ren

2013-09-01

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

A binocular iPad treatment for amblyopic children.

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Li, S L; Jost, R M; Morale, S E; Stager, D R; Dao, L; Stager, D; Birch, E E

2014-10-01

Monocular amblyopia treatment (patching or penalization) does not always result in 6/6 vision and amblyopia often recurs. As amblyopia arises from abnormal binocular visual experience, we evaluated the effectiveness of a novel home-based binocular amblyopia treatment. Children (4-12 y) wore anaglyphic glasses to play binocular games on an iPad platform for 4 h/w for 4 weeks. The first 25 children were assigned to sham games and then 50 children to binocular games. Children in the binocular group had the option of participating for an additional 4 weeks. Compliance was monitored with calendars and tracking fellow eye contrast settings. About half of the children in each group were also treated with patching at a different time of day. Best-corrected visual acuity, suppression, and stereoacuity were measured at baseline, at the 4- and 8-week outcome visits, and 3 months after cessation of treatment. Mean (±SE) visual acuity improved in the binocular group from 0.47±0.03 logMAR at baseline to 0.39±0.03 logMAR at 4 weeks (P<0.001); there was no significant change for the sham group. The effect of binocular games on visual acuity did not differ for children who were patched vs those who were not. The median stereoacuity remained unchanged in both groups. An additional 4 weeks of treatment did not yield additional visual acuity improvement. Visual acuity improvements were maintained for 3 months after the cessation of treatment. Binocular iPad treatment rapidly improved visual acuity, and visual acuity was stable for at least 3 months following the cessation of treatment.

Relating Standardized Visual Perception Measures to Simulator Visual System Performance

Science.gov (United States)

Kaiser, Mary K.; Sweet, Barbara T.

2013-01-01

Human vision is quantified through the use of standardized clinical vision measurements. These measurements typically include visual acuity (near and far), contrast sensitivity, color vision, stereopsis (a.k.a. stereo acuity), and visual field periphery. Simulator visual system performance is specified in terms such as brightness, contrast, color depth, color gamut, gamma, resolution, and field-of-view. How do these simulator performance characteristics relate to the perceptual experience of the pilot in the simulator? In this paper, visual acuity and contrast sensitivity will be related to simulator visual system resolution, contrast, and dynamic range; similarly, color vision will be related to color depth/color gamut. Finally, we will consider how some characteristics of human vision not typically included in current clinical assessments could be used to better inform simulator requirements (e.g., relating dynamic characteristics of human vision to update rate and other temporal display characteristics).

Reducing Short-Wavelength Blue Light in Dry Eye Patients with Unstable Tear Film Improves Performance on Tests of Visual Acuity.

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Kaido, Minako; Toda, Ikuko; Oobayashi, Tomoo; Kawashima, Motoko; Katada, Yusaku; Tsubota, Kazuo

2016-01-01

To investigate whether suppression of blue light can improve visual function in patients with short tear break up time (BUT) dry eye (DE). Twenty-two patients with short BUT DE (10 men, 12 women; mean age, 32.4 ± 6.4 years; age range, 23-43 years) and 18 healthy controls (10 men, 8 women; mean age, 30.1 ± 7.4 years; age range, 20-49 years) underwent functional visual acuity (VA) examinations with and without wearing eyeglasses with 50% blue light blocked lenses. The functional VA parameters were starting VA, functional VA, and visual maintenance ratio. The baseline mean values (logarithm of the minimum angle of resolution, logMAR) of functional VA and the visual maintenance ratio were significantly worse in the DE patients than in the controls (P 0.05). The DE patients had significant improvement in mean functional VA and visual maintenance ratio while wearing the glasses (P 0.05). Protecting the eyes from short-wavelength blue light may help to ameliorate visual impairment associated with tear instability in patients with DE. This finding represents a new concept, which is that the blue light exposure might be harmful to visual function in patients with short BUT DE.

Reducing Short-Wavelength Blue Light in Dry Eye Patients with Unstable Tear Film Improves Performance on Tests of Visual Acuity.

Directory of Open Access Journals (Sweden)

Minako Kaido

Full Text Available To investigate whether suppression of blue light can improve visual function in patients with short tear break up time (BUT dry eye (DE.Twenty-two patients with short BUT DE (10 men, 12 women; mean age, 32.4 ± 6.4 years; age range, 23-43 years and 18 healthy controls (10 men, 8 women; mean age, 30.1 ± 7.4 years; age range, 20-49 years underwent functional visual acuity (VA examinations with and without wearing eyeglasses with 50% blue light blocked lenses. The functional VA parameters were starting VA, functional VA, and visual maintenance ratio.The baseline mean values (logarithm of the minimum angle of resolution, logMAR of functional VA and the visual maintenance ratio were significantly worse in the DE patients than in the controls (P 0.05. The DE patients had significant improvement in mean functional VA and visual maintenance ratio while wearing the glasses (P 0.05.Protecting the eyes from short-wavelength blue light may help to ameliorate visual impairment associated with tear instability in patients with DE. This finding represents a new concept, which is that the blue light exposure might be harmful to visual function in patients with short BUT DE.

Relation between Visual Acuity and Slope of Psychometric Function in Young Adults

Directory of Open Access Journals (Sweden)

Tomoki Tokutake

2011-05-01

Full Text Available Mita et al. (2010 devised a technique of comparing a visual acuity (VA change in an individual with more accurate VA than conventional VA tests by significant difference examined logarithmic (Log VA ± standard deviation (SD. Using this technique, in this study, we examined a relation between VA and the slope of the psychometric function in normal young subjects. Six occlusion foil conditions were employed (1.0, 0.8, 0.6, 0.4, 0.1 and without the foil under a full refractive correction. Ten normal young adults (22.8 years old on average who have no ophthalmologic disease except ametropia participated in the measurement. The experiment was carried out with the constant method, a series of ten Landolt rings were used and each ring was presented 20 times randomly in a measurement. A 5.6-inch type of liquid crystal display driven by a computer, which has 1,280×800 pixels spatial resolution, was used to present the stimulus. In the normal young adults, the slope of the psychometric function did not change as the VA change systematically, and there was almost no correlation between them (r = −0.103.

Separating monocular and binocular neural mechanisms mediating chromatic contextual interactions.

Science.gov (United States)

D'Antona, Anthony D; Christiansen, Jens H; Shevell, Steven K

2014-04-17

When seen in isolation, a light that varies in chromaticity over time is perceived to oscillate in color. Perception of that same time-varying light may be altered by a surrounding light that is also temporally varying in chromaticity. The neural mechanisms that mediate these contextual interactions are the focus of this article. Observers viewed a central test stimulus that varied in chromaticity over time within a larger surround that also varied in chromaticity at the same temporal frequency. Center and surround were presented either to the same eye (monocular condition) or to opposite eyes (dichoptic condition) at the same frequency (3.125, 6.25, or 9.375 Hz). Relative phase between center and surround modulation was varied. In both the monocular and dichoptic conditions, the perceived modulation depth of the central light depended on the relative phase of the surround. A simple model implementing a linear combination of center and surround modulation fit the measurements well. At the lowest temporal frequency (3.125 Hz), the surround's influence was virtually identical for monocular and dichoptic conditions, suggesting that at this frequency, the surround's influence is mediated primarily by a binocular neural mechanism. At higher frequencies, the surround's influence was greater for the monocular condition than for the dichoptic condition, and this difference increased with temporal frequency. Our findings show that two separate neural mechanisms mediate chromatic contextual interactions: one binocular and dominant at lower temporal frequencies and the other monocular and dominant at higher frequencies (6-10 Hz).

The structure of visual spaces

NARCIS (Netherlands)

Koenderink, J.J.; van Doorn, A.J.

2008-01-01

The “visual space” of an optical observer situated at a single, fixed viewpoint is necessarily very ambiguous. Although the structure of the “visual field” (the lateral dimensions, i.e., the “image”) is well defined, the “depth” dimension has to be inferred from the image on the basis of “monocular

A Highest Order Hypothesis Compatibility Test for Monocular SLAM

OpenAIRE

Edmundo Guerra; Rodrigo Munguia; Yolanda Bolea; Antoni Grau

2013-01-01

Simultaneous Location and Mapping (SLAM) is a key problem to solve in order to build truly autonomous mobile robots. SLAM with a unique camera, or monocular SLAM, is probably one of the most complex SLAM variants, based entirely on a bearing-only sensor working over six DOF. The monocular SLAM method developed in this work is based on the Delayed Inverse-Depth (DI-D) Feature Initialization, with the contribution of a new data association batch validation technique, the Highest Order Hyp...

Agreement analysis comparing iPad LCVA and Sloan testing in multiple sclerosis patients.

Science.gov (United States)

Sattarnezhad, Neda; Farrow, Samantha; Kimbrough, Dorlan; Glanz, Bonnie; Healy, Brian; Chitnis, Tanuja

2017-06-01

Visual symptoms are common in multiple sclerosis (MS). Low-contrast visual acuity (LCVA) testing using Sloan charts has demonstrated increased sensitivity for visual deficits compared to high-contrast acuity testing. Computerized testing of visual acuity may facilitate use in the clinic setting. To evaluate the agreement between an iPad-based and Sloan testing of LCVA in a cohort of MS patients. A total of 38 patients with relapsing-remitting MS were enrolled after providing informed written consent at Partners MS Center, Brigham and Women's hospital. Monocular LCVA was measured using retroilluminated Sloan chart and iPad-based LogMAR chart. Number of correct letters and agreement between two measurements were assessed for each eye using Bland-Altman analysis and paired t-test. For both eyes, there was no significant difference in number correct between the two measurements using a paired t-test, and there was high correlation between two measurements (oculus dextrus (OD) r = 0.89, p iPad-based LCVA test shows good agreement with Sloan testing in MS patients.

LONG-TERM RETROSPECTIVE ANALYSIS OF VISUAL ACUITY AND OPTICAL COHERENCE TOPOGRAPHIC CHANGES AFTER SINGLE VERSUS DOUBLE PEELING DURING VITRECTOMY FOR MACULAR EPIRETINAL MEMBRANES.

Science.gov (United States)

Jung, Jesse J; Hoang, Quan V; Ridley-Lane, Megan L; Sebrow, Dov B; Dhrami-Gavazi, Elona; Chang, Stanley

2016-11-01

To determine the long-term effect of internal limiting membrane with associated epiretinal membrane (ERM) peeling versus single peeling alone in terms of best-corrected visual acuity and anatomical outcomes on spectral-domain optical coherence tomography. This retrospective comparative cohort study of patients who had follow-up of >1 year and underwent surgery for ERM by a single surgeon (S.C.) from January 1, 2008 to December 31, 2012 compared cases in which the internal limiting membrane was stained with brilliant blue G to facilitate double peeling (n = 42) and single peeling (n = 43) of the ERM alone for up to 3 years of follow-up. For continuous variables, an independent two-tailed t-test was performed. For binary variables, the Fisher's exact test was performed. Statistical significance was defined as P peeling group were more likely to have ERM remaining in the central fovea postoperatively (P = 0.0020, becoming significant by postoperative Year 1, P = 0.022) and less likely to develop inner retinal dimpling (P = 0.000, becoming significant by postoperative Month 3, P = 0.015). At 3 years, central foveal thickness had decreased in the single-peeling group by -136.9 µm and by -84.1 μm in the double-peeling group, which was not significantly different (P = 0.08). Mean best-corrected visual acuity improved in both the groups at all time points. There was no statistically significant difference between the 2 groups at 3 years (P = 0.44; single-peeling group, 0.32 ± 0.42, Snellen 20/42; double-peeling group, 0.23 ± 0.27, Snellen 20/34). Brilliant blue G-assisted internal limiting membrane peeling for ERM results in a more thorough removal of residual ERM around the paracentral fovea. However, there is no difference in long-term best-corrected visual acuity at 3 years and a greater likelihood of inner retinal dimpling.

An Approach for Environment Mapping and Control of Wall Follower Cellbot Through Monocular Vision and Fuzzy System

OpenAIRE

Farias, Karoline de M.; Rodrigues Junior, WIlson Leal; Bezerra Neto, Ranulfo P.; Rabelo, Ricardo A. L.; Santana, Andre M.

2017-01-01

This paper presents an approach using range measurement through homography calculation to build 2D visual occupancy grid and control the robot through monocular vision. This approach is designed for a Cellbot architecture. The robot is equipped with wall following behavior to explore the environment, which enables the robot to trail objects contours, residing in the fuzzy control the responsibility to provide commands for the correct execution of the robot movements while facing the advers...

Posttreatment visual acuity in patients treated with episcleral plaque therapy for choroidal melanomas: dose and dose rate effects

International Nuclear Information System (INIS)

Jones, Robert; Gore, Elizabeth; Mieler, William; Murray, Kevin; Gillin, Michael; Albano, Katherine; Erickson, Beth

2002-01-01

Purpose: To determine the relationship between the long-term visual function and the dose and dose rates delivered to critical ocular structures in patients with choroidal melanoma treated with 125 I episcleral plaque radiotherapy. Methods and Materials: From 1987 to 1994, 63 patients underwent 125 I episcleral plaque (Collaborative Ocular Melanoma Study [COMS] design) application for the treatment of choroidal melanoma. The mean tumor height was 4.5 mm (range 1.7-8.3). Doses and dose rates at the tumor apex, macula, and optic disc were calculated. Forty-three records were scored to assess whether a decrease in visual acuity of >2 lines on a standard Snellen eye chart had occurred. Patient age and the presence of hypertension or diabetes were noted. Statistical analysis was performed to assess both the rate at which visual decline had occurred and the presence of significant factors that had contributed to this decline. Results: With a median follow-up of 36 months, the 3-year actuarial survival rate was 93.6%. The 3-year actuarial local control rate was 86.9%. The median time to visual loss after therapy was 18.7 months. The 3-year actuarial rate of visual preservation was 40.5%. Multivariate analysis demonstrated higher macula dose rates (p=0.003) to forecast visual decline. Macula dose rates of 111±11.1 cGy/h were associated with a 50% risk of significant visual loss. Conclusion: Patients in our series treated with 125 I plaque brachytherapy for choroidal melanoma experienced favorable tumor control, but with a measurable incidence of visual decline. Higher dose rates to the macula correlated strongly with poorer posttreatment visual outcome. This information may be valuable in selecting the optimal dose rates to treat choroidal melanomas and to predict the risk of visual decline

Assessing the accommodation response after near visual tasks using different handheld electronic devices

Directory of Open Access Journals (Sweden)

Aikaterini I. Moulakaki

Full Text Available ABSTRACT Purpose: To assess the accommodation response after short reading periods using a tablet and a smartphone as well as determine potential differences in the accommodation response at various stimulus vergences using a Hartmann- Shack aberrometer. Methods: Eighteen healthy subjects with astigmatism of less than 1 D, corrected visual acuity of 20/20 or better, and normal findings in an ophthalmic examination were enrolled. Accommodation responses were obtained under three different conditions: accommodation system of the eye relaxed and visually stressed with a tablet and an smartphone for 10 min, at a distance of 0.25 m from the subject's eyes. Three measurements of accommodation response were monocularly acquired at stimulus vergences ranging from 0 to 4 D (1-D step. Results: No statistically significant differences were found in the accommodation responses among the conditions. A moderate but gradually increasing root mean square, coma-like aberration was found for every condition. Conversely, the spherical aberration decreased as stimulus vergences increased. These outcomes were identified in comparison to the one-to-one ideal accommodation response, implying that a certain lag value was present in all stimulus vergences different from 0 D. Conclusions: The results support the hypothesis that the difference between the ideal and real accommodation responses is mainly attributed to parameters associated with the accommodation process, such as the near visual acuity, depth of focus, pupil diameter, and wavefront aberrations. The wavefront aberrations were dependent on the 3-mm pupil size selected in this study. The accommoda tion response was not dependent on the electronic device employed in each condition, and it was mainly associated with young age and level of amplitude of accommodation of the subjects.

Pattern visual evoked potentials in malingering.

Science.gov (United States)

Nakamura, A; Akio, T; Matsuda, E; Wakami, Y

2001-03-01

We previously developed a new method for estimating objective visual acuity by means of pattern visual evoked potentials (PVEP). In this study, this method was applied to the diagnosis of malingering. Six patients ranging in age from 40 to 54 years (mean 47 years) with suspected malingering were evaluated by means of the visual evoked potential test, optokinetic nystagmus (OKN) inhibition test, and the visual field test. In the PVEP study, the stimulus consisted of black and white checkerboards (39', 26', 15', and 9') with a visual angle of 8 degrees, contrast level of 15%, and a frequency of 0.7 Hz. One hundred PVEP responses were averaged per session. Routine ophthalmic examinations were normal in all patients. Five patients had a tubularly constricted visual field, and the remaining patient had a normal visual field. The objective visual acuities of the six patients estimated from PVEP were better than their subjective visual acuities estimated with Landolt rings. Among a variety of psychophysical and electrophysiologic ancillary tests, we consider our PVEP method a useful method for objectively determining visual acuity in a patient with signs of ocular malingering.

[Epidemiological Study of Poor Visual Acuity among Schoolchildren in Bonin Islands].

Science.gov (United States)

Ito, Misae; Shimizu, Kimiya; Kawamorita, Takushi; Shoji, Nobuyuki

2016-04-01

To investigate the change in uncorrected visual acuity (UCVA) among schoolchildren in Bonin Islands. UCVA of schoolchildren aged 6 to 14 years, was collected from reports of School Health Examination Surveys conducted from 1981 to 2012. The proportion of schoolchildren with poor UCVA in the Bonin Islands was compared with those in metropolitan Tokyo. The results in Bonin Islands were also divided into two groups, before- and after-1996 when terrestrial television broadcasting service has been started, and the data of those two groups were compared. The proportion of schoolchildren with poor UCVA in Bonin Islands was lower than that in Tokyo. Among the residents of Bonin Islands, the proportion of schoolchildren with UCVA of < 1.0 was higher in the after-1996 group than in the before- 1996 group, with a clear increase in schoolchildren with poor UCVA after 1996 (p < 0.01, Fisher's exact test), examined among the 4th grade of elementary school or above. After 1996, 26.6% of first graders at a public junior high school had poor UCVA of < 0.7, whereas before 1996 no such case could be detected. The present study revealed that the proportions of schoolchildren with poor UCVA in Bonin Islands was lower than that in Tokyo; but in the residents of Bonin Islands after 1996, the proportion of the schoolchildren with poor UCVA increased.

Monocular depth effects on perceptual fading.

Science.gov (United States)

Hsu, Li-Chuan; Kramer, Peter; Yeh, Su-Ling

2010-08-06

After prolonged viewing, a static target among moving non-targets is perceived to repeatedly disappear and reappear. An uncrossed stereoscopic disparity of the target facilitates this Motion-Induced Blindness (MIB). Here we test whether monocular depth cues can affect MIB too, and whether they can also affect perceptual fading in static displays. Experiment 1 reveals an effect of interposition: more MIB when the target appears partially covered by, than when it appears to cover, its surroundings. Experiment 2 shows that the effect is indeed due to interposition and not to the target's contours. Experiment 3 induces depth with the watercolor illusion and replicates Experiment 1. Experiments 4 and 5 replicate Experiments 1 and 3 without the use of motion. Since almost any stimulus contains a monocular depth cue, we conclude that perceived depth affects perceptual fading in almost any stimulus, whether dynamic or static. Copyright 2010 Elsevier Ltd. All rights reserved.

Effect of Monocular Deprivation on Rabbit Neural Retinal Cell Densities

OpenAIRE

Mwachaka, Philip Maseghe; Saidi, Hassan; Odula, Paul Ochieng; Mandela, Pamela Idenya

2015-01-01

Purpose: To describe the effect of monocular deprivation on densities of neural retinal cells in rabbits. Methods: Thirty rabbits, comprised of 18 subject and 12 control animals, were included and monocular deprivation was achieved through unilateral lid suturing in all subject animals. The rabbits were observed for three weeks. At the end of each week, 6 experimental and 3 control animals were euthanized, their retinas was harvested and processed for light microscopy. Photomicrographs of ...

Visual evoked potentials (VEP and visual acuity improvement after cytidine 52 -diphosphocholine (CDP-Choline therapy in amblyopic patient

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Regina Halfeld Furtado de Mendonça

2012-10-01

Full Text Available Citicoline may be used in many neurological disorders. Combined treatment of citicoline with patching in amblyopia has previously been researched. The purpose of this paper is to illustrate the effect of citicoline in non-patching amblyopic patient. A 11-year-old amblyopic boy underwent complete ophthalmological examinations, including VEP with flash and pattern stimulus. Two averages of 100 sweep were performed for flash stimulus. Pattern reversal stimulus obtained with high contrast was performed with 60', 30' and 15' checks stimuli. The VEP was repeated 90 days later after a therapy with citicoline and vitamin and the results compared with the responses of the previous recording session. The visual acuity (VA was 0,7 in the RE and 1,0 in the LE. The VEP pattern amplitude was normal in both eyes. Delayed in latency was detected for all spatial frequency stimulus (SFS in the RE. Delay in latency was detected only for high SFS in the LE. After the treatment, the VA was 1,0 in both eyes. The latency was normalized with low SFS on the RE and with high SFS on the LE. The flash VEP was normal before and after the therapy. In conclusion, the citicoline demonstrated that it was effective in the treatment of amblyopic eye without patching. The VA and the VEP latency improvement demonstrated that the citicoline enhance the transmission of the electric impulse from retina to visual cortex. Further research is required to understand the immediate and long-term effect of coline treatment in amblyopic patients.

Lrit1, a Retinal Transmembrane Protein, Regulates Selective Synapse Formation in Cone Photoreceptor Cells and Visual Acuity.

Science.gov (United States)

Ueno, Akiko; Omori, Yoshihiro; Sugita, Yuko; Watanabe, Satoshi; Chaya, Taro; Kozuka, Takashi; Kon, Tetsuo; Yoshida, Satoyo; Matsushita, Kenji; Kuwahara, Ryusuke; Kajimura, Naoko; Okada, Yasushi; Furukawa, Takahisa

2018-03-27

In the vertebrate retina, cone photoreceptors play crucial roles in photopic vision by transmitting light-evoked signals to ON- and/or OFF-bipolar cells. However, the mechanisms underlying selective synapse formation in the cone photoreceptor pathway remain poorly understood. Here, we found that Lrit1, a leucine-rich transmembrane protein, localizes to the photoreceptor synaptic terminal and regulates the synaptic connection between cone photoreceptors and cone ON-bipolar cells. Lrit1-deficient retinas exhibit an aberrant morphology of cone photoreceptor pedicles, as well as an impairment of signal transmission from cone photoreceptors to cone ON-bipolar cells. Furthermore, we demonstrated that Lrit1 interacts with Frmpd2, a photoreceptor scaffold protein, and with mGluR6, an ON-bipolar cell-specific glutamate receptor. Additionally, Lrit1-null mice showed visual acuity impairments in their optokinetic responses. These results suggest that the Frmpd2-Lrit1-mGluR6 axis regulates selective synapse formation in cone photoreceptors and is essential for normal visual function. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Comparison on the visual quality after different multifocal lens implantation in cataract patients

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Si-Meng Qu

2018-02-01

Full Text Available AIM: To compare the visual quality after different multifocal lens(MIOLimplantation in cataract patients. METHODS:Totally 78 cases(78 eyesof cataract patients who receiving phacoemulsification and implantation of different MIOL were enrolled from February 2016 to June 2017 in our hospital. According to the different type of implanted MIOL, the 78 cases(78 eyeswere divided Group A, B and C, each group was 26 cases(26 eyes. Patients in the Group A were implanted regional refraction MIOL SBL-3; patients in the Group B implanted step progressive diffraction MIOL SN6AD1; patients in the Group C implanted all-optical plane diffraction MIOL Tecnis ZMB00. The visual acuity, contrast sensitivity, defocus testing, contrast visual acuity and satisfaction of visual quality were compared in 3 groups at postoperative 3mo. RESULTS: There was no statistically significant difference in postoperative adverse reactions between the three groups(P>0.05. There was statistical difference in uncorrected intermediate visual acuity, uncorrected near visual acuity, distance-corrected intermediate visual acuity and distance-corrected near visual acuity in 3 groups(PPPPPPPPPCONCLUSION:The region refraction MIOL SBL-3 not only could provide better distant, intermediate and near visual acuity, but also could provide better contrast sensitivity and contrast visual acuity, thereby greatly increase visual quality satisfaction.

Visual outcome with the Oculentis Mplus intraocular lens

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Si-Yuan Liu

2017-11-01

Full Text Available AIM: To evaluate the visual outcome of Oculentis Mplus intraocular lens(IOL.METHODS: Totally 20 eyes in 20 patients received phacoemulsification and Oculentis Mplus intraocular lens implantation were as test group, and 20 eyes(Aspira-aA IOLwere as control group. The following postoperative examinations were performed after operation for 3mo: uncorrected visual acuity of distance and near, refractive results, UBM examination, the rate of wearing spectacles and the complications. RESULTS: At 3mo after surgery, distance visual acuity of test group with Oculentis Mplus IOL were 0.10±0.03,the difference with control group was not significant(t=1.74, P>0.05. Eyes in test group had an uncorrected near acuity 0.11±0.04, the difference with control group was significant(t=15.53, PCONCLUSION: The implantation of Oculentis Mplus IOL not only has a good distance uncorrected visual acuity, but also with better near visual acuity. The surgery is safe, reliable and no special complication induced.

SURGICAL REMOVAL OF EPIRETINAL MEMBRANE WITH AND WITHOUT REMOVAL OF INTERNAL LIMITING MEMBRANE: Comparative Study of Visual Acuity, Features of Optical Coherence Tomography, and Recurrence Rate.

Science.gov (United States)

De Novelli, Fernando J; Goldbaum, Mauro; Monteiro, Mario L R; Bom Aggio, Fabio; Takahashi, Walter Y

2017-12-05

To study and compare visual acuity, foveal thickness, outer limiting layer, ellipsoid zone, and recurrence rate in patients undergoing removal of the epiretinal membrane with and without the removal of the internal limiting membrane (ILM). Sixty-three patients who had the epiretinal membrane removed by a single surgeon were randomly assigned into 2 groups: Group 1 without additional removal of the ILM and Group 2 with removal of the ILM. Patients were followed up and evaluated at the first month, third month, and sixth month, postoperatively. Patients from both groups had a gradual improvement in their vision over time. There was no significant difference in the improvement in visual acuity between the two groups. About tomographic assessment of alterations, no significant differences were found between the groups; however, Group 1 had a higher relapse rate (17%) compared with Group 2 (3.6%) (P = 0.09). Epiretinal membrane removal with and without ILM peeling shows similar functional and anatomical improvements, but the group in which the ILM was not removed seemed to have a higher recurrence rate.

Recognition versus Resolution: a Comparison of Visual Acuity Results Using Two Alternative Test Chart Optotype

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Jonathan S. Pointer

2008-01-01

Conclusions: For normally sighted subjects wearing an optimal refractive correction, a bias was recorded in favour of recognition over resolution acuity: the clinical difference amounted to approximately 40% of one logMAR chart line, with similar high repeatability for either chart optotype. We conclude that the assumption of clinical equivalence between letter and Landolt acuity is reasonable under optimum test conditions.

Refractive error and visual impairment in school children in Northern Ireland.

Science.gov (United States)

O'Donoghue, L; McClelland, J F; Logan, N S; Rudnicka, A R; Owen, C G; Saunders, K J

2010-09-01

To describe the prevalence of refractive error (myopia and hyperopia) and visual impairment in a representative sample of white school children. The Northern Ireland Childhood Errors of Refraction study, a population-based cross-sectional study, examined 661 white 12-13-year-old and 392 white 6-7-year-old children between 2006 and 2008. Procedures included assessment of monocular logarithm of the minimum angle of resolution (logMAR), visual acuity (unaided and presenting) and binocular open-field cycloplegic (1% cyclopentolate) autorefraction. Myopia was defined as -0.50DS or more myopic spherical equivalent refraction (SER) in either eye, hyperopia as > or =+2.00DS SER in either eye if not previously classified as myopic. Visual impairment was defined as >0.30 logMAR units (equivalent to 6/12). Levels of myopia were 2.8% (95% CI 1.3% to 4.3%) in younger and 17.7% (95% CI 13.2% to 22.2%) in older children: corresponding levels of hyperopia were 26% (95% CI 20% to 33%) and 14.7% (95% CI 9.9% to 19.4%). The prevalence of presenting visual impairment in the better eye was 3.6% in 12-13-year-old children compared with 1.5% in 6-7-year-old children. Almost one in four children fails to bring their spectacles to school. This study is the first to provide robust population-based data on the prevalence of refractive error and visual impairment in Northern Irish school children. Strategies to improve compliance with spectacle wear are required.

Retinotopic maps and foveal suppression in the visual cortex of amblyopic adults.

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Conner, Ian P; Odom, J Vernon; Schwartz, Terry L; Mendola, Janine D

2007-08-15

Amblyopia is a developmental visual disorder associated with loss of monocular acuity and sensitivity as well as profound alterations in binocular integration. Abnormal connections in visual cortex are known to underlie this loss, but the extent to which these abnormalities are regionally or retinotopically specific has not been fully determined. This functional magnetic resonance imaging (fMRI) study compared the retinotopic maps in visual cortex produced by each individual eye in 19 adults (7 esotropic strabismics, 6 anisometropes and 6 controls). In our standard viewing condition, the non-tested eye viewed a dichoptic homogeneous mid-level grey stimulus, thereby permitting some degree of binocular interaction. Regions-of-interest analysis was performed for extrafoveal V1, extrafoveal V2 and the foveal representation at the occipital pole. In general, the blood oxygenation level-dependent (BOLD) signal was reduced for the amblyopic eye. At the occipital pole, population receptive fields were shifted to represent more parafoveal locations for the amblyopic eye, compared with the fellow eye, in some subjects. Interestingly, occluding the fellow eye caused an expanded foveal representation for the amblyopic eye in one early-onset strabismic subject with binocular suppression, indicating real-time cortical remapping. In addition, a few subjects actually showed increased activity in parietal and temporal cortex when viewing with the amblyopic eye. We conclude that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations.

Visual evoked potentials in patients after methanol poisoning.

Science.gov (United States)

Urban, Pavel; Zakharov, Sergey; Diblík, Pavel; Pelclová, Daniela; Ridzoň, Petr

2016-01-01

We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Influence of visual acuity on suicidal ideation, suicide attempts and depression in South Korea.

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Rim, Tyler Hyungtaek; Lee, Christopher Seungkyu; Lee, Sung Chul; Chung, Byunghoon; Kim, Sung Soo

2015-08-01

To assess the influence of visual acuity (VA) on suicidal ideation, suicide attempts and depression. From 2008 to 2012, a total of 28 919 nationally representative participants aged 19 years or older in the Korea National Health and Nutrition Examination Survey underwent additional ophthalmological examinations by the Korean Ophthalmologic Society. Associations between best corrected VA in the better-seeing eye based on decimal fraction and mental health were identified using multivariable logistic regression analysis after adjusting for possible biopsychosocial confounders. Self-reported mental health (suicidal ideation, suicide attempt and depression), Euro Quality of Life-Visual Analog Scale and counselling experience were evaluated by direct interviews. A nomogram for risk of suicidal ideation was generated. By multivariable logistic regression analysis, low VA was significantly associated with suicidal ideation and suicide attempt but not depression. Participants with a VA of no light perception to 0.2 had a nearly twofold and threefold increased risk of suicidal ideation (adjusted OR, 1.85; 95% CI 1.04 to 3.27) and suicidal attempt (adjusted OR, 3.44; 95% CI 0.92 to 12.79), compared with participants with a VA of 1.0. Sociodemographic disparities, including age and socioeconomic status, existed for suicidal ideation, suicidal attempt and depression. Euro Quality of Life-Visual Analog Scale significantly decreased as VA decreased and was lower in participants who attempted suicide. Low VA was associated with the occurrence of suicidal ideation or a suicide attempt. Ophthalmologists should embrace their responsibility to help reduce suicidality and prevent suicides in patients with low VA by encouraging them to seek psychiatric care. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Clinical Evaluation of Functional Vision of +1.5 Diopters near Addition, Aspheric, Rotational Asymmetric Multifocal Intraocular Lens.

Science.gov (United States)

Kretz, Florian Tobias Alwin; Khoramnia, Rahmin; Attia, Mary Safwat; Koss, Michael Janusz; Linz, Katharina; Auffarth, Gerd Uwe

2016-10-01

To evaluate postoperative outcomes and visual performance in intermediate distance after implantation of a +1.5 diopters (D) addition, aspheric, rotational asymmetric multifocal intraocular lens (MIOL). Patients underwent bilateral cataract surgery with implantation of an aspheric, asymmetric MIOL with +1.5 D near addition. A complete ophthalmological examination was performed preoperatively and 3 months postoperatively. The main outcome measures were monocular and binocular uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA), distance corrected intermediate visual acuity (DCIVA), uncorrected near visual acuity (UNVA) and distance corrected keratometry, and manifest refraction. The Salzburg Reading Desk was used to analyze unilateral and bilateral functional vision with uncorrected and corrected reading acuity, reading distance, reading speed, and the smallest log-scaled print size that could be read effectively at near and intermediate distances. The study comprised 60 eyes of 30 patients (mean age, 68.30 ± 9.26 years; range, 34 to 80 years). There was significant improvement in UDVA and CDVA. Mean UIVA was 0.01 ± 0.09 logarithm of the minimum angle of resolution (logMAR) and mean DCIVA was -0.02 ± 0.11 logMAR. In Salzburg Reading Desk analysis for UIVA, the mean subjective intermediate distance was 67.58 ± 8.59 cm with mean UIVA of -0.02 ± 0.09 logMAR and mean word count of 96.38 ± 28.32 words/min. The new aspheric, asymmetric, +1.5 D near addition MIOL offers good results for distance visual function in combination with good performance for intermediate distances and functional results for near distance.

Visual memory for objects following foveal vision loss.

Science.gov (United States)

Geringswald, Franziska; Herbik, Anne; Hofmüller, Wolfram; Hoffmann, Michael B; Pollmann, Stefan

2015-09-01

Allocation of visual attention is crucial for encoding items into visual long-term memory. In free vision, attention is closely linked to the center of gaze, raising the question whether foveal vision loss entails suboptimal deployment of attention and subsequent impairment of object encoding. To investigate this question, we examined visual long-term memory for objects in patients suffering from foveal vision loss due to age-related macular degeneration. We measured patients' change detection sensitivity after a period of free scene exploration monocularly with their worse eye when possible, and under binocular vision, comparing sensitivity and eye movements to matched normal-sighted controls. A highly salient cue was used to capture attention to a nontarget location before a target change occurred in half of the trials, ensuring that change detection relied on memory. Patients' monocular and binocular sensitivity to object change was comparable to controls, even after more than 4 intervening fixations, and not significantly correlated with visual impairment. We conclude that extrafoveal vision suffices for efficient encoding into visual long-term memory. (c) 2015 APA, all rights reserved).

Monocular Vision SLAM for Indoor Aerial Vehicles

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Koray Çelik

2013-01-01

Full Text Available This paper presents a novel indoor navigation and ranging strategy via monocular camera. By exploiting the architectural orthogonality of the indoor environments, we introduce a new method to estimate range and vehicle states from a monocular camera for vision-based SLAM. The navigation strategy assumes an indoor or indoor-like manmade environment whose layout is previously unknown, GPS-denied, representable via energy based feature points, and straight architectural lines. We experimentally validate the proposed algorithms on a fully self-contained microaerial vehicle (MAV with sophisticated on-board image processing and SLAM capabilities. Building and enabling such a small aerial vehicle to fly in tight corridors is a significant technological challenge, especially in the absence of GPS signals and with limited sensing options. Experimental results show that the system is only limited by the capabilities of the camera and environmental entropy.

Maternal fish oil supplementation in lactation: Effect on visual acuity and n-3 fatty acid content of infant erythrocytes

DEFF Research Database (Denmark)

Lauritzen, L.; Jørgensen, M.H.; Mikkelsen, T.B.

2004-01-01

of fish oil (FO) supplements in lactating mothers. In this double-blinded randomized trial, Danish mothers with habitual fish intake below the 50th percentile of the Danish National Birth Cohort were randomized to microencapsulated FO [1.3 g/d long-chain n-3 FA (n-3 LCPUFA)] or olive oil (00......). The intervention started within a week after delivery and lasted 4 mon. Mothers with habitual high fish intake and their infants were included as a reference group. Ninety-seven infants completed the trial (44 OO-group, 53 FO-group) and 47 reference infants were followed up. The primary outcome measures were: DHA...... content of milk samples (0, 2, and 4 mon postnatal) and of infant red blood cell (RBC) membranes (4 mon postnatal), and infant visual acuity (measured by swept visual evoked potential at 2 and 4 mon of age). FO supplementation gave rise to a threefold increase in the DHA content of the 4-mon milk samples...

The effects of left and right monocular viewing on hemispheric activation.

Science.gov (United States)

Wang, Chao; Burtis, D Brandon; Ding, Mingzhou; Mo, Jue; Williamson, John B; Heilman, Kenneth M

2018-03-01

Prior research has revealed that whereas activation of the left hemisphere primarily increases the activity of the parasympathetic division of the autonomic nervous system, right-hemisphere activation increases the activity of the sympathetic division. In addition, each hemisphere primarily receives retinocollicular projections from the contralateral eye. A prior study reported that pupillary dilation was greater with left- than with right-eye monocular viewing. The goal of this study was to test the alternative hypotheses that this asymmetric pupil dilation with left-eye viewing was induced by activation of the right-hemispheric-mediated sympathetic activity, versus a reduction of left-hemisphere-mediated parasympathetic activity. Thus, this study was designed to learn whether there are changes in hemispheric activation, as measured by alteration of spontaneous alpha activity, during right versus left monocular viewing. High-density electroencephalography (EEG) was recorded from healthy participants viewing a crosshair with their right, left, or both eyes. There was a significantly less alpha power over the right hemisphere's parietal-occipital area with left and binocular viewing than with right-eye monocular viewing. The greater relative reduction of right-hemisphere alpha activity during left than during right monocular viewing provides further evidence that left-eye viewing induces greater increase in right-hemisphere activation than does right-eye viewing.

Subluxação congênita do cristalino: resultados visuais e posição das lentes intraoculares após a cirurgia Congenital lens subluxation: visual acuity outcomes and intraocular lens postoperative position

Directory of Open Access Journals (Sweden)

Caroline Arraes

2010-04-01

Full Text Available OBJETIVO: Avaliar os resultados visuais e investigar, através da biomicroscopia ultrassônica, o posicionamento das lentes intraoculares e do anel endocapsular em 17 olhos de 10 portadores de subluxação congênita do cristalino, submetidos à mesma técnica cirúrgica pelo mesmo cirurgião. MÉTODOS: O estudo foi realizado no Hospital de Olhos de Pernambuco e Fundação Altino Ventura. A técnica cirúrgica consistiu em facoaspiração com implante de anel endocapsular e de lentes intraoculares com amputação de uma das alças. A idade variou entre 7 e 22 anos. Foram coletados dados sobre acuidade visual para longe pré e pós-operatória, tempo de seguimento após a cirurgia e complicações. Os pacientes foram submetidos à biomicroscopia ultrassônica. RESULTADOS: O tempo de seguimento médio foi de 2,8 anos. Houve melhora da acuidade visual para longe nos 17 (100% olhos: 12 olhos (70,6% apresentaram acuidade visual para longe melhor que 20/40; 4 (23,5% apresentaram acuidade visual para longe entre 20/40 e 20/100 e 1 (5,9% apresentou acuidade visual para longe pior que 20/100, porém melhor que acuidade visual para longe pré-operatória. A opacificação da cápsula posterior ocorreu em 10 olhos (58,9%. Na biomicroscopia ultrassônica observou-se que todas as lentes intraoculares estavam parcialmente descentralizadas, contudo sem atingir o bordo pupilar. Em todos os casos observou-se um adequado posicionamento do anel e um bom suporte capsular. CONCLUSÃO É possível concluir que o tratamento cirúrgico avaliado proporciona uma boa centralização das lentes intraoculares e do anel endocapsular, com melhora da acuidade visual para longe, sendo uma opção viável, eficaz e segura na reabilitação visual dos pacientes com subluxação congênita do cristalino.PURPOSE: To evaluate the visual acuity outcomes and to investigate the intraocular lens (IOL and endocapsular ring positions with ultrasound biomicroscopy in 17 eyes of 10 patients

Merging Psychophysical and Psychometric Theory to Estimate Global Visual State Measures from Forced-Choices

International Nuclear Information System (INIS)

Massof, Robert W; Schmidt, Karen M; Laby, Daniel M; Kirschen, David; Meadows, David

2013-01-01

Visual acuity, a forced-choice psychophysical measure of visual spatial resolution, is the sine qua non of clinical visual impairment testing in ophthalmology and optometry patients with visual system disorders ranging from refractive error to retinal, optic nerve, or central visual system pathology. Visual acuity measures are standardized against a norm, but it is well known that visual acuity depends on a variety of stimulus parameters, including contrast and exposure duration. This paper asks if it is possible to estimate a single global visual state measure from visual acuity measures as a function of stimulus parameters that can represent the patient's overall visual health state with a single variable. Psychophysical theory (at the sensory level) and psychometric theory (at the decision level) are merged to identify the conditions that must be satisfied to derive a global visual state measure from parameterised visual acuity measures. A global visual state measurement model is developed and tested with forced-choice visual acuity measures from 116 subjects with no visual impairments and 560 subjects with uncorrected refractive error. The results are in agreement with the expectations of the model

Evaluation of the Role of Monocular Video Game Play as an Adjuvant to Occlusion Therapy in the Management of Anisometropic Amblyopia.

Science.gov (United States)

Singh, Archita; Sharma, Pradeep; Saxena, Rohit

2017-07-01

To evaluate the role of monocular video game play as an adjuvant to occlusion therapy in the treatment of anisometropic amblyopia. In a prospective randomized study design, 68 children with ages ranging from 6 to 14 years who had anisometropic amblyopia with a best corrected visual acuity (BCVA) in the amblyopic eye of better than 6/36 and worse than 6/12 and no manifest strabismus were recruited. They were randomly allocated into two groups: 34 children received 1 hour per day of video game play for the first month plus 6 hours per day of occlusion therapy (video game and occlusion group) and 34 children received 6 hours per day of occlusion therapy alone (occlusion only group). Patients were then evaluated at baseline and 1 and 3 months after treatment for BCVA, stereoacuity, and contrast sensitivity. In the video game and occlusion group, BCVA improved from 0.61 ± 0.12 logarithm of the minimum angle of resolution (logMAR) at baseline to 0.51 ± 0.14 logMAR (P = .001) at 1 month and 0.40 ± 0.15 logMAR (P = .001) at 3 months. In the occlusion only group, BCVA improved from 0.65 ± 0.09 logMAR at baseline to 0.60 ± 0.10 logMAR (P = .001) at 1 month and 0.48 ± 0.10 logMAR (P = .001) at 3 months. There was significantly more improvement in the video game and occlusion group compared to the occlusion only group (P = .003 at 1 month and P = .027 at 3 months). Video game play plus occlusion therapy enhances the visual recovery in anisometropic amblyopia. [J Pediatr Ophthalmol Strabismus. 2017;54(4):244-249.]. Copyright 2017, SLACK Incorporated.

Danish Rural Eye Study

DEFF Research Database (Denmark)

Høeg, Tracy B; Moldow, Birgitte; Ellervik, Christina

2015-01-01

and older from a Danish rural municipality received a complete general health examination and an ophthalmological interview and examination. This study included a comprehensive ophthalmologic interview, measurement of best corrected visual acuity (BCVA) in each eye, Hirschberg's test for strabismus and two...... 45-degree retinal fundus photographs of each eye. A complete ophthalmologic examination was performed when indicated. RESULTS: The prevalence of monocular visual impairment (MVI) was 4.26% (95% CI, 3.66-4.95, n = 163). Amblyopia was the most common cause, accounting for 33%. The prevalence...

A Highest Order Hypothesis Compatibility Test for Monocular SLAM

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Edmundo Guerra

2013-08-01

Full Text Available Simultaneous Location and Mapping (SLAM is a key problem to solve in order to build truly autonomous mobile robots. SLAM with a unique camera, or monocular SLAM, is probably one of the most complex SLAM variants, based entirely on a bearing-only sensor working over six DOF. The monocular SLAM method developed in this work is based on the Delayed Inverse-Depth (DI-D Feature Initialization, with the contribution of a new data association batch validation technique, the Highest Order Hypothesis Compatibility Test, HOHCT. The Delayed Inverse-Depth technique is used to initialize new features in the system and defines a single hypothesis for the initial depth of features with the use of a stochastic technique of triangulation. The introduced HOHCT method is based on the evaluation of statistically compatible hypotheses and a search algorithm designed to exploit the strengths of the Delayed Inverse-Depth technique to achieve good performance results. This work presents the HOHCT with a detailed formulation of the monocular DI-D SLAM problem. The performance of the proposed HOHCT is validated with experimental results, in both indoor and outdoor environments, while its costs are compared with other popular approaches.

Effects of Fluoxetine and Visual Experience on Glutamatergic and GABAergic Synaptic Proteins in Adult Rat Visual Cortex123

Science.gov (United States)

Beshara, Simon; Beston, Brett R.; Pinto, Joshua G. A.

2015-01-01

Abstract Fluoxetine has emerged as a novel treatment for persistent amblyopia because in adult animals it reinstates critical period-like ocular dominance plasticity and promotes recovery of visual acuity. Translation of these results from animal models to the clinic, however, has been challenging because of the lack of understanding of how this selective serotonin reuptake inhibitor affects glutamatergic and GABAergic synaptic mechanisms that are essential for experience-dependent plasticity. An appealing hypothesis is that fluoxetine recreates a critical period (CP)-like state by shifting synaptic mechanisms to be more juvenile. To test this we studied the effect of fluoxetine treatment in adult rats, alone or in combination with visual deprivation [monocular deprivation (MD)], on a set of highly conserved presynaptic and postsynaptic proteins (synapsin, synaptophysin, VGLUT1, VGAT, PSD-95, gephyrin, GluN1, GluA2, GluN2B, GluN2A, GABAAα1, GABAAα3). We did not find evidence that fluoxetine shifted the protein amounts or balances to a CP-like state. Instead, it drove the balances in favor of the more mature subunits (GluN2A, GABAAα1). In addition, when fluoxetine was paired with MD it created a neuroprotective-like environment by normalizing the glutamatergic gain found in adult MDs. Together, our results suggest that fluoxetine treatment creates a novel synaptic environment dominated by GluN2A- and GABAAα1-dependent plasticity. PMID:26730408

Effects of Binaural Sensory Aids on the Development of Visual Perceptual Abilities in Visually Handicapped Infants. Final Report, April 15, 1982-November 15, 1982.

Science.gov (United States)

Hart, Verna; Ferrell, Kay

Twenty-four congenitally visually handicapped infants, aged 6-24 months, participated in a study to determine (1) those stimuli best able to elicit visual attention, (2) the stability of visual acuity over time, and (3) the effects of binaural sensory aids on both visual attention and visual acuity. Ss were dichotomized into visually handicapped…

Diabetic macular oedema treated with intravitreal anti-vascular endothelial growth factor - 2-4 years follow-up of visual acuity and retinal thickness in 566 patients following Danish national guidelines

DEFF Research Database (Denmark)

Hodzic-Hadzibegovic, Delila; Sander, Birgit Agnes; Monberg, Tine Juul

2017-01-01

: Retrospective cohort study of 566 eyes in 566 patients with centre-involved DME who started intravitreal treatment with ranibizumab between January 2011 and December 2013 in the Greater Copenhagen region. Data were retrieved from a database and patient records between January 2011 and March 2016 and analysed...... using mixed-model statistics. Results: At the conclusion of follow-up, 24.6% were in active ranibizumab follow-up, 25.4% had switched to other intravitreal pharmacotherapy, 31.6% had been discontinued because of disease stability, 13.8% had been lost to follow-up, 1.4% had been discontinued because...... of low visual acuity (VA), and 3.2% had died. At baseline, mean best-corrected visual acuity (BCVA) and mean central subfield thickness (CST) were 64.9 (±15.0) letters and 400.2 (±120.3) μm. Mean change in BCVA and mean change in CST from baseline to 3, 12, 24, 36 and 48 months of follow-up were +3.9, +3...

The challenges of developing a contrast-based video game for treatment of amblyopia.

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Hussain, Zahra; Astle, Andrew T; Webb, Ben S; McGraw, Paul V

2014-01-01

Perceptual learning of visual tasks is emerging as a promising treatment for amblyopia, a developmental disorder of vision characterized by poor monocular visual acuity. The tasks tested thus far span the gamut from basic psychophysical discriminations to visually complex video games. One end of the spectrum offers precise control over stimulus parameters, whilst the other delivers the benefits of motivation and reward that sustain practice over long periods. Here, we combined the advantages of both approaches by developing a video game that trains contrast sensitivity, which in psychophysical experiments, is associated with significant improvements in visual acuity in amblyopia. Target contrast was varied adaptively in the game to derive a contrast threshold for each session. We tested the game on 20 amblyopic subjects (10 children and 10 adults), who played at home using their amblyopic eye for an average of 37 sessions (approximately 11 h). Contrast thresholds from the game improved reliably for adults but not for children. However, logMAR acuity improved for both groups (mean = 1.3 lines; range = 0-3.6 lines). We present the rationale leading to the development of the game and describe the challenges of incorporating psychophysical methods into game-like settings.

Effect of ocular transverse chromatic aberration on detection acuity for peripheral vision.

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Cheney, Frank; Thibos, Larry; Bradley, Arthur

2015-01-01

We examined the effect of transverse chromatic aberration (TCA) on detection acuity for white-light interference fringes seen in Maxwellian view at various orientations and locations in the visual field. A circular patch (3.5° diameter, 3.2 log Trolands) of nominally high-contrast fringes was produced on the retina by a commercial instrument (the Lotmar Visometer, Haag Streit) mounted on a gimbal for controlled positioning of the stimulus in the visual field from 0° to 35° eccentricity. Detection acuity for white light fringes for all meridians and eccentricities ≥15° was maximum when fringes were oriented parallel to the visual meridian line. This meridional effect disappeared when a narrow-band filter was used to eliminate TCA. The meridional effect also disappeared when the interferometric stimulator was displaced laterally to align the instrument with the eye's local achromatic axis. Modelling confirmed that TCA is the major factor responsible for white-light meridional bias, with minor contribution arising from higher-order monochromatic aberrations and neural factors. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

Influência do astigmatismo corneano na acuidade visual final após implante de AcrySof® ReSTOR®: relato de caso Influence of corneal astigmatism in final visual acuity after implantation of AcrySofTM ReSTOR TM: case report

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Ricardo de Carvalho Rocha

2007-12-01

Full Text Available Atualmente tem-se desenvolvido novos tipos de lentes intra-oculares (LIO que objetivam eliminar a presbiopia e o seu uso vem se popularizando. Descreve-se o caso de um paciente com catarata bilateral e irregularidades corneanas e astigmatismo maior que 2 D à topografia, no qual implantou-se a LIO AcrySof® ReSTOR® no olho esquerdo associado à realização de incisões limbares relaxantes para tentar diminuir o astigmatismo corneano observado. A acuidade visual pós-operatória, tanto para perto quanto para longe, ficou abaixo das expectativas, sem melhora à refração e sem uma outra alteração que a justificasse, além das citadas. Após 45 dias, sem melhora da acuidade visual, efetuou-se o explante desta LIO, seguindo-se de implante de uma monofocal, sendo observada melhora da acuidade visual corrigida final. Assim, o presente caso clínico reforça a necessidade de uma correta seleção pré-operatória dos pacientes candidatos ao implante deste tipo de LIO multifocal, atentando inclusive para os dados topográficos.Currently, new types of intraocular lenses have been developed aiming to eliminate presbyopia and the use has become more popular. The authors report the case of a patient with bilateral cataract and corneal irregularities and astigmatism higher than 2D in the corneal topography, in which AcrySofTM ReSTOR TM intraocular lens was implanted in the left eye associated to relaxing limbal incisions trying to reduce corneal astigmatism. The near and distance postoperative visual acuity were worse than expected, with no improvement with refraction. Apparently, no other reason apart from irregular astigmatism/multifocal lens justified the low vision. After 45 days, with no visual acuity improvement, the intraocular lens was explanted and a monofocal one was implanted. The final corrected visual acuity improved. Thus, the present case emphasizes the need of a correct preoperative selection of patients to implant this type of

The Correlation between Subjective and Objective Visual Function Test in Optic Neuropathy Patients

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Ungsoo Kim

2012-10-01

Full Text Available Purpose: To investigate the correlation between visual acuity and quantitative measurements of visual evoked potentials (VEP, optical coherence tomography (OCT, and visual field test (VF in optic neuropathy patients. Methods: We evaluated 28 patients with optic neuropathy. Patients who had pale disc, visual acuity of less than 0.5 and abnormal visual field defect were included. At the first visit, we performed visual acuity and VF as subjective methods and OCT and VEP as objective methods. In the spectral domain OCT, rim volume, average and temporal quadrant retinal nerve fiber layer (RNFL thickness were measured. And pattern VEP (N75, P100, N135 latency, and P100 amplitude and Humphrey 24-2 visual field test (mean deviation and pattern standard deviation were obtained. Using Spearman's correlation coefficient, the correlation between visual acuity and various techniques were assessed. Results: Visual acuity was most correlated with the mean deviation of Humphrey perimetry.

A geometric method for computing ocular kinematics and classifying gaze events using monocular remote eye tracking in a robotic environment.

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Singh, Tarkeshwar; Perry, Christopher M; Herter, Troy M

2016-01-26

Robotic and virtual-reality systems offer tremendous potential for improving assessment and rehabilitation of neurological disorders affecting the upper extremity. A key feature of these systems is that visual stimuli are often presented within the same workspace as the hands (i.e., peripersonal space). Integrating video-based remote eye tracking with robotic and virtual-reality systems can provide an additional tool for investigating how cognitive processes influence visuomotor learning and rehabilitation of the upper extremity. However, remote eye tracking systems typically compute ocular kinematics by assuming eye movements are made in a plane with constant depth (e.g. frontal plane). When visual stimuli are presented at variable depths (e.g. transverse plane), eye movements have a vergence component that may influence reliable detection of gaze events (fixations, smooth pursuits and saccades). To our knowledge, there are no available methods to classify gaze events in the transverse plane for monocular remote eye tracking systems. Here we present a geometrical method to compute ocular kinematics from a monocular remote eye tracking system when visual stimuli are presented in the transverse plane. We then use the obtained kinematics to compute velocity-based thresholds that allow us to accurately identify onsets and offsets of fixations, saccades and smooth pursuits. Finally, we validate our algorithm by comparing the gaze events computed by the algorithm with those obtained from the eye-tracking software and manual digitization. Within the transverse plane, our algorithm reliably differentiates saccades from fixations (static visual stimuli) and smooth pursuits from saccades and fixations when visual stimuli are dynamic. The proposed methods provide advancements for examining eye movements in robotic and virtual-reality systems. Our methods can also be used with other video-based or tablet-based systems in which eye movements are performed in a peripersonal

Changes in visual acuity in patients with malignant melanoma of the uvea treated with stereotactic radiosurgery (presentation)

International Nuclear Information System (INIS)

Mackova, K.; Waczultkova, I.; Furdova, Ad.; Furdova, Al.

2013-01-01

The goal was to assess the changes in visual acuity before and after 6 months of treatment, depending on the dose in risk structures (lens, optic nerve). This is a retrospective study of 19 patients group treated in 2011. The average age of the group was (57.3 ± 12.4) years (31-73 years). The analysis of the studied group did not demonstrate dependence of the tumour presence on gender. Higher prevalence of tumours was observed in the elderly population. Considered relationship of worse diagnosis with higher age (r = 0.39; p = 0.13) we could not prove to be significant due to the small group of patients. The median of melanoma volume was 0.77 cm 3 (0.11 to 1.76 cubic centimetres). The mean dose applied to melanoma was 37.34 Gy (Gy 36.74 to 44.65).

Visual Outcomes of Parapapillary Uveal Melanomas Following Proton Beam Therapy

International Nuclear Information System (INIS)

Thariat, Juliette; Grange, Jean-Daniel; Mosci, Carlo; Rosier, Laurence; Maschi, Celia; Lanza, Francesco; Nguyen, Anh Minh; Jaspart, Franck; Bacin, Franck; Bonnin, Nicolas; Gaucher, David; Sauerwein, Wolfgang; Angellier, Gaelle; Hérault, Joel; Caujolle, Jean-Pierre

2016-01-01

Purpose: In parapapillary melanoma patients, radiation-induced optic complications are frequent and visual acuity is often compromised. We investigated dose-effect relationships for the optic nerve with respect to visual acuity after proton therapy. Methods and Materials: Of 5205 patients treated between 1991 and 2014, those treated using computed tomography (CT)-based planning to 52 Gy (prescribed dose, not accounting for relative biologic effectiveness correction of 1.1) in 4 fractions, with minimal 6-month follow-up and documented initial and last visual acuity, were included. Deterioration of ≥0.3 logMAR between initial and last visual acuity results was reported. Results: A total of 865 consecutive patients were included. Median follow-up was 69 months, mean age was 61.7 years, tumor abutted the papilla in 35.1% of patients, and tumor-to-fovea distance was ≤3 mm in 74.2% of patients. Five-year relapse-free survival rate was 92.7%. Visual acuity was ≥20/200 in 72.6% of patients initially and 47.2% at last follow-up. A wedge filter was used in 47.8% of the patients, with a positive impact on vision and no impact on relapse. Glaucoma, radiation-induced optic neuropathy, maculopathy were reported in 17.9%, 47.5%, and 33.6% of patients, respectively. On multivariate analysis, age, diabetes, thickness, initial visual acuity and percentage of macula receiving 26 Gy were predictive of visual acuity. Furthermore, patients irradiated to ≥80% of their papilla had better visual acuity when limiting the 50% (30-Gy) and 20% (12-Gy) isodoses to ≤2 mm and 6 mm of optic nerve length, respectively. Conclusions: A personalized proton therapy plan with optic nerve and macular sparing can be used efficiently with good oncological and functional results in parapapillary melanoma patients.

Visual Outcomes of Parapapillary Uveal Melanomas Following Proton Beam Therapy

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Thariat, Juliette, E-mail: jthariat@gmail.com [Department of Radiation Therapy, Cancer Center Antoine Lacassagne-Nice Sophia Antipolis University Hospital, Nice (France); Grange, Jean-Daniel [Department of Ophthalmology, Eye University Clinic la Croix Rousse, Lyon (France); Mosci, Carlo [Department of Ophthalmology, National Institute for Cancer Research, Mura Delle Cappucine, Genova (Italy); Rosier, Laurence [Eye Clinic, Centre d' Exploration et de Traitement de la Retine et de la Macula, Bordeaux (France); Maschi, Celia [Department of Ophthalmology, Eye University Clinic Pasteur 2, Nice (France); Lanza, Francesco [Department of Ophthalmology, National Institute for Cancer Research, Mura Delle Cappucine, Genova (Italy); Nguyen, Anh Minh [Department of Ophthalmology, Eye University Clinic la Croix Rousse, Lyon (France); Jaspart, Franck; Bacin, Franck; Bonnin, Nicolas [Department of Ophthalmology, Eye University Clinic Gabriel Montpied, Clermont Ferrand (France); Gaucher, David [Department of Ophthalmology, Eye University Clinic, Hopital Civil, Strasbourg (France); Sauerwein, Wolfgang [Department of Radiation Therapy, NCTeam, Strahlenklinik, Universitätsklinikum Essen, Essen (Germany); Angellier, Gaelle; Hérault, Joel [Department of Radiation Therapy, Cancer Center Antoine Lacassagne-Nice Sophia Antipolis University Hospital, Nice (France); Caujolle, Jean-Pierre [Department of Ophthalmology, Eye University Clinic Pasteur 2, Nice (France)

2016-05-01

Purpose: In parapapillary melanoma patients, radiation-induced optic complications are frequent and visual acuity is often compromised. We investigated dose-effect relationships for the optic nerve with respect to visual acuity after proton therapy. Methods and Materials: Of 5205 patients treated between 1991 and 2014, those treated using computed tomography (CT)-based planning to 52 Gy (prescribed dose, not accounting for relative biologic effectiveness correction of 1.1) in 4 fractions, with minimal 6-month follow-up and documented initial and last visual acuity, were included. Deterioration of ≥0.3 logMAR between initial and last visual acuity results was reported. Results: A total of 865 consecutive patients were included. Median follow-up was 69 months, mean age was 61.7 years, tumor abutted the papilla in 35.1% of patients, and tumor-to-fovea distance was ≤3 mm in 74.2% of patients. Five-year relapse-free survival rate was 92.7%. Visual acuity was ≥20/200 in 72.6% of patients initially and 47.2% at last follow-up. A wedge filter was used in 47.8% of the patients, with a positive impact on vision and no impact on relapse. Glaucoma, radiation-induced optic neuropathy, maculopathy were reported in 17.9%, 47.5%, and 33.6% of patients, respectively. On multivariate analysis, age, diabetes, thickness, initial visual acuity and percentage of macula receiving 26 Gy were predictive of visual acuity. Furthermore, patients irradiated to ≥80% of their papilla had better visual acuity when limiting the 50% (30-Gy) and 20% (12-Gy) isodoses to ≤2 mm and 6 mm of optic nerve length, respectively. Conclusions: A personalized proton therapy plan with optic nerve and macular sparing can be used efficiently with good oncological and functional results in parapapillary melanoma patients.

Blocking PirB up-regulates spines and functional synapses to unlock visual cortical plasticity and facilitate recovery from amblyopia

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Bochner, David N.; Sapp, Richard W.; Adelson, Jaimie D.; Zhang, Siyu; Lee, Hanmi; Djurisic, Maja; Syken, Josh; Dan, Yang; Shatz, Carla J.

2015-01-01

During critical periods of development, the brain easily changes in response to environmental stimuli, but this neural plasticity declines by adulthood. By acutely disrupting paired immunoglobulin-like receptor B(PirB) function at specific ages, we show that PirB actively represses neural plasticity throughout life. We disrupted PirB function either by genetically introducing a conditional PirB allele into mice or by minipump infusion of a soluble PirB ectodomain (sPirB) into mouse visual cortex. We found that neural plasticity, as measured by depriving mice of vision in one eye and testing ocular dominance, was enhanced by this treatment both during the critical period and when PirB function was disrupted in adulthood. Acute blockade of PirB triggered the formation of new functional synapses, as indicated by increases in miniature excitatory postsynaptic current (mEPSC) frequency and spine density on dendrites of layer 5 pyramidal neurons. In addition, recovery from amblyopia— the decline in visual acuity and spine density resulting from long-term monocular deprivation— was possible after a 1-week infusion of sPirB after the deprivation period. Thus, neural plasticity in adult visual cortex is actively repressed and can be enhanced by blocking PirB function. PMID:25320232

Preliminary Results for a Monocular Marker-Free Gait Measurement System

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Jane Courtney

2006-01-01

Full Text Available This paper presents results from a novel monocular marker-free gait measurement system. The system was designed for physical and occupational therapists to monitor the progress of patients through therapy. It is based on a novel human motion capturemethod derived from model-based tracking. Testing is performed on two monocular, sagittal-view, sample gait videos – one with both the environment and the subject’s appearance and movement restricted and one in a natural environment with unrestrictedclothing and motion. Results of the modelling, tracking and analysis stages are presented along with standard gait graphs and parameters.

Reduction in spontaneous firing of mouse excitatory layer 4 cortical neurons following visual classical conditioning

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Bekisz, Marek; Shendye, Ninad; Raciborska, Ida; Wróbel, Andrzej; Waleszczyk, Wioletta J.

2017-08-01

The process of learning induces plastic changes in neuronal network of the brain. Our earlier studies on mice showed that classical conditioning in which monocular visual stimulation was paired with an electric shock to the tail enhanced GABA immunoreactivity within layer 4 of the monocular part of the primary visual cortex (V1), contralaterally to the stimulated eye. In the present experiment we investigated whether the same classical conditioning paradigm induces changes of neuronal excitability in this cortical area. Two experimental groups were used: mice that underwent 7-day visual classical conditioning and controls. Patch-clamp whole-cell recordings were performed from ex vivo slices of mouse V1. The slices were perfused with the modified artificial cerebrospinal fluid, the composition of which better mimics the brain interstitial fluid in situ and induces spontaneous activity. The neuronal excitability was characterized by measuring the frequency of spontaneous action potentials. We found that layer 4 star pyramidal cells located in the monocular representation of the "trained" eye in V1 had lower frequency of spontaneous activity in comparison with neurons from the same cortical region of control animals. Weaker spontaneous firing indicates decreased general excitability of star pyramidal neurons within layer 4 of the monocular representation of the "trained" eye in V1. Such effect could result from enhanced inhibitory processes accompanying learning in this cortical area.