Interocular Acuity Difference Research Articles

Effectiveness of optical treatment in amblyopia and validation of measuring spectacle compliance with the ODM.

The improvement in visual acuity (VA) was determined during optical treatment in children with amblyopia before their participation in a randomised clinical trial comparing the effect of dichoptic video gaming using virtual reality goggles with occlusion therapy. Children aged 4-12 years with an interocular VA difference ≥0.20 logMAR and an amblyogenic factor: strabismus <30Δ, ≥1.00 D anisometropia, astigmatism ≥1.50 D and/or hypermetropia ≥1.50 D were eligible for 16 weeks of optical treatment. Children with previous amblyopia treatment were excluded. Compliance with spectacle wear was measured electronically over 1 week using the occlusion dose monitor (ODM). The reliability of these measurements was verified. The main outcome was an increase in amblyopic eye VA from baseline to 16 weeks. Sixty-five children entered the optical treatment period. Mean age was 6.0 ± 2.2 years (range: 4-12 years; IQR 4.5-6.7 years). Amblyopia was caused by anisometropia in 53 (82%) children, strabismus in 6 (9%) and combined mechanism in 6 (9%). After optical treatment, mean VA improved by 0.20 logMAR (SD 0.28; p < 0.001) and 0.07 in the amblyopic and fellow eye, respectively (SD 0.20; p = 0.03). This resulted in 24 children (37%) with an interocular VA difference <0.20 logMAR and in 17% of children with VA at the start of 0.30 logMAR or worse. Poor VA in the amblyopic eye at baseline (p = 0.001) and high anisometropia (p = 0.001) were associated with VA improvement. On average, spectacles were worn 9.7 ± 2.4 h/day (range: 2.3-13.6 h); mean compliance was 73% ± 18% of estimated wake time. Only ambient temperature ≥ 31°C or when spectacles were worn on top of the head prevented a reliable ODM measurement. VA improved by two lines resulting in more than a third of the children being treated sufficiently with spectacles alone and no longer being classified as amblyopic. The ODM proved to be a reliable method of measuring compliance with spectacle wear.

Evaluation of the Amblyopia tracker app.

The Amblyopia tracker app has been developed to be a tool for parents to monitor changes in vision at home during amblyopia treatment. The aims of this study were to evaluate the feasibility and repeatability of parents testing their children at home and to compare home test results to an assessment in clinic by an orthoptist. Children (age < 18years) with amblyopia (interocular acuity difference of ≥ 0.2logMAR) were recruited. Parents were asked to test their child with the app three times during a two week period followed by an online questionnaire about the usability. Participants also tested within 48h of their appointment where the measurement was repeated by an orthoptist. Out of 277 potential participants contacted, 37 completed three home measurements, mean age 6.8years (SD 2.94). Home tests comparisons were made between test two and three to ensure familiarity with the process. Paired t-tests showed no statistically significant difference for either eye or the interocular acuity difference (IAD). However, 29% had a difference in IAD of more than 0.1logMAR on repeated testing, with a maximum of 0.4logMAR difference in the IAD. Questionnaire responses from the parents who participated were predominantly positive with 97% of respondents saying they would use it if were available. Comparison of home and clinical measurements (n = 23, mean age 6.72 SD 2.60) showed no statistically significant differences for either eye or interocular acuity difference (paired t-test, p > 0.3 in all cases). Results show no statistically significant differences for the Amblyopia tracker app when used by parents at home on repeated testing, or between the home test by a parent and the test by a clinician. However, variability in the results does indicate that further improvements are required to ensure the results can be used as a reliable clinical tool.

Phenotypic Features Determining Visual Acuity in Albinism and the Role of Amblyogenic Factors.

Albinism is a spectrum disorder causing foveal hypoplasia, nystagmus, and hypopigmentation of the iris and fundus along with other visual deficits, which can all impact vision. Albinism is also associated with amblyogenic factors which could affect monocular visual acuity. The foveal appearance in albinism can range from mild foveal hypoplasia to that which is indistinguishable from the peripheral retina. The appearance can be quickly and easily graded using the Leicester Grading System in the clinic. However, interquartile ranges of 0.3 logMAR for the grades associated with albinism limit the accuracy of the grading system in predicting vision. Here, we discuss the potential role of nystagmus presenting evidence that it may not be a major source of variability in the prediction of visual acuity. We also show that interocular differences in visual acuity are low in albinism despite high levels of amblyogenic factors indicating that active suppression of vision in one eye in albinism is uncommon.

Binocular balance across spatial frequency in anisomyopia

PurposeAnisomyopia is prevalent in myopia and studies have reported it exhibits impaired binocular function. We investigated the binocular balance across spatial frequency in adults with anisomyopia and compared it to in individuals with less differences in refractive error, and examined whether ocular characteristics can predict binocular balance in anisomyopia.MethodsFifteen anisomyopes, 15 isomyopes and 12 emmetropes were recruited. Binocular balance was quantitatively measured at 0.5, 1, 2 and 4 c/d. The first two groups of the observers were tested with and without optical correction with contact lenses. Emmetropes were tested without optical correction.ResultsBinocular balance across spatial frequency in optically corrected anisomyopes and isomyopes, as well as emmetropes were found to be similar. Their binocular balance nevertheless still got worse as a function of spatial frequency. However, before optical correction, anisomyopes but not isomyopes showed significant imbalance at higher spatial frequencies. There was a significant correlation between the dependence on spatial frequency of binocular imbalance in uncorrected anisomyopia and interocular difference in visual acuity, and between the dependence and interocular difference in spherical equivalent refraction.ConclusionAnisomyopes had intact binocular balance following correction across spatial frequency compared to those in isomyopes and emmetropes. Their balance was weakly correlated with their refractive status after optical correction. However, their binocular balance before correction and binocular improvement following optical correction were strongly correlated with differences in ocular characteristics between eyes.

Perceptual Learning Based on the Lateral Masking Paradigm in Anisometropic Amblyopia With or Without a Patching History.

Perceptual learning (PL) has shown promising performance in restoring visual function in adolescent amblyopes. We retrospectively compared the effect of a well-accepted PL paradigm on patients with anisometropic amblyopia with or without a patching therapy history (patching therapy [PT] group versus no patching therapy [NPT] group). Eighteen PT and 13 NPT patients with anisometropic amblyopia underwent monocular PL for 3 months. During training, patients practiced a Gabor detection task following the lateral masking paradigm by applying a temporal two-alternative forced choice procedure with the amblyopic eye. Monocular contrast sensitivity functions (CSF), visual acuity, interocular differences in visual function metrics, and stereoacuity were compared before and after training. PL improved the visual acuity of the amblyopia eyes by 0.5 lines on average in the PT group and 1.5 lines in the NPT group. A significant reduction in the interocular difference in visual acuity was observed in the NPT group (P < 0.01) but not in the PT group (P = 0.05). Regarding CSF metrics, the area under the log CSF and cutoff in the amblyopic eyes of the NPT groups increased after training (P < 0.05). In addition, the interocular differences of the CSF metrics (P < 0.05) in the NPT group were significantly reduced. However, in the PT group, all the CSF metrics were unchanged after training. A total of 27 of 31 patients in both groups had no measurable stereopsis pretraining, and recovery after training was not significant. PL based on a lateral masking training paradigm improved visual function in anisometropic amblyopia. Patients without a patching history achieved greater benefits. PL based on a lateral masking training paradigm could be a new treatment for amblyopia.

Factors affecting the benefit of glasses alone in treating childhood amblyopia: an analysis of PEDIG data

BackgroundTo evaluate factors associated with better outcomes from optical treatment alone in amblyopic children from 3 up to 7 years.MethodsData extracted from two studies with similar protocols, Amblyopic Treatment Studies 5 (n = 152) and 13 (n = 128) from the Pediatric Eye Disease Investigator Group database, were used to determine by regression analysis the factors associated with improvements in visual acuity in the amblyopic eye, inter-ocular visual acuity difference and stereoacuity. Input variables were aetiology of amblyopia (anisometropic, strabismic and combined-mechanism amblyopia), treatment compliance, visual acuity, interocular visual acuity difference, stereoacuity, tropia size at distance and near, age and refractive error at baseline.ResultsDespite the range of clinical factors considered, our models explain only a modest proportion of the variance in optical treatment outcomes. The better predictors of the degree of optical treatment success in amblyopic children are visual acuity of the amblyopic eye, interocular visual acuity difference, stereoacuity, treatment compliance and the amblyopic eye spherical-equivalent refractive error. While the aetiology of the amblyopia does not exert a major influence upon treatment outcome, combined-mechanism amblyopes experience the smallest improvement in visual acuity, tropia and stereoacuity and may need longer optical treatment periods.ConclusionsWhile results identify the factors influencing optical treatment outcome in amblyopic children, clinicians will be unable to predict accurately the benefits of optical treatment in individual patients. Whether this is because relevant clinical or non-clinical factors (e.g. nature and volume of daily activities undertaken) influences the outcomes from optical treatment has not yet been identified and remains to be discovered.

Refining Clinical Quantification of Depth of Suppression in Amblyopia through Synoptophore Measurement.

Amblyopia is associated with unbalanced suppression between the two eyes. Existing clinical measures of suppression, such as the Worth 4 Dot test, provide qualitative information about suppression but cannot precisely quantify it. The Synoptophore, a well-established instrument in binocular vision clinics, has historically been used to gauge suppression qualitatively as well but has the capability to quantify suppression. We extended the capability of the Synoptophore through the development of a systematic protocol of illumination manipulation to quantify suppression in amblyopia. Twenty-six previously treated adult amblyopes underwent our protocol on the Synoptophore to measure the illumination balance needed to obtain fusion responses. Separately, these same amblyopes were tested with Worth 4 Dot as it is classically performed in the United States, utilizing different test distances and room illuminations to qualify the suppression response. Smaller, more central targets revealed larger magnitudes of suppression for both the Synoptophore and Worth 4 Dot tests (Synoptophore: χ25,26 = 25.538, p < 0.001; Worth 4 Dot: χ23,26 = 39.020, p < 0.001). There was a significant correlation between the two tests for depth of suppression measurements (rΤ > 0.345, p < 0.036), with more sensitivity measured by the Synoptophore, as suppression could be graded on a quantitative scale. Strabismic amblyopes demonstrated more suppression than non-strabismic amblyopes (z > 2.410, p < 0.016). Additionally, depth of suppression was correlated with interocular difference in both visual acuity (rΤ = 0.604, p < 0.001) and stereoacuity (rΤ = 0.488, p = 0.001). We extended the utility of the Synoptophore by measuring its illuminance outputs and developing a suppression testing protocol that compared favorably with Worth 4 Dot (clinic standard) while improving upon the latter through more sensitive quantification of suppression.

Prevalence of residual amblyopia in adulthood and its association on educational outcome and quality of life in the Northern Finland Birth Cohort.

The purpose of the current study was to evaluate the prevalence of residual amblyopia in adults in a population screened and treated in childhood. We also wanted to evaluate the association of amblyopia on school success, level of education, and quality of life. This is a follow-up study of 2708 subjects of the Northern Finland Birth Cohort. At the age of 46, the subjects took part in ophthalmic examinations, including the measurement of best-corrected visual acuity (BCVA) and refraction. Residual amblyopia was defined as BCVA 20/30 or less (logMAR ≥0.2) in one or both eyes or a two-line interocular visual acuity difference and absence of any pathological ocular factors. The quality of life was assessed with a 15D questionnaire, and educational outcome, school success, and episodic memory with a CANTAB-PAL (paired associates learning) test were evaluated. The prevalence of amblyopia in the current adult population aged 46 years was 1.3% (n= 36). At 14 years, the amblyopia subjects had had significant differences in mean spherical equivalent between the amblyopic and fellow eye and strabismus more often than controls. No significant differences were observed in the CANTAB-PAL test or in educational outcome. However, amblyopia subjects had significant difficulties in the 15D questionnaire in terms of vision (54% vs. 34%, p= 0.01). Due to screening and treatment in childhood, the number of adults with residual amblyopia was low. Despite minor visual impairment and discomfort, they cope very well in life in terms of educational outcome and quality of life.

Combined therapy of bilateral transcranial direct current stimulation and ocular occlusion improves visual function in adults with amblyopia, a randomized pilot study.

Amblyopia is the interocular visual acuity difference of two lines or more with the best correction in both eyes. It is treated with ocular occlusion therapy, but its success depends on neuroplasticity, and thus is effective in children but not adults. Transcranial Direct Current Stimulation (tDCS) is suggested to increase neuroplasticity. To determine if combined intervention of bilateral tDCS and ocular occlusion improves visual function in adults with amblyopia. A double-blind randomized, controlled pilot trial was conducted in 10 volunteers with amblyopia. While applying ocular occlusion and performing a reading task, participants received bilateral tDCS (n = 5) or sham stimulation (n = 5), with the anodal tDCS electrode in the contralateral visual cortex and the cathodal in the ipsilateral visual cortex in relation to the amblyopic eye. Visual function (through visual acuity, stereopsis, and contrast sensitivity tests) and visual evoked potential (with checkerboard pattern stimuli presentation) were evaluated immediately after. A total of 30 min after treatment with bilateral tDCS, visual acuity improved by 0.16 (± 0.025) LogMAR in the treatment group compared with no improvement (-0.02 ± 0.02) in five controls (p = 0.0079), along with a significant increase in the amplitude of visual evoked potentials of the amblyopic eye response (p = 0.0286). No significant changes were observed in stereopsis and contrast sensitivity. No volunteer reported any harm derived from the intervention. Our study is the first to combine anodal and cathodal tDCS for the treatment of amblyopia, showing transient improved visual acuity in amblyopic adults.

The UCI EyeMobile Preschool Vision Screening Program: Refractive Error and Amblyopia Results from the 2019-2020 School Year.

To introduce the University of California Irvine (UCI) EyeMobile for Children preschool vision screening program and describe the ophthalmic examination results of children who failed screening with the PlusoptiX S12C photoscreener during one school year. Children aged 30-72 months were screened with the PlusoptiX using ROC mode 3 during the 2019-2020 school year. Children who failed screening were referred for comprehensive eye examination on the EyeMobile mobile clinic. Presence of amblyopia risk factors (ARFs), amblyopia, and refractive error was determined via retrospective review of records. Amblyopia was defined as unilateral if there was ≥ 2-line interocular difference in the best-corrected visual acuity (BCVA) and as bilateral if BCVA was < 20/50 for children < 4 years old and < 20/40 for children ≥ 4 years old. ARFs were defined using 2021 American Association for Pediatric Ophthalmology and Strabismus (AAPOS) instrument-based screening guidelines. 5226 children were screened during the study period. Of the 546 children who failed screening, 350 (64%) obtained consent and were examined. Mean age of examined children was 4.45 years. Amblyopia was found in 8% of examined children, with unilateral amblyopia seen in 79% of amblyopic subjects. Glasses were prescribed to 246 (70.3%) children. Of the 240 children who received cycloplegic examinations, 43% had hyperopia and 30% had myopia. The positive predictive value (PPV) of the PlusoptiX screening for ARFs in children who received cycloplegic examinations was 70.4%. A significant proportion of Orange County preschoolers with refractive errors and amblyopia have unmet refractive correction needs. The PlusoptiX S12C photoscreener is an adequate screening device for the UCI EyeMobile for Children program, although modification of device referral criteria may lead to increased PPV. Further research is necessary to understand and overcome the barriers to childhood vision care in our community.

Amblyopia is associated with impaired balance in 3–6-year-old children in China

PurposeSchool-age children in China have more advanced motor development than their North American counterparts. This is likely due to cultural differences in children’s regular motor activities. It is unknown whether the motor function impairments associated with binocular visual disorders (BVDs) such as amblyopia in children raised in North America exist for children raised in China.DesignProspective case-control study.MethodsA major tertiary eye hospital in China tested children aged 3 to <7 (n = 63) belonging to three groups: anisometropic or strabismic amblyopia (n = 22), anisometropia or strabismus without amblyopia (n = 20), or controls (n = 21). The main outcome measure was motor function scores (Movement Assessment Battery for Children 2nd edition).ResultsBalance scores varied significantly across groups (F2,61 = 4.2, p = 0.02) with the amblyopia group (mean ± SD: 12.5 ± 3.0) exhibiting significantly poorer scores than controls (14.8 ± 2.3). The no-amblyopia BVD group (12.8 ± 3.1) did not differ significantly from the other groups. Manual dexterity, catching and throwing and total scores did not vary significantly across the three groups. A separate pre-planned comparison of only the amblyopia and control groups revealed significantly poorer total motor scores in the amblyopia group (10.1 ± 3.2) vs. controls (12 ± 2.4). A linear regression model was unable to significantly predict associations between total motor score and binocular function score (standardized β = −0.09, 95%, p = 0.7), amblyopia etiology (standardized β = 0.14, 95%, p = 0.4), or inter-ocular acuity difference (standardized β = −0.18, 95%, p = 0.4), in the amblyopia group.ConclusionAmblyopia is associated with motor function impairment in children raised in China. Motor deficits that may impact everyday activities have been observed in patients with amblyopia across multiple cultures.

A STUDY OF MAGNITUDE OF ANISOMETROPIA AND ITS ASSOCIATION WITH AMBLYOPIA IN SCHOOL GOING CHILDREN

BACKGROUND: Visual impairment is a common handicap among school going children. In some, there are signicant interocular differences in refractive error (ANISOMETROPIA), which can be accompanied by an interocular difference in visual acuity that is optically uncorrectable ( AMBLYOPIA). The co-occurrence of these two anomalies with no additional abnormality is ANISOMETROPIC AMBLYOPIA. Present study is aimed to study magnitude ofANISOMETROPICAMBLYOPIAin children. OBJECTIVES: To study the magnitude ofAnisometropia and its association with amblyopia in school going children. To identify amblyopic children and provide suitable treatment. MATERIALS AND METHOD: A cross- sectional study done over a period of 18 months at a tertiary health care center. School going children of age 7-17 years with refractive error were assessed of their refractive status, ocular examination including slit lamp examination and fundoscopy was done. Children with interocular refractive error difference of &gt;0.75 D were labelled as Anisometropic. Children whose best corrected visual acuity difference of both the eyes was more than two lines on Snellen's chart in absence of other organic cause were considered Amblyopic. Prevalence of anisometropia and its relation with amblyopia was determined. Data were analyzed by Chi-square test .Appropriate refractive correction was given. RESULT: Out of 100 ametropic children, 14 were anisometropic. Out of 14 anisometropic children 5 were amblyopic .Association between anisometropia and amblyopia was statistically signicant (p value &lt; 0.05). It was found that as severity of anisometropia increases, predisposition of development of amblyopia also increases. CONCLUSION:Refractive ansiometropia has a considerable prevalence and is a well-known amblyogenic factor in children. Timely intervention should be done to prevent permanent vision loss.

Effect of refractive error type in the amblyopic eyes on factors for treatment success in anisometropic amblyopia

To investigate the factors for treatment success in anisometropic amblyopia according to the spherical equivalent (SE) type of amblyopic eyes. Medical records of 397 children with anisometropic amblyopia aged 3 to 12 years who presented in a secondary referral eye hospital during 2010 ~ 2016 were retrospectively reviewed. Anisometropia was defined as ≥ 1 diopter (D) difference in SE, or ≥ 1.5 D difference of cylindrical error between the eyes. According to the SE of amblyopic eyes, patients were categorized into hyperopia (SE ≥ 1D), emmetropia (− 1 < SE < + 1) and myopia (SE ≤ − 1D) groups. Treatment success was defined as achieving interocular logMAR visual acuity difference < 0.2. Multivariate logistic regression was used to analyze the factors for treatment success. Significant factors for the amblyopia treatment success in hyperopia group (n = 270) were younger age [adjusted odds ratio (aOR) (95% confidence interval, CI) = 0.529 (0.353, 0.792)], better BCVA in amblyopic eyes at presentation [aOR (95% CI) 0.004 (0, 0.096)], longer follow-up period [aOR (95%CI) = 1.098 (1.036, 1.162)], and no previous amblyopia treatment history [aOR (95% CI) 0.059 (0.010, 0.364)]. In myopia group (n = 68), younger age [aOR (95% CI) 0.440 (0.208, 0.928)] and better BCVA in amblyopic eyes [aOR (95% CI) 0.034 (0.003, 0.469)] were associated with higher odds of treatment success. There was no significant factor for treatment success in emmetropia group (n = 59) in this population. The refractive error type of amblyopic eyes at presentation affects the factors for treatment success in anisometropic amblyopia.

Electronically monitored occlusion therapy in amblyopia with eccentric fixation

PurposeAmblyopia with eccentric fixation, especially when not diagnosed early, is a therapeutic challenge, as visual outcome is known to be poorer than in amblyopia with central fixation. Consequently, treatment after late diagnosis is often denied. Electronic monitoring of occlusion provides us the chance to gain first focussed insight into age-dependent dose response and treatment efficiency, as well as the shift of fixation in this rare group of paediatric patients.MethodsIn our prospective pilot study, we examined amblyopes with eccentric fixation during 12 months of occlusion treatment. We evaluated their visual acuity, recorded patching duration using a TheraMon®-microsensor, and determined their fixation with a direct ophthalmoscope. Dose-response relationship and treatment efficiency were calculated.ResultsThe study included 12 participants with strabismic and combined amblyopia aged 2.9–12.4 years (mean 6.5). Median prescription of occlusion was 7.7 h/day (range 6.6–9.9) and median daily received occlusion was 5.2 h/day (range 0.7–9.7). At study end, median acuity gain was 0.6 log units (range 0–1.6) and residual interocular visual acuity difference (IOVAD) 0.3 log units (range 0–1.8). There was neither significant acuity gain nor reduction in IOVAD after the 6th month of treatment. Children younger than 4 years showed best response with lowest residual IOVAD at study end. Efficiency calculation showed an acuity gain of approximately one line from 100 h of patching in the first 2 months and half a line after 6 months. There was a significant decline of treatment efficiency with age (p = 0.01). Foveolar fixation was achieved after median 3 months (range 1–6). Three patients (> 6 years) did not gain central fixation.ConclusionEccentric fixation is a challenge to therapy success. Based on electronic monitoring, our study quantified for the first time the reduction of treatment efficiency with increasing age in amblyopes with eccentric fixation. Despite some improvement in patients up to 8 years, older patients showed significantly lower treatment efficiency. In younger patients with good adherence, despite poor initial acuity, central fixation and low residual IOVAD could be attained after median 3 months. Hence, the necessity of early diagnosis and intensive occlusion should be emphasized.

Evaluation of a New Method to Track Changes in Vision at Home for Children Undergoing Amblyopia Treatment.

Purpose:A new amblyopia tracker app has been designed to provide parents with a method of monitoring a child’s vision by presenting a single optotype size that the tester moves to identify the furthest distance the optotypes can be seen. The aim of this study is to evaluate this methodology in adults, comparing the findings to visual acuity (VA) measured with the iSight app and to determine the test retest variability.Methods:Adults, aged 18–39 years, with no known eye condition and VA ≤ 0.7 logMAR were recruited. Bangerter filters were used to simulate amblyopia, where VA was reduced below 0.0 with an interocular difference of at least 0.2 logMAR. Testing for both apps was performed monocularly, with the test order being randomised.Results:Data from 32 subjects were analysed. For the test retest variability analysis, paired t-tests showed no statistically significant difference between the tests for either eye, either app or the interocular acuity difference (p > 0.3 in all cases). Bland Altman plots showed similar limits of agreement between the two apps. When comparing measurements between the apps there was no statistically significant difference on the first or second test, either eye or the interocular acuity difference (p > 0.5 in all cases).Conclusion:The results support the theory that changing distance is a valid method of assessing VA as the measurements agree well with the standard approach of reducing optotype size. Test retest variability is similar between the two apps and there is good agreement between the measurements.

Prevalence of amblyopia and its determinants in a rural population: a population-based cross-sectional study

ABSTRACT To determine the prevalence of amblyopia and its determinants in underserved rural villages of Iran. This population-based cross-sectional study was conducted in 3850 subjects selected from two underserved districts in the north (Kojur District, Nowshahr County, Mazandaran Province) and southwest (Shahyun District, Dezful County, Khuzestan Province) of Iran using multi-stage cluster sampling. The subjects underwent complete ophthalmic examinations including the measurement of uncorrected (UCVA) and best-corrected (BCVA) visual acuity, objective and subjective refraction, unilateral and alternate cover tests and ocular health examination. Amblyopia was defined as a reduction of BCVA to 20/30 or less in one eye or a 2-line interocular optotype acuity difference in the absence of any pathological factors. Of 3850 selected subjects, 3314 participated in the study (response rate = 86.08%). The mean age of the participants was 36.90 ± 20.21 years (range: 3–93 years). The prevalence and 95% confidence interval of total, bilateral, and unilateral amblyopia were 2.73% (2.17 to 3.38), 0.50% (0.28 to 0.83), and 2.23% (1.73 to 2.83), respectively. The most common type of amblyopia was anisometropic followed by strabismic and mixed. The lowest and highest prevalence was seen in the age group 6–20 years (1.36%; 0.65 to 2.49) and above 70 years (5.97%; 3.02 to 10.44), respectively. According to the results of multiple logistic regression analysis, compared to illiterate subjects, the odds ratio of amblyopia was 0.321 (P = .033) in subjects with High school education, 0.181 (P = .030) in subjects with secondary School education, and 0.486 (P = .041) in subjects with primary school education. The odds ratio of amblyopia for north villages residence vs southwest villages residence was 2.105 (P = .012). The odds ratio of amblyopia was 2.765 for age group>70 years vs. 6–20 years (P = .033). The prevalence of amblyopia was higher in north region, in participants with lower education level and older individuals. The high prevalence of amblyopia in older people may be due to the lack of screening programs in previous generations and consequently the lack of timely diagnosis and treatment.

The effect of ocular dominance on macular function: A pattern electroretinogram study.

To investigate the effect of ocular dominance on pattern electroretinogram (PERG) recordings in the participants who have no ophthalmic diseases. One hundred and twelve eyes of 56 participants (mean age 32.96 ± 10.82 years) were included in this prospective, cross-sectional study. After detailed ophthalmological examination and determination of the ocular dominance with hole-in-a-card test, the PERG was performed to determine implicit time and amplitudes of P50 and N95. There were no significant interocular differences in visual acuity, refractive error, or intraocular pressure (p > 0.05 for all). Thirty-six (64.3%) of the participants had ocular dominance in the right eye. The dominant eyes had significantly higher P50 amplitude than in the fellow nondominant eyes (6.90 µV in dominant vs 5.87 µV in nondominant; p = 0.015; 95% confidence interval). There was no significant difference in N95 amplitude, N95/P50 ratio, and implicit times of P50 and N95 between the dominant and nondominant eyes of the participants (p = 0.090, p = 0.124 p = 0.817, p = 0.668; respectively). The analysis revealed a significantly increased P50 amplitude of the PERG, which is known to be highly associated with macular function, in dominant eyes of the patients when compared to fellow nondominant eyes.

Study to establish visual acuity norms with Teller Acuity Cards II for infants from southern China

ObjectivesTo establish the norms of binocular and monocular acuity and interocular acuity differences for southern Chinese infants and compare these norms with the results for northern Chinese infants.MethodsA prospective, comparative, and noninterventional study was conducted from January to August 2018. Teller Acuity Cards II were used to determine the binocular and monocular acuity of infants. The tolerance intervals and limits with a stated proportion and probability were used to evaluate the norms of binocular and monocular acuity and interocular acuity differences. An unpaired t-test was used to compare the obtained norms with the reported northern Chinese norms.ResultsThe tolerance intervals of binocular acuity (mean acuity of 3.73, 7.35, and 12.01 cpd, respectively, at 12, 24, and 36 months), monocular acuity (mean acuity of 2.88, 6.91, and 10.75 cpd, respectively, at 12, 24, and 36 months), and interocular acuity differences (mean difference of 0.92, 2.89, and 3.99 cpd, respectively, at 12, 24, and 36 months) were obtained, exhibiting an increasing trend with age. The binocular visual acuity norms of southern Chinese infants were significantly lower than those in northern China (4.37 vs. 6.9 cpd at 8 months and 7.35 vs. 26 cpd at 24 months) (P = 0.011).ConclusionsNorthern and southern Chinese infants exhibited distinct acuity norms and visual development patterns. The establishment of population-specific visual acuity norms is necessary for current populations of infants from different regions.

Quantifying Suppression in Anisometropic Amblyopia With VTS4 (Vision Therapy System 4)

PurposeVisual acuity (VA) of the amblyopic eye is usually considered for monitoring improvement with therapy. However, participation of the amblyopic eye under binocular viewing conditions is also important. This study investigated the use of a clinically available tool VTS4 (Vision Therapy System 4) to quantify the participation or suppression of the amblyopic eye under binocular viewing conditions.MethodsA cross-sectional study on patients with anisometropic amblyopia was undertaken. Monocular VA was thresholded. Stereo acuity was measured with Randot stereo test. Simultaneous macular perception (SMP) targets in VTS4 were dichoptically presented. SMP target size was reduced till the amblyopic eye's target disappeared (suppression scotoma size). An average of three measurements was taken for the suppression scotoma size.ResultsTwenty-eight patients participated (aged 6 to 21 years). The mean interocular VA difference was 0.50 ± 0.27 logMAR. The mean scotoma size was 8.2° ± 5.4°. Mean stereo acuity was 2.06 ± 0.34 log arc seconds from 21 patients on whom stereopsis could be measured. Suppression scotoma size showed a significant (P < 0.001) positive correlation with both interocular VA difference (r = 0.59) and stereoacuity (r = 0.72).ConclusionsParticipation of the amblyopic eye under binocular viewing condition can be assessed by measuring the suppression scotoma size in VTS4, even when stereoacuity is poor or not measurable. Smaller the suppression scotoma, better is the amblyopic eye's participation.Translational RelevanceVTS4 can be used in monitoring amblyopia therapy by quantifying suppression of the amblyopic eye.

Reading with central vision loss: binocular summation and inhibition.

PurposeThere are conflicting reports as to whether there is a binocular advantage or disadvantage when reading with central vision loss. This study examined binocular reading summation in patients with macular degeneration.MethodsSeventy‐one patients with bilateral central vision loss [mean age: 63 (S.D. = 21) years] participated. Reading performances during binocular and monocular viewing with the better eye (i.e., the eye with the best monocular visual acuity) were evaluated using different versions of the Italian MNREAD reading chart (www.precision‐vision.com). Fixation stability and preferred retinal loci (PRLs) were recorded monocularly for each eye. The overall sample was split into inhibition, equality, and summation groups based on the binocular ratio (i.e., binocular/monocular) of the maximum reading speed.Results41% of patients experienced binocular inhibition, 42% summation, and 17% equality. Binocular reading speed of the inhibition group was approximately 30 words per minute slower than those of the equality and summation groups, although the inhibition group had the best visual acuity. These patients generally had monocular PRLs in non‐corresponding locations temporal or nasal to the scotoma, had the largest interocular acuity difference and lacked residual stereopsis. The three groups did not differ in fixational control, contrast sensitivity or critical print size.ConclusionsEqual proportions of patients with central vision loss show binocular reading summation and inhibition. Patients with binocular reading inhibition have poorer reading performance and different clinical characteristics than those with binocular reading summation and equality.