Reliability of the electronic early treatment diabetic retinopathy study testing protocol in children 7 to <13 years old

PURPOSE: To assess the test-retest reliability of the electronic Early Treatment Diabetic Retinopathy Study (E-ETDRS) visual acuity algorithm using the computerized Electronic Visual Acuity (EVA) tester in children 7 to <13 years old. DESIGN: Test-retest reliability study. METHODS: This multicenter study involved 245 subjects at four clinical sites. As the main outcome measure, visual acuity was measured twice using the E-ETDRS testing protocol on the EVA system, which uses a programmed handheld device to communicate with a personal computer and a 17-inch monitor at a 3-m test distance. RESULTS: Test-retest reliability was high (r =.94 for right eyes and 0.96 for left eyes) and for both right and left eyes, 89% of retest scores were within 0.1 logarithm of the minimal angle of resolution (logMAR) (five letters) of the initial test score and 99% of retests were within 0.2 logMAR (10 letters). Reliability was high across the age range of 7 to <13 years. Based on 95% confidence level estimates, a change in visual acuity of 0.2 logMAR (10 letters) from a previous acuity measure is unlikely to result from measurement variability. CONCLUSIONS: The E-ETDRS protocol using the EVA has high test-retest reliability in children 7 to <13 years of age. Potential advantages include better standardization across multiple sites, the ability to directly capture data electronically with an automatic acuity score calculation, the reduction of potential bias by limiting the tester's role, and the requirement of only a single testing distance for measurements from 20/800 to 20/12. This computerized testing method should be considered when visual acuity is used as an outcome measure in eye research involving children 7 to <13 years old.     

A computerized method of visual acuity testing: adaptation of the early treatment of diabetic retinopathy study testing protocol

PURPOSE: To develop a computerized method of visual acuity testing for clinical research as an alternative to the standard Early Treatment for Diabetic Retinopathy Study (ETDRS) testing protocol, and to evaluate its test-retest reliability and concordance with standard ETDRS testing. DESIGN: Test-retest reliability study. METHODS: Multicenter setting of a study population of 265 patients at three clinical sites. Visual acuity was measured with both the electronic visual acuity testing algorithm (E-ETDRS) and standard ETDRS protocol (S-ETDRS) twice on one eye of each patient. E-ETDRS testing was conducted using the electronic visual acuity tester (EVA), which utilizes a programmed Palm (Palm, Inc, Santa Clara, California, USA) hand-held device communicating with a personal computer and 17-inch monitor at a test distance of 3 meters. RESULTS: For the E-ETDRS protocol, test-retest reliability was high (r = 0.99; with 89% and 98% of retests within 0.1 logMAR and 0.2 logMAR of initial tests, respectively) and comparable with that of S-ETDRS testing (r = 0.99; with 87% and 98% of retests within 0.1 logMAR and 0.2 logMAR of initial test, respectively). The E-ETDRS and S-ETDRS scores were highly correlated (r = 0.96 for initial tests and r = 0.97 for repeat tests). Based on estimates of 95% confidence intervals, a change in visual acuity of 0.2 logMAR (10 letters) from a baseline level is unlikely to be related to measurement variability using either the E-ETDRS or the S-ETDRS visual acuity testing protocol. CONCLUSIONS: The E-ETDRS protocol has high test-retest reliability and good concordance with S-ETDRS testing. The computerized method has advantages over the S-ETDRS testing in electronically capturing the data for each tested letter, requiring only a single distance for testing from 20/12 to 20/800, potentially reducing testing time, and potentially decreasing technician-related bias.     

Comparison of visual acuity levels in pediatric patients with amblyopia using Wright figures, Allen optotypes, and Snellen letters.

PURPOSE: To compare and correlate the clinical performance of Wright figures in visual acuity assessments of pediatric patients with amblyopia to those obtained through Allen cards and Snellen letters. SUBJECTS AND METHODS: Best-corrected visual acuity of 26 amblyopic children were measured with the Wright figures(c), Snellen letters, and isolated Allen optotypes, respectively. Amblyopia was defined as two lines of visual acuity difference or a visual acuity level of 20/30 or lower as determined by Snellen chart. The results were evaluated for statistical intergroup differences using the Wilks' Lambda multivariate analysis of variance and for correlation using the Pearson correlation coefficient test. RESULTS: The mean age of the subjects was 8.27 +/- 2.46 years (range: 5 to 15 years). The mean logMAR values for the Wright figures(c), Snellen letters, and Allen optotypes were 0.40 +/- 0.20, 0.47 +/- 0.23, and 0.29 +/- 0.28, respectively. When compared with Snellen letters, the Wright figures correlated to a higher degree ( r = 0.46, P < 0.001) than Allen optotypes ( r = 0.67, P < 0.001). With a visual acuity of 20/40 or worse on Snellen letter testing, the sensitivity of Wright figures(c) and Allen cards in diagnosing amblyopic eyes was 87.0 and 56.5%, respectively ( P = 0.016). CONCLUSIONS: Wright figures, designed primarily to evaluate the vision in the preliterate pediatric population, correlate more closely to Snellen letters and have a higher rate of correctly identifying amblyopia than isolated Allen optotypes in pediatric patients.     

Parent-administered visual acuity testing: is it reliable and can it improve office efficiency?

PURPOSE: To evaluate the accuracy of a parent-administered visual acuity test, using the electronic visual acuity tester (EVA) (JAEB Center, Tampa, FL) and evaluate its use as a means to improve efficiency of office acuity testing. METHODS: This was a prospective experimental study. Part I: Sixty-four children had their visual acuity determined using the EVA, first by their parents and then by an ophthalmic technician. Acuity scores were compared. Part II: Forty-four other children were randomly assigned to one of 2 groups. Group A (parent-prescreen) children had their visual acuity determined first by the parents using the EVA. The visual acuity result in that child was then rechecked by the technician using the Reinforcement Phase and Phase 2 of the Amblyopia Treatment Study (ATS) visual acuity testing protocol. Group B (full ATS protocol) children had their acuity determined by the technician using the full ATS protocol. The number of optotypes presented by the technician in order to determine the acuity in each group was compared. RESULTS: Part I: Reliability of parent-determined visual acuity scores was high (r = 0.91 and 0.81 for right eyes (OD) and left eyes (OS), respectively), with 93% of right eye parent scores and 85% of left eye parent scores within 0.11 logarithm of minimal angle of resolution (logMAR) units (ie, within one line of vision) of the technician score. Part II: The parent prescreen group (Group A) required presentation of 66% fewer optotypes to the OD and 68% fewer optotypes to the OS than the full ATS protocol group (Group B) (OD: P = 5.4 x 10(-18); OS: P = 6.5 x 10(-18)). CONCLUSIONS: Visual acuity testing results by parents using the EVA are reliable. Electronic visual acuity prescreening by parents reduces the number of optotype presentations required to be shown by the technician to accurately determine acuity. Use of a parent-assisted screening system in the waiting room may translate to increased office efficiency.     

Threshold visual acuity testing of preschool children using the crowded HOTV and Lea Symbols acuity tests

PURPOSE: To compare the testability and threshold acuity levels for very young children on the crowded HOTV logMAR distance visual acuity test presented on the BVAT apparatus and the Lea Symbols logMAR distance visual acuity chart. METHODS: Subjects were 87 Head Start children from age 3 to 3.5 years. Testing consisted of binocular pretraining at near using a lap card as needed, binocular pretraining at 3 m, and threshold testing for each eye. The testing procedure, adapted from the Amblyopia Treatment Study, presented optotypes until the child was unable to correctly name or match three of three or three of four optotypes of a given size. Threshold acuity was the smallest size for which at least three optotypes were correctly identified. RESULTS: Both near and distance pretraining were completed by 71% of children for HOTV and by 75% for Lea Symbols (P =.39). The distribution of threshold acuities differed between the two tests. For the 69 eyes of 53 children who were successfully tested with both optotypes, results from the crowded HOTV acuity test were on average 0.25 logMar (2.5 lines) better than those from the Lea Symbols acuity test (P <.001). CONCLUSIONS: The proportion of children between 3 and 3.5 years of age whose monocular visual acuity could be assessed was high and was similar for the two charts tested. Crowded HOTV acuity results were better on average than results using Lea symbols. The different formats of the two tests may explain the observed differences in threshold acuity level.     

The accuracy of the amblyopia treatment study visual acuity testing protocol

PURPOSE: To study the accuracy of the newly proposed Amblyopia Treatment Study (ATS) visual acuity testing protocol for 3- to 6-year-old children. Because no "gold standard" is available for acuity testing in pediatric patients, accuracy was evaluated using computer simulations based on a psychometric model. METHODS: Monte Carlo simulations of ATS acuity data were generated using a psychometric model that accounts for true acuity, noise in the visual system, and the rate of inadvertent misses. We varied true acuity from 20/15 to 20/400 (-0.1 to 1.3 logMAR). Visual system noise was represented by the slope beta of the psychometric function and ranged from 1 (noisy) to 8 (not noisy). The rate of inadvertent misses ranged from 0% to 10%. Accuracy of the ATS protocol was evaluated in terms of precision, bias, and stimulus range limitations. The same model was fitted to experimental ATS acuity data, thus allowing us to study the distributions of acuity, visual system noise, and level of attentiveness in 126 children ages 3 to <7 years. RESULTS: For conditions with little noise in the visual system (beta > 2), precision was well within 0.1 logMAR (corresponding to one line on a logMAR letter chart), except for acuities worse than 1.2 logMAR, and decreased to 0.15 to 0.2 logMAR for beta = 1. Bias was negligible, except in noisy conditions, where the ATS protocol tended to overestimate acuity by one line at the poor end of the true acuity range and underestimate acuity at the good end of the true acuity range. Effects of the rate of inadvertent misses were small. Fits to the real data showed a wide range of slope parameters, but only 11% had beta < or = 2. The rate of inadvertent misses was < or = 2% in 89% of cases. CONCLUSION: The simulations suggest that the ATS protocol offers an accurate method for assessing visual acuity in children in the range of 3 to 6 years of age with both precision and bias within 0.1 logMAR for typical values of the psychometric parameters.     

Visual acuity testability in African-American and Hispanic children: the multi-ethnic pediatric eye disease study

PURPOSE: To compare the age- and gender-specific testability rates for the Amblyopia Treatment Study (ATS) HOTV visual acuity testing protocol using the electronic visual acuity (EVA) tester in African-American and Hispanic preschool children. DESIGN: Population-based, cross-sectional study. METHODS: Measurement of presenting monocular distance visual acuity using the ATS HOTV protocol was attempted in all African-American and Hispanic children aged 30 to 72 months from the population-based Multi-Ethnic Pediatric Eye Disease Study (MEPEDS). Children able to be tested monocularly in both eyes were considered able. Age-, gender-, and ethnicity-specific testability rates were calculated. Comparisons of testability among different groups were performed using Chi-square analyses and the Cochran trend test. RESULTS: Testing was attempted on 3,126 children (1,471 African-American, 1,655 Hispanic; 50% female). Overall, 84% (83% African-American, 85% Hispanic; 86% female, 82% male) were testable. Older children were more likely to complete testing successfully than younger children (P < .0001). Age-specific testability in children 30 to 36 months of age, 37 to 48 months of age, 49 to 60 months of age, and 61 to 72 months of age was 39%, 84%, 98%, and 100%, respectively. After stratifying by age, there were no ethnicity-related differences in children testable (P = .12). Girls (86%) were slightly more likely to be testable than boys (82%; P > .003). CONCLUSIONS: Monocular threshold visual acuity testing using the ATS HOTV protocol on the EVA tester (Jaeb Center for Health Research, Tampa, Florida, USA) can be completed by most African-American and Hispanic preschool children, particularly those older than 36 months of age. This protocol therefore may be used in minority preschool children as an integral part of the diagnosis and management of amblyopia and other forms of visual impairment.     

Long-term changes in visual acuity and refractive error in amblyopes.

PURPOSE: To report long-term changes in visual acuity and refractive error for strabismic, anisometropic, and isoametropic amblyopes. METHODS: Records of patients with strabismic amblyopia, anisometropic amblyopia, and isoametropic amblyopia who were treated from 1983 to 1993 were reviewed. Excluded were patients having ocular or neurological diseases, developmental delay, and follow-up <4 years after treatment cessation. Data included best-correctable visual acuity and spherical equivalent refractive error of the amblyopic and the nonamblyopic eye at pretreatment, posttreatment, and long-term follow-up. RESULTS: Records for 61 patients met the inclusion criteria. For strabismic amblyopia (n = 22), mean visual acuity in amblyopic and nonamblyopic eyes improved 0.36 and 0.05 logarithm of the minimum angle of resolution (logMAR) units after a mean treatment time of 1 year. At long-term follow-up (mean = 9.3 years after treatment), visual acuity in the amblyopic eye regressed 0.09 logMAR and visual acuity in the nonamblyopic eye improved 0.10 logMAR units. For anisometropic amblyopia (n = 26), mean visual acuity in amblyopic and nonamblyopic eyes improved 0.30 and 0.02 logMAR units, respectively, after a mean treatment period of 1.1 year. At the long-term follow-up visit (mean = 7.1 years after treatment), visual acuity in the amblyopic eye regressed 0.09 logMAR unit and in the nonamblyopic eye improved 0.03 logMAR unit. Repeated-measures analysis of variance showed no significant effect of type of amblyopia on visual acuity of the amblyopic eye and a significant effect of visit due to treatment but not regression. The changes in visual acuity in the nonamblyopic eye from the pretreatment to the follow-up visit were significant and interacted with type, the changes being larger in strabismic amblyopia. For strabismic amblyopia, the mean refractive error in amblyopic and nonamblyopic eyes changed from +2.15 D and +1.85 D, respectively, initially to +0.45 D and +0.58 D, respectively, at the follow-up visit. For anisometropic amblyopia, the mean refractive error in amblyopic and nonamblyopic eyes changed from +1.04 D and +0.12 D, respectively, initially to +0.23 D and -0.94 D, respectively, at the follow-up visit. The effect of visit on amblyopic and nonamblyopic refractive errors was significant. For isoametropic amblyopia (n = 13), visual acuity in both right and left eyes initially was 0.39 logMAR unit and improved to 0.14 logMAR unit in each eye after a mean follow-up of 8.9 years. Refractive error in the right and the left eyes changed from -1.22 D and -1.14 D, respectively, to -2.68 D and -2.56 D, respectively, at follow-up. These differences were all significant. CONCLUSIONS: After treatment and with long-term follow up, visual acuity regresses but not significantly in the amblyopic eye in strabismic amblyopia and anisometropic amblyopia. At the same time, visual acuity in the nonamblyopic eye improves slightly. Visual acuity also improves significantly over time in isoametropic amblyopia. The refractive error of both amblyopic and nonamblyopic eyes tends to show a myopic shift regardless of the type of amblyopia.     

Computerized method of visual acuity testing: adaptation of the amblyopia treatment study visual acuity testing protocol

PURPOSE: To report a computerized method for determining visual acuity in children using the Amblyopia Treatment Study visual acuity testing protocol. METHODS: A computerized visual acuity tester was developed that uses a programmed handheld device that uses the Palm operating system (Palm, Inc, Santa Clara, California). The handheld device communicates with a personal computer running a Linux operating system and 17-inch monitor. At a test distance of 3 m, single letters can be displayed from 20/800 to 20/12. A C program on the handheld device runs the Amblyopia Treatment Study visual acuity testing protocol. Using this method, visual acuity was tested in both the right and left eyes, and then the testing was repeated in 156 children age 3 to 7 years at four clinical sites. RESULTS: Test-retest reliability was high (r =.92 and 0.95 for and right and left eyes, respectively), with 88% of right eye retests and 94% of left eye retests within 0.1 logarithm of minimal angle of resolution (logMAR) units of the initial test. The 95% confidence interval for an acuity score was calculated to be the score +/- 0.13 logMAR units. For a change between two acuity scores, the 95% confidence interval was the difference +/- 0.19 logMAR units. CONCLUSIONS: We have developed a computerized method for measurement of visual acuity. Automation of the Amblyopia Treatment Study visual acuity testing protocol is an effective method of testing visual acuity in children 3 to 7 years of age.     

The electronic visual acuity tester: testability in preschool children.

PURPOSE: To evaluate the ability of preschool children to have their threshold visual acuity assessed using a standardized, computer-based letter test. METHODS: Participants were 1195 3.5- to 5-year-old children enrolled in the Vision in Preschoolers Study. Monocular visual acuity was assessed by licensed eye care professionals (optometrists and pediatric ophthalmologists experimented in the examination of children), using the Electronic Visual Acuity tester, which uses the letters H, O, T, and V with a crowded surround. RESULTS: Overall, 99.1% of children passed the training that consisted of identifying the letters H, O, T, and V by naming or matching the letters at 60 cm. Among those who passed the training, 99.6% completed the binocular pretest at 3 m, and 97.6% of those passing the training and the pretest completed monocular threshold visual acuity testing of each eye with the Electronic Visual Acuity tester. Testability increased with age for training (p = 0.03), pretesting (p = 0.04), and acuity testing (p = 0.07). Overall, 93.3% of 3.5-year-olds, 96.7% of 4-year-olds, and 98.8% of 5-year-olds completed training, pretesting, and monocular threshold acuity testing of each eye using standard letter optotypes. CONCLUSION: Using the computer-based Electronic Visual Acuity system, nearly all 3.5- to 5-year-old children can complete monocular acuity testing of each eye.     

Differences in visual acuity between the eyes: determination of normal limits in a clinical population

We determined the difference in visual acuity between the right and left eyes of patients and also determined the maximal level of acuity expected in a group of visually normal individuals. Visual acuity was measured in the right and left eyes of 72 subjects aged from 16 to 67 years using Bailey-Lovie type charts. The chart was read until fewer than three letters were read on a line and acuities were based on each letter correct contributing ?0.02 to the overall score. For 12 of these subjects, visual acuity was measured a further four times. Average visual acuities for right and left eyes were ?0.137 and ?0.126logMAR, respectively. The signed visual acuity difference was normally distributed and had a standard deviation of 0.050logMAR. The mean visual acuity difference for the 12 subjects for whom the measures were repeated was 0.033logMAR (SD of the signed visual acuity difference: 0.049logMAR). We conclude that if a patient has a difference in visual acuity between the two eyes of more than 5 letters on a Bailey-Lovie style chart, further investigation is indicated.     

Risk factors for treatment failure of anisometropic amblyopia.

PURPOSE: This study sought to explore factors which might predict the lack of vision improvement following therapy of anisometropic amblyopia. METHODS: We retrospectively reviewed the records of 104 children aged 3 to 8 years who had anisometropic amblyopia with a difference in the refractive power between the two eyes of at least 1 diopter, a difference in corrected visual acuity between the two eyes of at least 3 logMAR units, visual acuity in the amblyopic eye of 20/50 or worse, and no ocular structural abnormalities. Patients were treated with either patching or atropine penalization therapy. Patients with strabismus were included. Treatment failure was defined in two ways: (1) functional failure indicating a final visual acuity in the amblyopic eye worse than 20/40 and (2) relative failure indicating less than three lines of logMAR visual acuity improvement regardless of final vision. RESULTS: Failure risk factors were as follows: age above 6 at the onset of treatment (adjusted odds ratio [OR] (95% confidence limits [CL] = 4.69 [1.55, 14.2]), the presence astigmatism of more than 1.50 diopters in the amblyopic eye (adjusted [OR] (95% CL) = 5.78 [1.27, 26.5]), poor compliance with treatment (adjusted [OR] (95% CL) = 5.47 [1.70, 17.6]), and initial visual acuity in the amblyopic eye of 20/200 or worse (adjusted [OR] (95% CL) = 3.79 [1.28, 11.2]). Strabismus was not found to be a significant risk factor. Neither the type or amount of refractive error nor the difference in the refractive power between the two eyes was a significant risk factor for treatment failure. CONCLUSION: Eyes with poor initial visual acuity, the presence of significant astigmatism, and age over 6 years were less likely to achieve successful outcome. The clinical profile of patients with anisometropic amblyopia may be useful in predicting response to therapy, but compliance with treatment has a major effect on response to therapy.     

Outcome of conventional treatment for adult amblyopia

Purpose

To ascertain whether conventional treatment can improve visual function in adults with amblyopia.

Methods

Sixteen patients aged 21–67 years old were instructed to wear glasses for refractive correction and to patch the non-amblyopic eye for at least 1 h per day. Visual acuity, measured with crowded optotypes for distance and near acuity, was checked every 3 months, and followed for a mean (SD) of 14.1 (4.2) months. Prognostic factors related to the subsequent results, an improvement of 3 or more lines logMAR in distance visual acuity, were evaluated.

Results

Of 16 patients, 5 (31 %) improved 3 or more lines of distance and 5 (31 %) in near acuity. The mean improvement in distance was 2.4 lines logMAR (95 % CI 1.4–3.5) and 2.4 lines logMAR for near acuity (95 % CI 1.5–3.3). Patients aged under 45 years (p = 0.0357) and with severe amblyopia (p = 0.0337), defined as a corrected distance visual acuity of worse than ?0.699 logMAR, were associated with a good response.

Conclusions

Conventional treatment may improve the visual acuity of amblyopic eyes even in adult patients.     

Long term visual outcome in amblyopia treatment

AIM: To evaluate long term visual outcome of treatment for amblyopia. METHODS: In a previous study, 44 children with unilateral amblyopia caused by strabismus or anisometropia were enrolled in a prospective study investigating the results of treatment. All children were regularly examined up to at least 8 years of age and outcome was evaluated. All subjects were invited to a re-examination and in total 26 subjects attended. Two of these were excluded because of insufficient records. The final sample consists of 24 subjects. Mean follow up time was 10.4 (SD 1.9) years. RESULTS: For the amblyopic eyes, 17% deteriorated in visual acuity, 50% were stable, and 33% gained in visual acuity. For the non-amblyopic eyes, 8% lost one line in visual acuity, 38% were stable, and 54% gained in visual acuity. No eye in any subject shifted more than 0.2 logMAR units. The increase in visual acuity for the non-amblyopic eyes was significant, while the increase for the amblyopic eyes was not. All straight eyed anisometropic amblyopes showed a distinct decrease in magnitude of anisometropia. CONCLUSIONS: Visual acuity was essentially stable in the amblyopic eyes 10 years after cessation of treatment in the studied population.     

Impact of amblyopia on vision at age 12 years: findings from a population-based study

AIMS: To report prevalence of amblyopia and long-term impact of its treatment on vision in a population-based sample of 12-year-old Australian children. METHODS: Logarithm of minimum angle of resolution (logMAR) visual acuity (VA) was measured in 2353 children (response rate 75.3%); visual impairment was defined as VA<6/12. Amblyopia was defined using various criteria of best-corrected VA, together with an amblyogenic factor and absence of significant organic pathology. Corroborative historical data on previous diagnosis and treatment were obtained from parental questionnaires. RESULTS: Forty-four children (1.9%) were diagnosed with amblyopia, unilateral in 40 and bilateral in four. Isolated anisometropia was the most frequent cause (41%), followed by strabismus (25%), combined anisometropia and strabismus (23%), and high ametropia (9%). Myopia, hyperopia, and astigmatism were present in 28, 51, and 44% of amblyopic children, respectively, compared to 12, 4, and 9% of non-amblyopic children. Mean best-corrected VA in amblyopic eyes was 44.5 logMAR letters (Snellen equivalent 6/9), range: 11-60 letters. Most children with amblyopia (84%) had been treated. Only 27% were visually impaired in their amblyopic eye. CONCLUSIONS: This report documents a low amblyopia prevalence in a population of 12-year-old Australian children. Amblyopic visual impairment was infrequent in this sample despite absence of mandatory vision screening.     

A pilot study of anisometropic amblyopia improved in adults and children by perceptual learning: an alternative treatment to patching

BACKGROUND: To compare the effects of perceptual learning or patching on improving visual acuity and contrast sensitivity in patients with anisometropic amblyopia. METHODS: Patients with anisometropic amblyopia received either patching or perceptual learning treatment. Corrected amblyopic logMAR visual acuity and contrast sensitivity function were measured at four-weekly intervals until visual acuity stabilized or amblyopia resolved. Improvements in visual acuity, contrast sensitivity and resolution of amblyopia were compared between the two groups. RESULTS: The mean visual acuities of the amblyopic eyes improved by 0.34 logMAR (95% CI: 0.22-0.47 logMAR) with patching and 0.25 logMAR (95% CI: 0.16-0.35 logMAR) with perceptual learning (p=0.125). Resolution of amblyopia was achieved in 10 of 26 patients (38%) in the perceptual learning group and 17 of 27 patients (63%) in the patching group (p=0.809). Amblyopia improved by two or more lines in 20 of 26 (76%) patients in the perceptual learning group and 26 of 27 (96%) patients in the patching group (p=0.0001). The mean time for patching was 37.3 weeks (522.2 h) and the average number of training sessions in the perceptual learning group was 48 (29.5 h) (p=0.0001). CONCLUSIONS: Visual acuity can be improved with perceptual learning and patching in older children and adult patients with anisometropic amblyopia. The improvements in visual acuity achieved with patching were one line better than those achieved with perceptual learning. Perceptual learning might provide an alternative treatment in patients with anisometropic amblyopia.     

Discrimination of paediatric acuity test optotypes by 6-year-old children

Purpose

To compare the discrimination performance of 6-year-old children for optotypes from six paediatric visual acuity tests and to fit Luce's Biased Choice Model to the data to estimate the relative similarities and bias for each optotype.

Methods

Full data sets were collected from 20 typically developing 6-year-olds who had passed a vision screening. They were presented with single optotypes labelled 6/12 at a distance of 9 m and were asked to identify the optotype using a matching task containing all optotypes from the relevant test. The data were combined to form a confusion matrix for each test and a biased choice model was fitted to the data.

Results

Median correct performance varied from 40% to 100% across optotypes, with the HOTV test having the highest values. Estimates of the similarity of each pair of optotypes indicated equal values for all pairs in the Landolt C, HOTV, Lea numbers and Tumbling E tests. The values differed for the picture tests, that is Lea Symbols and Allen figures. The estimates of bias for each individual optotype also indicated different values with the picture tests.

Conclusions

Previous studies of the threshold acuity of young children and adults have indicated differences in acuity estimates across paediatric tests. A recognition acuity task typically requires resolving the difference information between optotypes. The performance of the 6-year-olds here reveals variance in similarity and bias values for picture tests, particularly for the Allen figures when compared with the Lea Symbols. Ideally, this analysis should be performed when designing new tests, and these results motivate progression from the use of current picture tests to well calibrated letter or number tests at the earliest possible age.     

Normal visual acuity in 17--18 year olds

PURPOSE: The aim of this work was to establish visual acuity norms in 17-18-year-olds. METHODS: In a previous, population-based study carried out in 1998, a total of 1046 12-13-year-old children were examined with a full eye examination. In 2003, 25% (n=262) of these children were randomly selected and invited to a re-examination; 147 subjects agreed to participate and 116 attended. The examined group did not significantly differ from the original sample in terms of the prevalence of ocular and visual disorders. Best corrected monocular visual acuity (VA) was assessed with the revised 2000 ETDRS logMAR chart. RESULTS: Mean best corrected VA was -0.10 logMAR across the examined group. There was no significant difference between right and left eyes. By excluding nine subjects who had significant ametropia and/or ocular or visual pathology, mean VA increased to -0.12 logMAR (SD 0.07). The mean interocular difference in VA among normal subjects was 0.04 logMAR. CONCLUSIONS: Visual acuity in teenagers is significantly better than 0.0 logMAR and the interocular difference is low in healthy eyes.     

Visual acuity testability and comparability in Australian preschool children: the Sydney Paediatric Eye Disease Study

Purpose

To establish standardised protocols for vision screening, testability and comparability of three different vision tests were examined in a population-based, cross-sectional sample of preschool children (Sydney Paediatric Eye Disease Study).

Methods

Measurement of presenting monocular distance visual acuity (VA) using the Amblyopia Treatment Study (ATS) HOTV protocol, was attempted by all (1774) children aged≥24 months. In addition, in children aged≥60 months (576), VA was also tested using the logMAR retro-illuminated HOTV or Early Treatment Diabetic Retinopathy Study (ETDRS) linear charts (CSV 1000). Children able to have both eyes tested monocularly were considered.

Results

Testability significantly increased with age for all VA tests. The ATS HOTV with an overall testability of 80% (females: 82%, males: 78%) was the most testable of the VA tests (P<0.0001). In children aged <3 years testability was low (≤47%) rising to≥80% in children aged≥3. In children≥60 months, testability was higher for the HOTV (94%) than the ETDRS (59%) chart. In those that did two VA tests, mean difference of the ATS HOTV compared with the HOTV(CSV) was −0.1, and compared with ETDRS was −0.12 (P<0.0001).

Conclusions

Children aged <3 years had poor VA testability, whereas those 3 years and above were highly testable using the ATS HOTV. The HOTV (CSV) retro-illuminated test was appropriate for children aged >5 years, and may be possible in younger children with early educational exposure. When comparing VA measures using these tests, the higher VA attained using the ATS HOTV, needs to be taken into account.     

部分遮盖法治疗大龄儿童弱视的疗效分析

目的 比较每天全遮盖健眼不同时间治疗7～12岁单眼弱视儿童的疗效.方法 对84例诊断为屈光参差性、斜视性或混合性单眼弱视的7～12岁儿童采用部分时间全遮盖健眼,随机分为每天遮盖2 h组、4 h组和6 h组.4周复查1次,记录视力及对应的logMAR值.连续随访6个月.结果每天遮盖2、4和6 h组,治疗6个月后视力提高分别为:0.17±0.09、0.25±0.12及0.30±0.13(LogMAR值),三组间差异有统计学意义(P<0.01).遮盖4 h和6 h组间视力提高,差异无统计学意义(P>0.05),但与2 h组间差异均有统计学意义(P<0.01).各类型弱视视力提高差异无统计学意义(P>0.05).结论 对于7～12岁单眼弱视儿童,每天全遮盖健眼2～6 h均能改善视力,但遮盖4 h及6 h较2 h能更有效地提高视力.