Sensitivity and specificity of visual acuity screening for refractive errors in school children.

PURPOSE: To examine the optimal cutoff point for the use of the visual acuity test to screen for refractive errors in schoolchildren. METHODS: In a sample of schoolchildren between 7 and 9 years old, visual acuity testing was performed using modified ETDRS charts monocularly without optical aids by trained personnel. Cycloplegic autorefraction was performed in each eye. The screening efficacy of using various cutoff points for referring children for further optometric/ ophthalmic assessment was studied. Myopia was defined as a spherical equivalent of at least -0.5 D, hyperopia a spherical equivalent of at least +2.0 D, and astigmatism a cylinder of at least -1.0 D in at least one eye. The sensitivity, specificity, and predictive values were calculated using each patient as a case; a receiver operator curve was plotted. RESULTS: A total of 1,028 children were tested. A satisfactory sensitivity/specificity profile was obtained using a referral criterion of visual acuity worse than or equal to 0.28 logarithm of the minimum angle of resolution in at least one eye. In this scenario, the sensitivity and specificity of this screening test were 72% (95% confidence interval [CI], 68 to 76) and 97% (95%CI, 95 to 98), respectively. The positive and negative predictive values were 96% (95%CI, 93 to 98) and 78% (95%CI, 75 to 82), respectively. CONCLUSIONS: The modified ETDRS visual acuity chart can be used to predict refractive errors in schoolchildren in Singapore in a sensitive and specific manner using a referral criterion of worse than or equal to 0.28 logarithm of the minimum angle of resolution.     

The effect of optical defocus on the test-retest variability of visual acuity measurements

PURPOSE: To determine the effect of optical defocus on the test-retest variability (TRV) of visual acuity measurements in normal subjects. METHODS: Normal subjects underwent repeated visual acuity measurement with optical defocus of 0, 0.50, and 1.00 D. All measurements were taken using the Early Treatment Diabetic Retinopathy Study (ETDRS) version of the Bailey-Lovie logMAR chart. TRV was quantified in terms of its 95% range, both empirically and using the approach of Bland and Altman. RESULTS: According to the Bland and Altman approach, the estimated 95% TRV ranges were +/-0.11 logarithm of the minimum angle of resolution (logMAR) for 0-D defocus, +/-0.18 logMAR for 0.50-D defocus, and +/-0.25 logMAR for 1.00-D defocus. CONCLUSIONS: Optical defocus has a considerable effect on the TRV of visual acuity measurements. These findings have important implications for both clinical practice and clinical research. Uncorrected refractive errors as small as 0.50 D may compromise the detection of visual change in individuals, and contribute to unnecessarily large sample sizes in clinical trials in which visual acuity is used as a primary outcome measure.     

Evaluating a new logMAR chart designed to improve visual acuity assessment in population-based surveys

AIMS: This study aimed to evaluate a new chart designed to improve the collection of visual acuity data in population-based surveys. The Reduced logMAR E chart (RLME) employs three letters per line, 'tumbling E' optotypes, and conforms to accepted contemporary design principles. METHODS: The performance of the chart was assessed within a population-based glaucoma survey in Thailand. Performance indices were test-retest variability (TRV) and agreement with acuity data measured using the ETDRS logMAR chart which acted as the 'gold standard'. RESULTS: The 95% confidence limits for TRV of RLME acuity data were +/-0.15 logMAR. This figure is consistent with published data on the TRV of acuities measured using five-letter-per-line logMAR charts. The mean difference between RLME and ETDRS acuity data was 0.00 logMAR (95% confidence intervals of +/-0.05 logMAR) indicating that RLME acuities agreed well with those of the ETDRS chart. The chart and its method of use was readily accepted by the local ancillary staff who required only minimal training before acuity measurement could be delegated to them. CONCLUSIONS: The study demonstrated that the RLME chart is capable of accurate and repeatable acuity measurements. Certain aspects of the design of the RLME chart may be particularly pertinent to the measurement of vision in population-based surveys.     

Reproducibility of visual acuity assessment in normal and low visual acuity

PURPOSE: To assess the reproducibility of measurements of visual acuity in both the upper and lower range of visual acuity. MATERIALS AND METHODS: The retroilluminated ETDRS 1 and ETDRS 2 charts (Precision Vision) were used for measurement of visual acuity. Both charts use the same letters. The sequence of the charts followed a pseudorandomized protocol. The examination distance was 4.0 m. When the visual acuity was below 0.16 or 0.03, then the examination distance was reduced to 1 m or 0.4 m, respectively, using an appropriate near correction. Visual acuity measurements obtained during the same session with both charts were compared. A total of 100 patients (age 8-90 years; median 60.5) with various eye disorders, including 39 with amblyopia due to strabismus, were tested in addition to 13 healthy volunteers (age 18-33 years; median 24). At least 3 out of 5 optotypes per line had to be correctly identified to pass this line. Wrong answers were monitored. The interpolated logMAR score was calculated. In the patients, the eye with the lower visual acuity was assessed, and for the healthy subjects the right eye. Differences between ETDRS 1 and ETDRS 2-acuity were compared. RESULTS: The mean logMAR values for ETDRS 1 and ETDRS 2 were -0.17 and -0.14 in the healthy eyes and 0.55 and 0.57 in the entire group. The absolute difference between ETDRS 1 and ETDRS 2 was (mean +/- standard deviation) 0.051 +/- 0.04 for the healthy eyes and 0.063 +/- 0.05 in the entire group. In the acuity range below 0.1 (logMAR > 1.0), the absolute difference (mean +/- standard deviation) between ETDRS 1 and ETDRS 2 of 0.072 +/- 0.04 did not significantly exceed the mean absolute difference in healthy eyes (p = 0.17). Regression analysis (|ETDRS 1 - ETDRS 2| vs. ETDRS 1) showed a slight increase of the difference between the two values with lower visual acuity (p = 0.0505; r = 0.18). DISCUSSION: Assuming correct measurement, the reproducibilty of visual acuity measurements in the lower acuity range is not significantly worse than in normals.     

Automated determination of distance visual acuity: towards teleophthalmology services

Purpose: The aim of this study was to evaluate the visual acuity scores of a computer‐based visual function testing (CVFT) system. The automated chart uses logMAR notation (logarithm of the minimum angle of resolution) and randomised tilting E as optotype. The test was conducted using a laptop computer. Methods: This prospective, clinic‐based, test validation study was based on a model of repeatability in two observations. The right eyes of a total of 104 participants were randomly tested with both CVFT and the manual, gold standard Early Treatment of Diabetic Retinopathy Study (ETDRS) chart. Results: The mean difference between CVFT and ETDRS was ‐0.01 ± 0.11 (SD) logMAR units. The Spearman Rank correlation coefficient (r) between the absolute difference and the average was 0.35. The average time for testing one eye was 54.7 ± 11.89 seconds. The mean difference between two consecutive, repeated CVFT tests in the same eye was 0.02 ± 0.07 logMAR units (paired t‐test p = 0.046). Conclusions: A novel, automated visual acuity testing application is reported. This automated system should be a useful tool for mass screening of visual impairment in rural and remote regions with its ease of use and shorter testing time.     

Visual acuity measured via the Freiburg visual acuity test (FVT), Bailey Lovie chart and Landolt Ring chart

INTRODUCTION: If different ways for correcting refractive errors of the human eye have to be compared, accurate and reproducible measurement procedures are necessary. METHODS: Binocular visual acuity of 130 students without pathologies was measured with the Freiburg Visual Acuity Test, the Bailey-Lovie chart and a Landolt ring chart (4 orientations). The reproducibility of the FVT was determined by repeated measurements. RESULTS: The average visual acuity was 1.93 +/- 0.03 (= 20/10.4) with the FVT, 1.82 +/- 0.03 (= 20/11) with the Landolt ring chart, and 1.48 +/- 0.02 (= 20/13.5) with the Bailey-Lovie chart. 50 % of all repeated measurements with the FVT were within an interval of +/- 0.035 logMAR from the mean value. 95 % were within +/- 0.1 logMAR. Results of earlier studies are discussed. CONCLUSION: On average, visual acuity values found with the Freiburg Visual Acuity Test were slightly larger as compared to the Landolt ring chart (difference = 0.025 logMAR). Taking the maximal difference of 0.05 logMAR tolerated by the international standard DIN EN ISO 8597 into account, both tests are equivalent. The results found with the Bailey-Lovie chart were substantially lower as compared to the Landolt ring chart (difference = 0.09 logMAR). The Freiburg Visual Acuity Test has a high reproducibility and measures visual acuity on a continuous scale that is not limited to the traditional visual acuity steps. Thus, it can be recommended as a reference procedure for comparative visual acuity studies.     

Repeatability of ETDRS visual acuity in children

PURPOSE: To evaluate repeatability of the best corrected log minimum angle of resolution (MAR) Early-Treatment Diabetic Retinopathy Study (ETDRS) acuity in a group of 6- to 11-year old children with myopia. METHODS: Best corrected monocular visual acuity (VA) of a subset of children (n = 86) enrolled in the Correction of Myopia Evaluation Trial (COMET; mean spherical equivalent refractive error -2.35 D with no more than 1.25 D astigmatism) was measured at baseline and 1 month later with ETDRS logMAR charts. Children started with logMAR 0.4 (6/15 or 20/50) and read each letter on all subsequent lines until they missed all letters in 1 line. RESULTS: At baseline, the mean best corrected logMAR VA was 0.003 +/- 0.076 (6/6 or 20/20 +/- 3.8 letters) in the right eye and 0.008 +/- 0.059 (6/6 or 20/20 +/- 2.95 letters) in the left eye. The signed difference between VA measured at baseline and that measured at 1 month was not significantly different from zero in either eye. Repeatability was not associated with age, but a small, statistically significant association with gender was detected in the left eye, with boys approximately 2 letters more variable than girls. The kappa statistic (agreement within 1 line) was good to excellent. CONCLUSIONS: Based on the 95% limits of agreement, the criterion for a statistically significant change in VA is no more than +/-0.15 logMAR (or +/-8 letters). This value is similar to those reported for adults and indicates that logMAR VA provides a repeatable measure of acuity in children.     

Reading acuity in children: evaluation and reliability using MNREAD charts

PURPOSE: To study reading acuity in children and assess the reliability of its measurement using the Italian version of the MNREAD reading chart. METHODS: One hundred sixteen children from grades 3 to 8 with normal near vision were tested at a pediatric eye care institution in northeastern Italy. Visual acuity was evaluated with Early Treatment Diabetic Retinopathy Study (ETDRS) charts and reading acuity with MNREAD charts. Examination with charts 1 and 2 by the same examiner in the same visit were used as test-retest measurements. RESULTS: Mean improvement of performance from grades 3 to 8 was approximately 1 line for ETDRS acuity and 1.5 sentences for reading acuity and critical print size. Mean maximum reading speed increased from 96 to 167 words/minute. Regression analysis showed that a stable reading speed was obtained throughout sentences of decreasing size up to the critical print size. Measurement error, expressed as 95% limits of agreement, was +/- 0.136 logarithm of the minimum angle of resolution (logMAR) and +/- 0.142 logMAR for ETDRS acuity and reading acuity, respectively. Critical print size had the lowest reliability (+/- 0.193 logMAR). Maximum reading speed limits of agreement were +/- 0.077 logarithm of words per minute (logWPM), or a 19% change in words per minute. There were no detectable effects of grade and refractive error on measurement errors. CONCLUSIONS: In children, MNREAD charts provide measurements of reading acuity as reliable as ETDRS chart measurements of distance acuity on a logMAR scale. They also provide highly reliable measurements of the maximum reading speed across all grades, independent of its noticeable increase.     

The development of a "reduced logMAR" visual acuity chart for use in routine clinical practice

BACKGROUND/AIMS: The advantages of logMAR acuity data over the Snellen fraction are well known, and yet existing logMAR charts have not been adopted into routine ophthalmic clinical use. As this may be due in part to the time required for a logMAR measurement, this study was performed to determine whether an abbreviated logMAR chart design could combine the advantages of existing charts with a clinically acceptable measurement time. METHODS: The test-retest variability, agreement (with the gold standard), and time taken for "single letter" (interpolated) acuity measurements taken using three prototype "reduced logMAR" (RLM) charts and the Snellen chart were compared with those of the ETDRS chart which acted as the gold standard. The Snellen chart was also scored with the more familiar "line assignment" method. The subjects undergoing these measurements were drawn from a typical clinical outpatient population exhibiting a range of acuities. RESULTS: The RLM A prototype chart achieved a test-retest variability of +/-0.24 logMAR compared with +/-0.18 for the ETDRS chart. Test-retest variability for the Snellen chart was +/-0.24 logMAR using clinically prohibitive "single letter" scoring increasing to +/-0.33 with the more usual "line assignment" method. All charts produced acuity data which agreed well with those of the ETDRS chart. "Single letter" acuity measurements using the prototype RLM charts were completed in approximately half the time of those taken using the ETDRS and Snellen charts. The duration of a Snellen "line assignment" measurement was not evaluated. CONCLUSION: The RLM A chart offers an acceptable level of test-retest variability when compared with the gold standard ETDRS chart, while reducing the measurement time by half. Also, by allowing a faster, less variable acuity measurement than the Snellen chart, the RLM A chart can bring the benefits of logMAR acuity to routine clinical practice.     

Efficacy of neural vision therapy to enhance contrast sensitivity function and visual acuity in low myopia

PURPOSE: To evaluate the efficacy and safety of neural vision enhancement technology (NVC, NeuroVision, Inc.) to improve visual acuity and contrast sensitivity function in eyes with low myopia. SETTING: Singapore Eye Research Institute, Singapore, Singapore. METHODS: This noncomparative interventional case series comprised 20 Asian adults between 19 and 53 years of age with low myopia (cycloplegic spherical equivalence [SE] from -0.5 diopter [D] to -1.5 D in the worst eye; astigmatism not exceeding 0.5 D in either eye; uncorrected visual acuity [UCVA] < or =0.7 logMAR) who had NVC treatment. The main outcome measures were distance UCVA, uncorrected contrast sensitivity, refraction, accommodative amplitude, and safety. RESULTS: All eyes had improvement in UCVA and contrast sensitivity. After treatment, the mean distance UCVA improved by a mean of 2.1 lines on the Early Treatment Diabetic Retinopathy Study logMAR chart. The mean contrast sensitivity improved over a range of spatial frequencies on sine-wave contrast sensitivity chart testing (1.5 to 18 cycles per degree). Follow-up data up to 12 months posttreatment showed that the gains were retained. Treatment did not alter refraction (mean spherical equivalent) or accommodative amplitudes. No adverse effects were reported. CONCLUSION: Preliminary evidence suggests NVC treatment is safe and improves UCVA and uncorrected contrast sensitivity in adult patients with low myopia.     

The dependency of logMAR visual acuity measurements on chart design and scoring rule.

BACKGROUND: Visual acuity, increasingly measured using a logarithm of the minimum angle of resolution (logMAR) chart, is the "gold standard" by which the outcomes of the vast majority of clinical trials or interventions are judged. To allow comparison of results across studies, it is important that different charts provide equivalent results. METHODS: In a first experiment, we compared corrected visual acuity measurements from four different logMAR charts (Bailey-Lovie, ETDRS, Regan, and Waterloo). In a second experiment we compared unaided visual acuity scored using a psychometric function with the more clinical by-letter scoring. RESULTS: Experiment 1 showed significantly better visual acuity using the Regan chart compared with the other three charts, and further investigation suggested that this could be due to the font type used. Repeatability data from experiment 2 indicated that no extra repeatability was gained when using psychometric methods compared with the far simpler and quicker by-letter scoring. CONCLUSIONS: When comparing findings between studies, the type of chart and the scoring method used may have a significant effect on the results obtained and should therefore be taken into consideration. Also, the additional time and effort demanded for determining a psychometric function for single readings of the Regan visual acuity chart is not rewarded with improved repeatability.     

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.     

Association between intensity of posterior capsule opacification and visual acuity

PURPOSE: To investigate the correlation between the change in visual acuity and the difference in objective posterior capsule opacification (PCO) scores before and after neodymium:YAG (Nd:YAG) laser capsulotomy. SETTING: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. METHODS: Forty pseudophakic eyes of 35 patients with PCO of varying intensity were examined before and after Nd:YAG laser capsulotomy. Visual acuity was determined using the Early Treatment Diabetic Retinopathy Study (ETDRS) chart at 4 m and the Holladay reading chart at 40 cm. The pupil diameter under reading conditions was measured each time. Digital retroillumination images of the posterior capsule were taken, and the corresponding area inside the pupil was evaluated using the Automated Quantification of After-Cataract (AQUA) automated PCO analysis program. The change in visual acuity and difference between PCO scores before and after Nd:YAG laser capsulotomy were calculated for all eyes. RESULTS: The mean AQUA score (scale 0 to 10) was 3.56 before and 0.13 after Nd:YAG laser capsulotomy. The mean ETDRS visual acuity score (logMAR scale) was 0.28 and -0.07, respectively. The correlation coefficient between the differences in PCO score and distance visual acuity was 0.61 and near visual acuity, 0.62. CONCLUSIONS: The objective PCO score obtained by an automated image-analysis program correlates well with the PCO-induced decrease in visual acuity when the central area (inside the pupillary aperture) of the posterior lens capsule was evaluated. Objective PCO assessment by automated image-analysis systems is, therefore, a valuable and clinically relevant method for clinical studies of the development and prevention of PCO.     

Improving on ETDRS acuities: design and results for a computerised thresholding device

AIMS: All visual acuity data are subject to test-retest variability (TRV). This measurement error obscures true clinical change and reduces the statistical power of clinical trials using acuity as a primary outcome measure. This study was designed to assess whether a computerised system can reduce TRV by taking repeated acuity measurements and averaging them. A computerised system (PC-test) was developed for this purpose and compared in terms of TRV with the current Gold Standard ETDRS logMAR chart. METHODS: A total of 19 subjects with a mean acuity of +0.16 logMAR (range +0.49 to -0.10 logMAR) were recruited. The performance of two computerised tests (one averaging 10 repeats and one five) was compared with that of the ETDRS logMAR chart in terms of TRV and agreement of acuity data.Results The 10 and five repeat computerised tests (PC-tests) produced a TRV of +/-0.11 and +/-0.10 logMAR, respectively, compared with +/-0.18 logMAR for the ETDRS chart. No significant bias was observed between PC-test and ETDRS acuities. CONCLUSIONS: A computerised system that takes repeated acuity measurements and averages them is subject to less TRV than a single ETDRS acuity measurement. A reduced TRV of visual acuity data allows earlier detection of true clinical change in individual patients. It also allows smaller differences between groups to be detected in clinical trials for a given degree of statistical confidence and power.     

新型对数视力表与“C”形对数视力表的一致性与稳定性分析

目的评价新型对数视力表与具有8个方向视标选项的“C”形对数视力表之间的一致性与稳定性。方法 横断面研究。对48例应届高中毕业生分别进行新型对数视力表与“C”形对数视力表的视力检查,采用组内相关系数（ICC）和Cronbach′s Alpha系数分析视力测量结果的重复性,采用Bland-Altman分析一致性。结果 “C”形对数视力表Cronbach′s Alpha系数在0.8以上,ICC接近0.9,新型对数视力表Cronbach′s Alpha系数接近0.8,ICC＞0.75,均显示较好的重测稳定性。2种视力表第1次和第2次视力测量均具有较好的一致性,95％一致性界限分别为（0.173,-0.133）logMAR和（0.198,-0.116）logMAR。结论 新型对数视力表检查结果稳定,和“C”形对数视力表一致性较好。     

A computerized resolution visual acuity test in preschool and school age children

AIM: To study if one of the two molecules could lead to a lower number of follow up visits and intra-vitreous injection (IVI) with the same efficacy. METHODS: ELU (or “elected” in French) study is a retrospective study conducted in real life in patients presenting suboptimal response after ranibizumab IVI (phase 1) and secondary switched to aflibercept (phase 2). The number of follow up visits and IVI were compared in both phases. Visual acuity (VA) evolution and “switching” reasons were secondary analyzed. RESULTS: We retrospectively included data of 33 patients (38 eyes) with age-related macular degeneration (AMD; mean age: 77±7.7y). The number of monthly follow up visits [Median (Q1; Q3)]: was significantly lower with aflibercept (phase 2), respectively 1.0 (0.81; 1.49) visits in phase 1, versus 0.79 (0.67; 0.86) visits in phase 2. The median number of monthly IVI also significantly decreased in phase 2, respectively 0.67 (0.55; 0.90) IVI in phase 1, versus 0.55 (0.45; 0.67) IVI in phase 2. The mean VA evolution (VA final-VA initial) was similar in both phases, (P>0.05). Whatever the reason for “switching” (loss of efficacy, tachyphylaxis, tolerance problems), there was no incidence on VA evolution over the time. CONCLUSION: Our results show that switching from ranibizumab to aflibercept in “suboptimal” patients, significantly reduced the number of follow up visits and IVI, with a comparable efficacy. This decrease in visit number could improve patients’ quality of life and reduce surgical risk by reducing the number of injections.     

The effect of LASIK on best-corrected high-and low-contrast visual acuity.

PURPOSE: To evaluate the effects of laser in situ keratomileusis (LASIK) and LASIK with concurrent astigmatic keratectomy (LASIK/AK) on high- and low-contrast visual acuity. METHODS: The setting was a university refractive surgery practice. Patients were recruited from those undergoing LASIK or LASIK/AK for myopia (>1.00 D spherical equivalent) between May 1996 and August 1997. All subjects were at least 21 years of age. Testing occurred preoperatively and 3 and 6 months after LASIK. Main outcome measures were best spectacle-corrected, high- and low-contrast visual acuity. RESULTS: For all subjects, there was a significant effect of surgery on nondilated low-contrast visual acuity (repeated measures two-way analysis of variance, p < 0.0001). Tukey's posthoc analysis showed that preoperative low-contrast visual acuity scores were significantly different from 3-month [0.08 logarithm of the minimum angle of resolution (logMAR)] and 6-month (0.11 logMAR) scores for patients undergoing LASIK and LASIK/AK. Under dilated conditions, there was a significant effect of surgery for high- and low-contrast visual acuity (analysis of variance, p < 0.0001 for both). Only changes in low-contrast visual acuity were clinically meaningful [LASIK, visual acuity reduction of 0.1 logMAR (1 line); LASIK/AK, visual acuity reduction of 0.15 logMAR (1.5 lines)]. When considering high and low myopes separately (LASIK only), the level of myopia had a significant effect on the visual acuity after surgery (analysis of variance, p = 0.01). Preoperative, dilated, low-contrast visual acuity scores for high myopes were significantly different from 3-month (0.14 logMAR) and 6-month (0.13 logMAR) scores. No differences were noted for low myopes. CONCLUSIONS: Clinically meaningful postoperative changes in low-contrast visual acuity were noted in patients undergoing LASIK and LASIK/AK under natural and dilated conditions. Postoperative, dilated, low-contrast visual acuity scores were significantly worse than preoperative scores for high myopes, but remained unchanged for low myopes.     

Comparison of the amblyopia treatment study HOTV and electronic-early treatment of diabetic retinopathy study visual acuity protocols in children aged 5 to 12 years

PURPOSE: To compare two established visual acuity protocols: the Amblyopia Treatment Study HOTV (ATS HOTV) visual acuity protocol and the Electronic-Early Treatment of Diabetic Retinopathy Study (E-ETDRS) protocol, in children aged 5 to 12 years. DESIGN: Prospective cohort study. METHODS: Crowded HOTV optotypes and crowded ETDRS optotypes were presented to 236 consecutive children aged 5 to 12 years using an electronic visual acuity tester (Palm handheld, personal computer, and monitor). Twenty-three percent of the children were classified as amblyopic, 35% as having uncorrected refractive error, 36% as normal, and 6% as other. Visual acuity test results were converted to logarithm of minimal angle of resolution (logMAR) units for analysis. RESULTS: In developmentally normal children (n = 230), testability was 100% for HOTV in 5- to 12-year-olds and 100% for E-ETDRS in 7- to 12-year-olds. The E-ETDRS testing could be completed in 52% of 5-year-olds and in 87% of 6-year-olds. Visual acuity performance was better when measured by HOTV compared with E-ETDRS (median difference 0.06 logMAR [three letters on a chart with five letters/line], P =.0001), and the difference was found in normal eyes, eyes with refractive error, and amblyopic eyes. CONCLUSIONS: The ATS HOTV protocol yields slightly better visual acuity performance compared with E-ETDRS in 5- to 12-year-olds, but on average by less than a logMAR level. This systematic difference is important when a physician changes testing modality as a child matures and should be considered when interpreting the results of recent and ongoing clinical trials in amblyopia.     

ZyQv视力表在角膜屈光手术中的应用分析

目的 介绍一种新型的不同对比度视力表(ZyQv视力表,美国Baush&Lomb公司)及其临床应用.方法 以准分子激光原位角膜磨镶术治疗近视为例,使用ZyQv视力表测量54例近视患者手术前后不同对比度和不同照明环境下的视力,并与标准对数视力表的测量结果进行对比.结果 标准对数视力表测得的术前BCVA和术后不同时间点UCVA之间均无显著差异;使用ZyQv视力表发现:术后1周时,三组患者明暗环境中90%对比度视力均有显著下降,术后1月时均恢复至术前水平;三组患者明暗环境中10%对比度视力均于术后1周显著下降,其中低度近视组于术后1月恢复至术前水平,而中度和高度近视组在术后3月时仍低于术前水平(明环境中10%对比度视力除外).结论 ZyQv视力表操作便捷,在角膜屈光手术中可用于完善术前检查,综合评价术后视觉质量,动态观察术后视力恢复,协助临床实验和相关研究.     

A new Gujarati language logMAR visual acuity chart: Development and validation

Aims:

Gujarati is the main spoken language of a large proportion of the population of India. The aim of this study was to develop and validate a new Minimum Angle of Resolution (logMAR) visual acuity chart in the Gujarati language.

Materials and Methods:

A new Gujarati visual acuity chart was designed to logMAR specifications using Gujarati optotypes experimentally selected to have similar relative letter legibility under spherical and cylindrical defocus. The chart validation study was carried out using 153 adult subjects in a large clinical setting in India. Subjects who were literate in English and Gujarati participated in the study. Visual acuity was measured with the new Gujarati logMAR chart and a modified Early Treatment of Diabetic Retinopathy Study-(m-ETDRS) logMAR chart. The method of presentation was randomized between the charts. Repeat visual acuity was measured on a subsequent day with a second version of the Gujarati logMAR chart.

Results:

The Gujarati chart correlated highly with the m-ETDRS logMAR chart (r² = 0.974). The mean visual acuity difference (Gujarati – m-ETDRS logMAR) was equal to three letters (–0.06 logMAR). The Gujarati logMAR chart also proved to be highly repeatable (r² = 0.994, test-retest) with 95% CI of ± 0.04 logMAR.

Conclusions:

The new Gujarati logMAR visual acuity chart provides a valid and repeatable tool for the measurement of visual acuity in native Gujarati language speakers.