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M. Mocan, M. Najera-Covarrubias, K.W. Wright; Comparison of the Accuracy of the Wright Figures© and Allen Optotypes to Snellen Letters in the Evaluation of Visual Acuity Levels in Pediatric Amblyopic Subjects . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4798.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To compare and correlate the best-corrected visual acuity measurements of amblyopic subjects and their logMAR values, obtained through two separate, commercially-available, visual recognition cards designed for preverbal and illiterate children, to those obtained by the Snellen letters (gold-standard). Methods: Thirteen consecutive amblyopic pediatric patients were prospectively studied: 6 anisometropic, 2 strabismic, 1 meridional, 2 combined anisometropic and strabismic, 1 combined ametropic and strabismic, and 1 deprivation. Best-corrected visual acuity was tested using a standardized protocol with the Wright figures©, Allen optotypes and the Snellen letters. The optotypes were appropriately presented for each chart. The results were converted to their logarithmic equivalents of minimum angle of resolution and evaluated for statistical intergroup differences using the repeated measures of analysis of variance and for correlation using the Pearson correlation coefficient test. Results: The mean age of the subjects studied was 9.15±2.27 y (range: 5-14). The mean logMAR values for the Wright figures©, Allen optotypes and the Snellen letters were -0.34±0.20, -0.18±0.25 and -0.36±0.24 respectively. The difference in visual acuities obtained by the Wright figures© and the Snellen letters was statistically insignificant (p=0.370). However, there was a significant difference between the values obtained by the Allen optotypes and the Snellen letters (p=0.001) and the values obtained by the Wright figures© and the Allen optotypes (p=0.002). Of the 13 patients identified with amblyopia by Snellen letter testing, five (38%) had apparently normal visual acuity levels when tested with the Allen optotypes. All of the amblyopic patients were correctly identified as amblyopic with the Wright figures©. The Wright figures© correlated to a higher degree (r=0.957, p<0.001) than Allen optotypes (r=0.823, p<0.001) when compared to Snellen letters. Conclusions: Visual acuity obtained by Allen optotypes and Snellen letters was dissimilar. Allen optotypes tend to underdiagnose amblyopia and may lead to erroneous clinical decisions regarding the treatment of the amblyopic eye. Wright figures©, designed primarily to evaluate the vision in the preverbal pediatric population, correlate to a high degree with Snellen letters and have a higher rate of correctly identifying amblyopia than Allen optotypes in pediatric patients.
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