A chart for low visual acuities: Experience in a center for low vision and rehabilitation

Introduction: Commonly used visual test charts can be used to measure 1-m minimal visual acuities (VA) of 20/1000 (Snellen chart) and 1/40 (Early Treatment of Diabetic Retinopathy Study [ETDRS] charts). Methods: In a prospective study, we considered all patients who visited in a Low Vision and Rehabilitation Center between September 2007 and January 2009. Distance best corrected VA (DBCVA) was evaluated with the ETDRS LogMAR 4-m chart and a customized ETDRS 1-m chart, while near best corrected VA (NBCVA) was measured with the LogMAR conversion of the Parinaud 30-cm chart. Results: One hundred and sixteen eyes (58 patients; 34 males and 24 females with a mean age of 69 ± 19.4 [19-94] years) were included in the study. Mean DBCVA was 0.97 ± 0.58 LogMAR, mean NBCVA was 0.28 ± 0.2 LogMAR. In 52 eyes (44.8%), distance VA was less than 1/20 (DBCVA 1.86 ± 0.5 LogMAR, NBCVA 0.08 ± 0.05 LogMAR). Among the 58 best seeing eyes, DBCVA was 0.87 ± 0.6 LogMAR, while NBCVA was 0.34 ± 0.2 LogMAR. In 18 of 58 cases (31%), distance VA was less than 1/20 (DBCVA 1.86 ± 0.59 and NBCVA 1.51 ± 0.42). Conclusion: In a center for low vision and visual rehabilitation, a customized chart was necessary in 31% of cases for evaluation of VA. A fine measurement of low VA is useful for baseline assessment and for evaluation of changes during rehabilitation. © 2010 Elsevier Masson SAS. All rights reserved.