Quantification of visual acuity:

Abstract

Purpose: This study aims to compare the results of the Finger Count Test (FCT) for “Counting fingers” (CF) and “Hand movement” (HM) with the visual acuity (VA) obtained from the Berkeley Rudimentary Vision Test (BRVT) in low vision patients with different pathologies. Methods: Uncorrected visual acuity was estimated using BRVT and using the corresponding CF or HM in 38 low vision patients (VA range between 1.40 and 3.50 logMAR). Detailed ocular pathologies were recorded for each patient. Patients were categorized into two groups: one with severe visual field defects (constrictions of the central visual field or central scotomas) due to any cause and a general group which included all other ocular pathologies. Results: The mean age was 67 years, with an age range from 26 to 92 years. The General group revealed a median VA of 2.00 logMAR for CF and 2.60 logMAR for HM (p < 0.001). This study showed a large variation of VA from BRVT in the Visual field group and considerable overlap with the VA results for CF and HM; with a median VA of 2.10 logMAR for CF and 2.30 logMAR for HM (p = 0.824). Conclusion: The VA found in this study for CF confirmed values from earlier studies, while VA for HM was found to be slightly worse. These findings allow a translation of older VA data of CF and HM to logMAR for proper statistical analysis. Patients with central visual field defects showed a large variation of measured VA with BRVT.