Correlation Between Near Visual Performance Tests to Sustained Reading Performance

Abstract

Purpose:: To evaluate tests of visual performance and validate use of a letter counting task as a surrogate measure of sustained reading performance.

Methods:: 10 presbyopes and 10 non-presbyopes performed tasks of visual performance using their habitual correction that provided a best-corrected visual acuity of 20/20 or better in each eye. Monocular visual acuity (ETDRS chart) and letter contrast sensitivity were measured at distance 4m (Rabin chart), intermediate 65 cm, and near 40 cm (MARS chart). Monocular reading speed was evaluated using the Radner reading chart at near, and the letter counting task at intermediate (computer) and near (print). Sustained reading speed was measured, monocularly at intermediate (computer) and near (print), using texts that contained approximately 2500 words. Following the sustained reading task, subjects answered 5 multiple choice questions that served to ensure attention. The Student t-test was performed to test differences in visual performance between presbyopes and non-presbyopes and right vs. left eyes. Paired t-test was performed to test differences in visual performance within subjects at intermediate and near test distances. Correlation analysis was performed to evaluate use of letter counting task as a surrogate measure of sustained readability.

Results:: No significant difference was measured between presbyopes and non-presbyopes or between the two eyes of each subject across the different visual performance tests included in the study. A significant difference in reading speed was measured between the sustained reading task and Radner reading test (t = 6.47, p < 0.001). A significant correlation was measured between the letter counting speed (seconds) and the sustained text reading speed (r = 0.64, p< 0.0001).

Conclusions:: Letter counting task can be used as a surrogate measure of readability. No significant difference in best-corrected visual performance was measured between presbyopes and non-presbyopes.

Keywords: reading • contrast sensitivity • visual acuity