Abstract
Background: Previously we have shown high correlation between visual acuity (VA) measured using the GlassesOff application for near vision evaluation (eVA) and VA measured using a standard ETDRS chart. Moreover, we have shown that eVA can predict the functional reading acuity along with the minimal font size one can recognize under good illumination conditions. Methods: Near VA was measured in over 100 subjects with age ranging between 20-69 years performed eVA from 40 cm, using GlassesOff application on iOS-based mobile devices (iPhone, iPad, iPod). The stimuli were matrices composed of 25 letters "E" (5×5), each with a randomly chosen orientation out of 4 possibilities (left, right, up or down). Two variations of inter-letter spacing within matrices were used (0.4 and 1 letter). The task was to report the orientation of the central letter. The evaluation was performed using a staircase measuring the minimal detectable letter size. For each staircase, the duration of target presentation (30, 60, 120, 240 msec). Reading acuity was measured using the standard MNREAD chart. We aimed to evaluate whether age-related changes in crowding can explain the age-related reduction in reading abilities and whether eVA can reliably predict reading abilities. Results: Firstly, consistent with an earlier study (Baron & Westheimer, 1973), eVA decreases for shorter presentation durations. Moreover, crowding measured using eVA is correlated with age, with higher correlation for shorter presentation durations. Furthermore, crowding is highly correlated with the reading acuity, again with higher correlation for shorter presentation durations. Conclusions: The observed age-dependent increase in crowding and the consequent decrease in functional reading acuity indicate that remote eVA can accurately predict reading abilities. Moreover, our results suggest a neuronal mechanism for earlier reported reduction in crowding following training with our perceptual learning method, resulting in improved reading acuity in presbyopic and young subjects.
Meeting abstract presented at VSS 2014