Purpose
Sloan and Snellen optotypes are the global eye chart standard for visual acuity testing, but routinely patients struggle with the required endpoint of response confusion. A new Dynamic Optotype, or “Dyop”, using a dynamically sized, rotating, visual arc-area figure to measure acuity was prospectively, clinically compared to Sloan measures of visual acuity under various test conditions. The Dyop has a completely unique endpoint: the rotation animation appears to suddenly stop when threshold is reached.
Methods
Acuity was assessed with 162 subjects each randomly with the Dyop test (Konan Medical Chart2020) and Harris Stair-Step test (M&S Technologies) comparing each with the following strategies: BCVA, UCVA, + Lens (+2, +3, +4) over spectacles. The relationship between Sloan VA/20 and Dyop size in arc-minutes (both log-transformed) was investigated using correlations and repeated-measures log-log regression models.
Results
There was a strong linear relationship between Sloan and Dyop acuity measures (Pearson r=.94; p<001). In a single predictor model, the Dyop measure explained 89% of the variance in Sloan acuity. An interaction model relaxing the assumption of common slopes by testing condition indicated a significant measure X condition interaction (p=.004), and explained over 91% of the variance in Sloan acuity. Optimal conversion algorithms between Dyop and Sloan measures were developed via regression models.
Conclusions
The Dyop is a novel method of measuring visual acuity that is strongly associated with, and may offer a viable alternative to traditional visual acuity methods. Beyond high correlation with standard methods, the Dyop was observed to be advantaged by speed to threshold endpoint, finer acuity granularity compared to the typically used acuity “line” steps, and ease of endpoint interpretation by subjects.