Eye tracking for the classification of visual function in individuals with vision impairment: A validation in Para athletes

Eye tracking has the potential to be used as a meaningful measure of the consequences of vision impairment (VI), yet a comprehensive test battery is lacking. In this study, we sought to evaluate the feasibility and validity of a test battery of eye movements as a tool to measure visual performance in individuals with VI. A test battery including fixation stability, smooth pursuit, saccades, free viewing, and visual search was administered to 46 athletes with VI and 10 control participants. Feasibility was determined by test completion rates. Construct validity was assessed by comparing eye movement outcomes across different VI subgroups, and predictive validity was evaluated by examining the relationship between eye movement metrics and in-competition sport performance. The test battery proved feasible, with 88% of athletes with VI able to complete the tests. Eye movement variables distinguished between subgroups, supporting construct validity. For example, participants with combined central and peripheral vision loss showed longer fixation durations during free viewing and visual search, while those with central vision loss had prolonged saccades during free viewing and fewer and smaller eye movements during visual search. Predictive validity was indicated by significant correlations between eye movement metrics and sport performance, suggesting that eye tracking can predict real-world outcomes. Our findings suggest that an assessment of eye movements provides a feasible, valid, and largely objective measure of the functional consequences of VI that may extend beyond what information is obtained using traditional tests of visual acuity and visual field and that those measures can help to predict the sport performance of Para athletes.