Abstract
Eye-tracking offers a powerful tool for better understanding an individual’s functional visual capabilities, but it remains unclear how suitable the technique is for measuring the capabilities of people with vision impairment. Eye-tracking typically relies on an uncompromised and steady image of the pupil and cornea; however, this is not guaranteed in individuals with vision impairment, particularly for those with anterior eye and oculomotor abnormalities (e.g., in corneal opacity and nystagmus respectively). The aim of this study was to establish the degree to which eye tracking can be used to assess visual function in the presence of vision impairment. A systematic review was performed to survey the existing literature employing eye tracking in persons with vision impairment, specifically cataloguing the test paradigms that have been adopted, the equipment used, and the relative success of those approaches. Results revealed an emerging field of research, with 31 out of the 41 papers on eye-tracking in vision impairment published in the most recent ten years. Analysis of the papers revealed five key tests of visual function: (i) fixation stability; (ii) smooth pursuit; (iii) saccades; (iv) free viewing; and (v) visual search. The types of ocular conditions examined in those studies were mainly those that occur largely as a result of aging, with an over-representation of studies in glaucoma and macular degeneration, and an under-representation of conditions such as corneal opacity and retinopathy. The results revealed a high level of success in generating usable data from the tests of visual function, with usable data available from 96.5% of participants. The majority of the data was collected using an EyeLink eye-tracking model. Recommendations are provided based on the results for how to establish a standardised test capable of evaluating eye movements in individuals with vision impairment.