EYE-MOVEMENTS AND READING WITH SIMULATED VISUAL IMPAIRMENT

The purpose of this study was to investigate the effects of simulated visual impairment on the reading speed and reading eye movements of yo ung, normally-sighted observers. Afocal diffusing filters (Ryser occlu sion foils) were used to create three levels oi impairment and eye mov ements were recorded using a spectacle-mounted, infra-red limbal refle ction system. Reading speed decreased significantly (P < 0.01) as the level of impairment increased. Eye movement analysis revealed the main contributory factors to be increased fixation durations, shorter sacc ades (resulting in increased numbers of forward saccades per line) and , to a lesser extent, increased time required for page navigation. The results suggest that in order to achieve optimal reading speeds, prin t size should be at least four times the acuity threshold and that pri nt contrast should be at least twenty times contrast threshold. (C) 19 97 The College of Optometrists. Published by Elsevier Science Ltd.