Oculomotor adaptation with virtual reality scotomas

Abstract

A simulation of central blindness in normal human subjects was produced by linking a high- accuracy eye position sensor with a computer visual display. This eye controlled system may be classified as a form of virtual reality for safely exploring the effects of visual defects, diseases, and adaptability under experimental control. A circularly symmetric simulated scotoma or visual blindspot was stabilized on the fovea of 6 normal observers while they attempted to maintain a target in clear view. The subjects were naive and were free to view the target in any way they chose. Eccentric eye positioning developed within 2 minutes of viewing time with most subjects. Cumulated fixation positions showed that the edge of the scotoma was positioned next to the target. All subjects reported that they found an upper right position relative to the target easier to maintain as an eccentric vantage point and fixation maps showed that the majority of fixations were located there. The durations of correctly positioned fixations became longer during eccentric viewing practice indicating rapid improvements in fixation stability, while fixation durations of incorrect, error fixation positions became shorter demonstrating adaptability. A test for eye fixation stability around clock positions failed to explain the upper right field preference as an eccentric viewing point.