The influence of eye movement on soft contact lens visual performance

An apparently undocumented aspect of the correction provided by soft hydrophilic contact lenses, either at the fitting stage or in wear, is the influence of eye movement on visual performance. Using a televised visual discrimination task both spectacle (control) and soft contact lens (experimental) monocular visual performance was assessed in a group of human subjects (N = 5) under conditions of stationary fixation and subsequent to a defined 15 deg ocular excursion. For this subject group, analysis of variance revealed no statistically significant difference (P > 0.9) between visual performance under the control and any of the experimental conditions: the group psychometric functions were similar in all cases, regardless of the direction--or absence--of a deliberate eye movement. It is concluded that even in new and inexperienced soft contact lens wearers, provided that the lens fit is optimum, eye movement does not have a significant influence on the visual performance of the eye/lens system.