Eye movement in strabismic cats

Abstract

Strabismus is a common clinical condition in which the visual axes of the eyes do not intersect on the object being viewed¹. As such, the ability to achieve single binocular vision by fusing the images of a single object in the two eyes is lost. In most cases of strabismus, one of the two eyes is clearly deviated and the other eye is used for fixation, although in some cases each eye is used alternately for fixation^2,3. While much attention has been devoted to the motor capabilities of the deviating eye in strabismus^1–3, little attention has been given to the visuomotor competence of the other eye. We report here that, if one eye of a kitten is made to deviate by surgery, the visuomotor capacities of the other, ‘normal’, eye are affected. A reduction in the ability to follow the movement of a large striped drum is observed with binocular viewing, even when stimuli are viewed monocularly with the normal eye. This means that anomalous visual input from the deviated eye during stimulation is not the cause of the reduced oculomotor capacities.