Faulty depth perception caused by cyclotorsion.

Abstract

IN A RECENT paper, Nicholls1reviewed the literature dealing with the relation of heterophorias to depth perception. This author concludes that, within fairly wide limits, heterophoria seems to have little influence on the acuity of stereopsis. This is certainly true, inasmuch as cyclotorsional movements of the eyes are not involved. In this paper an attempt is made to show that, under certain circumstances, misinterpretations of space frequently occur owing to cyclotorsion, i. e., wheel-like rotations of the eyes about their lines of fixation (Ogle2). Cyclotorsion is normally performed in the interest of proper alignment of the eyes to provide binocular single vision and reliable distance discrimination of vertically located objects. Cyclomotions of the eyes for this purpose are called movements. According to Ogle,2the most evident characteristics of the cyclofusional mechanisms can be described as follows: 1. Both eyes perform essentially equal, but opposite, cyclotorsional movements