The binocular function as an indicator for the success of and need for unilateral contact lenses.

Abstract

Ninety‐five patients were referred for fitting with unilateral contact lenses. One half of the patients had non‐traumatic aphakia, a quarter of them had traumatic aphakia, and the rest had anisometropia or reduced vision for other reasons. Wearing a trial lens, all patients were examined at the major amblyoscope, prior to prescription.In prescribing a unilateral contact lens, the aim is to re‐establish a useful binocular vision. Pre‐existence of certain qualities of binocularity is thus considered to be a prerequisite for success. In consequence of this, about 30% of the patients were rejected primarily, mainly because of strabismus. This rather high frequency exceeds the general incidence of squint and points to the fact that the fusional range, even in adults, may disorganize when one eye has been deprived of useful vision. To prove this hypothesis, a contact lens was tried in a number of patients even though their binocular state was doubtful. Follow‐up studies demonstrated that simultaneous perception near zero degree, a fusional range around 20 pd. and stereopsis were found to have an ever increasing rate through the groups of unsuccessful to successful cases. Thus, an orthoptic study must not be underestimated as an indicator for the success of. unilateral contact lens prescription.