Benefits and side effects of prisms in the management of diplopia in adults: a prospective study

Purpose: To analyze the various factors affecting patient satisfaction with prism glasses in adults with diplopia.

Methods: In this prospective case series, the benefits and side effects of prisms and factors affecting prism satisfaction were assessed by means of a questionnaire.

Results: A total of 134 patients were included. Overall, 58% of patients were highly satisfied, 22% were somewhat satisfied, and 20% were either neutral, somewhat dissatisfied, or very dissatisfied with prism glasses. Prior history of prism use, amplitude of prisms, comitancy of deviation, and type of lenses worn, had no influence on satisfaction rates. The extent of resolution of diplopia was highly correlated with prism satisfaction (P < 0.001), improvement in depth perception (P < 0.001), driving (P < 0.001), and reading (P < 0.008). Up to 22% of the participants noted "bothersome" side effects, including headaches, dizziness, eye strain and pulling (22%), alteration of depth perception (16%), visual distortion (13%), halos (8%), and weight of the prisms (6%).

Conclusions: In this cohort of adults with diplopia, prisms were beneficial in treating diplopia of different etiologies, incomitance, and a wide range of deviations. The side effects experienced with prism glasses themselves accounted for patient dissatisfaction in our study.