Efficacy of Prism Adaptation in the Surgical Management of Acquired Esotropia

Prism adaptation, the preoperative use of prisms in acquired esotropia to determine the maximum angle of strabismus and to estimate fusional potential, has been suggested as a method of improving the results of initial surgery and minimizing the rate of reoperation. We performed a prospective, randomized, multicenter clinical trial of the effectiveness of prism adaptation. Two levels of randomization were used. Sixty percent of the patients underwent prism adaptation and 40% did not. Of those who responded to prisms with motor stability and sensory fusion, half underwent a conventional amount of surgery and half underwent augmented surgery based on the prism-adapted angle of deviation. Success rates were highest (54 89% of 61 patients) in prism adaptation responders who underwent augmented surgery and lowest (92 72% of 127 patients) in patients who did not undergo prism adaptation. Prism responders had better results with augmented surgery than with conventional surgery (54 89% of 61 patients vs 53 79% of 67 patients, P = .23). Our results indicated a significant beneficial overall effect of prism adaptation in patients with acquired esotropia (success rates, 83% vs 72%, P = .04). Although the process requires some additional time and effort, it appears to result in a higher rate of satisfactory alignment.