The management of strabismus in patients with chronic progressive external ophthalmoplegia

Abstract

Aims: To describe the clinical profiles and results of surgical and non-surgical interventions in a large cohort of patients with strabismus associated with chronic progressive external ophthalmoplegia (CPEO).

Methods: A retrospective case note review was conducted of all patients with a clinical diagnosis of CPEO referred to our institution's strabismus department in the United Kingdom between 1990 and 2008.

Results: The total number of patients in this series was 28 (12 male, 16 female). The main presenting symptoms were diplopia (14) or cosmetically objectionable strabismus (11). Three had symptoms unrelated to strabismus and were excluded from further analysis. The most common strabismus findings were large angle exotropias (mean 47 prism diopters), half of which had associated vertical deviations. Strabismus management consisted of prisms (3), occlusion (3), botulinum toxin (7), and surgery (8). Two patients were offered surgery but were deemed unfit for general anesthesia, and a further 2 declined surgery or defaulted follow-up. Three had no active treatment for strabismus. The most effective procedure for exotropia was maximal, bilateral lateral rectus recessions (8 mm or 17 mm from the limbus) with medial rectus resections (7 mm) using adjustable sutures. Patients who had less than maximal horizontal muscle surgery were inevitably undercorrected, even in the early postoperative period. Long-term stability of measurements was rarely achieved, with either progressive increase in the angle of exotropia, or with new onset vertical deviations.

Conclusions: In selected patients with CPEO and exotropia, maximal bilateral surgery significantly improves ocular alignment and may relieve symptoms of diplopia, but due to the progressive nature of the disease, strabismus often recurs. Toxin can be invaluable in maintaining a satisfactory ocular alignment in patients with residual or progressive exotropias, who have undergone maximal horizontal rectus muscle surgery or multiple previous strabismus procedures.