Unilateral lateral rectus resection for horizontal diplopia in adults with divergence insufficiency.

BACKGROUND: Divergence insufficiency (DI) is an acquired comitant strabismus in aging individuals, characterized by esotropia and diplopia at distance. Treatment options include occlusion, base-out prism glasses, and a variety of surgical procedures to the horizontal rectus extraocular muscles. Here, we present a large cohort of patients with DI who underwent unilateral resection of the lateral rectus muscle. This is a simple procedure, typically performed under regional anesthesia and on the non-dominant eye.

METHODS: Clinical characteristics and complaints were collected from patients with DI who underwent unilateral lateral rectus resection over a 6.5-year period. Treatment success was evaluated in terms of post-operative symptomatic deviation and the need for prisms in order to achieve sensory fusion.

RESULTS: The cohort consisted of 57 patients (age 54-89 years). The majority sought surgical care after prism glasses were no longer tolerated, or after onset of a larger symptomatic deviation (typically 10 to 18 prism diopters). After surgery (minimum 6 weeks follow-up; median 10 weeks), 86.0 % showed successful results with no further treatment; an additional 10.5 % stayed free of diplopia with a post-operative prism (horizontal or vertical), and only two patients (3.5 %) required further surgery and were considered failures.

CONCLUSIONS: Mild DI is usually treated with a base-out prism. Treatment of pronounced DI with unilateral lateral rectus resection was generally successful, with 96.5 % not requiring further surgery. Unilateral lateral rectus resection appears to be a valid option for treatment of DI.