Strabismus surgery for internuclear ophthalmoplegia with exotropia in multiple sclerosis

Background: Internuclear ophthalmoplegia (INO) is a disabling condition affecting up to 40% of patients with multiple sclerosis (MS). Management of bilateral internuclear ophthalmoplegia (BINO) with exotropia in MS has been controversial because of the uncertain course of MS. Diplopia associated with INO severely impacts the patient's quality of life and, therefore, treatment should be considered. Methods: Three patients (ages 28, 62, and 82 years) who had BINO with exotropia and disabling diplopia secondary to MS underwent bilateral medial rectus resections with either unilateral or bilateral adjustable lateral rectus recession(s). Alignment was measured preoperatively and postoperatively, and symptoms were recorded. Results: Preoperative exotropia ranged from 40^Δ to 64^Δ for distance fixation and from 50^Δ to 70^Δ for near fixation. Preoperatively, all patients had diplopia at distance and near fixation. Immediately after surgery, patients were adjusted to 10^Δ to18^Δ ET at distance fixation with the expectation of an exotropic drift. None of the patients had a tropia at distance and near fixation 6 months after surgery, with single vision in primary position and reading. Two patients had a 2-year follow-up examination; 1 required a small amount of base-in prism for comfortable reading. Conclusions: Three patients who had BINO with exotropia secondary to MS all benefited from surgery. Surgery should be considered as an option for symptomatic patients who have BINO with exotropia caused by MS.