Restoration of binocular single vision after long-term fusion disruption

Abstract

Background One of the most difficult situations faced by orthoptists and pediatric ophthalmologists is attempting to restore binocular single vision to a patient who has experienced a long-term disruption of fusion. Initial poor results with standard treatment modalities, including prisms and strabismus surgery, may lead to a diagnosis of intractable diplopia. Methods We examined, treated, and followed up 5 patients with strabismus after an extended period of monocular vision loss. All patients were diplopic after the restoration of visual acuity in the affected eye. Results All 5 patients experienced a period of uncomfortable intermittent fusion with the initial prismatic correction. After many months of close follow-up with prism and orthoptic therapy, comfortable fusion was restored for 3 patients. Convergence amplitudes improved with the orthoptic exercises, and we were eventually able to eliminate most or all of the horizontal prism in the 3 patients who regained binocular single vision; however vertical fusion was less responsive and most often required permanent prismatic correction. Conclusions A combination of prism therapy, orthoptic treatment, and follow-up during a period of many months to years can restore fusion in some patients who have experienced a long-term disruption of fusion.