Surgical therapy of convergence insufficiency.

Fourteen cases of intractable convergence insufficiency were surgically treated by resection of both medial rectus muscles. All 14 patients showed dramatic relief of severe asthenopic symptoms. Temporary diplopia due to consecutive esotropia is a necessary part of this surgery and is relieved by fresnel prisms. Exophoria at near will return, occasionally to the original angle of deviation, but the symptoms do not return. The preoperative symptoms can be of severity out of proportion to the deviation. Bimedial resection is a most efficacious surgical method for treatment of intractable convergence insufficiency.