Outcomes of Simultaneous Three- or Four-Horizontal Muscle Surgery for Very Large-Angle Convergence Insufficiency-Type and Basic-Type Exotropia

Purpose

We investigated the outcomes of simultaneous three- or four-horizontal muscle surgery for very large-angle exotropia (> 60 prism diopters [Δ]). Subjects and Methods: This retrospective study included 24 patients (16 with convergence insufficiency-type and 8 with basic-type exotropia). The deviation angle was measured using the alternate prism and cover test, and stereopsis was evaluated. Patients were classified into three groups (F: ≤ 60 arcsec ("), C: 60”<, and N: nil stereoacuity). A successful motor outcome was defined as ≤ 10Δ of orthotropia. Pre- and postoperative results were compared.