Characteristics and surgical outcomes of consecutive exotropia of different etiologies

To investigate the surgical results for consecutive exotropia with or without insertion abnormalities on the basis of the position of the lateral rectus muscle at surgery.

Patients with consecutive exotropia who had undergone medial rectus recession as a primary procedure or advancement of previously recessed medial rectus muscles from 2002 to 2012 were included in the study. The characteristics, postoperative courses, and final results were compared among 3 patient groups. The patients' characteristics including sex, refractive error, and age at the initial surgery were compared. The main outcome measures were the angles of deviation in the primary position and the average divergent drift per month after the exotropia surgery.

Twenty-four eyes of 23 patients were investigated. The patients were divided into 3 groups according to insertion status: with normal muscle insertion (4 men, 4 women), slipped muscles (9 women), and stretched scars (2 men, 4 women). The preoperative angles of deviation at near differed significantly between the slipped muscle group and the normal muscle insertion group (P = 0.02). Only patients with normal insertions had significantly greater hyperopia in the nondominant eye (0.95 D) than in the dominant eye (0.53 D). The postoperative divergent shift per month was similar among the groups (0.3, 0.1, and 0.2 prism diopters per month in the slipped muscle, stretched scar, and normal muscle insertion groups, respectively; P = 0.70).

Hyperopic anisometropia is an important factor in the natural course of outward drift. The postoperative course of advancement of the medial rectus muscle was equally stable in all 3 patient groups.