Adjustable surgical treatment of adult exotropia: postoperative target angles and surgical success.

Objectives: This study had 3 objectives: (i) to characterize clinical profiles of adults with consecutive exotropia (CXT), intermittent exotropia (IXT), and sensory exotropia (SXT); (ii) to correlate immediate postoperative target angles with successful long-term ocular alignment; and (iii) to compare the efficacy of adjustable versus nonadjustable medial rectus resection ± advancement.

Study Design: Retrospective, observational, and interventional cohort study.

Participants: A total of 133 adult exotropic patients treated surgically at 3 different hospitals between July 2012 and June 2013.

Methods: The patients were divided according to clinical profiles (CXT, IXT, and SXT) based on ophthalmic and orthoptic assessments. Two treatment groups were established: group I-adjustable medial rectus resection ± advancement and adjustable lateral rectus recession; group II-nonadjustable medial resection ± advancement and adjustable lateral rectus recession. Measurements of immediate postadjustment alignment (target angle) and 4-6 months of follow-up alignment were performed and compared between groups. Surgical success was defined as distance primary position alignment within 10 prism diopters (PD) of orthotropia 4-6 months postoperatively.

Results: Comparison of clinical profile groups showed that CXT patients had more hyperopia and amblyopia and smaller preoperative deviations; IXT patients had more diplopia and larger preoperative deviations (near > distance); and SXT patients had poor vision in the deviating eye and larger preoperative deviations. Immediate postoperative alignment was 5.2 PD of esodeviation in group I and 3.2 PD of esodeviation in group II. Overall success rates for ocular alignment at 4-6 months postoperatively were comparable with both surgical techniques (74.6% for group I and 74.3% for group II). Patients with a preoperative deviation ≥40 PD had a lower surgical success rate (63.8%) than patients with a deviation <40 PD (80%). Patients presenting with a significant (-1 or worse) abduction deficit in the operated eye at their first visit after surgery had a better success rate at 4-6 months' follow-up (83.3% vs 67.8%).

Conclusions: Adjustable and nonadjustable medial rectus surgeries seem equally successful. Creation of an abduction deficit in the early postoperative period seems predictive of a better outcome. Larger preoperative angles (≥40 PD) were associated with more exotropic drift and a lower percentage of surgical success. Future studies will continue to search for surgical strategies and the ideal target angle that will produce the best long-term alignment stability.