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

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.

Retrospective, observational, and interventional cohort study.

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

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.

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%).

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.