Surgical experiences with two-muscle surgery for the treatment of intermittent exotropia.

BACKGROUND: The surgical management of intermittent exotropia, or X(T), remains a challenge. Not only are some quoted success rates relatively low (40-83%), but the outcome is notoriously unpredictable with a tendency to exotropic drift over time. METHODS: In this retrospective study, 118 patients who underwent either bilateral lateral rectus muscle recession (BLR) or unilateral medial rectus muscle resection and lateral rectus muscle recession (R&R) surgery during a 4-year period were reviewed. Surgical outcome between the 2 groups in addition to factors that influence outcome within groups were analyzed. Success was defined as an X(T) < or = 10PD. RESULTS: Sixty-four subjects underwent BLR, and 54 subjects underwent R&R surgery. Mean preoperative distant X(T) size was 38.7 +/- 6.7 PD. Subjects who underwent R&R did significantly better at 1-year follow-up (success 74.2% vs. 42.2%) but showed significantly more exotropic drift over time (P = 0.01). Within both BLR and R&R groups, subjects with basic-type X(T) did worse than those with divergence-excess X(T) at 1-year follow-up. Consecutive esotropias, however, were more likely with R&R surgery and in those with divergence excess X(T). Preoperative strabismus control, distant X(T) size, and patient age at surgery did not significantly influence outcome. CONCLUSION: In many cases, selection of surgery type continues to depend on the surgeon's preference, which is in turn influenced by his/her past experiences. The debate about which surgical type is best for different X(T) types continues.