Factors associated with atypical postoperative drift following surgery for consecutive exotropia

Purpose To evaluate the associations of clinical and surgical factors with atypical postoperative drift following surgery for consecutive exotropia. Methods A total of 66 patients with consecutive exotropia (≥10^Δ at distance), after historical surgery for esotropia were retrospectively identified at a tertiary medical center. All patients underwent unilateral lateral rectus recession (on adjustable suture) with medial rectus advancement and/or resection. Immediate postoperative target angle was 4^Δ-10^Δ of esotropia at distance, anticipating mild postoperative exodrift. Actual postoperative drift was calculated as change in distance deviation from immediately postadjustment to 6 weeks. Typical drift was defined as 0^Δ-9^Δ of exodrift. Excessive exodrift was defined as ≥10^Δ. Esodrift was defined as 1^Δ or more. Univariate and multiple logistic regression analyses were performed to evaluate for associations with a wide range of clinical and surgical factors. Results Overall there was a median exodrift (4^Δ, quartiles 0^Δ-10^Δ). Of the 66 patients, 18 (27%) showed excessive exodrift; 15 (23%), esodrift. In multiple logistic analyses, larger preoperative distance exodeviation was associated with excessive exodrift (P = 0.01), and non-normal medial rectus attachment status (abnormal [stretched scar, pseudo-tendon], attached to pulley, or behind pulley) was associated with esodrift (P = 0.02). Conclusions Approximately half of patients show atypical drift following unilateral surgery for consecutive exotropia, with larger preoperative distance exodeviation associated with exodrift and non-normal medial rectus muscle status with esodrift. Knowing these associations may help when counseling patients regarding surgical outcomes.