Preoperative factors associated with multiple strabismus surgeries in basic exotropia

Purpose: To compare the preoperative clinical features in patients with basic unilateral exotropia who underwent single versus two and three or more strabismus surgeries. Design: retrospective Method: Two thousand four hundred fifty-seven patients with unilateral basic exotropia were recruited over 10 years. Of these, 1886 (76.8%) had one surgery, 411 (16.7%) had two, and 160 (6.5%) had three or more surgical interventions. Preoperative data included the best corrected distance visual acuity (BCVA), refractive error, magnitude of exotropia, and amblyopia type and severity. Results: The mean age at first surgery was 26.3 ± 13.35 years (age range: 2–77) with no significant difference between groups with one, two, and three or more surgeries ( p = 0.770). Mean BCVA in the strabismic eye was significantly worse in patients who underwent three or more surgeries (0.82 ± 0.076 logMAR) than those who had one (0.55 ± 0.018 logMAR; p < 0.001) or two surgeries (0.52 ± 0.038 logMAR; p < 0.001). Spherical equivalent refraction in the strabismic eye was significantly more hyperopic in patients who underwent three or more surgeries (0.79 ± 0.37 D), compared with those with one (−0.95 ± 0.094 D; p < 0.001) or two surgeries (−0.36 ± 0.16 D; p < 0.001). Relative to one surgery, undergoing two surgeries was independently associated with larger distance horizontal deviation (adjusted odds ratio (aOR) per prism diopter = 1.012; 95% CI, 1.003–1.022; p = 0.009). Undergoing three or more surgeries was independently associated with amblyopia severity (aOR = 2.368; 95% CI, 1.279–4.384; p = 0.006); in the strabismic eye, and higher spherical power markedly increased the odds (aOR = 13.553; 95% CI, 12.801–14.348; p < .001). Conclusion: Worse preoperative BCVA, greater hyperopia, and higher angle of deviation were associated with a greater likelihood of requiring more than one surgery. Surgeons should optimize preoperative refractive and amblyopia management and counsel high-risk patients about the increased likelihood of additional procedures.