Surgical Approach and Reoperation Risk in Intermittent Exotropia in the IRIS Registry

Importance There is no consensus on the optimal surgical treatment for children with intermittent exotropia (IXT).Objective To compare the 5-year reoperation rates for children with IXT treated with horizontal muscle strabismus surgery using bilateral lateral rectus recession (BLR) vs unilateral lateral rectus recession with medial rectus resection (RR).Design, Setting, and Participants This cohort study examined data obtained from the Intelligent Research in Sight (IRIS) Registry on 7482 children (age, <18 years) with IXT who underwent horizontal eye muscle strabismus surgery between January 1, 2013, and December 31, 2017. Children undergoing initial surgeries involving 3 or more horizontal muscles, vertical muscles, or reoperations were excluded.Main Outcomes and Measures The primary outcome was the adjusted cumulative incidence of repeat horizontal muscle surgery within 5 years after the initial surgery. Reoperation risk was analyzed using adjusted hazard ratios (AHRs) derived from multivariable Cox regression models, adjusting for individual demographic and surgical factors (age, sex, race and ethnicity, US Census region, and surgeon subspecialty). Data were analyzed between January 16 and September 20, 2023.Results The study included 7482 children (median [IQR] age at initial surgery, 6 [4-9] years; 3945 females [53%]) with IXT treated with horizontal muscle strabismus surgery. Bilateral lateral rectus recession was performed more frequently than RR (85.3% vs 14.7%, P < .001), especially in younger children (rates of BLR vs RR by age: age 0 to <= 4 years, 88.4% vs 11.6%; age 5 to <= 11 years, 84.7% vs 15.3%; age 12 to <= 17 years, 78.1% vs 21.9%; P < 0.001). After data adjustment, the 5-year cumulative incidence of reoperation was 21.3% (95% CI, 20.1%-22.5%). The adjusted 5-year cumulative incidence of reoperation was higher for BLR than for RR (22.2% vs 17.2%; difference, 4.9%; 95% CI, 1.9%-8.0%). Unilateral lateral rectus recession with medial rectus resection was associated with a lower 5-year reoperation risk compared with BLR (AHR, 0.77; 95% CI, 0.64-0.93). Younger age at time of initial surgery was associated with a higher reoperation risk (AHR per 1-year decrease, 1.09; 95% CI, 1.07-1.11) after adjusting for all other covariates.Conclusions and Relevance In this nationwide registry, approximately 1 in 5 children with IXT underwent reoperation within 5 years after the initial surgery. Children treated with RR were less likely to require a reoperation within 5 years compared with those treated with BLR. Further efforts to identify modifiable risk factors for reoperation are needed to reduce the surgical burden and improve outcomes for children with IXT.