Risk Factors of Residual Exotropia After Surgery in Patients with Intermittent and Sensory Exotropia: A Systematic Review and Meta-Analysis.

Background: Residual exotropia remains a common challenge following surgical correction of intermittent exotropia (IXT) and sensory exotropia (SX). Identifying prognostic factors associated with postoperative misalignment is essential to improve surgical planning and long-term outcomes. Objective: To systematically review and evaluate patient- and surgery-related risk factors for residual exotropia after surgical correction, and to compare these factors between intermittent and sensory exotropia. Methods: A systematic review was conducted in accordance with PRISMA guidelines. PubMed, Scopus, the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar were searched from January 2010 to 2025. Eligible studies included patients undergoing surgery for intermittent or sensory exotropia with reported postoperative alignment outcomes. Data extraction and risk-of-bias assessment were performed independently by multiple reviewers, using the MINORS tool for non-randomised studies and the Cochrane RoB 2 tool for randomised trials. The primary synthesis was narrative; where studies were sufficiently comparable, random-effects meta-analyses were additionally performed (single-arm success proportions were pooled with a random-intercept logistic model using maximum-likelihood estimation, and the between-technique odds ratio was pooled by the inverse-variance method with the DerSimonian-Laird estimator). Results: A total of 53 studies (approximately 7470 patients) were included. Reported surgical success ranged widely, from approximately 38% to 91.6%, depending on the success criterion and follow-up duration. Residual exotropia and postoperative exodrift were consistently reported across studies. Larger preoperative deviation, poor preoperative control, amblyopia, reduced stereoacuity, and sensory exotropia were associated with higher rates of residual deviation and recurrence. Early postoperative alignment emerged as one of the strongest predictors of long-term success, with early overcorrection associated with improved stability. Patients with intermittent exotropia demonstrated better sensory recovery than those with sensory exotropia. The predictive value of risk factors differed by subtype: poor preoperative visual acuity and the chronicity of visual loss dominated in sensory exotropia, whereas fusional control, stereoacuity, and the early postoperative target angle dominated in intermittent exotropia. No statistically significant difference between surgical techniques was detected. On meta-analysis, the pooled surgical success rate was 68.7% (95% CI 63.8-73.2; I Conclusion: Residual exotropia after surgery is influenced by multiple patient- and surgery-related factors, particularly preoperative sensory status and early postoperative alignment, with a modest early overcorrection (a small postoperative esodeviation) associated with greater long-term stability. Intermittent and sensory exotropia differ in functional outcomes, underscoring the importance of individualized surgical planning and long-term follow-up. Standardized outcome definitions and prospective studies are needed to improve comparability and long-term outcome prediction.