Binocular Diplopia After Cataract Surgery: Incidence and Associated Factors in a Tertiary Teaching Eye Center

Objective: To determine the incidence and risk factors for binocular diplopia following cataract surgery at Siriraj Hospital, Mahidol University. Materials and Methods: This retrospective case–control study included patients who underwent cataract surgery between January 2000 and June 2023. Postoperative binocular diplopia was defined as symptomatic diplopia with documented ocular misalignment within 90 days of surgery, identified using ICD-10 codes. Demographic, systemic, biometric, and operative data were extracted. Each case was matched to ten controls by age, sex, and year of surgery. Statistical analyses included Chi-square tests, paired t-tests, and logistic regression. Results: Among 90,885 cataract surgeries, 13 cases of postoperative binocular diplopia were identified, yielding an incidence of 0.0143%, substantially lower than previously reported rates (0.18–0.85%). The mean age of affected patients was 70.4 years, and 69.2% were female. Esotropia was the most common strabismic pattern (46.2%), while muscle restriction or paresis accounted for the majority of mechanisms (53.9%). Compared with matched controls, cases had significantly longer axial lengths (24.58 ± 2.30 mm vs. 23.40 ± 1.33 mm; p = 0.024), corresponding to an odds ratio of 1.426 (95% CI: 1.047–1.942) per millimeter increase. No significant associations were found with systemic comorbidities (diabetes, hypertension, dyslipidemia) or anesthesia type. Conclusion: Postoperative binocular diplopia following cataract surgery was rare in this large tertiary center cohort. Longer axial length was the only significant risk factor identified, suggesting a potential role of myopia-related extraocular muscle pathomechanics. Awareness of this risk factor may aid in preoperative counseling and surgical planning.