Gender-based analysis of visual and refractive characteristics in exotropia

PURPOSE: To analyze gender-based differences in visual acuity, refractive error, angle of deviation, and amblyopia in patients with alternate exotropia (Alt XT) and intermittent exotropia (IXT). METHOD: A retrospective study of 4,417 surgical exotropia patients (2,970 Alt XT; 1,447 IXT) compared sex-based differences in CDVA, refraction, deviation angles, and amblyopia within each subtype. Alongside unadjusted tests, subtype-specific multivariable models were used: linear regression for right-eye logMAR CDVA (adjusting for age, near/distance deviation, spherical equivalent, and astigmatism), linear regression for distance deviation angle (adjusting for age, spherical refractive error, astigmatism, and amblyopia status), and binary logistic regression for amblyopia (yes/no) (adjusting for age, distance deviation, spherical refractive error, and astigmatism). An ordinal model for amblyopia severity was explored but interpreted cautiously due to sparse data. RESULTS: In Alt XT, females had higher mean cylindrical error (0.86 ± 1.23 D vs. 0.76 ± 1.07 D; p = 0.024), while males had larger horizontal deviations at near (37.2 ± 16.6Δ vs. 35.0 ± 16.6Δ; p < 0.001) and distance (35.9 ± 16.0Δ vs. 34.3 ± 15.8Δ; p = 0.008) and a higher prevalence of severe amblyopia (12.2% vs. 7.8%; p < 0.001). In IXT, females were younger (16.7 ± 11.6 vs. 18.8 ± 11.9 years; p = 0.001), whereas males had larger deviations at near (28.1 ± 11.7Δ vs. 26.2 ± 10.0Δ; p = 0.001) and distance (28.4 ± 11.4Δ vs. 27.2 ± 9.8Δ; p = 0.025) and higher overall amblyopia prevalence (13.0% vs. 8.7%; p = 0.010), mainly mild (10.4% vs. 7.0%; p = 0.031). CDVA and spherical equivalent did not differ by sex in either subtype. In adjusted models, sex was not associated with right-eye logMAR CDVA in Alt XT (B = 0.005; p = 0.814) or IXT (B = 0.005; p = 0.506). Sex was associated with a small difference in distance deviation magnitude in Alt XT (B = 1.33 prism diopters; p = 0.018) but not in IXT (p = 0.114). In adjusted logistic regression, sex was not associated with amblyopia prevalence in Alt XT (OR = 1.12; p = 0.159) but was associated in IXT (OR = 1.51; p = 0.025). CONCLUSION: Gender-specific differences were observed in astigmatism, deviation magnitude, age at surgery, and amblyopia patterns across exotropia subtypes. After adjustment, sex remained associated with distance deviation in Alt XT and amblyopia prevalence in IXT, but not with CDVA in either subtype. Overall, sex appears to be a relevant clinical variable in exotropia and should be considered in assessment and future research.