Association of Accommodation and Convergence with Axial Length Elongation in Children with Basic Intermittent Exotropia: A 12-Month Observational Study.

Introduction: The aim of the study was to investigate the association of parameters related to accommodation and convergence and axial elongation in basic intermittent exotropia (IXT) patients and the potential clinical predictors of axial length (AL) growth.

Methods: A total of 140 basic IXT patients were recruited in this study. The medians of AL growth in different age brackets were chosen to divide the subjects into group A (slower axial elongation group, n = 69) and group B (faster axial elongation group, n = 71). Parameters of dominant and nondominant eyes were compared and analyzed during the 12-month follow-up period. The parameters, including baseline refraction, angle of deviation, Newcastle control score (NCS), accommodative amplitude (AMP), accommodative facility (AMF), accommodative response, positive or negative relative accommodation (PRA/NRA), and near point of convergence (NPC), were analyzed via univariate and multivariate regression.

Results: Subjects in the faster axial elongation group tended to have more myopic spherical equivalents (t = 3.956, p < 0.001), greater AMPs of dominant eyes (t = -2.238, p = 0.027), and fewer near points of convergence (t = 2.347, p = 0.020) than in the slower axial elongation group. For dominant eyes, logistic and linear regression analysis revealed that more negative spherical equivalents (OR = 0.603, p < 0.001; β = -0.045, p < 0.001), greater AMPs (OR = 1.201, p = 0.027; β = 0.023, p = 0.010), and less near points of convergence (OR = 0.883, p = 0.021; β = -0.012, p = 0.019) were correlated with the faster axial elongation. For nondominant eyes, a more myopic spherical equivalent (OR = 0.682; p = 0.001; β = -0.029, p = 0.005) was the only parameter correlated with faster axial elongation through regression analysis.

Conclusion: In children with basic IXT, faster axial elongation in the dominant eyes was associated with more myopic spherical equivalents, greater AMPs, and lower NPCs. These accommodative parameters can serve as potential clinical indicators for monitoring myopia progression in addition to AL.