Interocular difference in crystalline lens morphology in children and adolescents with unilateral high myopia

PURPOSE:To investigate the between-eye differences of the crystalline lens in subjects with unilateral high myopia and assess its contribution to the interocular refractive error disparity. METHODS:Children and adolescents with unilateral high myopia, defined as cycloplegic spherical equivalent (SE) ≤ -5D in one eye and ≥ -3D in the other eye, were recruited. Ocular biometric parameters, including axial length (AL) and lens thickness (LT), were measured by IOLMaster 700. Other lens-related parameters, including anterior lens radius of curvature (ALR) and posterior lens radius of curvature (PLR), were measured by CASIA2 swept-source optical coherence tomography. Lens power (LP) was calculated using Bennett's formula. Paired t-test was used to assess the between-eye difference in biometric parameters, and multiple regression analysis was used to assess factors associated with the between-eye SE difference. RESULTS:Ninety-one participants (6-18 years of age; 52.75% girls) were included. The highly myopic eyes showed significantly lower LP (P < 0.001) and smaller ALR (P < 0.001) than the contralateral eyes, while no significant difference was found in central LT. In both eyes, ALR was significantly related to SE (P = 0.001 and P = 0.006, respectively); while LT was not associated with SE (P = 0.051 and P = 0.052, respectively). Paired-eye analysis showed that the between-eye difference in ALR was the only lenticular parameter significantly associated with the between-eye difference in SE (P = 0.005). CONCLUSION:In highly myopic eyes, the crystalline lens reduced total power but morphologically changed to a more curved shape without significant lens thinning, suggesting that the LP loss is mainly achieved by reducing its internal power in high myopes.