[Analysis of peripheral retinal defocus and wavefront aberrations in children with unilateral myopic anisometropia]

Objective: To compare the differences in peripheral retinal defocus values (RDVs) and wavefront aberrations between myopic and emmetropic eyes in children with unilateral myopic anisometropia, and to analyze the association between RDVs and wavefront aberrations. Methods: The cross-sectional study consecutively enrolled patients aged 8 to 15 years, who were initially diagnosed as unilateral myopic anisometropia in the Department of Ophthalmology in Peking University Third Hospital from August 2023 to November 2024. Multispectral refraction topography was used to measure RDVs in the regions with eccentricity of 0° to <15° (RDV-15), 15° to <30° (RDV-30), and 30° to 45° (RDV-45), as well as in the superior (RDV-S), inferior (RDV-I), nasal (RDV-N), and temporal (RDV-T) directions under the mesopic condition at physiologic pupil sizes. A visual function analyzer was used to measure and calculate the higher order aberrations (HOAs), astigmatism (Z₂⁻², Z₂²), trefoil (Z₃⁻³, Z₃³), coma (Z₃⁻¹, Z₃¹), and spherical aberration (Z₄⁰) of the eyes and those arising from internal and corneal components within a pupil diameter of 4 mm. Results: There were 69 eligible patients (138 eyes), including 35 males (70 eyes) and 34 females (68 eyes). The age was (10.6±1.6) years. The myopic eyes showed higher RDV-30 [-0.06 (-0.19, 0.05) D], RDV-45 [0.01 (-0.34, 0.39) D], RDV-S [-0.75 (-1.16, -0.09) D], RDV-I [0.35 (-0.14, 0.95) D], RDV-T [-0.02 (-0.34, 0.40) D], and RDV-N [0.21 (-0.35, 0.88) D] values compared to the emmetropic eyes [-0.14 (-0.28, 0.00), -0.29 (-0.50, -0.02), -0.93 (-1.47, -0.39), -0.02 (-0.62, 0.54), -0.28 (-0.82, 0.04), -0.14 (-0.64, 0.20) D], with statistically significant differences (all P<0.05). The myopic eyes had lower ocular astigmatism Z₂^-2 [0.062 (0.032, 0.112) μm] and Z₂² [0.149 (0.085, 0.249) μm], corneal astigmatism Z₂² [0.276 (0.193, 0.389) μm], and internal ocular HOA [0.121 (0.088, 0.160) μm] values compared to the emmetropic eyes [0.078 (0.035, 0.151), 0.199 (0.098, 0.339), 0.327 (0.215, 0.501), 0.134 (0.088, 0.203) μm], with statistically significant differences (all P<0.05). The ocular spherical aberration Z₄⁰ [0.036 (0.017, 0.058) μm] was higher in myopic eyes than the emmetropic eyes [0.026 (0.009, 0.051) μm] (P<0.05). In myopic eyes, the spherical equivalent (SE) showed negative correlations with RDV-30 (r=-0.294), RDV-45 (r=-0.475), RDV-S (r=-0.253), and RDV-N (r=-0.471) (P<0.05). The ocular astigmatism Z₂² positively correlated with RDV-S (r=0.240) and RDV-N (r=0.273) (P<0.05). In the emmetropic eyes, the axial length positively correlated with RDV-15 (r=0.268, P<0.05), the ocular astigmatism Z₂² negatively correlated with RDV-15 (r=-0.335, P<0.05), and corneal astigmatism Z₂² positively correlated with RDV-S (r=0.254, P<0.05). The interocular SE differences negatively correlated with the RDV-30 (r=-0.388), RDV-45 (r=-0.469), RDV-I (r=-0.361), RDV-T (r=-0.328), and RDV-N (r=-0.337) differences (all P<0.05). The interocular axial length differences positively correlated with the RDV-30 (r=0.294), RDV-45 (r=0.463), RDV-I (r=0.312), RDV-T (r=0.293), and RDV-N (r=0.306) differences (P<0.05). The interocular RDV-15 differences positively correlated with the ocular spherical aberration Z₄⁰ differences (r=0.306, P<0.05) and negatively correlated with the ocular astigmatism Z₂² differences (r=-0.249, P<0.05). Conclusions: In children with unilateral myopic anisometropia, the myopic defocus changed into hyperopic defocus in the region of 15° to 45°, which was associated with the degree of myopia. The increase of the RDV of 0° to 15° was correlated to the decrease of ocular astigmatism (Z₂²) and the increase of ocular spherical aberration (Z₄⁰).