Longitudinal Evaluation of Static and Dynamic Accommodation in Young Children.

Purpose: To evaluate longitudinal (3 years) accommodation responses (ARs) in children at high risk (HR) or low risk (LR) for myopia, including a subgroup of children who developed myopia. Methods: Accommodation was measured in young children (n = 92; 7.54 ± 0.97 years) with functional emmetropia (+0.97 ± 0.54 D) at baseline under static and dynamic conditions using an open-field autorefractor. Linear mixed models assessed group differences and the predictor role of accommodation on myopia onset. Results: At baseline and all visits (7 total), the LR group showed greater static AR (P < 0.01) and dynamic amplitude (P < 0.01); these effects remained after adjusting for age (AR P = 0.02; amplitude P = 0.01). After further adjusting for refractive error (spherical equivalent of cycloplegic refraction [M]), risk group differences were no longer significant. Logistic regression indicated AR was a significant predictor of myopia onset when age was included (P < 0.01), but not after accounting for M (P = 0.39), reflecting M's stronger influence. Accommodation was primarily associated with age and M in this cohort with homogeneous ages and M. A Sobel test (P = 0.06) suggested a possible mediating effect for AR on myopia development. Conclusions: A lower AR was associated with a greater myopia risk, but its effect appears secondary to refractive error. Similar patterns were observed for dynamic amplitude. Longitudinal evaluations were minimal, suggesting group differences likely emerged before clinical myopia onset.