Hyperopic reserve insufficiency and myopic pre-disposition in pre-school children aged 3-6 years: a large-scale cross-sectional survey.

OBJECTIVE: To estimate the prevalence of hyperopic reserve insufficiency (HRI) and examine its associated factors among pre-school children aged 3-6 years in Ganzhou, China. METHODS: This cross-sectional study included 3,360 pre-school children aged 3-6 years. All participants underwent cycloplegic autorefraction and axial length (AL) measurement. HRI was defined using age-specific spherical equivalent refraction (SER) thresholds. SER was also used to describe age-specific refractive status and to conduct a sensitivity analysis using the International Myopia Institute (IMI) pre-myopia criterion (-0.50 D < SER ≤ +0.75 D). Guardian-completed Questionnaires assessed paternal/maternal high myopia, outdoor time, near-work, and residence. Multivariable logistic regression was performed with HRI coded as 1 and sufficient hyperopic reserve coded as 0. RESULTS: HRI was identified in 380 children (11.3%, 95% CI: 10.3-12.4%). Age-specific HRI prevalence increased from 4.1% (95% CI: 2.8-6.0%) at age 3 to 27.5% (95% CI: 23.9-31.5%) at age six. Mean SER declined from +2.35 ± 0.37 D at age 3 to +1.05 ± 0.54 D at age 6. IMI-defined pre-myopia was found in 179 (5.3%). In multivariable analysis, older age (OR = 1.86), longer AL (OR = 1.70), paternal (OR = 1.28) and maternal (OR = 1.31) high myopia, near-work (OR = 1.06), and urban residence (OR = 1.40) were associated with higher HRI odds. Male sex was protective (OR = 0.75, 95% CI: 0.60-0.94). Outdoor time showed lower odds but was non-significant (OR = 0.93, 95% CI: 0.85-1.01). IMI sensitivity analysis showed consistent directions. CONCLUSIONS: HRI was detectable in a notable proportion of pre-schoolers and was accompanied by an age-related decline in SER. HRI was associated with age, AL, parental myopia, residence, and early-life visual behaviors. Due to the cross-sectional design, findings are associational, not causal.