Early refractive and biometric changes in Irish children aged 6-7 years: a 12-month study

Longitudinal monitoring of refractive error and ocular biometry helps improve understanding of normal refractive development during childhood and may assist interpretation of ocular growth in clinical practice.

Childhood refractive development is characterised by coordinated changes in ocular biometry and refractive error, yet longitudinal data describing refractive and biometric development during the early school years in European populations remain limited.

The Child Eye Health Study was a longitudinal cohort study including schoolchildren in Ireland aged 6-7 years old. Participants underwent cycloplegic autorefraction at baseline and 12 months and ocular biometry at baseline, 6 months and 12 months. Changes in spherical equivalent refraction and axial length were assessed using descriptive statistics and linear mixed-effects models.

A total of 134 participants were examined at baseline, of whom 111 completed the 12-month follow-up. Mean axial length increased by 0.22 ± 0.10 mm per year, while spherical equivalent refraction decreased by -0.11 ± 0.38 D per year, representing a small reduction in hyperopia. Axial elongation was moderately negatively correlated with refractive change (r =  -0.55, p < 0.001). The incidence of categorical myopia (≤-0.50 D) remained low (1.0%). Individual participants exhibited bidirectional movement between refractive categories over 12 months, alongside a small reduction in mean hyperopia.

Irish children aged 6-7 years demonstrated measurable axial elongation and a small reduction in mean hyperopia over 12 months, while the incidence of categorical myopia remained low. These findings provide contemporary longitudinal data describing refractive and biometric development in Irish schoolchildren. Longer follow-up is required to determine whether these early changes are associated with subsequent myopia onset.