Ocular Biometry Distribution and One-Year Growth in Eight-Year-Old Southern European Schoolchildren Under the CISViT Project.

Objective: To analyse variations in axial length (AL), corneal radius (CR) and the AL/CR ratio over one year in eight-year-old schoolchildren, considering sex, ethnicity and refractive error. Methods: Vision screenings were conducted in 16 schools in Terrassa (Barcelona, Spain) with eight-year-old children as part of the CISViT project. Measurements included ocular biometrics (AL and CR) and non-cycloplegic autorefraction for refractive error. Parental questionnaires provided demographic data (birth date, ethnicity). The same procedures were repeated after one year. Results: Ocular biometric parameters differed by sex and ethnicity. Boys and children of Maghreb descent had longer AL and flatter CR than girls and Caucasian children (p < 0.001 for both visits). The AL/CR ratio was higher in boys than girls (p = 0.002 in the initial visit and p = 0.011 in the follow-up visit) but consistent across ethnicities (p = 0.291 and p = 0.390). AL and AL/CR ratio differed significantly by refractive error status (p < 0.001 in both visits), increasing in more myopic children, while CR showed no significant difference. In myopic children, the AL/CR ratio exceeded 3.0, and typical sex-based biometric differences diminished. Growth rates for AL and AL/CR ratio were similar across sex and ethnicity, indicating minimal demographic influence. Conclusions: AL and CR differ significantly by sex and ethnicity, with demographic differences evident in baseline measurements but not in growth rates over one year. The consistency of the AL/CR ratio across ethnicities, despite sex-based differences, supports its utility as a reliable metric for assessing refractive development in diverse populations.