Incidence and Risk Factors of Refractive Error in Children in Spain: CISViT Project.

BACKGROUND

The incidence of refractive errors (RE), particularly myopia, has increased in recent years, presenting significant geographic variations. This prospective longitudinal cohort study aims to assess the incidence of RE in a school-based cohort in northeastern Spain and identify associated risk factors.

METHODS

The study followed up 1189 children with an ~1-year interval (mean age: 8.74 years at visit 1 and 10.00 years at visit 2) from a school-based cohort in northeast Spain (2021-2024). RE was measured using an autorefractometer and retinoscopy without cycloplegia. A preliminary questionnaire was used to collect data on potential risk factors such as visual habits and socioeconomic status.

RESULTS

The spherical equivalent (SE) at the initial visit was +0.29 ± 0.03 D, decreasing to +0.14 ± 0.04 D at follow-up. The prevalence of myopia increased from 12.3% at baseline to 17.1% at follow-up. A total of 56 incident cases were identified, corresponding to a cumulative incidence of 5.4%. In multivariable logistic regression, baseline SE ≤ +1.00 D was associated with a clinically significant myopic shift (odds ratio (OR) = 1.67, 95% CI 1.29-2.16; p < 0.001). Parental myopia was strongly associated with the outcome (maternal: OR = 23.36, 95% CI 8.33-65.49; p < 0.001; paternal: OR = 4.25, 95% CI 1.74-10.38; p < 0.001). Lower outdoor exposure was also associated with higher odds of a clinically significant myopic shift (low vs. high: OR = 9.33, 95% CI 5.89-14.79; p < 0.001). Parental education was not significantly associated, whereas parental unemployment was associated with higher odds of myopic shift in the fully adjusted model.

CONCLUSIONS

The incidence of myopia and progression of RE (change in SE) in this school-based cohort of northeastern Spanish schoolchildren was significant over 1 year. Factors such as paternal/maternal myopia, reduced outdoor time and both paternal and maternal unemployment were associated with a higher risk of a clinically significant myopic shift (ΔSE ≤ -0.50 D).