Age-based Estimation of Contact Lens Base Curve in Filipino Infants

Abstract

Objective. To create an age-based formula to estimate the base curve needed for contact lens fitting using measured central corneal curvature (CCC) with a handheld auto keratometer from ophthalmologically normal infants. Methods. This is a prospective cross-sectional study involving 70 ophthalmologically normal full-term infants aged 0 to 12 months. The infants were divided into four groups: 0–3 months, >3–6 months, >6–9 months and >9–12 months. CCC was measured with a handheld auto keratometer and was used to compute for the base curve. Differences in CCC between the four groups were measured and linear regression models were used for formula creation. Results. The mean CCC was highest in group 1 at 45.5 ±2.4 diopters (D). These values slowly decreased as age increased. A formula predictive of the base curve based on the infants age was derived using linear regression analysis. It predicted that for every month increase in age, there is a 0.063 millimeter increase in the base curve (p<0.001). Conclusion. Infant CCC is highest at birth and gradually decreases as age increases. The formula can predict the base curve needed for contact lens fitting in infants without the need for a handheld autokeratometer.