[Relationship between birth month and corneal radius or axial length].

ABSTRACT

PURPOSE: Hyperopia prevalence is higher in children born in the autumn. This study attempted to detect whether corneal curvature or axial length are related to this phenomenon. METHODS: Using data from a total of 4056 cataract patients aged 40 and over from three medical facilities, corneal radius and axial length, measured to determine the intraocular lens power needed for cataract surgery, were reviewed. Mean corneal radius and mean axial length were calculated for each birth month. The means were then graphically analyzed to determine the relationship of corneal radius or axial length with birth month. RESULTS: No correlation was noted between axial length and birth month. However, a correlation between corneal radius and birth month was observed in each of the three facilities. Specifically, subjects born from October through December tended to have larger corneal radii. Numerically, the corneal radius showed a statistical relationship in terms of birth month (p < 0.001, ANOVA), while the axial length showed no relationship (p = 0.907, ANOVA). CONCLUSION: A statistically meaningful relationship between corneal curvature and birth month was detected. Corneal development might be affected by seasonal daylight variations in infancy, thus contributing to the occurrence of hyperopia.