Growth of the cornea from infancy to adolescence

The intraocular distance and iris diameter of children and young adolescents were measured, with the aid of a measuring microscope, from photographs of their faces. True intraocular distance was measured with an intraocular caliper at the same time that the photographs were taken. These data were then compiled and horizontal visible iris diameters (HVIDs) were calculated. An equation was derived from the optics of the Gullstrand model eye to calculate horizontal corneal diameter (HCD) from HVID. Comparisons of HVIDs revealed no significant correlation with age in either a regression plot of cross-sectional data for subjects aged 1 month to 1 year, or all subjects whose ages ranged from 1 month to adolescence. Additional longitudinal data for 13 individuals, who had been photographed as both an infant (mean = 3.4 months) and as an older child or adolescent (mean = 8.6 years), were then compiled and HVIDs for these subjects at two different ages were compared. A Wilcoxon signed rank test revealed a small but significant amount of growth, 0.318 mm (p-value = 0.013), in the HVIDs over a mean age difference of 8.3 years for individuals measured twice during their lifetimes. The regression equation for this growth was: HVID = 10.52 (+/-0.095 S.E.) + 0.0305 (+/-0.014) x Age (years). From a comparison of data from earlier literature and our own measurements, we conclude that, after birth, the fastest growth of the cornea must occur during the first few months of life.