Cone photoreceptor density in the Copenhagen Child Cohort at age 16-17years.

Abstract

To examine cone density in relation to gestational and morphological parameters in the Copenhagen Child Cohort (CCC2000). The macula was imaged using adaptive optics in 1,296 adolescents aged 16-17years. Axial length and distance visual acuity were determined. Absolute and angular cone photoreceptor density were analysed for an 80×80-pixel area, 2degrees temporal to the fovea. Association with axial length was analysed with linear regression. Correlation with visual acuity was described with a Pearson correlation coefficient. Associations of cone density with gestational parameters, maternal smoking, sex and age were analysed using multiple regression adjusted for axial length. Mean absolute cone density was 30,007cones/mm2 (SD±3,802) and mean angular cone density was 2,383cones/deg2 (SD±231). Peri- and postnatal parameters, sex and age had no statistically significant effect on cone density (p>0.05). Absolute cone density decreased with longer axial length (-2,855cones/mm2 per mm or -9.7% per mm, p<0.0001). For angular density, which included a correction for the geometrical enlargement of the eye with axial length, a decrease with axial length was detectable, but it was small (-20cones/deg2 per mm or -0.84% per mm, p=0.009). The decrease in cone density per unit solid angle with increasing axial length was small, less than 1 percent per mm, indicating that expansion of the posterior pole during the development of refraction takes place without a clinically significant loss of cones. Perinatal parameters, within the spectrum presented by the study population, had no detectable effect on cone density.