Melanin concentration in normal human retinal pigment epithelium. Regional variation and age-related reduction

Abstract

Melanin concentrations were analyzed in the pigment epithelium of 61 postmortem normal human eyes from donors 14-97 yr of age. The content of soluble melanin in the pigment epithelium declined with age from the highest values of 95 micrograms/mg in the 14-50 yr age group to the lowest values of 22 micrograms/mg dry weight in the over 70 yr age group. In 16 of these eyes, regional measurements revealed that melanin concentrations were lowest in the macula-perimacular area (a region 5-8 mm in diameter centered on the fovea), were higher in the mid-periphery, and were highest in the far periphery. In the macular region, melanin concentrations were similarly low at all ages, whereas, in the mid- and far-peripheral regions, melanin concentrations decreased with age. These studies demonstrate age-related reductions and regional variations in melanin concentrations in the pigment epithelium of postmortem normal human eyes, and establish a baseline for future comparison with donor eyes from patients with hereditary retinal degenerations.