Foveal cone photopigment distribution: small alterations associated with macular pigment distribution

Abstract

Purpose: To map the photopigment distribution of central foveal cones in healthy adult subjects before potential onset of age-related macular degeneration. To compare alterations in cone photopigment distribution to those of macular pigment and examine those loci for subretinal changes.

Methods: Eleven healthy subjects (age range, 31-59 years) underwent reflectometry with a scanning laser ophthalmoscope. The difference in cone photopigment density in the fovea was mapped for the long-wavelength- and middle-wavelength-sensitive cones, using 594-nm light. Macular pigment was mapped with 488-nm and 514-nm light. Subretinal changes were investigated with infrared imaging (830-860 nm).

Results: Most subjects had small alterations in the regularity of their foveal cone photopigment distribution. Alterations were spatially related to macular pigment alterations but not to the presence of subretinal defects. Subjects were classified into three groups according to the type of alterations in the regularity of pigment distributions: central peak of photopigment and macular pigment, small foveal alterations, and broad distribution with missing central peak of photopigment or macular pigment. The resultant groups differed significantly in age, 43, 46, and 59 years, for groups 1, 2, and 3, respectively (P < 0.05).

Conclusions: Small alterations in the distributions of foveal cone photopigment or macular pigment were found that varied among the subjects. Larger alterations in older subjects may indicate changes in foveal architecture with age, including potential vulnerability of central cones before the onset of clinically significant changes in the retinal pigment epithelium.