Abstract

Because of the possible role of melanin in various ocular pathologies, it is important to develop a noninvasive objective measurement of this ocular pigment. We have used imaging fundus reflectometry to assess the spatial distribution of melanin within the macular region. A microchannel plate-intensifier solid-state video camera viewed an area of the fundus (21° horizontally by 16° vertically) through the optics of a modified Zeiss fundus camera. A fiber-optic lightguide illuminated by a computer-controlled optical system replaced the normal Zeiss light source. Images of the unbleached and bleached fundus were obtained at thirteen wavelengths (460-700 nm). For the present study, digitally processed images of the bleached fundus obtained at long wavelengths (>620 nm) were used to provide an estimate of the spatial distribution of melanin in the macular region. In three Caucasian subjects, our measurements show a region of lower reflectance in these long wavelengths that is ~10° in diameter and centered on the fovea. This result is consistent with previous anatomic studies reporting that the melanin optical density is higher in the central macula than in the surrounding region.

© 1988 Optical Society of America