We used a noninvasive technique to investigate changes in photoreceptor function with aging in observers 13-69 years of age. This technique, steady-state color matching, provides estimates of the optical density of cone photopigments, the illuminance that bleaches half of the photopigment, and the ratio of the primaries required at moderate light levels. In normal human retinas, we found that the optical density for a 4-deg field is affected minimally by aging from the second through the seventh decades. The average optical density is 0.27 ± 0.054. The optical densities of older observers varied more than those of younger observers. The change in optical density with age is nonmonotonic, with slightly lower values for the youngest and oldest observers in our study. The retinal illuminance that bleaches half of the cone photopigment varied little across observers, averaging 4.37 log Td ± 0.119. The change with age, which averages 0.00018 log Td per year over all observers, also is nonmonotonic. Moderate illuminance color matches did change with age, as expected, with a monotonic decrease with age in the ratio of the long-wavelength primary to the short-wavelength primary required for the color match.

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SUMMARY Hamartoma of the retinal pigment epithelium is an uncommon tumour of young adults. We have seen 2 patients with this clinical diagnosis, both with unusual manifestations. In one patient growth of the tumour was observed over a 5-year period. In the second patient arterialarterial anastomoses were detected at a site distal to the tumour.Retinal pigment epithelial (RPE) hamartomas are rare tumours that are classically described as having no growth potential.' They have on occasion been misdiagnosed as juxtapapillary choroidal melanomas, especially in the small percentage ofRPE hamartomas that were believed to show growth.2 We have recently seen an adolescent with an RPE hamartoma showing photographic and angiographic evidence of marked growth. We also present a patient with an RPE hamartoma associated with arterial-arterial anastomoses in a site distal to the tumour.