Aging and human cone photopigments

Abstract

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.

Cone photopigment in older subjects: decreased optical density in early age-related macular degeneration

“…28 There are only small individual differences across subjects, indicating well-regulated kinetics in normal subjects. Several methods have shown changes with normal aging in both the kinetics [26][27][28][29] and the optical density of cone photopigment in the centralmost fovea.…”

“…28 There are only small individual differences across subjects, indicating well-regulated kinetics in normal subjects. Several methods have shown changes with normal aging in both the kinetics [26][27][28][29] and the optical density of cone photopigment in the centralmost fovea. 33,37,38 In retinal disease, this color matching technique has been able to reveal changes in optical density [39][40][41] and kinetics.…”

“…30,32,36 In normal subjects over a broad range of ages, four parameters are necessary and sufficient to describe these data. 28,29 A cumulative normal model, which is based on a Gaussian curve having symmetry about the mean, fits the data well (Fig. 1).28 -31 The first parameter, optical density (OD), is calculated from the amplitude of the Gaussian function, which is steeper than a diffusion model.…”

“…32 Color matching at moderate light levels has been used successfully over a wide range of ages by several groups 12,[33][34][35] and by us over a wide range of retinal illuminances and ages. 28,29,36 Data are fitted by using the Smith-Pokorny cone photopigment fundamentals. 30,32,36 In normal subjects over a broad range of ages, four parameters are necessary and sufficient to describe these data.…”

Photopigment optical density of the human foveola and a paradoxical senescent increase outside the fovea

“…Previous studies have reported age-related decreases in photopigment OD based on reflection densitometry (Kilbride et al, 1986;Keunen et al, 1987;Coile & Baker, 1992) and color matching (Eisner et al, 1987;Elsner et al, 1988;Swanson & Fish, 1996). Because these aging studies have been conducted with trichromats, the photopigment OD of M-and L-cones may have been confounded.…”