Density of foveal cone pigments at older age.

We investigated foveal cone photopigment kinetics by retinal densitometry in 34 eyes of 29 healthy subjects with clear optical media and good visual acuity, ranging in age from 39 to 79 years. Our aim was to assess possible senile disturbances of foveal cones. To assess the effects of ocular straylight, we measured not only in subjects with a clear crystalline lens, but also in pseudophakia and aphakia. In a limited number of subjects color vision was assessed with a Nagel anomaloscope; no systematic changes with age were found. A significant decrease in two-way density and in time constant of regeneration was found to occur only after age 60, with large individual variations. There was no indication that results for subjects with their natural crystalline lens, in aphakia, or in pseudophakia were different. We argue that a reduction in the number of cones with age, rather than an increase in ocular stray light is the most likely explanation of our findings.