Purpose: To evaluate the effect of age on the density of retinal photoreceptors in humans.
Methods: Fifty-five normal eyes from human donors, with a mean age of 58.7 +/- 19.1 years and an axial length of less than 27 mm, were examined. After opening of the globes by a 16-mm corneoscleral trephination, 25 retinal tissue samples were obtained in four meridians. The photoreceptors were counted on photographs taken from the photoreceptor inner segments after sonographic removal of the outer segments. The cones in the foveal center could not be evaluated.
Results: Outside the foveal center, the photoreceptor density decreased significantly with increasing age. In absolute and relative terms, the decline was more marked for the rods (mean rod loss, 236 +/- 63 cells or 0.37% +/- 0.10%/mm2 and year of a mean density of 62.987 rods/mm2) than for the cones (mean cone loss, 5.90 +/- 0.68 cells or 0.18% +/- 0.02%/mm2 and year of a mean density of 3320 +/- 578 cones/mm2). For both cones and rods, the cell loss was more marked at an eccentricity of approximately 5-8 mm than in the retinal periphery at an eccentricity of 14 to 20 mm. There were no significant differences between the superior, inferior, temporal, or nasal meridian nor between women and men.
Conclusions: The photoreceptors decrease in density with increasing age. The annual cell loss of approximately 0.2% to 0.4% is similar to the age-related loss of retinal ganglion cells and pigment epithelium cells. The decline in photoreceptor count affects more rods than cones. It does not prefer special age groups. It is more pronounced at an eccentricity of 5 to 8 mm than in the retinal periphery at an eccentricity of more than 14 mm. It may be important for an age-related decrease in visual functions and for diseases affecting the photoreceptors in elderly patients.