Distribution patterns of photoreceptors, protein, and cyclic nucleotides in the human retina

The concentration of cGMP, cAMP, protein and the number of cone and rod photoreceptors have been measured in parallel arrays of punches, 3 mm in diameter, taken from each quadrant of normal human retinas. A separate punch containing the fovea and parafoveal region was also analyzed. Eyes were obtained from four male donors ranging in age from 35 to 67 yr. The retina thins considerably from the center to the periphery, and consequently the protein content forms a gradient in the same direction. Similar gradients were observed for cAMP and cGMP concentrations. In all eyes studied, the foveal-parafoveal region had higher levels of cAMP than cGMP. The data was analyzed with the aid of a computer in order to obtain three-dimensional maps of the patterns of distribution of the different parameters. A strong correlation between the areas of higher cone density, non-photoreceptor neurons, and cAMP, and an equally strong correlation between rod distribution and that of cGMP was observed. These maps will serve as baseline data in studies of pathological conditions such as retinitis pigmentosa.