Abstract

Asymmetries in the distribution of photoreceptor size, density, and packing order have important consequences for the intepretation of anatomic models of retinal development and models of visual function that make assumptions about the geometry of the photoreceptor mosaic. Cone density and inner segment diameter were measured in whole mounted, nondehydrated pigtail macaque (Macaca nemestrina) retinas, viewed under Nomarski optics. Highest cone densities in the foveal center of two adult animals averaged 189,000 cones/mm². Along the horizontal meridian, there were more cones at equal eccentricities in the peripheral nasal retina than in the peripheral temporal retina. The nasotemporal ratio increased with eccentricity, reaching a maximum of 3:1. On the vertical meridian, the inferior retina was higher in density than the superior retina by a maximum ratio of 1.5:1. Cone inner segment diameter in one animal ranged from 2.6 μm at the foveal center to over 11 μm in the periphery, in all retinal quadrants. Since cones at comparable eccentricities in nasal and temporal retina have equal diameters, the proportion of peripheral retina covered by cones is greater nasally than temporally.

© 1986 Optical Society of America