The cone density of the fovea in all age groups is high and reduces rapidly with the eccentricity and in a small amount in an area that extends around the optic disk and in the nasal retina. The density of cones is variable in the different groups of age (coefficient of variability from 15 to 30%) around the optic disk; it is nonetheless lower (<15%) over 1mm of eccentricity. In the map (personal unpublished results) the average difference between the older age groups and the younger group is significant; cold colors indicate a density lower than that of the younger group, and warm colors indicate that the average density is higher than that of the younger group. The map, which is yellow-green, indicates that the difference between the groups is minimal.
The map indicates that the group from 44 to 58 years has the smallest cone density difference (88% of the younger group), but small differences were also seen in older groups. The mapped retinal region in all the eyes was of 8 mm diameter; that is, 5% of the whole retinal area of the eye contains 10% of the cones that are found in the central 28.5°. The average number of cones over all the eyes in this region was 488,600.
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