1Ctr for Vis Science, University of Rochester, Rochester, New York
2College of Optometry, University of Houston, Houston, Texas
3Department of Ophthalmology, The Medical College of Wisconsin, Milwaukee, Wisconsin
Commercial Relationships: O. Masuda, None; H. Hofer, None; J. Carroll, None; D.R. Williams, Optos, Inc., C; adaptive optics, P.
Support: NIH EY04367, NIH EY01319 and the NSF Science and Technology Center for Adaptive Optics (cooperative agreement no.: AST-9876783 with UCSC)
Purpose:Previous studies have concluded that the packing arrangement of L and M cones near the center of the human fovea is not distinguishable from random in most eyes. We sought to determine whether this is also true for extrafoveal retina.
Methods:We classified the L, M, and S cones in one female color-normal subject with adaptive optics imaging combined with retinal densitometry at 1.25 , 4, and 10 deg in the temporal retina. We evaluated the packing arrangement of the 3 cone classes by comparing the frequencies of distances between all cones of the same type with those expected based on a random pigment assignment rule.
Results:314 cones were classified at 10 deg, 739 at 4 deg, and 1456 at 1.25 deg. The number of misidentified L and M cones at each location was estimated at 3.9 %, 2.8 %, and 2.5 % respectively. Though the ratio of L to M cones did not differ significantly across the eccentricities tested, peripheral L and M cones exhibited significant clumping whereas those at 1.25 deg did not.
Conclusions:The organization of L and M cones outside the fovea, at least in one subject, shows a clear tendency toward clumping of cones of like type. This clumping may have implications for the strength of red-green color vision in peripheral retina since it increases the probability that peripheral midget cell centers will be driven by predominantly one class of cone.
Keywords: retina color vision receptors
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