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O. Masuda, H. Hofer, J. Carroll, D. R. Williams; Arrangement of the Human Trichromatic Cone Mosaic in Peripheral Retina. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3832.
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© ARVO (1962-2015); The Authors (2016-present)
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.
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.
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.
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.
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