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Ann E Elsner, Joel A Papay, Stephen A Burns; Differences in the distribution of cone density for younger vs. older healthy subjects. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3433.
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© ARVO (1962-2015); The Authors (2016-present)
Older subjects with healthy eyes have relatively lower cone densities than younger subjects, measurable in living eyes with adaptive optics scanning laser ophthalmoscope (AOSLO) despite large intra-Individual differences. We compared for each eye the distribution of cone density and retinal layer thicknesses at specific eccentricities as a function of meridian. We probed the extent to which older eyes have higher cone densities than younger eyes in specific locations, e.g. the parapapillary nasal retina.
To quantify aging changes at specific retinal locations, we used individual nasal, temporal, inferior, and superior meridian cone densities from the Indiana AOSLO aging norms. The 8 younger subjects were 24–32 yr, mean 27.2 yr. The 8 older subjects were 51–65 yr, mean 56.2 yr). The effects of myopia on cone density and layer thickness were minimized by constraining refractive error and axial length. Spherical equivalent was +1.00 to -3.75 diopters for younger subjects and +2.50 to -3.75 D for older subjects. Using linear regression and 2 factor ANOVAs, we compared focal results, e.g. ratio of cone density for a given meridian to the average of all 4 meridians.
The ratio of cone density in the nasal retina to the average for all 4 meridians increased with retinal eccentricity, from 1.07 at 300 microns to 1.25 at 1890 microns nasal to the fovea for older subjects, but only from .975 to 1.02 for younger subjects. This trend was not observed consistently for temporal retinas, and inferior and superior retina have lower cone density ratios overall. ANOVA comparing nasal vs. temporal retina indicated that both older and younger subjects had higher cone densities in the nasal than in temporal retina (p = .0006, p = .019, and p = .0016) at 1890, 2070, and 2160 microns nasal to the fovea, respectively. The tendency for the cone density ratio to be greater in parapapillary nasal retina occurs consistently in older eyes, and the interaction (meridian X age group) was statistically significant at 1890 microns nasal to the fovea (p = .0495).
Cone density, known to decrease systematically with increasing distance from the fovea, is relatively preserved in older eyes in nasal retina that is temporal to the peripapillary region. The parapillary region may offer relatively more resources for preservation of cones in aging.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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