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Shagun Arora, Alia Rashid, Micah Chrenek, Qing Zhang, Soojung Park, Hans Grossniklaus, John Nickerson; Analysis of Human Retinal Pigment Epithelium (RPE) Morphometry in the Macula of the Normal Aging Eye. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2014.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study was to describe normal changes in RPE mophometry of the macula that occur with aging. These described changes can be used to detect individuals who fall out of the normal range, facilitating the development of diagnostic tools for earlier detection of retinal diseases such as age-related macular degeneration (AMD).
Cadaveric human donor eyes of varying ages were obtained from the Georgia and North Carolina eye banks. Donor eyes were microdissected and RPE flatmounts were immunostained for AF635-phalloidin, nuclei stained by propidium iodide, and imaged by confocal miscroscopy. Image analysis was performed using ImageJ (NIH) and Cellprofiler software (Broad Institute, Cambridge, MA). A large number of quantitative parameters were obtained from these analyses to characterize individual and groups of RPE cells. Measurements were taken from selected areas spanning the length of the retina, from the macula to the far periphery.
Seventeen eyes from 11 donors of varying ages ranging from 29-82 years were used. An overall trend of decreasing RPE cell density with age was seen in the macula (r2= 0.42). When individuals were divided into two age groups, <60 years old and >60 years old, there was a higher cell density in the younger group (p< 0.05). A trend of increasing average cell area with age was observed in the macula (r2=0.37). Cell area was higher in the older group (p<0.05). The percent of hexagonal RPE cells in the macula showed a slight decreasing trend with age (r2=0.16), but when older and younger groups were compared, there was no statistically significant difference (p>0.05). Average eccentricity showed a trend towards a higher value and a more elongated shape with age (r2= 0.50), and was higher in the older group (p< 0.05). Form factor, another measure of cell shape, displayed a decreasing trend with age (r2=0.33) and a lower average value in the older group (p<0.05).
RPE cell density in the macula, percent of hexagonal cells and average form factor show a decreasing trend with age, while the average cell area and eccentricity show an increasing trend. This suggests that with age, cell density decreases and therefore cell size increases. The RPE cells also lose their prototypical hexagonal shape and become more elongated. These observed differences in the aging eye may resemble early changes seen in the pathologic RPE of AMD.
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