Changes In The Cellular Density

It has been observed that with aging, a physiological decline in the number of RPE cells occurs, especially in the macula. In the peripheral retina, however, the number of RPE cells can increase, diminish, or remain the same

with aging, whereas in the central retina the density of RPE cells decreases with age (Dorey et al, 1989). More precisely, Panda-Jonas et al. (1996) observed an average annual loss of 17 RPE cells/mm2 per year with respect to an original RPE cell population of 5,232 cells/mm2. These authors estimated that in the course of a life of 100 years, around 30% of RPE cells are lost. These values are associated with an age-related loss of 3000 to 5000 optic nerve fibers, around 0.3% per year, in a population of 1.4 million fibers at birth and a diminution in the density of cones and rods of 0.3 to 0.5% per year with respect to the photoreceptor density at birth. These observations indicate a reduced reserve capacity in elderly patients with respect to younger individuals. This fact may be the cause of the decline in vision function even in the absence of active pathologic processes. Given that the RPE cells do not have the capacity to reproduce, the cells adjacent to those lost increase their cell volume, restoring the normal continuity of the RPE cells/photoreceptors. Dorey et al. (1989) have found that the average ratio of photorecep-tors/RPE cells is higher in the macula with respect to the paramacular and equatorial areas, and that this ratio increases with age. The is one of the most reactive tissues of the eye and can undergo atrophic, hypertrophic, and hyperplastic modifications as well as migration processes.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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