Retinal vessls of canine eyes at different ages—A qualitative and quantitative study

Abstract

Diameter and number of cells per unit length of vessel wall and endothelial cell frequency were determined in capillaries of trypsin-digested Foxhound retinas from different age groups. Capillary diameters increased and number of cells per unit length of capillary wall decreased with age and distance from the optic disc. Endothelial cell frequency was constant at approximately 79% of the total cells in capillary walls in all areas measured. Peripheral cystoid degeneration and peripheral annular and focal degeneration were found in aged dog retinas. Sclerosis of retinal arterioles was observed ophthalmoscopically, histologically, and in trypsin-digested retinas from aged dogs. The significance of this change in relation to the peripheral retinal degeneration is undetermined. It is proposed that thickening of basement membranes observed in peripheral capillaries of retinas causes chronic, low-level hypoxia leading to peripheral retinal degeneration in aged retinas.