Decreased endothelial pump function with aging

Endothelial function may be affected by the endothelial cell loss and increased variability in cell shape and size (polymegathism) that accompany normal aging. Endothelial function can be evaluated by monitoring corneal hydration recovery following hypoxic stress. The authors compared corneal recovery and endothelial morphology between a group of younger (mean = 26.7 yr) and older (means = 65.7 yr) subjects with normal corneas. Edema (60 microns) was induced with hydrogel lenses worn with the eyes closed. Following lens removal, the decrease in corneal thickness was monitored for 4 hr with one eye open while the contralateral eye remained closed. For both age groups, corneal recovery followed a non-linear time course. The open eye required 2.5 hr and 3.0 hr to return to baseline for the younger and older age groups, respectively. Recovery during eye closure took 3.5 hr to reach the normal closed eye level for the younger subjects and was not complete at 4 hr for the older subjects. Recovery rates were significantly slower for the older vs younger subjects during the first 2 hr of closed eye recovery, 10.5 vs 15.0 microns/hr, and for the initial 1 hr of open eye recovery, 26.5 vs 35.6 microns/hr. For both age groups combined, the rate of recovery was negatively correlated with the coefficient of variation in cell area, r = -0.62 and -0.69 (P less than 0.01), for both closed and open eye recovery, respectively. When each morphological characteristic was isolated, the only significant correlation found was between the coefficient of variation in cell area and the rate of recovery during eye closure, r = -0.66 (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)