Human lens capsule thickness as a function of age and location along the sagittal lens perimeter.

PURPOSE: To investigate the variation in the thickness of the human lens capsule along the lens perimeter, as well as its changes with age.
METHODS: Altogether, 26 human donor lenses, aged 12 to 103 years, were histologically processed. Sagittal sections were stained for collagen with periodic acid-Schiff (PAS). Serial images of the lens border were taken with a photomicroscope and 25x objective. Capsular thickness was measured every 250 microm along the entire lens perimeter.
RESULTS: All studied capsules were thicker anteriorly, continuously increasing with age from 11 to 15 microm in average at the anterior lens pole. Maximum thickness was located at the anterior midperiphery, increasing with age from 13.5 to 16 microm. In most cases, there was a local thinning at a pre-equatorial zone, recovering to approximately 7 microm at the equator. The latter value, as well as the minimal thickness at the posterior pole (mean 3.5 microm), did not change with age, whereas the average thickness at the posterior periphery decreased from 9 to 4 microm.
CONCLUSIONS: The human lens capsule thickness is at its maximum at the anterior midperiphery, which appears to be located central to the zonular insertion. It increases with age, especially at the anterior pole, while the midperipheral zone stabilizes or slightly decreases after the seventh decade. The anterior zonular insertion is actually related to a local pre-equatorial thinning, which remains unchanged with age. There was no posterior peripheral thickening, except in a few younger patients, with a modest relative maximum roughly at the equator. From here, the posterior capsule becomes progressively thinner and also diminishes with age, except for the thinnest, but stable posterior pole.