Location of the stress-bearing layers of the cornea.

In order to determine which layers of the corneal stroma bear the stress of the intraocular pressure, 6.0-mm nonpenetrating trephine incisions were made centrally in one eye of each of 16 adult albino rabbits. After epithelial healing, the central corneal thickness was measured over 3 hr at 50 mmHg intraocular pressure in both eyes of the anesthetized rabbits. The animals were then killed and the uniformity and depth of trephine cut determined histologically. The mean differences in swelling rates between the cut and the opposite uncut eyes for trephine incisions of different depths were as follows: 1 +/- 2 micron/hr for 8-20% depth, 5 +/- 2 micron/hr for 21-40% depth, and 14 +/- 3 micron/hr for 41-60% depth (P less than 0.01 for all groups). These results indicate that the intraocular tension is probably distributed across all the corneal stromal lamellae rather than being borne primarily by the anterior or posterior layers.