Human Corneal Anatomy Redefined

Abstract

Purpose To define and characterize a novel pre-Descemet's layer in the human cornea. Design Clinical and experimental study. Participants We included 31 human donor sclerocorneal discs, including 6 controls (mean age, 77.7 years). Methods Air was injected into the stroma of donor whole globes (n = 4) and sclerocorneal discs (n = 21) as in the clinical deep anterior lamellar keratoplasty procedure with the big bubble (BB) technique. The following experiments were performed: (1) creation of BB followed by peeling of the Descemet's membrane (DM); (2) peeling off of the DM followed by creation of the BB, and (3) creation of the BB and continued inflation until the bubble popped to measure the popping pressure. Tissue obtained from these experiments was subjected to histologic examination. Main outcome measures Demonstration of a novel pre-Descemet's layer (Dua's layer) in the human cornea. Results Three types of BB were obtained. Type-1, is a well-circumscribed, central dome-shaped elevation up to 8.5 mm in diameter (n = 14). Type-2, is a thin-walled, large BB of maximum 10.5 mm diameter, which always started at the periphery, enlarging centrally to form a large BB (n = 5), and a mixed type (n = 3). With type-1 BB, unlike type-2 BB, it was possible to peel off DM completely without deflating the BB, indicating the presence of an additional layer of tissue. A type-1 BB could be created after first peeling off the DM (n = 5), confirming that DM was not essential to create a type-1…