Efficiency and survival of the corneal endothelial pump

In this article the state of knowledge on the biochemical requirements of the corneal endothelial fluid pump is summarized. This pump is a general interest for the study of transport mechanisms. It is a single layer of homogenous cells, very actively transporting fluid out of the cornea (25-40 μl/cm²/hr). The transmembrane potential, if there is any, is less than 1 mV. Its regulatory role is largely responsible for the maintenance of corneal thickness in vivo; changing the fluid composition on the epithelial side in vitro has no effect on the course of deturgescence. From the histological, biochemical and biophysical viewpoints, the corneal endothelium seems to be a simpler system for the study of active transcellular water and salt movement than accepted models.