Functional measurements on the enlarged endothelial cells of corneal transplants

To measure the morphologic and functional status of the endothelium of long-term corneal transplants.

We induced hypoxic corneal edema and measured corneal deswelling (expressed as percent recovery per hour, PRPH, over 7 hours) with a modified optical pachometer in 12 corneas of 8 patients transplanted 7-18 years previously and in 21 normal adult control subjects. Fluorophotometry and specular microscopy were also performed on each eye. Results in the 2 groups were compared with a 2-tailed Student T test for means.

The transplanted corneas had significantly decreased PRPH, induced swelling, endothelial permeability to fluorescein, and endothelial cell density compared to the controls, despite a similar estimated open-eye steady-state thickness.

The markedly enlarged endothelial cells of long-term corneal transplants have a reduced ability to deturgesce the cornea and decreased permeability to small solutes. These findings could result from a reduction in intercellular space that occurs when the number of cells lining the posterior surface of the cornea is substantially decreased.