Corneal endothelium bicarbonate transport and the effect of carbonic anhydrase inhibitors on endothelial permeability and fluxes and corneal thickness.

Unidirectional fluxes of bicarbonate across the corneal endothelium were determined. A net flux of bicarbonate from the stromal to aqueous-facing surface was demonstrated. Under conditions of carbonic anhydrase inhibition the net bicarbonate flux was reduced by 54 percent and the passive water permeability of the endothelium was increased. Experiments with the specular microscope demonstrated an increased rate of corneal swelling under conditions of carbonic anhydrase inhibition. Attempts to identify H+ as the cation moving with the bicarbonate ion to maintain electroneutrality were not successful because of the impossibility of sustaining a differential H+ concentration difference across the endothelium.