Direct in vivo measurement of corneal epithelial metabolic activity using a polarographic oxygen sensor

The component oxygen fluxes that constitute a single recording of corneal oxygen uptake when a polarographic oxygen sensor (POS) is placed in contact with the cornea were determined in the in vivo rabbit eye by removing the epithelium and injecting an air bubble into the anterior chamber. The relative contribution of epithelial oxygen consumption, stromal oxygen consumption and diffusion were approximately 55, 5 and 40%, respectively. It is demonstrated that differences in corneal oxygen uptake rates recorded with a POS primarily indicate differences in epithelial metabolic activity. Changes in epithelial metabolism can be determined by measuring both corneal oxygen uptake and corneal thickness. For example, if corneal thickness is constant, differences in epithelial oxygen flux (a) between two eyes of one person, or (b) before and after a procedure in the same eye, can be calculated by multiplying the difference in oxygen consumption measured with a POS by a factor of 1.8.