Electrical fields in the vicinity of epithelial wounds in the isolated bovine eye.

A lateral potential drop along the outer surface of the cornea could be measured at the edge of wounds made in the corneal epithelium of the isolated bovine eye when the cornea was covered by simulated tear film of modified Hanks' solution. These lateral fields (LFs) had an average magnitude of 42 +/- 1.4 mV mm-1 in the first 0.25 mm from the wound edge. The polarity of these surface LFs is more positive at the wound than in regions away from the wound. Very little if any lateral field could be measured at the edge of wounds along the inner surface of the corneal epithelium. The surface LFs depend on the cornea's transepithelial potential (TEP), which in this isolated bovine eye preparation we determined (with conventional microelectrode techniques) to have an average value of 24.7 +/- 2.2 mV, stroma-side positive. We found that this TEP drives a current from wounds in the epithelium with an average current density of 55 +/- 12 microA cm-2. We also have found that the average transcorneal potential (TCP) was 3.2 +/- 0.5 mV greater than the average TEP, confirming that the major contribution to the TCP comes from the corneal epithelium.