Measurement of wettability of the corneal epithelium. I. Particle attachment method.

Surface wettability of the adult rabbit cornea, as indicated by the epithelium/air surface tension, was estimated from the attachment of particles of several different types from suspension in dimethyl sulphoxide-saline bathing solutions. The mean surface tension of corneas where mucus had been removed by rinsing with N-acetyl cysteine was 67.5 +/- 0.6 mN/m, and for corneas retaining their native covering of mucus was 68.3 +/- 0.8 mN/m. Thus the wettability of the normal cornea does not depend on the presence of mucus to overcome its previously-supposed hydrophobicity. Removal of mucus by wiping gave a damaged surface for which no surface tension could be determined within the range of solution surface tensions studied.