Effects of soft contacts of differing thickness on corneal wound healing in rabbits

This study was undertaken to determine the effects of thin (60 microns) and thick (240 microns) soft contact lenses of equal water content (70%) and power on nonlesioned and lesioned rabbit corneas. In one group of animals, corneas were not lesioned. Thin lenses were placed on left corneas and thick lenses on right corneas. In a second group, lesions were made in both corneas. Left corneas were covered with thin lenses and right corneas with thick lenses. Post-treatment times were 8 hr and 24 hr. At sacrifice, one-half of the cornea was fixed in 4% buffered glutaraldehyde for SEM study. The other half was cut into segments, fixed in a buffered glutaraldehyde-ruthenium red (RR) solution post-osmicated in osmium containing RR and prepared for TEM. At both 8 hr and 24 hr SEM showed cell migration in lesioned corneas covered with thin lenses but not in lesioned corneas covered with thick lenses. At 8 hr, TEM of nonlesioned and lesioned corneas showed no changes in the thickness of the corneal epithelium or the RR staining of the surface. At 24 hr, in nonlesioned corneas covered with thick lenses, the RR staining of microvilli and the height of the corneal epithelium were less than in nonlesioned corneas covered with thin lenses. In lesioned corneas covered with thick lenses, the thickness of the cornea was markedly reduced, the RR staining of microvilli was less and basal cells were more compressed than in lesioned corneas covered with thin lenses. The results of this study indicate that the thickness of a soft contact lens is important in treating corneal trauma.