Corneal epithelial healing under contact lenses. Quantitative analysis in the rabbit.

The rate of corneal epithelial healing was determined as a function of the oxygen level present at the tear-cornea interface. Oxygen levels of 1.77, 2.3, 5.3, 8.55, 10.12, and 16.45% were created over the rabbit cornea with tarsorrhaphy and various contact lenses. Full depth epithelial defects of 4.5 mm diameter were created in 6 animals for each test condition with the fellow eye serving as a control and healing in air (21.09% oxygen). The defect (radius) was measured at 24-h intervals until healing occurred. Statistically significant (p less than 0.05, paired Student t-test) delays in healing were found with oxygen levels of 8.55% and below. These delays were most profound over the initial 24 h. The healing rate with tarsorrhaphy, at the 1.77% oxygen level, over the first 24 h was 5.2 microns/h radius, only 15.2% of the paired control, 34.0 microns/h radius, healing in air (21.09% oxygen). Healing rates over the initial 24 h under contact lenses allowing 2.3, 5.3, 8.55, 10.12, and 16.45% oxygen were 6.1, 23.5, 26.5, 43.0, and 45.0 microns/h in radius, respectively.