Response of ocular surface epithelium to corneal wounding in retinol-deficient rabbits

The purpose of this study was to explore the nature and time course of the functional effects of early retinol deficiency on the ocular surface epithelium. To this end, the conjunctival epithelial healing rate, mitotic rate, and goblet cell frequency were determined following experimental ocular surface epithelial wounding in 15 rabbits sustained on a retinol-deficient diet and in 12 pair-fed controls. The animals were sacrificed at 2, 7, and 14 days after wound closure. The mean serum retinol level (+/- SEM) prior to wounding was 6.0 +/- 0.9 microgram/dl for the group fed the deficient diet. The mean serum and liver retinol levels for this group following defect closure were 4.0 +/- 0.5 micrograms/dl and 0 micrograms/g, respectively. These values are all significantly less than the analogous respective control values of 83.2 +/- 2.4 micrograms/dl, 77.6 +/- 2.3 micrograms/dl and 35.1 +/- 3.0 micrograms/g (P less than 0.001 for each pair, student t-test). In the retinol-deficient animals, the unwounded eyes had an abnormally high rate of conjunctival epithelial cell mitosis, the earliest ocular surface cellular abnormality detected. Hypermitosis of the unwounded corneal epithelium was also noted, though somewhat later than in the conjunctiva. Epithelial wound healing was delayed considerably in the retinol-deficient group, with only 33% of eyes in this group healed within the same time period as the controls (P less than 0.05, Chi-square). Normal numbers of goblet cells were noted in the conjunctiva of retinol-deficient animals, despite at least 5, and up to 8 weeks of profoundly depleted retinol stores.(ABSTRACT TRUNCATED AT 250 WORDS)