Female pigmented rabbits received two drops of a chlorobutanol 0.5%-preserved, polyvinyl alcohol-based artificial tear at 21.00 h and 09.00 h for 1, 2, 3, 6 or 12 consecutive days. The animals were killed at 15.00, 6 h after the last treatment. Scanning electron microscopy of the corneal epithelial surface at x 200 magnification revealed only occasional cell exfoliation averaging < 8% of the surface analysed at central, mid-peripheral and peripheral sites, showing minimal cytotoxic effects. The level of exfoliation was maximal after 2 to 3 days treatment and then returned to close to zero, so the eye adapts to repeated use of the artificial tears. Evaluation of the surface microplicae of the cells at x 15,000 indicated subtle, but distinct, changes in what might be the mucus material associated with the cell surface, especially after 2 and 3 days treatment.