Corneal wound healing after excimer laser ablation in rabbits: expanding versus contracting apertures

Photorefractive keratectomy for myopia can be performed using an expanding or contracting iris diaphragm, either of which allows for greater ablation centrally and less tissue ablation toward the edge of the treatment zone.

To compare the effects of these two strategies, eight rabbits underwent bilateral 5.00-diopter myopic ablations, performed with a contracting diaphragm in one eye and an expanding diaphragm in the other.

The rate of epithelial healing and degree of anterior stromal haze, monitored by a masked observer, were similar for the two groups, as was the amount of corneal flattening.

These results in rabbit corneas do not suggest a particular advantage of either the expanding or contracting apertures for achieving central corneal flattening in photorefractive keratectomy.