Healing of Excimer Laser Ablated Monkey Corneas

The healing response of the cornea following excimer laser anterior keratomileusis (a 4-mm-diameter ablation to a depth of 11, 23, or 46 microns) was analyzed immunohistochemically in adult rhesus monkeys. The ablated surface had reepithelialized and the synthesis of type VII collagen (a major component of anchoring fibrils) was evident by 7 days; the reestablishment of a nearly continuous anchoring fibril zone was evident after 12 weeks. Stromal fibroblasts, activated in response to wounding, expressed a fetal antigen for approximately 6 weeks. Although fibronectin and type VII collagen were present only transiently in the regenerating subepithelial stromal matrix in the subepithelial regions, some other alterations, including the presence of type III collagen, increased levels of keratan sulfates, and discontinuities in the anchoring fibril zone were evident even 18 months after wounding. The depths of the regenerated stroma, which were estimated from the depths of remnant staining for type VII collagen in the stromal matrix, generally, but not always, corresponded to the depths of the calculated ablation.