Treatment of the Alkali-Burned Cornea

Recent studies have shown that the ulcers and perforations of the severely alkaliburned rabbit cornea are caused by a collagenolytic enzyme produced by the cornea.' Investigation revealed that all the cells of the cornea were destroyed immediately after ex­ posure to alkali. Seven to 10 days later, the regrowing epithelial cells and cellular ele­ ments that are repopulating the stroma pro­ duce a collagenase which ultimately ulcerates the cornea.' Treatment of the acute alkali-burned rab­ bit cornea with collagenase inhibitors pre­ vented the usually inevitable formation of ulcers." Brown and Hook treated 21 eyes having either total alkali burns or ulcerated alkali-burned corneas with the collagenase inhibitor, cystein, and reported uniformly good results. Because it was likely that sig­ nificant quantities of collagenase were not being produced before the end of the first week after alkali burning, Brown recom­ mended that the use of collagenase inhibitors could be delayed until seven days after expo­ sure to alkali. Furthermore, it was suggested that the inhibitors should be continued until the epithelium again covered the cornea, since an intact epithelial layer does not pro­ duce collagenase.