Antiproteolytic activities found in human tears.

Human tears were found to inhibit the thiol-dependent protease, papain. Inhibitory activity in normal tears was compared with that in patients with blepharitis, infectious and allergic conjunctivitis, and herpes simplex. Activities lower than normal were found in some patients with infectious conjunctivitis and blepharitis. Higher than normal activities were found in patients with herpes simplex and allergic conjunctivitis. Differences from normal values were found to be statistically significant in allergic conjunctivitis and blepharitis by analyses of sample medians, means, and geometric means. A function of this inhibitor in external ocular inflammations is suggested.