Cystatins in tears of patients with different corneal conditions.

A presence of cystatins, inhibitors of cysteine protease, was investigated in tears of patients with different corneal pathologies. Tear fluid samples were collected with glass capillaries in 28 patients (28 eyes) and 15 healthy controls (15 eyes). Only after corneal transplantation (8) or in corneal dystrophy (6) but not after cataract extraction (5) or other traumatic conditions of the cornea (9) was a significant difference in inhibitory activity of cystatins measured in comparison with the 15 controls. In this study it could not be decided whether the lower level of cystatins was related to the cause or the effect of the condition of the eye.