Lysosomal Enzyme Activities in Conjunctival Tissues of Patients With Keratoconus

OBJECTIVE: To examine the lysosomal enzyme activities in the conjunctival tissues of patients with keratoconus. METHODS: Tissues collected from 11 patients with keratoconus, eight patients with senile cataract, three patients with Fuchs' corneal dystrophy, and 11 normal control subjects were processed for histochemical staining for two lysosomal hydrolases, acid esterase and acid phosphatase. RESULTS: The epithelium of all conjunctival specimens stained positively for the two enzymes. The staining in the conjunctival tissues of patients with keratoconus was more prominent than that seen in specimens from either normal control subjects or patients with other diseases. CONCLUSION: Our results suggest that the conjunctival epithelium may be altered in keratoconus. Elevation of lysosomal enzyme levels has been demonstrated in the epithelium of corneas with keratoconus, implicating a role of this layer in the disease. The conjunctival abnormality seems to corroborate the corneal epithelial theory. It also adds one dimension to the pathogenesis of keratoconus.