Levels of alpha1-proteinase inhibitor and alpha2-macroglobulin in the tear film of patients with keratoconus.

OBJECTIVE

Levels of alpha1-proteinase inhibitor and alpha2-macroglobulin in the tear film of patients with keratoconus were measured to elucidate their possible roles in the pathogenesis of keratoconus.

METHODS

Tear samples were collected from 15 keratoconus patients and 14 age-similar human control subjects. Levels of alpha1-proteinase inhibitor and alpha2-macroglobulin in each tear sample were quantified and compared between the two groups.

RESULTS

Mean values for alpha1-proteinase inhibitor were 101.0+/-35.5 and 106.1+/-41.7 ng/microg protein for the keratoconus and control groups, respectively. The corresponding mean values for alpha2-macroglobulin were 13.5+/-6.8 and 14.8+/-7.5 ng/microg protein. Neither inhibitor showed a statistically significant difference between the keratoconus and control specimens. Subset analysis to evaluate the effects of contact lens wear and the presence of a graft in the fellow eye did not reveal a statistically significant difference.

CONCLUSIONS

The tear film of patients with keratoconus contains normal levels of protease inhibitors. Therefore, the tear film may not be a source of the reduced inhibitor levels shown in the corneas of patients with keratoconus.