Paraoxonase 1 status in keratoconus: a preliminary study of activity and polymorphism.

OBJECTIVE To determine the activity of paraoxonase 1 (PON1) in keratoconus in a Malaysian population in comparison with non-keratoconic subjects. METHODS Clinical eye examinations were performed on patients with keratoconus and non-keratoconic subjects after questionnaires were completed. Blood samples were collected and subjected to spectrophotometric analysis of paraoxonase and diazoxonase activities for the determination of the status of PON1 of every individual. RESULTS Of the 11 keratoconic patients and 55 non-keratoconic control samples collected, eight patients of Indian ethnicity were keratoconic (73%), whereas 33 non-Indians were non-keratoconic (60%; p = 0.047). Paraoxonase activity was lower in Indians compared to the non-Indians ie Malays and Chinese (p = 0.008). Keratoconic subjects had a lower paraoxonase activity compared to non-keratoconics (p = 0.038). CONCLUSIONS The reduced paraoxonase activity in keratoconic patients suggests that the keratoconic corneas were more susceptible to oxidative stress. Reduced paraoxonase activity and keratoconus status appears to be associated with ethnicity.