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.

Accuracy of visual correction in photorefractive keratectomy.

PURPOSE: To investigate the accuracy of preoperative optical assessment and other factors that influenced the final visual outcome after photorefractive keratectomy (PRK). METHODS: The records of 126 eyes from 54 male and 72 female eyes were studied retrospectively, ranging from 6 months to 3 years post-PRK. Refractive errors ranged from low to high myopia and astigmatism, and proper and careful preoperative selection of patients was made. A single standard ablation zone (AZ) of 6.00 mm and transition zone (TZ) of 7.00 mm was made in all cases. RESULTS: The study population showed a high degree of accuracy in visual outcome. In simple myopia, 92.3% of female eyes and 84.1% of male eyes had a visual acuity of more than 6/9 or better. In myopia with astigmatism, 83.05% of female and 65.9% of male eyes had a visual acuity of 6/9 (20/40) or better. However, despite the residual myopia, whether with or induced astigmatism, post PRK visual acuity seemed to be less influenced by it, than as in the pre-PRK status. CONCLUSION: This study showed an accuracy in visual outcome of > 90% for females and > 80% for males. The Nidek EC-500 was satisfactory for its purpose.

Ocular chlamydial infection in a university eye clinic.

In the University Hospital, Kuala Lumpur, from 1984 to 1990, 184 patients with acute conjunctivitis were examined for chlamydial infection by direct immunofluorescence. Overall, 52 (28.3%) were found to be positive for chlamydial antigen. There was no significant difference in the detection rate between men and women and among the 3 major ethnic groups. The detection rate was highest among sexually active adults. Epidemiological and clinical features suggest that most of the chlamydial ocular infections seen were inclusion conjunctivitis and not classical trachoma.