Survival of bacteria on the ocular surface following double application of povidone-iodine before cataract surgery

Abstract

This study assessed the effectiveness of one vs two applications of povidone-iodine in decontaminating the eye before cataract surgery. This was a prospective, interventional study of 52 patients having elective unilateral phacoemulsification cataract surgery in a tertiary care centre. Each patient had two applications of povidone-iodine before phacoemulsification cataract surgery, separated by 10 min. Conjunctival swabs were taken before and after each application and cultured in 5% CO(2) and anaerobically. Statistical analysis was performed using McNemar's test for correlated proportions. In all, 15 of 52 (29%) patients had positive cultures before the first application and 21 of 52 (40%) patients had positive cultures after it. This was not statistically significant (P=0.239). A total of 25 of 52 (48%) patients were culture positive before the second application. This was not statistically significantly different from 10 min earlier (P=0.423). Six of 52 (12%) patients were positive after the second application (P<0.001). We conclude that the initial application of povidone-iodine was not effective in decontaminating the eye. Recontamination did not take place between applications. The difference in the proportion of patients with positive results before and after the second application of povidone-iodine was statistically significant. We infer from this that double application of povidone-iodine before cataract surgery is advisable.