Effects of chloramphenicol, povidone-iodine 1% and 5% eye drops on the colonisation of conjunctival flora in patients undergoing cataract surgery

Objectives: the aim was to compare 2 drops of either 5% chloramphenicol, 1% povidone-iodine or 5% povidone-iodine before cataract surgery on reducing the colonisation of bacterial flora in the conjunctiva.Design: This was a double-blind, randomised clinical trial study.Setting: Patients referred to Shahid Sadoughi Hospital in Yazd, Iran, for cataract surgery were studied.Participants: Totally 260 patients were enrolled.Intervention: The affected lower fornix was gently sampled with a sterile swab and cultured on appropriate microbiological media. Then one of the 3 solutions mentioned above was instilled into the conjunctival sac of the cases in groups 1, 2 and 3, respectively. After thirty minutes, new conjunctival swabs were taken and cultured.Main outcome measures: The type of bacteria isolated and their colony-forming unit per mL (CFU/mL) number were primary end-points. The statistical tests of Phi and Cramer's V and Wilcoxon and Kruskal-Wallis were applied to evaluate the relationship between the studied variables and culture results as the secondary end-point.Results: The studied patients were 129 (49.6%) males and 131 (50.4%) females. Bacterial growth was observed in 49 cases (18.85%); the most commonly isolated bacteria were Staphylococcus epidermidis (71.42%). In the povidone-iodine 5% and chloramphenicol groups (but not the povidone-iodine 1%), the decrease in the number of CFU/mL was statistically significant (P = 0.032 and P = 0.005, respectively, Wilcoxon test).Conclusion: A single dose of povidone-iodine 5% and chloramphenicol effectively reduces the colonisation of normal conjunctival bacteria and can be used as effective prophylaxis.