The effect of recurrent povidone-iodine usage on conjunctival flora in diabetic patients undergoing intravitreal injections

Purpose: The purpose was to evaluate the change in the microbiological profile of diabetic patients undergoing intravitreal injections for diabetic macular edema. Methods: Patients were included in this prospective study when referred for the first time for intravitreal injection to treat diabetic macular edema. For each patient, conjunctival cultures were taken from the lower fornix of each eye prior to the povidone-iodine application and the intravitreal injection. An additional culture was taken from the treated eye 20 min after the injection. The same culture protocol was used for the two following injections of these patients. A later conjunctival culture was also taken a month after the last injection. Results: Twenty-one eyes of 21 patients were included. The mean duration of diabetes was 13.7 ± 7.9 years. Prior to the first intravitreal injection, 33% of cultures were positive. Prior to the third intravitreal injection, 26% of cultures were positive (p = 0.63), and 1 month after the last injection, 18% of cultures were positive (p = 0.495). The mean HbA1C was 8.1% ± 1.7%. HbA1C of patients with positive cultures was 8.0% ± 1.1% at the first intravitreal injection and 8.2% ± 1.0% at the third intravitreal injection. This was compared with HBA1C in eyes with negative cultures: 7.4% ± 1.2% (p = 0.45) and 7.1% ± 1.0% (p = 0.14), respectively. Conclusion: Repeated intravitreal injection for diabetic macular edema with application of povidone-iodine 5% in diabetic patients did not lead to a significant change in the percentage of positive conjunctival cultures. Patients with higher HbA1C had a slight, non-statistically significant trend for positive cultures.