Povidone-iodine contact time and lid speculum use during intravitreal injection

To determine the time necessary for 5% povidone-iodine (PI) to cause a significant reduction in colony-forming units and whether a lid speculum increases the conjunctival flora.

This was a prospective randomized study of 131 eyes undergoing intravitreal injection. Conjunctival samples were collected in a prospective protocol at three points before intravitreal injection: (1) no intervention (baseline), (2) after placement of a lid speculum, and (3) after treatment with 5% PI. Participants were randomized into three different PI exposure intervals. Cultures were incubated for 6 days, and the resulting colony-forming units were tallied for each intervention.

Use of 5% PI caused significant decrease in the number of colony-forming units (P < 0.0001). Exposure to PI for 15 seconds did not cause a significant reduction in conjunctival bacteria (P = 0.08), but a significant reduction was observed after 30 seconds of exposure and beyond (P = 0.0003). Placement of a lid speculum did not result in a significant increase or decrease in the number of colony-forming units when compared with baseline (P = 0.47).

The use of 5% PI causes a significant reduction in bacterial colonies, and 30 seconds of exposure appears to be an adequate time to decrease conjunctival bacterial counts. Lid speculum use before intravitreal injection does not affect the overall conjunctival flora.