Study finds 1% povidone-iodine as effective as 5% formulation

Cornea. 2011;30(3):333-237.

Povidone-iodine is equally effective in the 1% and 5% formulations for the chemical preparation of donor corneas, and the 1% formulation should be considered to avoid toxicity of the tissues, according to a study.

The consecutive, randomized study included 100 pairs of donor corneas in which either 1% or 5% povidone-iodine drops were applied for 2 minutes. Researchers took limbal cultures before and after the solutions were instilled and identified 25 different species.

The flora living in the eye before povidone-iodine instillation were coagulase-negative staphylococci (62%), Corynebacterium species (27%), gram-negative bacilli (14.5%), anaerobes (10%), streptococcal species (9.5%), Staphylococcus aureus (5%) and yeast (2%).

After povidone-iodine instillation, researchers found 74 isolates in the 1% povidone-iodine group, and 49 eyes had sterile cultures. The 5% povidone-iodine group revealed 76 isolates, and 47 eyes had sterile cultures, according to the study. Both groups had similar microorganism colony-forming units.

Compared with the limbal cultures taken before instillation, the number of negative cultures and the reduction in isolates were significantly affected by the povidone-iodine preparation in both groups, the study found.

"Because [povidone-iodine] is known to be toxic to the corneal endothelium and corneal fibroblasts, this study suggests that 1% [povidone-iodine] should be the preferred disinfectant for the recovery of corneal donors," the authors said.