Preoperative antibiotic and povidone-iodine preparation of the eye.

We compared gentamicin 0.3% one drop every three hours the night before and the morning of surgery ("half-day regimen") with the same drug one drop qid for three days ("three-day regimen") in 15 eyes undergoing intraocular surgery. Conjunctival cultures of both groups taken before povidone-iodine preparation showed mean colony counts of 3.67 +/- 0.82 in the half-day regimen versus 1.0 +/- 0.43 in the three-day regimen. Conjunctival cultures taken after the administration of a povidone-iodine 5% preparation showed 7.17 +/- 3.52 and 2.75 +/- 0.88, respectively, in the two groups. Although there was a statistical difference in colony counts, topical gentamicin 0.3% given the night before and day of surgery had comparable low colony counts with the three-day course. The 5% povidone-iodine solution was not effective in reducing bacterial flora although it did eliminate all fungal colonies.