The challenge of determining aqueous contamination rate in anterior segment intraocular surgery

PURPOSE: To determine aqueous contamination rate in anterior segment intraocular surgery using two different techniques of obtaining aqueous fluid and to assess whether a 3-day application of topical 0.3% ofloxacin reduces this contamination rate compared with a 1-hour application. DESIGN: Randomized clinical trial. METHODS: One hundred and thirty-three eyes of 130 patients undergoing anterior segment intraocular surgery were randomized to either control (64 eyes received topical ofloxacin 1 hour before surgery) or study groups (69 eyes received topical ofloxacin four times a day for 3 days before surgery in addition to 1 hour preoperatively). Eyes in both groups received a periorbital iodine scrub and two drops of topical 5% iodine. Aqueous fluid was obtained at the beginning and conclusion of surgery using a cannula. passed through a paracentesis or a needle passed through clear cornea. The aqueous, cannula, and needles were inoculated in blood culture media broth and bacterial growth was identified. RESULTS: Overall, eight of 89 aqueous samples (9%) obtained using a cannula at the beginning of surgery were culture-positive. Similarly, six of 41 aqueous samples (15%) obtained through a needle through clear cornea a the beginning of surgery showed contamination. At the conclusion of surgery, nine of 112 samples (8%) showed positive cultures. There was no difference in the aqueous contamination rates between the control and study groups. CONCLUSIONS: Despite the use of a needle to obtain aqueous fluid at the beginning of surgery before creating a paracentesis, the aqueous contamination rate remained higher than that found at the conclusion of surgery. A 3-day application of topical ofloxacin before surgery did not reduce the anterior chamber aqueous contamination rate relative to a 1 hour application. (C) 2004 by Elsevier Inc. All rights reserved.