Study highlights limits of topical antibiotics, povidone-iodine prep for achieving complete asepsis

Current techniques for endophthalmitis prophylaxis can reduce microbial contamination of the ocular surface, but fail to achieve 100% sterilization at the time of surgery, said Hiroko Bissen-Miyajima, MD, director, Department of Ophthalmology, Tokyo Dental College Suidobashi Hospital, Tokyo, Japan.

"Surgeons need to keep in mind that postoperative endophthalmitis remains a threat of cataract surgery, and further investigation is necessary to identify techniques that can better help to prevent these serious infections," Dr. Bissen-Miyajima said.

The effects of routine prophylaxis measures on ocular surface bacteria were investigated in a prospective study involving 29 eyes of 29 patients who underwent microcoaxial clear corneal phacoemulsification and IOL insertion. All patients used gatifloxacin (Zymar, Allergan) four times a day prior to surgery and had a conjunctival swab obtained before starting that regimen and when they arrived on the day of surgery. In the operating room, patients underwent a povidone-iodine scrub. After a balanced salt solution rinse, fluid was aspirated from the lid speculum and collected for culture. In addition, all fluid from the ocular surface was collected during surgery. The swabs and collected fluid specimens were submitted for direct culture and enrichment techniques and analyzed for bacteria.

Gatifloxacin use was associated with a decrease in positive bacterial culture rates prior to surgery and there was a further benefit from the povidone-iodine prep. After that procedure, however, positive cultures were still obtained in 6.9% of eyes by direct culture and 17.2% by enrichment culture. Positive culture rates by both methods were increased in the ocular surface fluids collected during the surgery.