Results of a preclinical study undertaken at the John A. Moran Eye Center, University of Utah, Salt Lake City, indicate higher aqueous humor concentrations of fourth-generation fluoroquinolones can be achieved by implanting an antibiotic-presoaked IOL compared with standard topical administration, reported Guy Kleinmann, MD.

The study included two groups of 15 rabbits each. One group received a hydrophilic acrylic IOL (C-flex, Rayner) that had been presoaked for 24 hours in moxifloxacin 0.5% (Vigamox, Alcon Laboratories) or gatifloxacin 0.3% (Zymar, Allergan). The second group of animals received the standard IOL and was treated with topical antibiotic drops prior to and post-implantation using a typical cataract surgery prophylaxis protocol.

Aqueous humor samples were obtained at 4, 8, and 12 hours after implantation and antibiotic concentrations were analyzed with high performance liquid chromatography. The results showed that the antibiotic levels achieved after topical administration were consistent with those that have been reported previously in the literature.

However, with one exception, levels achieved with both antibiotics at all time periods were significantly higher in animals implanted with the antibiotic-soaked IOLs compared with after topical instillation. Slit-lamp examination performed 24 hours after implantation revealed no clinical signs of toxicity in any eyes.

"Recent reports indicate a gradual increase of postoperative endophthalmitis in the United States since 1992, and in response to significant increases in pathogen resistance to ciprofloxacin, cataract surgeons have switched to use of fourth-generation fluoroquinolones as endophthalmitis prophylaxis," Dr. Kleinmann said. "These results indicate this hydrophilic acrylic IOL can serve as an excellent drug delivery system to enhance achieved aqueous humor concentrations of the fourth-generation fluoroquinolones."

The study was supported by a grant from the American Society of Cataract and Refractive Surgery Foundation.