A retrospective review suggests that administration of intracameral moxifloxacin 0.5% (Vigamox, Alcon Laboratories) is safe for endophthalmitis prophylaxis during cataract surgery.
Dr. Arbisser, who is in private practice in Bettendorf, IA, implemented an intracameral moxifloxacin protocol of diluted moxifloxacin for endophthalmitis prophylaxis after reading reports of success with cefuroxime (Ceftin, GlaxoSmithKline), a second-generation cephalosporin, and a subsequent account of prophylaxis using moxifloxacin. In her protocol, moxifloxacin is diluted to a 100 μg/0.1 ml solution and dosed as a 0.2-ml injection.
She has followed this protocol on an estimated 1,000 patients and presented the results on a portion of those cases.
She also performed a prospective study in which she analyzed optical coherence tomography (OCT) results in 18 patients (31 eyes) who received intracameral dilute moxifloxacin. Macular thickness measurements were taken before and 6 weeks after surgery, and adverse events were recorded.
Results from the prospective study showed a mean increase of <10 µm in all areas of macular thickness and a mean increase of <4% for macular volume at all locations. The differences observed before and after surgery were within the margin of error of OCT, Dr. Arbisser said.
In results from the retrospective study, four (2.0%) moxifloxacin-treated eyes had aqueous cell counts greater than 3+ on day 1 postoperatively, compared with 11 (11.0%) in the control group (p = 0.0007) At week 1, however, no difference was observed between the groups in the number of patients with trace or no cells.
Although visual acuity was a study parameter, it could not be analyzed because the difference between the two groups was not comparable at baseline. The acuity in both groups was approximately 20/25 1 week postoperatively.
No adverse events, such as epithelial defects or stromal edema, were observed.
Some clinicians use undiluted antibiotics for intracameral endophthalmitis prophylaxis, but Dr. Arbisser said that she continues to use the diluted solution on the basis of a study by Steven A. Arshinoff, MD, showing that moxifloxacin diluted at the strength she uses in her practice should be effective at MIC 90 in the anterior chamber. The solution is administered around the lens so that some of it irrigates into the posterior chamber as well.
Like many other clinicians, Dr. Arbisser began investigating new ways of preventing endophthalmitis because of a change in the status of this infection worldwide, although she said she had not seen an increase in her own practice. The incidence of endophthalmitis following cataract surgery is climbing, from a rate widely accepted in the past of 1 in 12,000 to as high as 1 in 400 in some reports.
"I think everyone is driven to try to reduce that incidence as low as possible," Dr. Arbisser said.
She had relied on topical antibiotics to reduce the risk of endophthalmitis until a recent European study showed that cefuroxime reduced the incidence of endophthalmitis. "It was the first evidence that we saw for certain in a prospective clinical trial that intracameral antibiotics work," she said.
Rather than use cefuroxime, Dr. Arbisser became interested in the experiences of Dr. Arshinoff, who had published a letter outlining his procedure for performing simultaneous bilateral cataract surgery with intracameral moxifloxacin for antibacterial prophylaxis.
"It seemed sensible to me, since moxifloxacin is packaged commercially at an acceptable pH and is self-preserved, that he had a track record of safe use," Dr. Arbisser said.