EyeWorld Asia-Pacific March 2015 Issue

March 2015 17 EWAP FEATURE the risk of endophthalmitis is lower than the risk of TASS or at the equivalent level,” she said. Extrapolating definitive statements from survey data is problematic, Dr. Mamalis said, cautioning over interpretation of the results. They are good to show trends, but they are still only a sampling of practitioners. Studies from Europe and the U.S. do show that intracameral antibiotics can decrease the inci- dence of endophthalmitis. So why are more surgeons not adding them to their treatment regimens? Dr. Mamalis thinks it might be because in the U.S. “there is nothing commercially available,” and a good sterile surgical technique coupled with using fourth-generation fluoroquinolones has reduced the risk of endophthalmitis to their current low levels. Various choices For surgeons who use topical antibiotics, there are numerous choices commercially available; in the U.S. the majority use topical moxifloxacin or gatifloxacin perioperatively. Third-generation quinolones are showing “some significant resistance, especially in the Staph bacteria,” he said, adding that he encourages surgeons to use fourth-generation drugs with less (although ever-increasing) resistance issues. There is no such clear- cut majority when it comes to intracameral antibiotics. However, moxifloxacin (directly injected from topical Vigamox) and vancomycin are most commonly used. “I’m surprised there are still a lot of people who use vancomycin added to the balanced salt solution infusion bottle (15%),” Dr. Mamalis said. Treatment differences Because neither the U.S. nor Canada has an approved intracameral antibiotic, “there may be some reformulation issues with preparation that prevent surgeons from including intracameral antibiotics in their surgical routine,” Dr. Braga-Mele said. In Canada, most surgeons use an antibiotic “at least a day prior to surgery or starting on the day of the surgery, but 3 days prior is falling out of favor,” she said. A patient’s insurance coverage may also play a role in the choice of antibiotics, Dr. Mamalis said, noting it is not unusual for the center’s postop nurse to note a specific fourth- generation fluoroquinolone is not covered by insurance. Surgeons are then left with the option of choosing another drug, another drug class, or an earlier generation of fluoroquinolones, he said. But if postoperative antibiotics are not being used, it is possible that surgeons are opting for intracameral use or instilling a drop themselves at the end of surgery, Dr. Braga-Mele said. “I think we should raise the question that perhaps those who are starting their postoperative topical antibiotic on day 1 are instilling a drop at the end of the case or using an intracameral antibiotic,” she said. “The other thing is they might be the doctors who patch their patients, and patches aren’t removed until day 1 postop. That’s when they have their patients start the drops.” Dr. Braga-Mele said she does not use intracameral antibiotics because her rate of endophthalmitis “is almost non-existent,” and a review of 16,000 cases in Canada found such a low rate of endophthalmitis that she is not swayed by the literature that exists. Some may be using moxifloxacin (either in direct injection mixed from the topical solution or compounded for direct injection) because it’s not preserved and readily available. In the U.S., the OR nursing staff will typically mix the solution (which is not a concern when using something like moxifloxacin), but in Europe where the trend is to use cefuroxime, “that’s a complicated, several-step procedure to mix it properly,” Dr. Mamalis said. In a busy surgery center, the more complicated the procedure is, “the greater the chance that there may be a problem in properly following the procedure,” he said. When to start—and stop— antibiotic use Three percent of respondents opt not to use any postop topical antibiotic, but just under half of the respondents said not only do they use intracameral antibiotics, they use topical antibiotics postoperatively. “That’s a belt-and-suspenders type of approach,” Dr. Mamalis said. “If you believe that intracameral antibiotics are all it takes to stave off endophthalmitis, then there is less need for a topical antibiotic to supplement it.” There’s been “some compelling data” that shows bacteria on the surface of the eye at the beginning of the case exists, and that would be from the patient’s lid and conjunctival flora. As far as Dr. Mamalis is concerned, “the most important thing is sterilizing preoperatively with topical povidone-iodine as well as topical antibiotics,” he said, to decrease the amount of surface bacteria at the start of surgery. He thinks tapering the antibiotic postoperatively is not recommended. Tapering runs the risk of increasing resistance and reduces efficacy. Some surgeons will have patients buy the topical antibiotic ahead of time, have the operating room team open it and draw what is needed, and have the patient use the same bottle postop for 7 days, Dr. Mamalis said, which reduces the cost for the patient. Of those who do not inject intracamerally, almost half cite mixing/compounding issues and cost as barriers. “If we could eliminate the mixing risk, the compounding risk with an approved single use antibiotic, we could eliminate two-thirds of the reasons people don’t use them,” Dr. Mamalis said, adding the additional cost to the surgery would be negligible. Yet there’s “an interesting dichotomy” in that 41% of respondents believe intracameral antibiotic prophylaxis is very important, but 53% of respondents are not injecting, Dr. Mamalis said. Down the road Although a commercial formulation of cefuroxime is available in Europe, it is unlikely U.S. regulators will approve the same formulation based on European study results showing both safety and efficacy. A safety study would only entail around 1,000 patients to show no adverse side effects from injecting intracamerally, but to power a study for efficacy would necessitate tens of thousands of patients given the low incidence of endophthalmitis. Ideally, the U.S. Food and Drug Administration should require safety data only, as it’s fairly well accepted these drugs are efficacious. “If the FDA requires efficacy data, we are unlikely to have an approved intracameral antibiotic in the near future,” Dr. Mamalis said. EWAP Editors’ note: The physicians have no financial interests related to their comments. Contact information Braga-Mele: rbragamele@rogers.com Mamalis: nick.mamalis@hsc.utah.edu