EyeWorld Asia-Pacific September 2018 Issue

March 2018 59 EWAP PHARMACEUTICALS September use of vancomycin for prophylaxis of endophthalmitis during cata- ract surgery. “People are moving to alternatives, which can include cefuroxime and moxifloxacin,” Dr. Mamalis said. While the task force was care- ful not to give a blanket condem- nation of vancomycin, Dr. Mama- lis also urges caution. “There are some who have used vancomycin for tens of thousands of cases for prophylaxis without ever seeing this,” he said. “But now that this has been reported, I think the sur- geon has to carefully reevaluate his or her choice of antibiotic for the prevention of endophthalmitis.” Understanding HORV HORV cases seem to have declined considerably. “Fortunately, the amount of cases that have been reported have dropped markedly over the past year,” Dr. Mamalis said, adding that he thinks this has to do with practitioners now being aware of the possible link to intracameral vancomycin use. As a result, they are turning to alterna- tive antibiotics. The crux of what is happening with the vancomycin involves a leukoplastic vasculitis, Dr. Mama- lis explained. “It’s thought to be a type III autoimmune reaction, leukoplastic vasculitis, meaning it’s an autoimmune inflammation and it affects the retinal blood vessels,” he said. “You get inflam- mation around the blood vessels and then an actual occlusion of the blood vessels, hemorrhages, and a subsequent blockage of blood supply to the retina, so there will be areas of non-profusion.” Once that happens, the retina becomes ischemic and secondary conditions such as cystoid macular edema can occur, he continued, adding that just from the ischemia itself, there can be a tremendous amount of damage to the retina. Dr. Hoffman stressed that the indirect nature of the type III hy- persensitivity reaction sets it apart from antibiotics that have a direct toxicity to the retina. “It’s not a direct toxicity, which is why some of these pa- tients are getting small amounts in an irrigating bottle and still having a reaction,” Dr. Hoffman said. “That being said, the more vanco- mycin they’re exposed to, the more severe the condition is.” While many have wondered whether patients could be skin- tested beforehand to determine if they are among the few who are likely to react, this is not possible. “There’s no way to know before- hand who’s going to react to it,” Dr. Hoffman said. However, if someone is known to have had a reaction to systemic vancomycin, Dr. Hoffman thinks this would likely put them at risk of develop- ing HORV from an intracameral injection. While there are other antibiot- ics that can cause direct toxicity to the retina if injected in too high a concentration, this is not com- parable, Dr. Hoffman stressed. “If you inject too much tobramycin into the vitreous, the next day the patient has visual loss,” he said. “It’s not a slow onset visual loss that you get from a type III hyper- sensitivity reaction; it’s immediate toxicity with a completely different clinical picture.” While any antibiotic in the wrong dose could cause toxicity, so far the type III hypersensitivity reaction has only been described with vancomycin. Given the potentially devastat- ing consequences, Dr. Hoffman encourages practitioners to stop using vancomycin prophylacti- cally. “I would switch to a different antibiotic,” he said, adding that if a physician is set on using vancomy- cin, he or she might not want to do bilateral simultaneous surgery. While 3–4 weeks between eyes is recommended, if practitioners are not inclined to wait that long, Dr. Hoffman stressed the need to at least delay the second eye for 1 or 2 weeks, since first eyes develop symptoms within 8 days on aver- age. Dr. Mamalis likewise urged practitioners to think carefully about their choice of antibiotics for trying to prevent endophthalmitis. He is pleased at the marked drop in HORV cases. “People are still monitoring these and looking for cases, but the large outbreak that we had a couple of years ago seems to have subsided,” he said. “The HORV registry and the task force is still looking into this issue and hoping that we’re going to see the incidence continue to drop.” EWAP Reference 1. Witkin AJ, et al. Vancomycin-associated hemorrhagic occlusive retinal vasculitis: clinical characteristics of 36 eyes. Ophthal- mol. 2017;124:583–595. Editors’ note: Dr. Hoffman and Dr. Mamalis have no financial interests related to their comments. Contact information Hoffman: rshoffman@finemd.com Mamalis: nick.mamalis@hsc.utah.edu