Eyeworld

EW CATARACT 45 June 2018 developing HORV from an intraca- meral injection. While there are other antibi- otics 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 hypersensitivity 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 re- action has only been described with vancomycin. Given the potentially devas- tating consequences, Dr. Hoffman encourages practitioners to stop using vancomycin prophylactical- ly. "I would switch to a different antibiotic," he said, adding that if a physician is set on using vanco- mycin, 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 symp- toms within 8 days on average. Dr. Mamalis likewise urged prac- titioners 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 subsid- ed," 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." EW Reference 1. Witkin AJ, et al. Vancomycin-associated hemorrhagic occlusive retinal vasculitis: clini- cal characteristics of 36 eyes. Ophthalmology. 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 without ever seeing this," he said. "But now that this has been re- ported, I think the surgeon 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 intraca- meral vancomycin use. As a result, they are turning to alternative antibiotics. The crux of what is happening with the vancomycin involves a leukoplastic vasculitis, Dr. Mamalis explained. "It's thought to be a type III autoimmune reaction, leuko- plastic vasculitis, meaning it's an autoimmune inflammation and it affects the retinal blood vessels," he said. "You get inflammation around the blood vessels and then an actual occlusion of the blood vessels, hem- orrhages, and a subsequent blockage of blood supply to the retina, so there will be areas of non-profu- sion." 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 patients are getting small amounts in an irrigating bottle and still having a reaction," Dr. Hoff- man said. "That being said, the more vancomycin they're exposed to, the more severe the condition is." While many have wondered whether patients could be skin-test- ed beforehand to determine if they are among the few who are likely to react, this is not possible. "There's no way to know beforehand 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 to weigh the rare risk of HORV with the risk of endophthalmitis." Retina surgeons are still using vancomycin in combination with a gram-negative antibiotic for treating endophthalmitis. "In confirmed or highly suspicious endophthalmitis, I think that's still being used," Dr. Hoffman said. "This is extremely rare, so the chances that a retina surgeon is going to create HORV is rare and worth the risk of using vancomycin in that situation." Even prophylactically, some are still using it. "I think there are still some surgeons who use vancomycin because they think it's better than moxifloxacin or cefuroxime, which are the other antibiotics commonly used," he said. "They think that the risk is relatively low." In such cases, Dr. Hoffman advised that if vancomycin is used, patients should undergo a dilated fundus examina- tion after the first eye to make sure they're not developing HORV before they have vancomycin injected into the second eye. "There's also a debate about whether or not it's a good idea to do eyes very close together," Dr. Hoff- man said, adding that some may do one eye and do the second with vancomycin 1 week later. There are even some surgeons who are doing bilateral simultaneous cataract surgery. "I think that it would not be wise to be using vancomycin in those patients because you don't know if they're 1 in 1 million until you've injected both of their eyes," Dr. Hoffman said. "There were some prominent surgeons who were using it and have done thousands of cases with intracameral vancomycin, never had a problem, and decided that it wasn't worth it," he said. Dr. Mamalis said that since the task force report has come out there has been a decrease in the use of vancomycin for prophylaxis of endophthalmitis during cataract sur- gery. "People are moving to alterna- tives, which can include cefuroxime and moxifloxacin," Dr. Mamalis said. While the task force was careful not to give a blanket condemnation of vancomycin, Dr. Mamalis also urges caution. "There are some who have used vancomycin for tens of thousands of cases for prophylaxis it's acute," Dr. Mamalis said, adding that such immediate reactions are usually associate with toxic anterior segment syndrome (TASS), which oc- curs acutely in the anterior segment. However, this was different because it arose posteriorly in the retina and took place 1–2 weeks after the initial cataract surgery in cases that involved the use of vancomycin. Dr. Hoffman stressed that HORV is a devastating but very rare condi- tion. "They tended to be bilateral, so they received surgery in one eye and the problem was that this either had a very mild vasculitis or hadn't even developed when they received surgery in the second eye," he said, adding that this resulted in bilateral disease of varying severity. To determine if a case might be HORV requires the use of indirect ophthalmoscopy, Dr. Hoffman explained. If you look at the back of the eye, you see peripheral mas- sive hemorrhages that look like a vasculitis involving the venules. "There's ischemia of the veins and massive hemorrhages that's more pronounced in the periphery and just a mild cellular reaction," Dr. Hoffman said. The distinct clinical onset of HORV sets it apart. For in- stance, endophthalmitis has a severe cellular reaction with pain and a severe anterior chamber reaction; by contrast HORV patients have a mild anterior reaction and no pain. Anyone with visual loss and fairly massive peripheral hemor- rhages who has received vancomy- cin either in the irrigating solution or as a bolus should be considered a suspect for having the condition, Dr. Hoffman said. "So far, we don't have any cases that are confirmed HORV that haven't received vanco- mycin," he said. Looking at vancomycin use Despite the HORV risk, there are still some surgeons using vancomycin, Dr. Hoffman noted, adding that be- cause the condition is rare, the pa- per the task force published did not recommend completely eliminating vancomycin use. "For instance, if you have a patient with MRSA, vancomycin is an ideal medication," he said. "So there are still surgeons who are using it. In the paper we didn't recommend they stop using vancomycin, but the surgeon needs

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