Eyeworld

EW RETINA 66 October 2016 by Maxine Lipner EyeWorld Senior Contributing Writer Preventing endophthalmitis Update on retina drug prophylaxis W hile rare, when en- dophthalmitis rears its head, loss of vision can be severe, which is why prophylaxis is so important. While many attempt to stave this off with topical drops, some practitioners have instead taken to relying on intracameral or intravitreal injections of drugs during the cataract procedure. They look to drugs such as Tri-Moxi (tri- amcinolone/moxifloxacin, Imprimis, San Diego), Tri-Moxi-Vanc (triam- cinolone/moxifloxacin/vancomycin, Imprimis), cefuroxime, moxiflox- acin, and vancomycin to ward off potential endophthalmitis. Dropless prophylaxis Stephen Hamilton, MD, Eye Consultants of Atlanta, uses Tri- Moxi intraocularly during cataract procedures in addition to the usual povidone iodine prep of the eye and conjunctival cul de sac. In his view, there are three basic advantages to using this prophylactic approach. First, you're putting the antibiotic inside the eye during the case where the bacteria may be introduced. "That's what you want—you want the kill to be inside the eye," he said. Second, this approach is easier for both the patient and the staff. "Patients get confused about how to use the drops, and there are always questions about compliance and whether they use the drops at all, not to mention all the phone calls about formulary coverage and cost of medications," Dr. Hamilton said, adding that injecting the medica- tion not only addresses the issue of compliance, but also simplifies the question of patient education. Then there is the issue of cost. "Tri-Moxi costs $25 and the top- ical meds are usually much more expensive than that," Dr. Hamilton said. In some cases, it is necessary to add drops to the patient's regimen. "Regarding the need to add a drop a week or two later, in my experience, it's not unheard of, but rarely do they break through and have ongo- ing inflammation," Dr. Hamilton said. "Sometimes you have to add a drop—they're recovering well, but still have more inflammation than you would like and you put them on a topical steroid or a nonsteroidal drop." Often it's mild enough that a sample will suffice, he added. In addition to breakthrough inflammation, there are complica- tions that can arise with this intra- ocular prophylaxis. You may have an uncooperative patient. "Maybe they moved at the wrong time and caused some type of zonular or capsular damage," Dr. Hamilton said, adding that this has never happened to him. He has come up against another issue: a postoper- ative pressure spike. "For a time, I got some postoperative pressure rise presumably because we are putting more volume in the eye at the end of the case," he said. "We have to be careful not to put too much back there, but enough to be effective." Otherwise, the iris can prolapse because of that pressure. "We're putting pressure behind the lens implant and the iris and as a result, the physician can push everything else forward, the anterior chamber can shallow, and the iris can even prolapse through the wound. This is a question of becoming experienced with the procedure," Dr. Hamilton said. "I also avoid using Tri-Moxi in glaucoma patients due to the risk of an early or late pressure rise." To help avoid complications, he advises practitioners to inject the medication through the inferior zonule. "I usually go through the inferior zonule because of the access, moving the cannula carefully, know- ing where it is, and which way it is pointed; when you bring it back out, you're reversing your movements and you're not damaging anything," he said. He is also very consistent in the amount of medication that he delivers. "I always put in 2 mls," he said, adding that any more may be hard to get in the eye. He also stressed the need to administer this with care. "I give this very slowly and with some viscoelastic in the eye," Dr. Hamilton said. "You have to let the wound gape a little so that there's some egress of the viscoelas- tic out of the eye." Otherwise, a lot of posterior pressure will build up, he warned. While the type of viscoelastic used here generally doesn't mat- ter, Dr. Hamilton does recommend avoiding one that's too thick, such as Healon 5 (Abbott Medical Optics, Abbott Park, Illinois). "You have to be careful because it doesn't egress easily, and when it does come out, it usually comes out all at once," he said. This approach for endoph- thalmitis prophylaxis can be more difficult to administer during cataract surgery in certain types of eyes. "It can be challenging to give the intravitreal injection in an eye that has IFIS or a smaller eye that doesn't have a lot of volume to take it up," Dr. Hamilton said, adding that it's important to make sure that you have the chamber formed. Since these eyes can be more difficult, sometimes he does the injections in another way. "I've had cases like this where I'll give it through the pars plana, like they give intravitreal injections in the clinic," he said. "I know I can't do it otherwise—with IFIS or a smaller eye, you're not going to be able to get it done." Instead he goes through the pars plana with a 30-gauge needle. "In a shallow or small eye, if I think I'm going to have trouble, I'll do it that way," he said. Dr. Hamilton also advises against using toric IOLs with the dropless approach since theoretically it could move the lens out of posi- tion. "I don't use it with toric IOLs Postop endophthalmitis Source: Nick Mamalis, MD Pharmaceutical focus

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