Eyeworld

EW NEWS & OPINION 20 U se of anterior peribulbar injections of triamci- nolone acetonide for dia- betic macular edema can result in an increased risk of cataract development, as well as a possible increase in IOP when com- pared with posterior peribulbar in- jections or laser, according to Emily Y. Chew, M.D., deputy director of the division of epidemiology and clinical research, National Eye Insti- tute, National Institutes of Health, Bethesda, Md. In the October 2010 e-edition of Retina, investigators led by Dr. Chew reported on their 2-year results with the injections. "We were interested in looking at whether there are other ways to deliver steroids to treat macular edema," Dr. Chew said. "We felt that macular edema is well-treated with triamcinolone, and we know that the side effects with intravitreal (in- jections) are so much greater that we thought that we could get away with fewer side effects and also help pa- tients." With this in mind, investigators launched the pilot, prospective, ran- domized trial. "We wanted to know whether we would be able to extend it to a larger study," Dr. Chew said. Included in the study were 96 eyes with diabetic macular edema. Each eye was randomized to receive either laser photocoagulation, a 20 mg tri- amcinolone acetonide anterior injec- tion, anterior injection followed by laser, a 40 mg triamcinolone ace- tonide posterior injection, or a pos- terior injection followed by laser. Innocuous assumptions Initially investigators thought that all three treatments would fare well. "We thought that this was pretty in- nocuous," Dr. Chew said. "Doctors do this a lot for other diseases such as uveitis, so we thought that small subconjunctival injections or sub- tenons shouldn't hurt them." At the 2-year mark, however, in- vestigators found that a surprising 17% of those who received anterior injections had undergone cataract removal compared with just 3% in the posterior groups and none in the laser photocoagulation group. In ad- dition, 31% of those in the anterior groups experienced a pressure rise of at least 10 mm Hg compared with 17% in the posterior groups and just 8% in the laser group. Dr. Chew was surprised to find that 2 years later, more patients who had been treated using the anterior approach had a greater intraocular pressure rise. "The point is that we saw more side effects than we ex- pected," she said. "It was surprising that after 2 years when we thought that the drug was all gone, we're still having problems." She has a couple of theories as to why the posterior injection may have fared better. One possibility is that the anterior depot was so big that the drug sat in the area for a long time. "We don't see it, but is it still giving out the drug when we think that it's all gone?" Dr. Chew said. "Maybe it's still leaking out drug and that's the reason why we have that problem."Dr. Chew thinks that the location of the injection may be another factor in the equa- tion, with the drug in close proxim- ity to the lens. "It's slowly creeping in and it's right there," she said. "The trabecular meshwork where the fluid goes out might also be in close proximity to where the deposits were." Clinical implications To Dr. Chew, the clinical implica- tions are clear. "I think the implica- tions are that this is not an innocuous injection," she said. "It's not something that we should take lightly." Dr. Chew pointed out that use of the anterior injections re- quires long-term follow up. "If doc- tors do further study they need to be sure that they follow patients for at least 2 years because some of these side effects are not going to manifest until 2 years later," she said. Overall, at least for mild macu- lar edema, Dr. Chew sees the ante- rior intravitreal approach as being too costly in terms of side effects to the patients. "The side effects here far outweigh the benefits, at least for diabetic macular edema," she said. "This should be abandoned in terms of treatment for the very mild type." Dr. Chew pointed out that the same might hold true for other con- ditions as well. "Doctors should know that if they're using this for other diseases, it also applies—not only for diabetic macular edema, but also for uveitis and others," she said. However, she acknowledged that for something like uveitis where there might not be an alternative, the up- side of using the treatment might outweigh the risks. "For some cases such as uveitis it might be very ap- propriate because we can't get the medication down any other way," she said. "Patients have to live with the side effects because the disease itself can cause a cataract." EW Editors' note: Dr. Chew has no finan- cial interests related to her comments. Contact information Chew: echew@nei.nih.gov March 2011 by Maxine Lipner Senior EyeWorld Contributing Editor Anterior injections for diabetic macular edema front and center A study examines possible ways to deliver steroids to treat macular edema other than intravitreal injections, which have risks Source: María H. Berrocal, M.D. Study continued from page 14 Dr. Johansson reported that reg- ulatory authorities only recently reg- istered moxifloxacin in Sweden and it is not yet used widely, but it has been studied at an eye hospital in Stockholm where comparisons were made with an older prophylaxis treatment to prevent post-op en- dophthalmitis. Infections appeared in that study even with treatment with moxifloxacin. "Pneumococcal keratitis can be a troublesome condition," Dr. Johansson said. Nanotechnology may be able to help in the future. "Nanomolecule machines could as- sist us in targeting infectious organ- isms," he concluded. EW Editors' note: Dr. Johansson has no fi- nancial interests related to his com- ments. Dr. Marquart has no financial interests related to this study. Contact information Johansson: bjorn.johansson@lio.se Marquart: Mmarquart@umc.edu

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