Eyeworld

34 April 2015 by Michelle Dalton EyeWorld Contributing Writer EW RETINA In previously vitrectomized eyes, steroid implants may migrate into the anterior chamber, resulting in persistent corneal edema P rior vitrectomy and the absence of a lens capsule are 2 risk factors that can contribute to anterior chamber migration of interventional devices, said Rahul N. Khurana, MD, in practice at Northern California Retina Vitreous Associates, Mountain View, Calif. While Dr. Khurana has recently had the phenomenon happen with Ozurdex (dexamethasone, Allergan, Irvine, Calif.), "when you inject something in the back of the eye, it can unfortunately come to the front of the eye." For example, there are reports of this occurring after use of intrav- itreal triamcinolone. With triamcin- olone, the crystals would come to the front of the eye, and physicians would think it was an infection "because of the pseudohypopyon observed in the front of the eye. However, it was not an infection but the triamcinolone crystals layered in the anterior chamber," he said. The next time reports sur- faced, they were after surgeons had implanted Retisert (fluocinolone acetonide 0.59 mg, Bausch + Lomb, Bridgewater, N.J.). Dr. Khurana said even though the implant was su- tured, it would occasionally dissoci- ate, and "we basically had this pellet that would then migrate to the front of the eye. There have been reports of that causing corneal edema and corneal issues, and it had to be removed," but Dr. Khurana also said these had been fairly isolated cases. "Retisert is sutured to the sclera so it's not free-floating. There is only a problem when it falls apart, and that's what these initial cases described," he said. Free-floating Ozurdex, however, is free-floating, so "it can go anywhere, including the front of the eye, especially in vitrectomized eyes," he said. When that migration does occur, Dr. Khurana warned that some patients may develop permanent corneal edema, one of the most common complications he found in his retro- spective analysis of 15 patients. 1 "Our data show that if an Ozurdex implant comes forward, 70% of those affected developed permanent corneal edema," he said. In his case series, it took about 2 weeks from the date of injection to diagnosis of anterior migration; 16 episodes of corneal edema occurred, all in patients with early migra- tion. Of those, 11 required surgical removal of the implant. Where persistent corneal edema was present (defined as present at 3 months after implantation), the interval from implantation to re- moval was 17.7 days compared to 10 days in cases of resolved edema, Dr. Khurana said. In the analysis, the authors noted anterior chamber migration of the Ozurdex implant "was first reported in a vitrectomized eye with an anterior chamber IOL and then in aphakic vitrectomized eyes." Dr. Khurana stressed it was "notable" the implant can manip- ulate itself around the pupil and around an IOL to enter the anterior chamber. "We don't know what causes the corneal edema. Is it the mechan- ical trauma from having this device bouncing around, or is it from the medication? I think it's more from the medicine. We normally think of steroids as an effective treatment for cornea edema. However, when you're giving it in such high doses it may not be as harmless," he said. In the cases with early migra- tion, it is possible that the implant may have been more rigid because of the proximity in timing to the in- jection, increasing the likelihood of mechanical endothelial trauma. Dr. Khurana noted most of the patients had also undergone several previous surgeries, meaning they likely had reduced endothelial cell counts. Management options If the implant does migrate but without corneal edema, observation is a viable option, Dr. Khurana said. Positioning the patient in a supine position and dilating the pupil may help the implant "fall" back into its proper placement. Physicians can use a slit lamp to manually repo- sition the implant, but migration could recur. "If you see a patient who has this implant in the front of the eye, with corneal edema, that's some- thing you need to act quickly on because if left untreated, the patient may end up needing a corneal trans- plant," Dr. Khurana said. In this analysis, 6 patients (43%) required corneal transplants. Because retina specialists are injecting for a variety of disorders— diabetes, vein occlusions, uveitis— and are injecting regularly, "to have this horrible complication, where now they need corneal transplant surgery, is not a small issue," he said. Intravitreal injections are so rou- tine in practice that ophthalmolo- gists need to be aware of this serious complication, especially in certain high-risk populations, he said. Vitrectomized eyes are lacking the gel necessary to hold the im- plant, which means any kind of IOL (anterior chamber, laterally fixated, iris-fixated) is not enough to "hold" the implant back, Dr. Khurana said. "In non-vitrectomized eyes, the implant lodges in the vitreous and just stays there, so you get the best therapeutic effect. In vitrectomy, though, "there's nothing to secure it, so it has the ability to come to the front of the eye." All implants? Iluvien (fluocinolone, Alimera Sciences, Atlanta) was approved in the U.S. last year for the treatment of diabetic macular edema. "It's like Ozurdex in that it's free-floating, so it's possible that implant will migrate as well," he said, although he has yet to have personal experience with the Iluvien implant. Retinal implants may have devastating corneal complications Anterior chamber migration of a dexamethasone implant. In an eye with an anterior chamber intraocular lens, there is a dexamethasone implant present in the anterior chamber in addition to corneal edema. Source: David J. Parks, MD continued on page 36

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