Intravitreal implant shows promise in DME, vein occlusion

Durham, NC-The Retisert implant (Bausch & Lomb), a nonbiogradable device containing fluocinolone acetonide, is approved for the treatment of posterior uveitis and seems promising in the treatment of diabetic macular edema (DME) and vein occlusion in clinical trials, according to Glenn Jaffe, MD.

The device is also being tested in clinical trials to treat neovascular age-related macular degeneration.

"The advantages of this therapeutic approach are linear continuous drug delivery, the drug is contained within a nontoxic device, and the device is suitable for sustained delivery of the drug for years," said Dr. Jaffee, a professor of ophthalmology at Duke University, Durham, NC.

A potential disadvantage of a device such as this is that it is retained in the eye, which, as Dr. Jaffe pointed out, is not problematic if the device is nontoxic and does not cause adverse mechanical effects.

The Retisert intravitreal implant is constructed of a 1.5-mm core of drug and a silicone/polyvinyl acetate laminated coating, affixed to a PVA suture strut. The device contains 0.59 mg of drug that is intended to be released at the rate of 0.5 μg per day, Dr. Jaffe explained.

Dr. Jaffe and colleagues evaluated two fluocinolone acetonide implants, one containing 0.59 mg, like the commercially available Retisert, and another containing 2.1 mg, to treat uveitis during an individual investigator (IND) trial in 36 eyes of 32 patients who had severe noninfectious uveitis with posterior segment involvement that was refractory to standard therapy. The average follow-up in this group was 2 years.

"Both implants had potent anti-inflammatory effects. Whereas these patients had had an average of 2.5 recurrences of uveitis per eye annually, postoperatively there were no recurrences at 2 years and only two recurrences at 29 months to 3 years," Dr. Jaffe reported.

Controlling inflammation

From this IND trial, which served as the basis for larger, multicenter trials, Dr. Jaffe found that the device helped control inflammation, helped maintain visual acuity over an extended period, and decreased the need for anti-inflammatory medication. Larger clinical trials showed results that were similar to Dr. Jaffe's. Based on these trials, the FDA approved the device for the treatment of chronic noninfectious uveitis that has a posterior component.

The Retisert implant is also being tested to treat DME and as salvage therapy in patients with vein occlusion, and appears promising in both cases. In the DME multicenter, controlled, randomized trial, 180 patients were enrolled and 2-year results are available. Patients received either a 0.59-mg implant or standard care that consisted of repeated applications of laser or observation.