The 12-week, multicenter, multinational Macular Edema Ranibizumab v Intravitreal Anti-inflammatory Therapy Trial (MERIT) compared the results of three intravitreal therapies for this type of macular edema: insertion of a dexamethasone implant (Ozurdex), injections of the antivascular endothelial growth factor (anti-VEGF) agent ranibizumab (Lucentis), and injections of the anti-inflammatory drug methotrexate.
The study, published June 13 in Ophthalmology, was conducted at 33 clinical centers in the United States, the United Kingdom, Australia, and India by the Multicenter Uveitis Steroid Treatment Trial research group, which had previously established that treatment with intraocular steroids produced superior results to treatment with systemic oral agents.
Funded by the National Eye Institute (NEI), MERIT enrolled 194 participants who had well-controlled uveitis yet persistent or recurrent macular edema and had previously undergone at least one intravitreal injection of a corticosteroid. The dexamethasone implant group and the ranibizumab group included 65 participants each, and the methotrexate group included 64 people. The study evaluated these treatments in 225 eyes. For each agent, treatment was provided in accordance with the schedule typically used in clinical practice.
Better Vision With Dexamethasone
By the end of the study, use of the dexamethasone implant was associated with a 35% reduction in retinal swelling, compared with 22% for ranibizumab and 11% for methotrexate (P = .02), according to the researchers. Improved vision was observed only in the group that received the dexamethasone implant (P < .001); that gain amounted to an increase of nearly five letters, or about one row on an eye chart, they report.
"The MERIT trial provides robust evidence about the best treatment for persistent or recurrent macular edema in patients with uveitis," said Nisha Acharya, MD, Elizabeth C. Proctor Distinguished Professor at the F. I. Proctor Foundation and Departments of Ophthalmology, Epidemiology, and Biostatistics at the University of California, San Francisco, who led the study. "These results suggest that intravitreal corticosteroid therapy, unless contraindicated, should be the preferred therapy for this indication."
"I've done 2000 Ozurdex injections in my career, and the results of the trial were not unexpected, " said Sam S. Dahr, MD, professor and director of the retina division and retina fellowship at McGovern Medical School at UTHealth Houston. "These results underscore current practice patterns and are hence unlikely to change those patterns."
However, Dahr said, "Ozurdex should not be utilized in patients who are aphakic or who have significant defects in the posterior capsule, since there is a risk the implant may migrate into the anterior chamber and damage the cornea." Prior laser capsulotomy is acceptable, he added.
"I think it's a pretty convincing study," Garvin P. Davis, MD, a vitreoretinal surgeon at Houston Methodist Eye Associates, in Texas, said. "Whenever we have a clinical study that's been carefully done, controlled, and sponsored by the NEI, we need to sit up and take notice."
He added that the dexamethasone implant not only improves vision but may also reduce the number of injections needed to resolve macular edema.
"I'm a big fan of decreasing the patient's treatment burden," Davis said. "Treatment with anti-VEGF agents is typically given as a shot once monthly for 3 months no matter what."
If edema does not resolve after baseline injection, methotrexate is used every 4 to 8 weeks, and the dexamethasone implant is injected again after 8 weeks. Thus, the implant imposes the lowest treatment burden of all three agents studied.
In the MERIT trial, the incidence of increases in intraocular pressure (IOP) to at least 24 mm Hg was higher among patients who received intravitreal dexamethasone than among those who received ranibizumab (P = .013) or methotrexate (P = .002). Although the incidence of increases in IOP of at least 30 mm Hg was 10% in the steroid group, compared with 1% for the comparator groups, this difference was not statistically significant (P = .051 for the comparison with methotrexate and P = .09 for that with ranibizumab).
"The intraocular pressure issues seen with Ozurdex tend to be mild," Dahr observed. "Patients can usually be managed for a few months' time with IOP-lowering drops and subsequently tapered off drops." Fewer than 1% of patients require surgery to reduce IOP after an injection, he said.
However, for patients with advanced glaucoma damage ― a cup-to-disc ratio of 0.8 or more ― the risks of the implant must be carefully weighed against the potential benefit, he said.
Regarding study limitations, Acharya acknowledged that at 12 weeks, the duration of follow-up for the primary outcome was relatively short, which limits the ability of the investigators to assess long-term outcomes and to detect adverse events that take longer to develop, such as cataract. She stressed the need to evaluate outcomes at 24 weeks and beyond to assess durability of effect and the need for repeat injections.
The study was funded by the NEI. Acharya has received support from AbbVie. Davis serves on advisory boards for Allergan and Genentech. Dahr reports no relevant financial relationships.
Ophthalmol. Published online June 13, 2023. Abstract
A former staff reporter for Cardio magazine and contributor to MD Magazine's vision disease coverage, Ellen Kurek earned her bachelor's from Swarthmore College, where she covered mental health issues for the campus newspaper and researched learning and memory neurophysiology. She earned her nonfiction writing certificate from the University of Washington, where she studied with writing coach and former Seattle Times reporter Jim Molnar.
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Cite this: Steroid Implants Best for Improving Vision in Uveitis ME - Medscape - Jun 13, 2023.