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Macular thickness reduced more with dexamethasone than bevacizumab in DME
However, the mean final best corrected visual acuity was comparable for the two treatment groups.
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A delayed delivery system of dexamethasone significantly reduced central subfield thickness compared with intravitreal bevacizumab in patients with persistent diabetic macular edema, according to a study.
“Even after 2 years of treatment with anti-VEGF agents alone, approximately 40% of patients continue to have macular edema,” co-author Raj K. Maturi, MD, a partner at Midwest Eye Institute in Indianapolis, said. “We wanted to find out if we could get rid of the macular edema, which over time can cause vision loss, by giving patients a different treatment. The treatment we thought might be most beneficial was a long-term dexamethasone implant.”
Maturi and colleagues conducted a previous study using a combination of Ozurdex (dexamethasone 0.7 mg intravitreal implant, Allergan) and an anti-VEGF agent vs. an anti-VEGF alone. “We found that the combination therapy was not helped much by the anti-VEGF agent in patients who had chronic edema,” Maturi told Ocular Surgery News.
Maturi said the standard of care in patients with chronic edema is to continue anti-VEGF agents, which was one of the two arms of the current study, whereas dexamethasone alone, every 3 months, was the other arm.
The protocol for the previous study was dexamethasone once every 4 months, “which resulted in some edema returning by month 4, so the drug was not lasting the full 4 months for chronic diabetic macular edema,” Maturi said.
Macular thickness reduction
The current single-center study enrolled 23 eyes in the Avastin (bevacizumab, Genentech) group and 27 eyes in the dexamethasone group. The number of injections was seven for the former and 2.7 for the latter over a 1-year period.
The results, which appeared in Retina, found that the mean final macular thickness was 471 µm for bevacizumab vs. 336 µm for dexamethasone, which was a statistically significant difference.
The mean change in macular thickness was –13 µm for bevacizumab and –122 µm for dexamethasone.
“I did not expect patients who have had treatments for many years for continued edema would achieve such a flattened macula with Ozurdex,” Maturi said. “A large percentage of these patients had almost complete resolution of the edema. This did not occur in the anti-VEGF arm of the study.”
Maturi said when an anti-VEGF injection is given, the drug only impacts the VEGF in the eye, in contrast to the steroid dexamethasone, “which affects not only the anti-VEGF, but also the other components, such as inflammatory cytokines, that are present in the eye as well. Because the implant works on more than one mechanism of action, it is likely that the implant will have a much more overall benefit effect than simply an anti-VEGF injection.”
However, the mean final best corrected visual acuity was comparable for the two groups, likely due to the chronic nature of the disease, according to Maturi, “although I was hoping to see more of a visual acuity gain with the resolution of edema. There may be too much damage to the photoceptors to restore vision.”
Start treatment early
Maturi encourages clinicians to use dexamethasone, in part because it is less expensive. “It is also important to begin treatment before the edema becomes too chronic; otherwise, there may not be as much vision gain possible,” he said.
Patient compliance may be enhanced with the dexamethasone implant due to fewer office visits in general for an injection. “However, IOP needs to be checked 8 weeks after the first and second implant to ensure pressure is not worsening,” Maturi said.
A handful of patients in the dexamethasone group required drops to control IOP.
The Diabetic Retinopathy Clinical Research Network recently completed recruitment for Protocol U, in which patients are given either an anti-VEGF injection or a dexamethasone implant and anti-VEGF injection. – by Bob Kronemyer
- Reference:
- Shah SU, et al. Retina. 2016;doi:10.1097/IAE.0000000000001038.
- For more information:
- Raj K. Maturi, MD, can be reached at Midwest Eye Institute, 200 W. 103 St., Suite 1060, Indianapolis, IN 46290; email: rmaturi@gmail.com.
Disclosure: Maturi reports he has received research funding from Genentech and Allergan.