Should We Treat or Observe Diabetic Macular Edema With Good Vision?

Since the mid-1980s, center-involved diabetic macular edema (CI-DME) was primarily treated by laser photocoagulation. This began to change approximately a decade ago, when multiple trials demonstrated that anti–vascular endothelial growth factor (VEGF) agents achieved superior visual outcomes to focal/grid laser therapy in patients with CI-DME. Importantly, these positive results were achieved in patients with CI-DME with reduced visual acuity (VA). The proper management strategy for CI-DME with good VA, however, remained unknown.

To bring some much-needed clarity to this question, the Diabetic Retinopathy Clinical Research (DRCR) Retina Network evaluated three different treatment strategies in 702 eyes with CI-DME and VA of 20/25 or better. Patients meeting inclusion criteria were randomly assigned to receive intravitreal aflibercept (2.0 mg) every 4 weeks, laser photocoagulation therapy every 13 weeks, or observation, and were followed for 2 years.

If the VA decreased by one line on an eye chart at two consecutive visits or two lines at one visit, patients in the photocoagulation and observation groups were started on aflibercept. The primary outcome was a five-letter or greater VA decrease from baseline.

At 2 years, the percentage of eyes with at least a five-letter VA decrease was 16%, 17%, and 19% in the aflibercept, laser photocoagulation, and observation groups, respectively, with no statistically significant differences among the groups. Aflibercept was initiated in 25% and 34% of the laser photocoagulation and observation groups, respectively, owing to decreased VA from baseline. VA of 20/20 or better at 2 years was present in 77% of eyes with aflibercept, 71% with laser photocoagulation, and 66% with observation.

No cases of endophthalmitis were reported, and the rate of adverse events (myocardial infarction, stroke, or vascular or unknown death) were not significantly different in the treatment groups.

Is a Change in Practice Warranted?

This is an important article from the standpoint of public health and system-based care and cost analysis. Despite the lack of substantial evidence, most ophthalmologists initiate anti-VEGF therapy in patients with CI-DME who have good VA, owing to the concern that vision may worsen with time if it is deferred. However, this study shows that VA remained intact over the 2-year follow-up period.

Treating these eyes with intravitreal injections creates unnecessary costs for the patient and payer, poses the risk for endophthalmitis (albeit a small one), and leads to excessive eye exams. Anti-VEGF therapy is expensive, with ranibizumab and aflibercept accounting for up to 12% of Medicare Part B claim spending. In addition, treatment with intravitreal injections requires frequent follow-up visits in patients with diabetes who are probably already burdened from healthcare visits for other systemic comorbidities and complications of their disease. A more conservative approach to the treatment of CI-DME with intact VA would have a tremendous impact on the financial, psychological, and logistical demands of patients and their families.

Going forward, ophthalmologists must consider the generalizability of this study to their own patients. Participants in this study had tight glycemic control with well-managed A1c levels, as well as excellent adherence to follow-up visits and monitoring at certain intervals. Although similar results would be expected with other available anti-VEGF agents, including ranibizumab and bevacizumab, this was not examined and cannot be confirmed.

Keeping these limitations in mind, the DRCR Retina Network has nonetheless delivered strong evidence to guide clinical practice in terms of whether or not to treat patients with CI-DME who have good vision.

Saumya M. Shah, BS, is a member of the ophthalmology department at the Mayo Clinic School of Medicine in Rochester, Minnesota.

Sophie J. Bakri, MD, a long-time contributor to Medscape, specializes in diseases and surgery of the retina and vitreous, including age-related macular degeneration. She also undertakes both clinical and translational research in the pathogenesis and treatment of retinal diseases.

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