COVER STORY: Retina specialists explore anti-VEGF treatments for diabetic eye disease

As the rising prevalence of diabetes drives demand for care across medical specialties, ophthalmologists are increasingly focused on the causes, prevention and treatment of diabetic eye disease.

Overall, 4.2 million adults have diabetic retinopathy and 655,000 have vision-threatening diabetic retinopathy. Indeed, diabetic retinopathy affects almost one-third of adults with diabetes who are older than 40 years of age, according to the Centers for Disease Control and Prevention.

“Because the incidence of diabetes is increasing worldwide, the risk for developing central vision loss due to diabetic macular edema is also increasing. In my clinical practice, I frequently encounter diabetic patients who are referred for symptomatic vision loss and I diagnose them with center-involved diabetic macular edema,” Diana V. Do, MD, said.

Risk, management, prevention

Diabetic macular edema is the major cause of vision loss among people with type 2 diabetes and “is invariably present in patients with type 2 diabetes with [proliferative diabetic retinopathy],” according to one study in Eye and Vision. In another report, Varma and colleagues reported a greater burden of DME among non-Hispanic blacks, individuals with high blood glucose levels and those with a longer duration of diabetes.

Carl D. Regillo, MD, FACS, OSN Retina/Vitreous Board Member, described a correlation between severity of diabetic retinopathy and risk of DME, saying that as the level of diabetic retinopathy increases, from mild to moderate to severe, VEGF levels in the eye tend to increase, resulting in a greater likelihood that patients will have DME and its related vision problems.

“It is true that DME can occur at any stage of diabetic retinopathy, but it is more likely to be present and to affect vision as the level goes up,” Regillo said. “It is often stated that the correlation between drying and vision is not strong, that’s true, but the reason the correlation isn’t perfect is because you can reduce the swelling but not necessarily improve the vision. However, what is important to realize is that you can’t improve the vision without reducing the edema.”

There are also correlations between DME and systemic factors, such as lipid levels, hypertension and renal failure, although the degree of influence on DME is not well established, Regillo said.

Oral diabetes medications can influence DME severity as well. In particular, glitazones, which mitigate insulin resistance in patients with type 2 diabetes, are known precipitators of DME.

“That’s always something that we keep in mind when we see a patient with type 2 diabetes mellitus on oral medicines,” Regillo said. “The glitazone class of drugs is not used quite as often as it used to be, but it can cause edema or make edema worse.”

Important to prevention of diabetic eye disease is control of blood glucose levels. At 4 years after stopping intensive glycemic control in patients with type 2 diabetes, the risk for diabetic retinopathy development was reduced by half, Chew and colleagues reported in the National Eye Institute’s ACCORD Eye Study.

“The ACCORD follow-on study results underscore the importance of intense glycemic control by showing that the benefits of good control, even later in the course of disease, persist over a long time frame,” Regillo said.

In the study, diabetic retinopathy progressed in 5.8% of patients with intensive glycemic treatment and in 12.7% of those with standard treatment; the difference was statistically significant (P < .0001). Diabetic retinopathy progressed in 11.8% of patients who had received fenofibrate and in 10.2% of those who received a placebo. Fenofibrate did not show a lasting benefit, and intensive blood pressure control had no discernible effect, the authors wrote.

Click here to read the full cover story published in Ocular Surgery News U.S. Edition, August 10, 2016.