An Overview of Diabetic Retinopathy

W. Lloyd Clark, MD: Let’s narrow our discussion to an overview of diabetic retinopathy. Ehsan, can you give us a broad discussion of diabetic retinopathy in general? What are the classification schemes of diabetic retinopathy, what’s the prevalence of the various severity scales of diabetic eye disease?

Ehsan Rahimy, MD: Certainly. Joe touched base on this earlier, the recommendation is at the time of diagnosis for patients with type 2 diabetes, that they get a diabetic eye screen. Overall, diabetic retinopathy incidence is about 1 in 3 patients have some degree of retinopathy. We have close to 30 million patients in this country with diabetes. About a third of those are not even diagnosed yet, and there are almost 2 to 3 times as many who have what is termed as prediabetes. There is a huge population at risk that’s here. I mentioned about 1 in 3 of them have some degree of diabetic retinopathy. We then subclassify the severity of involvement, so we have nonproliferative and proliferative diabetic retinopathy. Within nonproliferative, your degree of involvement, roughly speaking, most of us grade clinically as mild, moderate, severe, you can say very severe, and then you go on to proliferative disease. And the hallmark of proliferative disease is you’re having neovascularization. This is the whole angiogenesis path that we had discussed, where there’s enough tissue, ischemia, hypoxia that stimulates the growth of new blood vessels, thought to be largely driven by VEGF as well as other cytokines.

Once you’re in proliferative disease, you’re at significant risk to progress to significant vision loss, potentially blindness. This is when patients get bad vitreous hemorrhage, tractional retinal detachments, etc. Then along the way, at any of these stages, one can develop diabetic macular edema, which we had discussed. When you look at prevalence numbers, it honestly depends on what patient population you’re looking at. One thing we’d all agree here is there are significant ethnic differences in terms of diabetes, diabetic retinopathy, how it affects certain populations at risk. Not only here in America, but across the globe, they’ve done a number of these population studies in certain countries that show very different numbers. Some of these pooled meta-analyses have shown that across the globe, of patients with diabetic retinopathy, anywhere from maybe 15% to 20% of them have proliferative disease. Here at home, the number of patients with PDR [proliferative diabetic retinopathy] is somewhere around a million or so, it’s estimated, which their prevalence is probably a little lower, maybe around 10%. But it goes to show you that different countries have significantly different PDR rates. Whether you’re in China, India, the Middle East, with our Latino community here, or African-American community as well, it depends on what group you’re looking at.

W. Lloyd Clark, MD: Diana, what kind of symptoms do our patients suffer from with diabetic retinopathy?

Diana V. Do, MD: There are a variety of symptoms that can happen in a patient with diabetic eye disease. Commonly, they might present with blurry central vision that affects them both for driving and for reading or activities at work. And that’s often caused by the presence of diabetic macular edema, which is swelling in the center of the retina. In addition, patients who have more advanced stages of diabetic eye disease can present with new floaters in the eye that obscure both their central and their peripheral vision due to bleeding into the vitreous cavity. Therefore, it’s important for patients with diabetes to get regular ophthalmic dilated examinations to assess their severity state and also to discuss treatment options.

W. Lloyd Clark, MD: Yes, of course, one of the major symptom complexes that patients have with diabetic retinopathy is that many of them don’t have any symptoms at all. That’s a huge problem because many patients start developing substantial anatomic changes, and they are unaware, and that underscores the importance of our relationship with primary care providers. And it underscores our critical relationship with primary eye care, including general ophthalmology and optometry. We’ve done a great job with disease awareness with AMD [age-related macular degeneration] over the last 15 years obviously, and we’re getting better with diabetes. But we’ve still got a long way to go because there are a lot of patients who go undiagnosed for sure.

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Transcript edited for clarity.