Diagnostic Testing for Diabetic Macular Edema

Nancy Holekamp, MD: Dr Leng, we’re in the middle of a diabetes epidemic, and a high percentage of these patients with diabetes will have diabetic retinopathy. Can you discuss the tests that you use in your practice, particularly when you’re looking for diabetic macular edema [DME]?

Theodore Leng, MD, FACS: The physical examination is sensitive at picking up diabetic macular edema. A few decades ago, we were using more macular contact lens exams with the slit lamp, and with the stereoscopy that you can get on that exam, it’s quite easy to see swollen retinas. Now we’re in an era of diagnostic testing. Also, 20 years ago, a fluorescein angiogram was the best way of detecting diabetic macular edema, the vascular endothelial damage, and seeing the fluorescein dye leaking out of those vessels and into the later frames of the fluorescein angiogram. But today, the mainstay would be optical coherence tomography, or OCT, which is a tomographic test that is performed in less than 2 seconds on an eye. That eye doesn’t need to be dilated, and it uses a comfortable infrared wavelength light, so patients aren’t annoyed by a bright flash of light. We get volumetric data to look at that retina carefully down to the microscopic layers with 5-μm resolution, to see if there is macular edema, where it’s located, and its severity. Today, the OCT is where we’re going to find the diabetic macular edema.

Nancy Holekamp, MD: OCT is a very important test; but who has these, retina specialists, ophthalmologists, optometrists? How can patients with diabetic retinopathy, where there’s a concern for DME, get this test?

Theodore Leng, MD, FACS: Fortunately OCTs are widely available now. They’ve been out for about 20 years now, and widely distributed. The largest purchasers of OCT machines are not ophthalmologists, but optometrists. There are about 10 times more optometrists than ophthalmologists and retina specialists. Many patients are seeing optometrists as their primary eye care provider, and many of them have these devices in their offices and can detect DME.

Nancy Holekamp, MD: How often should patients with DME get screened using this test? Or how often should patients for whom you think DME might be a concern, be monitored with this test?

Theodore Leng, MD, FACS: There’s a bit of variation, but the American Academy of Ophthalmology puts out Preferred Practice Patterns guidelines for diabetic eye disease. At baseline, people should be screened annually for all diabetic eye disease. But if there is DME that’s already present, those patients might come in as often as every 2 months to monitor the status of the DME, its location, if it’s worsening or improving, and whether they need therapy and the reaction to the therapy.

Nancy Holekamp, MD: Thanks to all of you for this rich and informative discussion, and thank you for watching this HCPLive® Peer Exchange. If you enjoyed the content, please subscribe to our e-newsletters to receive upcoming Peer Exchanges and other great content right in your inbox.

Transcript edited for clarity.