OCT Angiography: A New Perspective on Diabetic Retinopathy

Sep 29, 2021
7 min read

Diabetic retinopathy is one of the quintessential ocular diseases. It’s a chronic condition without a simple cure, requires long-term management, and vigilance in patient education to achieve great outcomes. With the increasing prevalence of diabetes, diabetic retinopathy is something that all eyecare practitioners are familiar with. OCT angiography (OCTA) provides a different perspective on diabetic retinopathy, one that may move us from an era of counting hemorrhages to a future where we personalize care based on microvascular changes invisible to our funduscopic examination.

Preclinical diabetic retinopathy

The earliest signs of diabetic retinopathy—pericyte loss and vascular basement membrane thickening—occur on a cellular level. These changes eventually result in retinal vascular nonperfusion and alteration of the foveal avascular zone (FAZ). These pathological abnormalities are considered to be the preclinical signs of diabetic retinopathy because at this stage the clinical examination is completely normal. With very precise measurements of contrast sensitivity, microperimetry, or retino-electrophysiological testing the functional deficits of these preclinical retinal diabetic changes may be assessed.

Preclinical diabetic retinopathy is a relatively new concept, one that is likely to become more important due to the advent of OCTA. Whereas before, angiography was usually reserved for acutely vision-threatening pathology, OCTA allows us to perform angiography without any potential side effects within a few seconds.

Figure 1 demonstrates the power of OCTA, on the left is a normal non-diabetic patient and on the right is a 67-year-old with a 7-year history of moderately well-controlled diabetes (A1C 7.5%). His funduscopic examination is unremarkable and his best-corrected visual acuity is 20/20 in each eye. But looking at his OCTA image we can already visualize irregularity of the FAZ and areas of nonperfusion most prominent in the superior and temporal perifoveal region.

Unfortunately, there are no preferred practice guidelines on how to manage preclinical diabetic retinopathy so cases like this often leave me with more questions than answers.

Currently, images like this provide me another tool with which to convince my patients that they must continue to practice strict blood glucose control. But I believe that in the near future, OCTA data will be included in the expanded clinical classification systems of diabetic retinopathy, one which will help us provide better care for our patients.

Figure 1 shows a normal OCTA on the left and, on the right, a patient without clinical diabetic retinopathy but with OCTA changes.