Optical coherence tomography angiography (OCT-A) is changing the way clinicians evaluate the retinal vasculature and providing new metrics by which to monitor disease progression. This is particularly true for patients with diabetes whose vascular systems are compromised.

New research presented at last week’s ARVO meeting shows that the technology can detect the slightest signs of microvascular change in diabetic eyes, even before the development of clinically detectable retinopathy (DR).¹And those microscopic changes can be observed throughout the course of the disease, suggesting that a whole new parameter for stratifying diabetic retinopathy and guiding treatment is on the horoizon.^1,2

OCT-A Pros and Cons

Research presented by a University of California San Francisco-based team analyzed cross-sectional data of eyes from the diabetic retinopathy screening clinic and optometry clinic in San Francisco between April and October 2018. They divided participants into two groups, healthy eyes and diabetes without DR, to test the diagnostic efficacy of OCT-A using various measurements, such as superficial retinal vessel density (SVD), superficial retinal perfusion density (SPD), foveal avascular zone area (FAZ area) and foveal avascular zone circularity index (FAZ CI). The researchers also used software to process the images and calculate the deep retinal vessel density (DVD) and deep retinal perfusion density (DPD).

DVD was the most precise measurement OCT-A was able to gather and provided the most accurate diagnostic efficacy when distinguishing healthy eyes from those with diabetes without DR. DPD and FAZ CI also ranked high. However, the technology was not particularly adept at gathering SVD or SPD data.

Integrating the New with the Old

The vessel density data that OCT-A does capture is significantly correlated with the grading scale put forth by the Early Treatment Diabetic Retinopathy Study (ETDRS), according to a New York-based research team who also presented at ARVO. They performed a retrospective analysis of records from 2015 to 2018 for 72 diabetic eyes and found that 38% had an ETDRS score of 60, or extensive old pan-retinal photocoagulation, while 22% had a score greater than 60, or with neovascularization. When comparing these results with the ETDRS grading for each of the patients, the researchers found a significant inverse relationship between the scored provided by OCT-A and those of the traditional grading scale, suggesting OCT-A’s suitability in monitoring DR.