OCT Angiography a Good Way to Detect Diabetic Retinopathy

Laird Harrison

July 28, 2020

Wide-field swept-source optical coherence tomography angiography (WF OCTA) can detect diabetic retinopathy as well as fluorescein angiography and ultrawide-field color fundus photography, according to results from two analyses.

The new technology saves time and is less invasive and less risky than fluorescein angiography, said Dan Gong, MD, from Massachusetts Eye and Ear in Boston. "The finding from both these studies is that this technology is just as good, if not better," he told Medscape Medical News.

Fluorescein angiography, the gold standard for detecting neovascularizations in diabetic retinopathy, requires the injection of sodium fluorescein dye, which can cause nausea, vomiting, itching, and occasionally anaphylaxis.

"The overall question is whether there are faster and less-invasive methods that would get the same information," Gong said.

One alternative is ultrawide-field color fundus photography. A newer option, OCTA, works by scanning the same location repeated times, so that variable backscattering, which indicates blood flow, can be assessed. The wide-field version provides a larger field of view by scanning multiple areas of the fundus and stitching them together in a montage.

The retrospective analyses conducted by Gong, John Miller, MD, also from Massachusetts Eye and Ear, and their colleagues involved images of 152 eyes from 101 patients, 23 with type 1 diabetes and 78 with type 2 diabetes. The severity of diabetic retinopathy in the study cohort varied.

Results from the first analysis — a comparison of WF OCTA (PLEX Elite 9000, Carl Zeiss Meditec) and ultrawide-field color fundus photography (California, Optos) in the 152 eyes — were presented by Gong at the virtual American Society of Retina Specialists 2020 Annual Meeting.

The two graders who independently evaluated the images were more likely to detect intraretinal microvascular abnormalities, neovascularization elsewhere, and neovascularization of the optic disc with WF OCTA than with color fundus photography, but were less likely to detect microaneurysms.

Table 1. WF OCTA vs Ultrawide-Field Color Fundus Photography
Sign of Diabetic Retinopathy WF OCTA, % Color Fundus Photography, % P Value
Microaneurysm 80.3 88.2 .004
Intraretinal microvascular abnormality 69.1 44.1 <.001
Neovascularization elsewhere 37.5 28.9 .015
Neovascularization elsewhere and of the optic disc 39.5 30.3 .007

Results from the second analysis — a comparison of WF OCTA and ultrawide-field fundus fluorescein angiography in 48 of the eyes — were presented by Miller.

The graders detected fewer signs of diabetic retinopathy with WF OCTA than with fluorescein angiography in most categories, but the differences were not significant.

Table 2. WF OCTA vs Ultrawide-Field Fundus Fluorescein Angiography
Sign of Diabetic Retinopathy WF OCTA, % Fluorescein Angiography, % P Value
Microaneurysm 91.7 97.9 .250
Intraretinal microvascular abnormality 83.3 87.5 .625
Neovascularization elsewhere 54.2 56.3 1.000
Neovascularization elsewhere and of the optic disc 60.4 60.4 1.000

In this analysis, the graders were also asked to examine detection rates with the combination of WF OCTA plus color fundus photography images and rates with fluorescein angiography images alone. Detection rates were exactly the same for all signs of diabetic retinopathy.

Miller and Gong agree that WF OCTA might offer a less-invasive alternative to fluorescein angiography, and one that could be used more frequently to monitor disease progression.

"You can do this every clinic visit if you want without a needle stick," Miller told Medscape Medical News. "And it doesn't require a nurse."

These findings confirm those from a comparison of the three imaging techniques conducted by Caroline Baumal, MD, from Tufts University School of Medicine in Boston, and her colleagues.

That team used WF OCTA with 12 mm × 12 mm fields, instead of the 15 mm × 15 mm montage used in the current analyses. "We looked at one type of scan, they looked at another type of scan, and we reached similar conclusions," she told Medscape Medical News.

Researchers are trying to pinpoint the best scan to use, she said. "Once we have that, we can even use this type of technology to screen patients, especially now with COVID, when patients might not want to come into an office for lengthy testing."

WF OCTA is also valuable as a research tool. "It has taught us more about the change in the blood vessels of the eye than we could learn from fluorescein angiography," Baumal explained.

The analyses were supported by Lions International Equipment Fund and the Massachusetts Lions Club. Gong has disclosed no relevant financial relationships. Miller reports relationships with Zeiss and Heidelberg Imaging. Baumal reports relationships with Zeiss, Novartis, and Genentech

American Society of Retina Specialists (ASRS) 2020 Annual Meeting. Presented July 25, 2020.

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