Swept-source OCT angiography (OCT-A) that uses vitreoretinal interface (VRI) slab images may be a good, noninvasive alternative to fluorescein angiography (FA) since it showed similar results in detecting neovascularization in proliferative diabetic retinopathy (PDR), a study in Ophthalmology Retina reports. The investigation also suggested OCT-A VRI slab images might be a better option in distinguishing intraretinal microvascular abnormalities and diabetic papillopathy from neovascularization.

Fluorescein angiography is considered the gold standard to evaluate retinal vascular changes in DR, but it still presents potential complications including the time it takes to administer the test and its use of intravenous dye injection, which may cause nausea and other issues.

The investigation enrolled 42 eyes of 30 treatment-naïve PDR patients, all of whom underwent comprehensive eye exams, including OCT-A and FA. The researchers compared neovascularization detected by OCT-A 15x15mm VRI slab images and those found on fluorescein angiography in the same 15x15mm areas.

Among 100 cases of neovascularization detected by FA, 73 were also identified as such in the OCT-A VRI slab images using automated segmentation, or a 73% percent sensitivity rate.

Among the remaining 27 neovascular cases detected only by FA, 15 were intraretinal microvascular abnormalities with fluorescence leakage, one was a diabetic papillopathy and 11 were flat vessels on the internal limiting membrane surface that were missed because of segmentation error.

Conversely, among the 98 instances of neovascularization detected on the VRI slab images, fluorescein angiography wasn’t able to detect 25 of them. These included nine small vessels that exhibited too little leakage on FA and 16 false-positives due to segmentation errors.

After reconsidering the VRI slab images with manual segmentation, the sensitivity increased to 84%. Additionally, after manual segmentation, researchers said they were able to observe, in detail, every single capillary that constituted the new vessel growth in the widefield OCT-A slab images.

The results of a sub-analysis found the average maximum diameter of new vessels identified on VRI slab images but not by FA was as small as 271 ± 84µm.         

OCT-A VRI slab images may be a valuable adjunct examination for evaluating neovascular growth in PDR, since they can verify penetration of the internal limiting membrane into the posterior vitreous membrane by flow signals in cross-sectional images, the researchers noted.

The technique of using VRI slab images by OCT-A provides “subtle anatomic insights and may be more accurate than clinical examination or leakage on FA,” the investigators wrote in their paper.