Retinal Neovascularization in DR May Be Detected With En Face OCT

Retinal neovascularization may be detected among patients with nonproliferative diabetic retinopathy (NPDR) using en face optical coherence tomography (OCT), according to research published in Ophthalmology Retina.

The retrospective cross-sectional study, which was conducted at the Oregon Health Science University, included individuals with NPDR (N=63; mean age, 61 years; 48% women) who underwent comprehensive examinations and wide-field OCT-angiography (OCT-A) between 2020 and 2022. To optimize retinal neovascularization detection, the investigators created 2 custom slabs for en face OCT and en face OCT-A by projecting angiographic signals from the internal limiting membrane (ILM) to an area above the outer boundary of the ILM, and by projecting the structural OCT signal from the ILM to an area above the ILM, respectively. A total of 2 experts graded data from the en face scans.

At clinical examination, 43% of eyes were graded as severe, 25% as moderate, and 32% as mild NPDR. The graders confirmed clinically occult retinal neovascularization lesions in 19% of eyes by en face OCT, en face OCT-A, and cross-sectional OCT-A. Of these eyes, 67% were graded as severe, 17% as moderate, and 17% as mild NPDR.

The mean [SD] retinal neovascularization membrane lesion was 0.12 [0.30] mm² measured by en face OCT, which was larger by a factor of 3.4 than the mean flow of en face OCT-A (0.027 mm²; P <.001), according to the report.

The en face scans had high interobserver reliability, with interclass correlation coefficients (ICC) of 0.889 and 0.996 for OCT and OCT-A, respectively. The en face OCT and OCT-A demonstrated sensitivities of 100% and 92% (P =.32) and specificities of 32% and 73% (P <.001), respectively, for detecting retinal neovascularization.

Lesions that were missed were significantly smaller than manually detected lesions (mean flow area, 0.015 vs 0.16 mm²; P <.001). False positives were observed in eyes with vessel crossings.

“Since a single OCTA scan can generate both en face OCT and en face OCTA simultaneously, combining these two imaging modalities may be an efficient method for screening for [retinal neovascularization],” according to the study authors. “For detecting individual RNV lesions, the en face OCT alone was significantly more sensitive than the en face OCTA, as the area of the [retinal neovascularization] membrane detected by en face OCT was larger than the area of RNV flow on en face OCTA. Thus, en face OCT may be a valuable tool for the initial screening of small [retinal neovascularization] in eyes with DR.”

A total of 33% of eyes did not have an available fundus photo at the date of widefield OCT-A imaging and were graded for retinal neovascularization based on previous fundus photos, which is an acknowledged limitation to the research. 

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.