En face OCT for Detection of Clinically Unsuspected Retinal Neovascularization in Patients with Diabetic Retinopathy

Abstract

Purpose : To assess the value of en face OCT for detecting clinically unsuspected retinal neovascularization (RNV) in patients with nonproliferative diabetic retinopathy (NPDR).

Methods : A retrospective, cross-sectional study included treatment-naïve patients clinically graded as NPDR in an ongoing prospective observational OCT angiography (OCTA) study at a tertiary care center. Each patient underwent imaging of one eye with a spectral-domain OCTA (Solix; Visionix/Optovue, Inc., California, USA), generating a 17x17-mm widefield image by montaging four 9x9-mm scans, each with a pixel density of 600x600. Two independent graders examined a combination of en face OCT, en face OCTA with custom vitreoretinal interface slab, and cross-sectional OCTA to determine the ground truth for the presence of RNV. We measured the area of RNV flow within RNV lesions on en face OCTA. The main outcome measure is the detection rate of clinically occult RNV with OCT and OCTA.

Results : Of 63 eyes, 27 (43%) were clinically graded as severe NPDR, 16 (25%) as moderate, and 20 (32%) as mild. Using the combination of en face OCT, en face OCTA and cross-sectional OCTA, the graders detected 42 RNV lesions in 12 (19%) eyes, of which 8 (67%) were graded as severe NPDR, 2 (17%) moderate, and 2 (17%) mild. The sensitivity of en face OCT alone for detecting eyes with RNV was similar to that of en face OCTA alone (100% vs. 92%, P = 0.32), while the specificity of en face OCT alone was significantly lower than that of en face OCTA alone (32% vs. 73%, p < 0.001). For detecting individual RNV lesions, the en face OCT was 100% sensitive, compared to 67% sensitivity for the en face OCTA (P < 0.001). The mean area of RNV lesions that were missed by manual grading with en face OCTA was significantly smaller than that of manually detectable RNV (Mean [SD] RNV flow area, 0.015 [0.020] mm² vs. 0.16 [0.36] mm², p < 0.001).

Conclusions : The combination of en face OCT and OCTA can objectively detect clinically occult RNV. For the purpose of screening for these small, subclinical RNV using a single 2D map, en face OCT may be a better modality than en face OCTA.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

In an eye clinically graded as moderate NPDR, en face OCTA disclosed 12 lesions with flow above the internal limiting membrane (ILM) and en face OCT 16 lesions with epiretinal hyperreflective material. Corresponding OCT B-scans demonstrated flow signals above the ILM (yellow).