Abstract
Purpose:
It have been reported that ganglion cells are degenerated in diabetic retinopathy (DR), which is supported by the clinical data using fundus imaging to some extent. We herein investigated the findings in the nerve fiber layer (NFL) and ganglion cell layer (GCL) of DR on the en face images of swept-source optical coherence tomography (SS-OCT).
Methods:
Fifty eyes from 34 patients with DR were included in this study (10 eyes with each grade of international DR severity scale). We obtained three-dimensional images in 6x6mm centering the fovea using SS-OCT (DRI OCT-1, TOPCON). After individual B-scan images were aligned by the ‘flattening’ function using the border between NFL and GCL, we observed en face images constructed by 256 B-scan images. We characterized the patchy lesions which had both lower reflectivity than the surrounding areas in NFL and higher reflectivity in GCL.
Results:
The patchy lesions in NFL and GCL had the various shapes on en face OCT images, and their areas were 0.125±0.057 mm² at the level of NFL. Most lesions resided within NFL and GCL, and did not show any findings in the corresponding areas on color fundus photography. We further investigated the association between findings on fluorescein angiography (FA) and OCT in 23 eyes on whom both images were obtained. Mild hypofluorescence was accompanied with retinal capillaries in the areas corresponding to 78 patchy lesions on OCT images, and typical nonperfused areas were depicted in 8 lesions. Eyes with moderate nonproliferative diabetic retinopathy (NPDR), severe NPDR, and proliferative diabetic retinopathy were accompanied with the patchy lesions (the numbers in the individual grades were 4.4±3.7, 3.3±3.7, and 4.3±4.8, respectively), compared to no such lesions in eyes with no apparent retinopathy or mild NPDR.
Conclusions:
We characterized a novel finding, the patchy lesion, at the levels of NFL and GCL on en face OCT images in DR, most of which did not correspond to any fundus findings but to mild hypofluorescence on FA images.