Near-infrared reflectance imaging of neovascularization in proliferative diabetic retinopathy
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(2020) 6:59 Vaz‑Pereira et al. Int J Retin Vitr https://doi.org/10.1186/s40942-020-00263-8
Open Access
ORIGINAL ARTICLE
Near‑infrared reflectance imaging of neovascularization in proliferative diabetic retinopathy Sara Vaz‑Pereira1,2* , Manuel Monteiro‑Grillo2,3 and Michael Engelbert4,5,6
Abstract Background: Blood is one of the main absorbers in the near-infrared spectrum and thus retinal vessels appear dark in near-infrared reflectance (NIR) images. Proliferative diabetic retinopathy (PDR) is characterized by abnormal neovas‑ cularization which also absorbs light and appears dark against a lighter fundus background. We analyzed neovascular‑ ization in PDR using NIR imaging, by observing changes in the neovascular complexes (NVCs) contrast and reflectivity over time. Methods: Retrospective case series of 20 eyes of 17 patients with PDR who underwent NIR imaging with optical coherence tomography (OCT) using the Spectralis System. NVCs presence and activity was determined using clinical, tomographic and angiographic criteria. At baseline, all NVCs were qualitatively graded in the NIR image into 3 groups (absent, present and inactive and present and active) and their evolution over time was registered as progression, regression or same status. Results: Twenty-seven NVCs were imaged, of which, 52% were neovascularization of the disc (NVD) and 48% were elsewhere (NVE). Consecutive NIR images were obtained from baseline to up to 5 time-points with a mean follow-up of 3.2 ± 1.7 years. All eyes underwent laser treatment and 30% had additional intravitreal therapy. Using NIR imaging, NVCs were classified at baseline as absent, present and inactive and present and active, respectively in 11, 4 and 85% of cases. NIR identified active neovascularization as hyporeflective irregular dark vessels originating from the retinal venules in NVE or from the disc in NVD. In all groups during follow-up, progression was identified as the development of new vascular hyporeflective dark fronds while regression was shown by reduced dark perfusion. Five eyes devel‑ oped a wolf’s jaw configuration with vascular hyporeflective new vessels and hyperreflective tissue from extensive fibrosis. Fibrosis was more apparent in later images, reaching 86%. In 3 cases (11%), the NVC was no longer seen in NIR, although was still identifiable on OCT over the NVC area. Conclusions: NIR is a non-invasive imaging modality commonly performed alongside OCT and frequently over‑ looked which can be useful to evaluate NVCs in PDR. Changes in NVC contrast and reflectivity due to blood perfusion can help in the detection and monitoring of diabetic proliferative disease and aid clinicians in daily practice. Keywords: Diabetes mellitus, Diabetic retinopathy, Diagnostic imaging, Near-infrared reflectance imaging, Optical coherence tomography, Proliferative diabetic retinopathy, Retinal neovascularization
*Correspondence: [email protected] 1 Department of Ophthalmology, Centro Hospitalar Universitário de Lisboa Norte, EPE - Hospital de Santa Maria,
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