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Sara Vaz-Pereira, Manuel Monteiro-Grillo, Michael Engelbert; Near-infrared reflectance imaging of proliferative diabetic retinopathy. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1940. doi: https://doi.org/.
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Blood is one of the main absorbers in the near-infrared spectrum and therefore retinal vessels appear dark in near-infrared reflectance (NIR) images. Proliferative diabetic retinopathy (PDR) is characterized by the growth of abnormal vessels which also absorb light and appear dark against a lighter fundus background.We aim to study the usefulness of NIR imaging in the detection and follow-up of neovascular complexes (NVCs) in PDR.
Retrospective study of 20 eyes of 17 patients with PDR who underwent NIR imaging with optical coherence tomography (OCT) using the Spectralis System as part of routine clinical examination. NVCs presence and activity was determined using clinical, tomographic and angiographic criteria.
Twenty-seven NVCs were imaged, of which, 48% were neovascularization of the disc (NVD) and 52% were elsewhere (NVE). Mean patient follow-up was 3.7 years. Consecutive images were obtained from 3 to 5 time-points. All patients underwent laser treatment and 7 had additional intravitreal therapy. At baseline, NVCs were absent, present and active and present and inactive, respectively in 11%, 85% and 4% of cases. NIR identified active NVCs as hyporreflective irregular dark vessels originating from the retinal venules in NVE or from the disc in NVD. Associated hyperreflective fibrotic tissue was seen at baseline in 26%. NIR regression shown by reduced dark perfusion was observed in the 1st follow-up visit in 33% of cases and in 70% of cases in the 4th visit, consistent with various laser sessions. Progression with new vascular dark fronds was documented in about 40% scans in all time points. Four eyes developed a wolf’s jaw configuration with vascular hyporreflective new vessels and hyperreflective tissue from extensive fibrosis. Fibrosis was more apparent in later images, reaching 77%. In a minority of cases (7%) the NVC was no longer seen in NIR, although was still identifiable on OCT over the NVC area.
NIR is a non-invasive imaging modality commonly performed alongside OCT and frequently overlooked which can be useful to evaluate NVCs in PDR. Blood is one of the main absorbers in the NIR spectrum and therefore 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.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
NIR sequence of progressing (A) and regressing (B) neovascular complexes.
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