The hallmark of proliferative diabetic retinopathy (PDR) is retinal neovascularization (NV). Tortuous intraretinal vascular segments known as intraretinal microvascular abnormalities (IRMAs) are a known risk factor for NV, but whether IRMA represents a biomarker or a vascular precursor lesion to NV has not been demonstrated. The purpose of this study was to document that IRMA may directly evolve into NV.
Retrospective analysis of prospective, observational case series PARTICIPANTS: Patients with treatment-naïve PDR METHODS: Patients were imaged longitudinally with fluorescein angiography (FA) and swept source OCT angiography (SS-OCTA) before and after panretinal photocoagulation (PRP) MAIN OUTCOME MEASURES: Presence and co-localization of IRMA and NV on serial FA and SS-OCTA.
Two PDR patients had multiple NV and IRMA lesions at baseline examination. Three months following PRP, FA demonstrated profuse leakage from 3 new NV lesions in one patient and 1 new NV lesion in another patient. Multimodal imaging showed that these 4 lesions were IRMAs at baseline. SS-OCTA performed before PRP and 1 week, 1 month, and 3 months after PRP confirmed that the precursor IRMA lesions were intraretinal tortuous vascular lesions at baseline and that they developed into preretinal NV with contiguous intraretinal components. NV was found to develop and adhere to the posterior hyaloid even in areas of pre-existing hyaloidal detachment.
and relevance: Diabetic retinal NV can develop from IRMA. Early identification of IRMAs may be an accurate means of predicting progression to PDR, and frequent monitoring of IRMAs with SS-OCTA may facilitate early diagnosis of PDR.

Copyright © 2020. Published by Elsevier Inc.