Clinical characterization of intraretinal microvascular abnormality and associated neovascularization

Abstract

AIM: To determine the clinical characteristics of intraretinal microvascular abnormality(IRMA)and associated neovascularization. METHODS:This was a prospective, observational study. We recruited treatment-naive patients with diabetic retinopathy(DR)with IRMAs or retinal neovascularization, confirmed using fundus fluorescein angiography(FFA)between October 7, 2016 and December 10, 2017. Under the guidance of FFA, IRMAs and neovascularizations were scanned using optical coherence tomography angiography(OCTA). Origins, initial layers, morphologic features, retinal nonperfusion areas(NPAs), location with capillary nonperfusion(CNP)and leakages demonstrated by FFA of IRMAs and associated neovascularization were documented and compared. Retinal nonperfusion areas were measured using Image J software. RESULTS: Thirty-nine eyes of 36 patients were enrolled in this prospective study. High quality images of twenty IRMAs and 22 IRMA-associated neovascularizations were identified using OCTA. All IRMAs originated from and drained into veins in pruned-tree-like shapes. IRMAs originated from the major retinal vessels at the margin of the CNP, extended into retina and were always confined within a single original nonperfused area. All IRMA-associated neovascularizations originated from IRMAs with a sea-fan-like appearance. The IRMA associated neovascularizations crossed retinal venous and extended to both sides. The main part of these structures was intraretinal, except some advancing tips that breached the internal limiting membrane(ILM)to form neovascularization, and were adhered firmly to the retina; 91%(20/22)of IRMA-associated neovascularizations were located in the CNPs, and 9%(2/22)were located at the margin of CNPs. The affiliated NPAs of IRMA-associated neovascularizations were 26.1mm2±4.2mm2, significantly larger than the IRMAs(12.9mm2±4.7mm2, P<0.05). The initial layers showed no statistic difference between the groups(P>0.05).CONCLUSION: OCTA is an effective method for detecting both IRMA and neovascularization in DR. IRMA and associated neovascularization had significantly different clinical characteristics that can be differentiated by OCTA, and therefore may be useful to better understand pathophysiological mechanisms and to guide efficient therapeutic strategies for DR patients.

Keywords

• intraretinal microvascular abnormality
• neovascularization
• optical coherence tomography angiography
• clinical characteristics