Intraretinal microvascular abnormalities (IRMA) are abnormalities of the blood vessels that supply the retina of the eye, a sign of
diabetic retinopathy. IRMA can be difficult to distinguish from and is likely a precursor to retinal neovascularization. One way to distinguish IRMA from retinal neovascularization is to perform
fluorescein angiography. Since IRMA blood vessels are patent, unlike neovascular vessels, they do not leak, and therefore exhibit hypofluorescence on fluorescein angiography.