Author: Konstantinos Douglas, MD, Jose Daniel Diaz, MD; Patrick Oellers, MD; John B. Miller, MD

Clinical Presentation: A 63-year-old healthy woman was referred for retinal examination. She denied any vision changes. On examination, best-corrected visual acuity was 20/20 OU. Biomicroscopy of the anterior segment was unremarkable apart from mild nuclear sclerosis of both eyes. Dilated fundus examination of the left eye revealed small retinal hemorrhage with surrounding exudation, most consistent with a large retinal microaneurysm, which was confirmed by fluorescein angiography  (FA) and optical coherence tomography angiography (OCT-A) . The patient was referred to her internist for workup of cardiovascular risk factors. The lesion was observed with plans for laser treatment for foveal threatening complications such as progression of lipid exudates or development of intraretinal fluid.

Imaging findings: FA showed correlating hyperfluorescence, consistent with a retinal microaneurysm (Fig.1). Optical Coherence Tomography-Angiography (OCTA; Avanti, Optovue) with segmentation of the superficial retinal layers accurately depicted the exact anatomy of the microaneurysm (Fig. 2). In addition, structural en-face OCT revealed exudation nearby. OCTA B-scan indicated blood flow through the aneurysm and a high resolution OCT image demonstrated hard exudates and focal retinal edema.

Discussion points: Retinal microaneurysms, small saccular outpouchings that arise from the retinal capillary system, are most commonly seen in patients with underlying systemic conditions such as diabetes mellitus, hypertension, and atherosclerosis. This case is interesting, since the aneurysm is fairly large, yet isolated without any other fundus abnormalities consistent with vascular disease. While microaneurysms can be visualized on fundus examination, further imaging modalities such as fluorescein angiography and OCT-A can be used to confirm the diagnosis, especially if they occur in the setting of hemorrhage and/or exudation. The recent development of OCT-A provides a quick and noninvasive option for the detection and monitoring of retinal microvasculature changes. As shown in this case, OCT-A has the potential to clearly delineate the anatomy of retinal aneurysms and could be used for diagnosis and surveillance of such lesions, possibly replacing the current gold-standard fluorescein angiography in appropriate cases. OCT-A imaging allows for efficient and noninvasive detection of a large retinal microaneurysms and provides detailed anatomical information.

Fig. 1
Fig. 2