Utilizing Optical Coherence Tomography Angiography (OCTA) and visible light OCT in the at-risk patients with Non-arteritic Anterior Ischaemic Optic Neuropathy (NAION)

Non-arteritic anterior ischemic optic neuropathy (NAION) affects 2.3 to 10.3 per 10000 people in the United States, making it one of the most common acute optic neuropathy that leads to loss of vision in the elderly population. With no definitive treatments available, NAION is characterized by acute, painless unilateral visual loss and visual field (VF) defect with optic disc swelling. Patients are at an increased risk of developing NAION if they have conditions such as diabetes, hypertension, sleep apnea, small optic discs, and especially if they had a previous episode ofNAION. NAION is thought to be caused by an impaired circulation of blood to the front of the optic nerve without true inflammation, although the exact pathophysiological mechanism is still unproven. Optical coherence tomography angiography (OCTA) is a novel imaging technique used to detect ocular perfusion and provide high-resolution images of retinal capillaries. Using a non-invasive infrared laser that shines on the retina, it is possible to construct cross-sectional structures and obtain blood flow information to quantitatively assess the retinal and choroidal microvasculature. Although OCT A has been broadly used to study patients with glaucoma and retina pathologies, this tool has not been extensively employed in studying NAION. Another novel imaging modality that provides more functional measurements of retinal capillaries and optic nerve heads is visible-light optical coherence tomography (vis-OCT). Given its ability to measure microvascular sO2 and simultaneously provide three-dimensional anatomical tissue morphology, vis-OCT is another promising tool to delineate the pathophysiology of NAION. We aim to utilize OCTA and vis-OCT to determine the progression and the risk factors for NAION, and better understand the pathophysiology to inform the clinical treatments for this debilitating disease.