Analysis of emboli and blood flow in the ophthalmic artery to understand retinal artery occlusion.

Retinal artery occlusion (RAO) is a common ocular vascular occlusive disorder that may lead to partial or complete retinal ischemia with sudden visual deterioration and visual field defects. Although RAO has been investigated since 1859, the main mechanism is still not fully understood. While hypoperfusion of the ophthalmic artery (OA) due to severe stenosis of the internal carotid artery might lead to RAO, emboli are assumed to be the main reason. Intra-arterial thrombolysis is not a sufficient treatment for RAO, and current research is mainly focused on risk factors. In this study, a computational fluid dynamic model is presented to analyse flow conditions and clot behaviour at the junction of the internal carotid artery and OA based on a realistic geometry from a RAO patient. Clot diameters varied between 5 and 200 μm, and the probability of clots reaching the OA or being washed into the brain was analysed. Results show sufficient blood flow and perfusion pressure at the end of OA. The probability that clots from the main blood flow will to be washed into the brain is 7.32 ± 1.08%. A wall shear stress hotspot is observed at the curvature proximal to the internal carotid artery/OA junction. Clots released from this hotspot have a higher probability of causing RAO. The occurrence of such patient-specific pathophysiologies will have to be considered in the future.