Retinal vein occlusion (RVO) is a condition in which a blood clot slows or stops circulation in a vein within the retinal tissue. RVO is the second leading cause of retinal vascular disease after diabetic retinopathy and a significant cause of blindness worldwide. The global prevalence is estimated at 16.4 million cases worldwide.
Current treatment options for RVO include laser photocoagulation, intravitreal steroid or anti-VEGF drug injection, and less frequently, vitrectomy with and without sheathotomy. Most of these approaches are painful and inconvenient to the patient and do not address the thrombus, which is the underlying cause of the pathology. Early attempts with systemic or local administration of thrombolytic therapy using tissue plasminogen activator (tPA) have been shown to be associated with serious complications.
Microsphere-mediated ultrasound represents a new treatment modality for RVO that addresses the underlying cause of the condition. Cerevast’s microspheres have a mean diameter of 1.1 – 3.3 microns and are comprised of a lipid shell and gas core. These microspheres can pass through the retinal vasculature due to their small size. Concomitantly administering ophthalmic ultrasound induces non-linear oscillations, or cavitation of the microspheres in the retinal veins thereby causing a release of energy and subsequent fluid motion in the region of the thrombus. This cavitation-induced energy of fluid motion is believed to be the underlying mechanism leading to clot lysis and reperfusion of retinal tissue. Pre-clinical and clinical studies of microsphere-mediated ophthalmic ultrasound have shown encouraging results as a non-invasive treatment for retinal vein occlusion leading to restored blood flow, reduction in intra-retinal hemorrhage volume and improved visual acuity scores.