Proper functioning of the eye requires nourishment from the vascular system. A disruption in blood flow can lead to a disruption in vision or even blindness. A variety of diseases and disorders can cause disruption in ocular blood flow.
Retinal vein occlusion (RVO) is a condition in which a blood clot slows or stops circulation in a vein within the retinal tissue. There are two primary types of RVO. Central retinal vein occlusion (CRVO) involves a blockage of the main vein of the retina. Branch retinal vein occlusion (BRVO) involves a blockage of the tributary vein(s) of the retina. RVO is the second most common retinal vascular disease and is a significant cause of blindness worldwide. In the U.S. alone, 150,000 new cases of RVO occur each year.
Various pharmacological and non-pharmacological treatments for RVO have been explored. Pharmacological treatments include systemic/intravitreal thrombolytics, intravitreal triamcinolone (SCORE: Standard Care Vs. Corticosteroid for Retinal Vein Occlusion; Ozurdex, Allergan), and intravitreal anti-VEGF (bevacizumab, ranibizumab, pegaptanib). Non-pharmacological treatments for BRVO include limited sheath manipulation, macular laser and sheathotomy. Non-pharmacological treatments for CRVO include laser/surgical chorioretinal anastomosis, posterior scleral ring sheathotomy, radial optic neurotomy and retinal vein cannulation. The surgical approaches to RVO treatment are technically challenging, but when successful, produce significant results.
U.S. Patent Application Publication No. 2009/0030323 to Fawzi et al., titled “Ultrasound and Microbubbles in Ocular Diagnostics and Therapies” described methods, systems, and techniques for applying contrast-enhanced ultrasound to locate areas of blockage within retinal vessels and to break up clots that are causing damage.
There remains a need for improved treatments for diseases and disorders caused by disruption in ocular blood flow, including RVO.
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