With neovascularization, abnormal blood vessels grow inside the eye, causing significant retinal damage. These blood vessels can also grow into the front of the eye, covering the surface of the iris, and into the trabecular meshwork drain. If this drain becomes blocked with abnormal vessels, aqueous fluid can’t exit back into the blood stream. This causes extremely high pressure inside, leading to acute glaucoma. Neovascular glaucoma is very difficult to treat as the pressure is recalcitrant to normal glaucoma drops. In these cases, a tube-shunt procedure is often required to create a new drainage pathway out of the eye. There are several causes for neovascular glaucoma but the most common is after a central retinal vein occlusion.