Those of Asian and Native American descent are at higher risk for acute (angle closure) glaucoma. It occurs when the drainage system of the eye becomes blocked. It causes a sudden rise in pressure, requiring immediate, emergency medical care. The signs are usually serious and may include blurred vision, severe headaches, eye pain, nausea, vomiting or seeing rainbow-like halos around lights. Occasionally, the condition may be without symptoms; similar to open angle.