Glaucoma. Simulated view of a hand with four fingers held up as seen by someone with glaucoma. This eye condition is caused by increased pressure inside the eye (intraocular pressure). Symptoms are rare in the early stages of the disease, but once advanced there can be loss of peripheral vision, as seen here. If untreated, glaucoma can cause total blindness. For an image showing how this scene would appear to someone with normal vision, see image C025/9030.