In the U.S., 2.7 million people have glaucoma. Half know, and half don't. This is because glaucoma often has no warning signs.
At first, open-angle glaucoma has no symptoms. It causes no pain, and vision stays normal. Without detection and treatment, people with glaucoma will slowly lose their peripheral (side) vision, and vision lost from the disease cannot be restored.
Early detection is important for treating glaucoma and slowing its progression.