Glaucoma is a leading cause of blindness for people over 60 years old. Glaucoma has no symptoms in its early stages. In fact, half of the people with glaucoma do not know they have it! Glaucoma is an eye disease that develops gradually, usually over several years, causes no pain and presents only subtle symptoms that worsen over time. These symptoms include blurred vision, loss of peripheral (side) vision and inability to adjust your eyes to darkened rooms.