The term glaucoma refers to multiple diseases where the eye's optic nerve can become damaged. The most common kind, open-angle glaucoma, happens as a result of high eye pressure. Also known as ocular hypertension, this is when fluid drains too slowly out of the front part of the eye. This fluid builds up, and the pressure inside the eye rises.

Glaucoma can cause peripheral and central vision loss and even blindness. Anyone can get it, and there are no symptoms early on. That's one reason why regular eye exams are important.

Watch Peter Netland, MD, explain eye pressure and glaucoma.