Glaucoma is one of the most common eye diseases among adults. Three million Americans have the disease, and it is the second leading cause of blindness. 

It encompasses a range of conditions that cause damage to the optic nerve due to increased pressure in the fluid of the eye. This fluid drains typically where the iris and cornea meet through mesh-like tissue. When the body overproduces fluid or drainage is inhibited, pressure builds up.

The gradual damage to the nerve is painless, with vision problems developing very slowly. With little to no symptoms at the onset of the disease, nearly half of the people affected do not know they have the disease.