Glaucoma is a group of eye diseases that damage the optic nerve, which is the crucial connection between your eye and your brain. This damage can lead to irreversible vision loss and, if left untreated, can result in blindness.

The most common cause of this damage is a buildup of pressure inside the eye, known as intraocular pressure. This happens when the fluid that circulates within the eye (aqueous humor) doesn't drain properly. However, some people can develop glaucoma even with normal eye pressure.