• What Is Glaucoma?

    Leer en Español:
    Written By: Kierstan Boyd
    Reviewed By: J Kevin McKinney MD
    Mar. 01, 2017

    Glaucoma is a disease that damages your eye’s optic nerve. It usually happens when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve.


    Glaucoma is a leading cause of blindness for people over 60 years old. But blindness from glaucoma can often be prevented with early treatment.

    In a healthy eye, excess fluid leaves the eye through the drainage angle, keeping pressure stable.

    Types of glaucoma

    There are two major types of glaucoma.

    Primary open-angle glaucoma

    This is the most common type of glaucoma. It happens gradually, where the eye does not drain fluid as well as it should (like a clogged drain). As a result, eye pressure builds and starts to damage the optic nerve. This type of glaucoma is painless and causes no vision changes at first.

    Some people can have optic nerves that are sensitive to normal eye pressure. This means their risk of getting glaucoma is higher than normal. Regular eye exams are important to find early signs of damage to their optic nerve.

    Angle-closure glaucoma (also called “closed-angle glaucoma” or “narrow-angle glaucoma”)

    This type happens when someone’s iris is very close to the drainage angle in their eye. The iris can end up blocking the drainage angle. You can think of it like a piece of paper sliding over a sink drain. When the drainage angle gets completely blocked, eye pressure rises very quickly. This is called an acute attack. It is a true eye emergency, and you should call your ophthalmologist right away or you might go blind.

    Here are the signs of an acute angle-closure glaucoma attack:

    • Your vision is suddenly blurry
    • You have severe eye pain
    • You have a headache
    • You feel sick to your stomach (nausea)
    • You throw up (vomit)
    • You see rainbow-colored rings or halos around lights

    Many people with angle-closure glaucoma develop it slowly. This is called chronic angle-closure glaucoma. There are no symptoms at first, so they don’t know they have it until the damage is severe or they have an attack.

    Angle-closure glaucoma can cause blindness if not treated right away.