What is Glaucoma?

What Is Glaucoma?

Glaucoma is a progressive disease of the eye that if left untreated, can eventually lead to blindness. Glaucoma is commonly associated with increased pressure in the eye due to an imbalance in production and outflow of ocular fluid. In a healthy eye, fluid is produced to help maintain the eye’s shape. Normally, this natural fluid flows out through an area called the trabecular meshwork, and is absorbed into the bloodstream. If the fluid does not drain at the same rate that it is produced, pressure will begin to build in the eye. Over time, this increased pressure can damage the optic nerve and destroy vision.


Glaucoma & Eye Pressure

It’s easy to confuse eye pressure and glaucoma but important to understand the difference. Although intraocular pressure (IOP) is often associated with glaucoma, it’s possible to develop the disease without it. Whether you develop glaucoma depends on the level of pressure your optic nerve can tolerate without being damaged. This level varies from person to person, and in some cases, may never develop into glaucoma. That’s why it’s so important to schedule a comprehensive dilated eye exam at least once a year. It can help your eye care professional determine what level of eye pressure is appropriate for you.

Types of Glaucoma

There are two main types of glaucoma: open-angle glaucoma and angle-closure glaucoma.


The most common type of glaucoma, open-angle glaucoma, accounts for approximately 70% to 90% of all cases. The disease is progressive and has no detectable early signs. Elevated IOP is the most significant risk factor for the development and progression of open-angle glaucoma. As eye pressure builds, it gradually can lead to:

• Damage of the optic nerve
• Loss of peripheral vision
• Blindness, if left untreated


The second most common type of glaucoma — angle-closure glaucoma — occurs when the drainage pathways in the eye become blocked by the iris. As a result, fluid cannot circulate through the eye and pressure increases. The condition can occur suddenly (acute angle-closure glaucoma) or gradually (chronic angle-closure glaucoma).

Your eye care professional can perform a simple eye test to determine if the angle in your eye is normal and wide or abnormal and narrow.

An image of a flowery field depicts how peripheral vision can begin to diminish in patients with glaucoma.