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What is Primary Open-Angle Glaucoma?

Primary Open-Angle Glaucoma (POAG) is the most common form of glaucoma, affecting about three million Americans. It happens when the eye's drainage canals become clogged over time.

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Medical illustration of an eye with glaucoma
Medical illustration of an eye with glaucoma

What is Primary Open-Angle Glaucoma?

Primary Open-Angle Glaucoma (POAG) is the most common form of glaucoma, affecting about three million Americans. It happens when the eye's drainage canals become clogged over time.

The inner eye pressure (also called intraocular pressure or IOP) rises because the correct amount of fluid can’t drain out of the eye. With open-angle glaucoma, the entrances to the drainage canals are clear and should be working correctly. The clogging problem occurs further inside the drainage canals, similar to a clogged pipe below the drain in a sink.

Most people have no symptoms and no early warning signs. If open-angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma develops slowly and sometimes without noticeable sight loss for many years. It usually responds well to medication, especially if caught early and treated.

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Video Transcript

In most cases, glaucoma is caused by increased pressure in the eye. In a healthy eye a balance exists between the fluid produced and the fluid that leaves the eye. Primary open-angle glaucoma occurs when the drainage channels are open, but do not drain fluid properly. In order to maintain a healthy balance, the eye has a built-in drainage system.

Primary open-angle glaucoma occurs due to a deeper issue that impacts the eye’s natural drainage system. The eye’s drainage system works like a sink. If a blockage develops, or if fluid is produced faster than it can escape, an overflow will occur. In the eye, this overflow causes the pressure to elevate. The optic nerve is the structure most vulnerable to damage from elevated pressure. Continuous elevated pressure or spikes in pressure, can damage the optic nerve. If left untreated, glaucoma can lead to blindness which is irreversible.

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