Understanding Glaucoma

The eye has about one million tiny nerve fibers that run from the back of the eye to the brain. Glaucoma is a disease that causes the destruction of these fibers. It was once thought that the loss of these fibers was due to strictly to high pressure in the eye. But now it is known that even patients with normal eye pressure can have glaucoma and loss of these nerve fibers.

The eye produces a natural fluid, called the aqueous, that maintains eye pressure. The aqueous fluid circulates throughout the eye and leaves through a drainage system called the angle. The angle is between the outer layer and the iris of the eye. The reason that eye pressure is high in many glaucoma patients is that the drainage system is not working properly.

Types of Glaucoma

There are several kinds of glaucoma. The most common form of glaucoma is called open-angle glaucoma. The drainage angle is open in these patients, but the eye fluid does not drain as quickly as it should.

Narrow-angle glaucoma occurs when the drainage angle closes, and almost no eye fluid can escape. Narrow-angle glaucoma is an emergency and must be treated immediately.


In the early stages of open-angle glaucoma, there is no pain or noticeable changes in vision. Early detection, which can be made during a routine eye exam, is the key to the prevention of vision damage.


Our doctors at NH Eye Associates have extensive experience diagnosing and treating glaucoma. In many patients, eye drops that help lower eye pressure are the first line of treatment.

If the pressure does not fall to a low enough level with drops, then laser or surgery may be necessary. Glaucoma laser and surgery help eye fluid flow more freely through the angle.

What To Expect During Your Visit

An evaluation for glaucoma will typically last about one to two hours from the time you enter the exam room. Before you see your doctor, you may undergo a visual field test, which usually takes about half an hour. Visual field testing measures your peripheral vision and is one way to help diagnose and monitor glaucoma.

During your eye exam, a soft blue light will be used to check your eye pressure. You also may be given eye drops that will dilate your pupils. They may make your eyes light sensitive and difficult to focus, especially up close, for several hours.

Your doctor will then shine several lights into your eyes, using both an eye microscope and ophthalmoscope. These instruments allow for a thorough examination of the various parts that make up both the outside and inside of your eyes, including your nerve fibers. Specialized imaging of your nerve fibers, known as optical coherence tomography (OCT), may also be obtained. This imaging technique can detect early signs of glaucoma and help monitor your condition over time. At the completion of your visit, your doctor will review the results of your evaluation and discuss treatment options with you.

Open-Angle Glaucoma
Narrow-Angle Glaucoma