What is Glaucoma?

Glaucomatous Nerve With Cupping

Glaucomatous Nerve With Cupping

Glaucoma is a disease of the optic nerve — the part of the eye that carries the images we see to the brain. The optic nerve is made up of many nerve fibers, like an electric cable containing numerous wires. When damage to the optic nerve fibers occurs, blind spots develop. These blind spots usually go undetected until the optic nerve is significantly damaged. If the entire nerve is destroyed, blindness results.

Glaucoma is a leading cause of blindness in the United States, especially for older people. But loss of sight from glaucoma can often be prevented with early detection and treatment.

What Are the Different Types of Glaucoma?

Clear liquid called aqueous humor circulates inside the front portion of the eye. To maintain a healthy level of pressure within the eye, a small amount of this fluid is produced constantly while an equal amount flows out of the eye through a microscopic drainage system. (This liquid is not part of the tears on the outer surface of the eye.)

Because the eye is a closed structure, if the drainage area for the aqueous humor—called the drainage angle—is blocked, the excess fluid cannot flow out of the eye. Fluid pressure within the eye increases, pushing against the optic nerve and causing damage.

What Causes Glaucoma?

Primary Open-angle Glaucoma

This is the most common form of glaucoma in the United States. The risk of developing primary open-angle glaucoma increases with age. The drainage angle of the eye becomes less efficient over time, and pressure within the eye gradually increases, which can damage the optic nerve. In some patients, the optic nerve becomes sensitive even to normal eye pressure and is at risk for damage. Treatment is necessary to prevent further vision loss.

Typically, open-angle glaucoma has no symptoms in its early stages, and vision remains normal. As the optic nerve becomes more damaged, blank spots begin to appear in your field of vision. Initially, these blank spots are in your peripheral vision, but as the disease progresses these blank spots progress to your central vision. You typically won’t notice these blank spots in your day-to-day activities until the optic nerve is significantly damaged and these spots become large. If all the optic nerve fibers die, blindness results.

Angle Closure Glaucoma

glaucoma-treatment-southern-idaho-opthalmology-twin-falls-idahoSome eyes are formed with the iris (the colored part of the eye) too close to the drainage angle. In these eyes, which are often small and farsighted, the iris can be pushed forward, blocking the drainage channel completely. Since the fluid cannot exit the eye, pressure inside the eye builds rapidly and causes an acute closed-angle attack.

Symptoms of acute angle closure glaucoma may include:

  • Blurred vision
  • Severe eye pain
  • Headache
  • Rainbow-colored halos around lights
  • Nausea and vomiting

This is a true eye emergency. If you have any of these symptoms, call us immediately. Permanent blindness can result in acute angle closure if not treated promptly.

Who Is at Risk For Glaucoma?

We consider many sources of information to determine your risk for developing glaucoma.

The most important risk factors include:

  • Advanced age
  • Elevated eye pressure
  • Family history of glaucoma
  • African or Hispanic ancestry
  • Significant farsightedness or nearsightedness
  • Past eye injuries
  • Thinner central corneal thickness
  • Systemic health problems, including diabetes, migraine headaches, and poor circulation
  • Pre-existing thinning of the optic nerve
  • Exposure to certain medications, such as prolonged steroid use

We will weigh all of these factors before deciding whether you need treatment for glaucoma, or whether you should be monitored closely as a glaucoma suspect. This means your risk of developing glaucoma is higher than normal, and you need to have regular examinations to detect the early signs of damage to the optic nerve.

How Is Glaucoma Detected?

Regular eye examinations by your ophthalmologist are the best way to detect glaucoma. A glaucoma screening that checks only the pressure of the eye is not sufficient to determine if you have glaucoma. The only sure way to detect glaucoma is to have a complete eye examination that checks for optic nerve damage.

During your glaucoma evaluation, we will:

  • Review your history and any predisposing risk factors
  • Measure your intraocular pressure (tonometry)
  • Inspect the drainage angle of your eye (gonioscopy)
  • Evaluate whether or not there is any optic nerve damage (ophthalmoscopy)
  • Test the peripheral vision of each eye (visual field testing, or perimetry)
  • Photography of the optic nerve or other computerized imaging (ocular coherence tomography) may be recommended

Some of these tests may not be necessary for everyone. These tests may need to be repeated on a regular basis to monitor any changes in your condition.

How Is Glaucoma Treated?

Damage caused by glaucoma cannot be reversed. Eyedrops, laser surgery, and surgery in the operating room are used to lower eye pressure and help prevent further damage. In some cases, oral medications also may be prescribed.

Because glaucoma can progress without your knowledge, periodic appointments are very important to prevent further vision loss. Adjustments to your treatment may be necessary from time to time.


Glaucoma is usually controlled with eyedrops taken daily. These medications lower eye pressure, either by decreasing the amount of aqueous fluid produced within the eye or by improving the flow through the drainage angle.

Never change or stop taking your medications without consulting your ophthalmologist. If you are about to run out of your medication, ask us if you should have your prescription refilled.

All medications can have side effects or can interact with other medications. Therefore, it is important that you make a list of the medications you take regularly and share this list with each doctor you see.

reatment may be necessary from time to time.

Laser Surgery

Laser surgery treatments may be recommended for different types of glaucoma.

In open-angle glaucoma, the drain itself is treated. The laser is used to modify the drain (trabeculoplasty) to help control eye pressure.

In closed-angle glaucoma, the laser creates a hole in the iris (iridotomy) to improve the flow of aqueous fluid to the drain.

Surgery in the Operating Room

When surgery in the operating room is needed to treat glaucoma, we use fine microsurgical instruments to create a new drainage channel for the aqueous fluid to leave the eye. Surgery is recommended if we feel it is necessary to prevent further damage to the optic nerve. As with laser surgery, surgery in the operating room is typically an outpatient procedure.

What Is Your Part in Treatment?

Treatment for glaucoma requires teamwork between you and your doctor. We can prescribe treatment for glaucoma, but only you can make sure that you follow your doctor’s instructions and use your eyedrops.

Once you are taking medications for glaucoma, we will want to see you more frequently. Typically, you can expect an appointment every three to six months. This will vary depending on your treatment needs and severity of disease.

Loss of Vision Can Be Prevented

Regular medical eye exams can help prevent unnecessary vision loss. People at any age with symptoms of or risk factors for glaucoma, such as those with diabetes, a family history of glaucoma, or those of African descent, should see an ophthalmologist for an exam. We will let you know how often to return for follow-up exams.

Adults 20 to 64 years of age with no signs of or risk factors for glaucoma should get an eye disease screening at age 40—the time when early signs of disease and changes in vision may start to happen. Based on the results of the initial screening, we will let you know how often to return for follow-up exams.

Adults 65 years or old should have an eye exam every one to two years, as recommended by your ophthalmologist.