Glaucoma Management


What is Glaucoma?

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. It is like an electric cable containing numerous wires. Damage to the optic nerve results in areas of vision loss. These blind spots usually start in the peripheral vision and often go undetected until the optic nerve is significantly damaged. If the entire nerve is destroyed, blindness results. Because nerve tissue does not regenerate, vision loss from glaucoma is not reversible.

Glaucoma is a leading cause of blindness in the United States, especially for older people and African Americans. Glaucoma can often be prevented. Early detection and treatment are the keys to preventing optic nerve damage and blindness from glaucoma.

What Causes Glaucoma?

A clear liquid, called aqueous humor, circulates inside the front part of the eye. To maintain normal 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 called the trabecular meshwork. 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 or damaged, the excess fluid cannot flow out of the eye. This causes pressure within the eye to increase and may result in optic nerve damage.

What are the Different Types of Glaucoma?

Primary Open Angle Glaucoma

This is the most common form of glaucoma in the United States. While we do not know what causes most glaucoma, there are well-established risk factors for developing primary open angle glaucoma. These include:

  • Age
  • Family history of glaucoma
  • African or Hispanic ancestry
  • Farsightedness or nearsightedness
  • Elevated eye pressure
  • Past eye injury
  • Having a thinner central cornea (the clear, front part of the eye covering the pupil and colored iris)
  • Not having eye examinations when they are recommended
  • Low blood pressure
  • Conditions that affect blood flow, such as migraines, diabetes and low blood pressure.

If glaucoma is the result of another eye condition or disease, it is referred as secondary glaucoma. Some causes of secondary glaucoma are:

  • Eye injury
  • Inflammation of the eye
  • Abnormal blood vessel formation from diabetes or retinal blood vessel blockage
  • Use of steroid-containing medications (pills, eye drops, sprays
  • Pigment dispersion, where tiny fragments or granules from the iris (the colored part of the eye) can circulate in the aqueous humor (the fluid within the front portion of the eye) and block the trabecular meshwork (the tiny drain for the eye’s aqueous humor)

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. As the disease progresses, the optic nerve becomes more damaged and blind spots begin to appear in your field of vision. These early changes are not usually noticeable 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.

Video: Open Angle Glaucoma

This video explains how Open Angle Glaucoma develops and can cause permanent loss of vision with visual symptoms. The three types of treatment are medicines, laser surgery and filtration surgery.

Closed Angle Glaucoma

In some eyes the iris (the colored part of the eye) is too close to the drainage angle. In these eyes the iris can be pushed forward, blocking the drainage channel completely. The eye continues to make aqueous humor but it cannot exit the eye. The pressure inside the eye builds rapidly and causes an acute angle closure attack. Symptoms of angle closure include:

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

If you have any of these symptoms, call your ophthalmologist immediately. Unless this type of glaucoma is treated quickly, blindness can result. Two-thirds of those with closed angle glaucoma develop it slowly without any symptoms prior to an attack.

Video: Narrow Angle Glaucoma

This video explains how permanent damage from Narrow Angle Glaucoma can have a rapid onset. Symptoms are covered as well as treatment with Laser Iridotomy.

How is Glaucoma Detected?

Regular eye examinations by your ophthalmologist are the best way to detect glaucoma. While determining the pressure inside the eye (the intraocular pressure or IOP) is important, it is not sufficient to determine if you have glaucoma. The most important part of the evaluation for glaucoma is examination of the optic nerve. This is done during a complete dilated eye examination. If Dr. Callahan is concerned that you may have glaucoma, she may perform other tests such as gonioscopy (examination of the drainage angle of your eye), visual field testing (automated evaluation of your peripheral vision), pachymetry (measurement of the thickness of the central part of the cornea) and nerve fiber layer analysis (determination of the health of the fibers in the retina that make up the optic nerve).

Some of these tests may need to be repeated on a regular basis to monitor any changes in your condition.

How is Glaucoma Treated?

Dr. Callahan has extensive experience in the medical and surgical treatment of glaucoma. As a rule, loss of vision caused by glaucoma cannot be reversed. Lowering pressure inside the eye is the only proven way to treat glaucoma. Eye drops, laser surgery and surgery in the operating room are options to lower eye pressure and help prevent further damage. In some cases, oral medications may also be prescribed.

Even significant changes in your pressure generally do not cause symptoms. An examination by Dr. Callahan (usually every three to six months) is very important to maintain your target intraocular pressure and prevent vision loss. Treatment for glaucoma requires teamwork. Dr. Callahan can prescribe treatment for glaucoma, but only you can make sure that you follow the doctor’s instructions and use your eye drops.


Glaucoma is usually controlled with eye drops used 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. Compliance with all medications is critical to prevent vision loss. 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.

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 (selective laser trabeculoplasty or SLT) to help control eye pressure. In closed-angle glaucoma, the laser creates a hole in the iris (peripheral iridotomy) to improve the flow of aqueous fluid to the drain. Dr. Callahan performs both of these procedures.

Surgery in the Operating Room

When surgery in the operating room is needed to treat glaucoma, Dr. Callahan uses fine microsurgical instruments to create a new drainage channel for the aqueous fluid to leave the eye. Surgery is recommended if your pressure cannot be controlled by medications and/or laser and if you are at risk for continued optic nerve damage and vision loss.

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 Dr. Callahan for an exam. She will let you know how often to return for follow-up exams.

Adults with no symptoms of or risk factors for eye disease should have a complete screening at age 40. This is the time when early signs of disease and changes in vision may start to happen. Based on the results of the initial screening, Dr. Callahan will let you know how often to return for follow-up exams.