Glaucoma FAQs

What is a Glaucoma?
How common is Glaucoma?
Risk factors for Glaucoma
Types of Glaucoma
Glaucoma Animation

Can blindness from Glaucoma be prevented?
Treatment for Glaucoma
EX-PRESS® Glaucoma Filtration Device Surgical Procedure
Our Technological Advances

Glaucoma (pronounced glaw-coma) is a disease of the eye in which damage occurs to the optic nerve, typically as a result of an elevated pressure within the eye. The optic nerve is responsible for sending messages from the eye to the brain, which allow us to see. Damage to the optic nerve causes progressive loss in peripheral vision and can eventually lead to blindness.

Normally, the eye produces a fluid called aqueous humor which is essential in maintaining the eye's shape and normal function. Eye pressure can be increased due to poor access of the aqueous humor to the drainage system (closed-angle glaucoma) or problems within the drainage system (open-angle glaucoma).

The normal eye

Early Glaucoma

Severe Glaucoma
normal optic nerve
Normal optic nerve
Damaged Optic Nerve with severe cupping
Damaged optic nerve





The problem is that a lot of people with glaucoma may not even know they have it, because chronic glaucoma generally takes away vision slowly and without pain. By the time a person notices changes in vision, the glaucoma has already caused permanent damage. This is the reason individuals need to be screened for glaucoma with both a pressure check and an examination of their optic nerves.



    • Increasing age
    • Race (African-American, Latin-American, Caucasian)
    • Family history
    • Steroid treatment
    • History of eye injury
    • Diabetes
    • Hypertension
    • High Nearsightedness or Farsightedness


There are many types of glaucoma, but they can generally be divided into two major categories based on the configuration of the drainage angle within the eye.

    • Open-Angle Glaucoma: This is the most common type, accounting for about 70% of cases. The drainage area in the eye is open but does not function properly. Pressure generally builds up and vision is lost slowly. There are no symptoms early in the course of the disease.
    • Closed-Angle Glaucoma: In this condition, the drainage area of the eye becomes blocked by the iris, and the pressure within the eye can become quite elevated. This disease has a rapid onset and can cause severe eye pain, headaches, blurred vision, halos around lights and even nausea and vomiting. Certain patients with narrow anterior chamber angles may be predisposed to develop this type of glaucoma and may require laser treatment to prevent it.


Animation showing field of view reduction related to optic nerve damage from glaucoma

Irreversible damage from glaucoma may be prevented, especially if it is detected early. Treatment usually keeps the disease from getting worse. However, sight destroyed by glaucoma cannot be restored. This is why it is so important to be screened for glaucoma with a routine eye examination.


Many treatment modalities, both medical and surical, are available for glaucoma. Treatment must be individualized for each patient, considering such as factors as the type and severity of the disease, patiemt's needs and occupation, previous surgery, etc. In open-angle glaucoma, initial treatment is usually with either drops or a laser. In closed-angle glaucoma, initial treatment is with a laser.

• Medical Treatment: There are many excellent drops available now to treat glaucoma. Dr. Yong, our glaucoma specialist, will discuss the pros and cons of different medications.

• Surgical Treatment: There are also many different surgeries we use to treat glaucoma.

• Argon Laser Trabeculoplasty (ALT) is used in patients with open-angle glaucoma to lower the eye pressure by placing small burns adjacent to the drainage angle.

• A Laser Peripheral Iridotomy (LPI) is performed in patients who have narrow angles, closed-angle glaucoma or pigmentary glaucoma to reestablish the normal drainage angle configuration. In this type of laser, we make a small hole in the iris (the colored part of the eye).

• A Trabeculectomy is performed in patients who have failed drops and laser surgery. Dr. Yong will create a new drain in your eye to reduce the eye pressure.

• A Shunt Procedure, such as a Baerveldt Implant, places a small plastic tube into the eye to relieve the pressure more permanently when other methods have failed.


Medication and laser surgeries may not always be effective enough for treatment of glaucoma; therefore, at times, your doctor may recommend what is called glaucoma filtration surgery. The traditional glaucoma filtration surgery is called trabeculectomy. In this operation, a small flap is made in the wall of the eye (sclera) to create an opening or new filtering pathway for the fluid to exit the eye. After this, a small section of the iris is excised (cut out) to ensure the fluid pathway will not be blocked. Trabeculectomy surgery has been done for the past 30 years.

In a variation on standard trabeculectomy, a small device known as an ExPRESS® Mini glaucoma shunt may be implanted in the eye, just beneath the scleral flap. This tiny tube serves to create the opening into the anterior chamber, and is used in lieu of removing a small piece of scera. An iridectomy is usually not necessary. This shunt may be used in patients at high risk for bleeding or excessive inflammation, or in cases with other ocular abnormalities.   

The shunt is used to direct fluid through the alternative pathway created by an extremely small tube to the outside of the eye. This is placed under a protective flap identical to the opening created for a trabeculectomy.

The EX-PRESS™ Glaucoma Filtration Device is a small unit - similar in size to a grain of rice - that is implanted between the inner region and the outer region of the eye. The EX-PRESS™ Glaucoma Filtration Device enables the drainage system of the eye, which has been damaged by glaucoma, to be bypassed. 

Click Here to learn more about this procedure

Glaucoma is an eye disease which causes damage to the optic nerve and leads to vision loss. Once the nerve has been damaged, vision loss is generally permanent. Fortunately, such damage may be prevented if the disease is caught early and this is why we encourage routine eye evaluation for all individuals, especially those at risk. Our doctors are more than happy to further examine you and treat you as necessary to maintain good vision.



Typically, open-angle glaucoma has no symptoms in its early stages and vision remains normal. As the optic nerve becomes more damaged and fibers are lost, blank spots begin to appear in the field of vision. Since the early stages of glaucoma can be symptom-less, early detection is crucial and is often the result of a careful eye exam coupled with testing such as visual field testing and laser nerve analysis. These tests are available at Centre for Sight, where we have a Zeiss-Humphrey visual Field Analyzer as well as the Stratus OCT laser nerve analyzer. The latter of these devices measures the amount of nerve tissue present in the eye to a resolution of approximately ten microns (about the length of a red blood cell). These tests, while important, are only part of the process to evaluate a patient for glaucoma. The results are considered in light of other findings from the eye exam and other risk factors that may be present.

Zeiss-Humphrey visual Field Analyzer