Frequently Asked Questions

Glaucoma is actually a group of eye diseases that lead to damage of the optic nerve (the bundle of nerve fibers that carries information from the eye to the brain), which can then lead to vision loss and possibly blindness. Optic nerve damage usually occurs in the presence of high eye (intraocular) pressure; however, it can occur with normal or even less than normal eye pressure. Glaucoma is estimated to affect approximately three million Americans, but up to half of these individuals may be unaware that they have the disease. Worldwide, an estimated 66.8 million people are visually impaired due to glaucoma, and an estimated 6.7 million are blind.

There are two main forms of glaucoma: open-angle (the most common form affecting approximately 95% of individuals) and closed-angle. There are also several other forms of glaucoma, including normal-tension, congenital, juvenile and secondary.

• Open-angle glaucoma, the most common form of the disease, is progressive and characterized by optic nerve damage. The most significant risk factor for the development and advancement of this form is high eye pressure. Initially, there are usually no symptoms, but as eye pressure gradually builds, at some point the optic nerve is impaired, and peripheral vision is lost. Without treatment, an individual can become totally blind.
  
  
• Normal-tension glaucoma occurs when eye pressure is normal, yet the optic nerve is damaged and peripheral vision is lost. Lowering eye pressure through medication sometimes slows the progress of the disease, but this type of glaucoma may worsen despite low pressure. The treatment is generally the same as for open-angle glaucoma.
  
  
• Closed-angle glaucoma may be acute or chronic. In acute closed-angle glaucoma the normal flow of eye fluid (aqueous humor) between the iris and the lens is suddenly blocked. Symptoms may include severe pain, nausea, vomiting, blurred vision and seeing a rainbow halo around lights. Acute closed-angle glaucoma is a medical emergency and must be treated immediately or blindness could result in one or two days. Chronic closed-angle glaucoma progresses more slowly and can damage the eye without symptoms, similar to open-angle glaucoma.
  
  
• Congenital glaucoma affects infants born with defects that prevent the normal drainage of fluid from the eye.
  
  
• Juvenile glaucoma is open-angle glaucoma that affects children, adolescents and young adults.
  
  
• Secondary glaucoma can be open-angle or closed-angle, and is the result of some other medical condition in the eye or the body. Examples of secondary glaucoma include:
  
  
• Pigmentary glaucoma in which pigment granules from the iris flake off into the eye fluid (aqueous humor) and clog the eye’s drainage system (trabecular meshwork).
  
  
• Pseudoexfoliation Syndrome occurs when white material flakes off the lens of the eye and blocks normal flow of the aqueous humor.
  
  
• Neovascular glaucoma occurs when abnormal blood vessel growth blocks the eye’s fluid drainage channels and leads to increased eye pressure. This abnormal growth can be caused by low blood supply to the eye due to diabetes, insufficient blood flow to the head because of blocked neck arteries, or blood vessel blockage in the back of the eye.
  
  
• Iridocorneal Endothelial Syndrome (ICE) is extremely rare, and has a number of features, including the breaking off of cells from the cornea, which blocks the drainage channels in the eye and leads to increased eye pressure. Scars may also connect the iris to the cornea.
  

Glaucoma is a leading cause of blindness among African Americans and Hispanics in the U.S. Three times as many African Americans have glaucoma than Caucasians, and four times as many are blind. Between the ages of 45 and 64, glaucoma is fifteen times more likely to cause blindness in African Americans than in Caucasians. All people over 60 are at a greater risk of developing glaucoma.

Individuals at high risk for glaucoma should have a dilated pupil eye examination at least every two years. Eye doctors use several tests to detect glaucoma; these tests include:

• Tonometry measures the pressure inside the eye. Examples of tonometers include: 1) The air puff or noncontact tonometer emits a puff of air. Eye pressure is measured by the eye’s resistance to the air. 2) The applanation tonometer touches the eye’s surface after the eye has been numbed, and measures the amount of pressure necessary to flatten the cornea. This is the most sensitive tonometer, but a clear, regularly-shaped cornea is needed for it to function properly. 3) The electronic indentation method measures pressure by directly contacting anesthetized eyes with a digital pen-like instrument.
  
  
• In pupil dilation, special drops temporarily enlarge the pupil so that the doctor can better view the inside of the eye.
  
  
• Visual field testing measures the entire area seen by the forward-looking eye to document straight-ahead (central) and/or side (peripheral) vision. It measures the dimmest light seen at each spot tested. Each time a flash of light is perceived, the patient responds by pressing a button.
  
  
• A visual acuity test measures sight at various distances. While seated 20 feet from an eye chart, the patient is asked to read standardized visual charts with each eye, with and without corrective lenses.
  
  
• Pachymetry uses an ultrasonic wave instrument to help determine the thickness of the cornea and better evaluate eye pressure.
  
  
• Ophthalmoscopy allows the doctor to examine the interior of the eye by looking through the pupil with a special instrument. This can help detect damage to the optic nerve caused by glaucoma.
  
  
• Gonioscopy allows the doctor to view the front part of the eye (anterior chamber) to determine if the iris is closer than normal to the back of the cornea. This test can help diagnose closed-angle glaucoma.
  
  
• Optic nerve imaging helps document optic nerve changes over time. An eye doctor may choose to use one or more of the four available scanning techniques, all of which are painless and non-invasive.

Laser surgery can help control the symptoms of glaucoma, but no treatments currently available will cure the disease. Several forms of laser surgery can help fluid drain from the eye or decrease the amount of fluid produced; these include trabeculoplasty (two types), laser peripheral iridotomy (LPI) and cyclophotocoagulation. These techniques help maintain normal eye pressure and minimize the risk of further damage to the optic nerve.

Treatments vary depending on the type of glaucoma:

• Open-angle glaucoma treatment normally begins with medications, usually eye drops or rarely, pills that either help eye fluid drain more effectively or cause the eye to produce less fluid. Several forms of laser surgery can also help fluid drain from the eye; these include trabeculoplasty and cyclophotocoagulation. Conventional filtration surgery (trabeculectomy, glaucoma drainage implant, peripheral iridectomy or Trabectome procedure), are sometimes used to create a new opening for fluid drainage.
  
  
• Acute closed-angle glaucoma (a medical emergency) is treated with medications, laser peripheral iridotomy or peripheral iridectomy.
  
  
• Chronic closed-angle glaucoma is treated with laser peripheral iridotomy and medications.
  
  
• Normal-tension glaucoma is currently treated in the same ways as open-angle glaucoma. When this form of the disease is better understood, treatment strategies may be modified.
  
  
• Congenital glaucoma is usually treated with medications and either goniotomy or trabeculotomy, two forms of eye surgery.
  
  
• Juvenile glaucoma is treated using medications, laser surgery and conventional filtration surgery.
  
  
• Secondary glaucoma can be open-angle or closed-angle, and acute or chronic. Treatment depends on these factors and whether the underlying condition causing increased eye pressure needs to be addressed. Treatments for secondary glaucoma include:
  
  
• Pigmentary glaucoma is treated using medications, laser surgery and filtration surgery.
  
  
• Pseudoexfoliation Syndrome is treated with medications, laser surgery and filtration surgery. Surgery may be performed earlier than in open-angle secondary glaucoma.
  
  
• Neovascular glaucoma may be managed with medications, and if abnormal blood vessel growth is occurring in the back of the eye (for example, in diabetic retinopathy), with a laser procedure called scatter panretinal photocoagulation. Treating abnormal growth of blood vessels in the retina may improve abnormal blood vessel growth blocking fluid drainage near the front of the eye. Trabeculectomy and cyclophotocoagulation (aimed at the eye-fluid producing ciliary body) may also be used to try to decrease eye pressure.
  
  
• Iridocorneal Endothelial (ICE) Syndrome is extremely rare and not well understood, and it is not known how to halt its progression. Medications are often used to help manage the glaucoma, and corneal transplants are sometimes needed to treat swelling of the cornea.

New research is focused on lowering pressure inside the eye, and finding medications to protect and preserve the optic nerve from the damage that causes vision loss. Scientists are also investigating the role of genetics in glaucoma, and over the last few years their understanding of this factor has progressed. Researchers have discovered genes associated with congenital glaucoma, juvenile glaucoma, normal-tension glaucoma, adult-onset open-angle glaucoma, pigmentary glaucoma and other conditions related to secondary glaucoma.

In glaucoma, it is optic nerve damage that can lead to vision loss and possibly blindness. In many people, fluid pressure increases inside the eye and damages the optic nerve (the bundle of nerve fibers that carries information from the eye to the brain). Elevated eye pressure increases the risk of developing glaucoma; however, the disease can occur in people with normal or even lower than normal eye pressure. In addition, individuals with higher than normal eye pressure do not always develop the symptoms of glaucoma. Since normal-tension glaucoma does not involve high eye pressure, it is diagnosed by observing the optic nerve for any signs of damage. The eye doctor will use an ophthalmoscope to look through the pupil at the shape and color of the optic nerve. In addition, a visual field test can help determine if there is any loss of peripheral vision.

The risk factors for developing normal-tension glaucoma include a family history of glaucoma, low eye pressure, and cardiovascular disease. Ongoing research is aimed at determining all of the factors that contribute to the optic nerve damage. For example, scientists believe the optic nerve may be affected by blood flow in the eye. They are also investigating susceptibility and genetic factors.