By: J. Chevonte’ Alexander
According to the American Optometric Association, glaucoma is the second-leading cause of blindness in the United States. It most often occurs in people over age 40. Glaucoma is a disease that damages your eye’s optic nerve. The optic nerve is a bundle of more than 1 million nerve fibers. It connects the retina to the brain. The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision. Glaucoma usually happens when fluid builds up in the front part of your eye. That extra fluid increases the pressure in your eye, damaging the optic nerve.
How the Eye Works & Glaucoma
William Benson, chair of the Department of Ophthalmology at VCU School of Medicine comments, “Think of the eye as your kitchen sink. If you wash dishes in that sink and put food down the disposal for 30 years, the drain plumbing becomes restricted with buildup of residue and does not drain as well as when it was new, and water may rise inside the sink if the faucet is turned on full. The same happens inside the eye with glaucoma.”
Some people have a higher than normal risk of getting glaucoma. This includes people who:
- are over age 40
- have family members with glaucoma
- A family history of glaucoma is the single most important risk factor for those at risk of developing glaucoma.
- are of African or Hispanic heritage
- have high eye pressure
- are farsighted or nearsighted
- have had an eye injury
- have corneas that are thin in the center
- have thinning of the optic nerve
- have diabetes, migraines, poor blood circulation or other health problems affecting the whole body
Primary open-angle glaucoma is the most common type of glaucoma. It happens gradually, where the eye does not drain fluid as well as it should. This type of glaucoma is painless and causes no vision changes at first.
“Glaucoma should be considered similar to ’high blood pressure inside the eye’, and can be treated with medications or surgery but cannot be cured.” says Dr. Benson.
Here are the signs of an acute angle-closure glaucoma attack:
- Your vision is suddenly blurry
- You have severe eye pain
- You have a headache
- You feel sick to your stomach (nausea)
- You throw up (vomit)
- You see rainbow-colored rings or halos around lights
Without treatment, people with glaucoma will slowly lose their peripheral vision. As glaucoma remains untreated, people may miss objects to the side and out of the corner of their eye. They seem to be looking through a tunnel. Over time, straight-ahead vision may decrease until no vision remains.
“Advanced glaucoma occurs from high pressure inside the eye that is untreated and transfers that pressure to the optic nerve that becomes impaired, just as if the light cord of the lamp becomes severed and cannot provide electricity from the outlet to the lamp.” comments Dr. Benson.
Glaucoma is detected through a comprehensive dilated eye exam that includes the following:
Visual acuity test. This eye chart test measures how well you see at various distances.
Visual field test. This test measures your peripheral (side vision). It helps your eye care professional tell if you have lost peripheral vision, a sign of glaucoma.
Dilated eye exam. In this exam, drops are placed in your eyes to widen, or dilate, the pupils. Your eye care professional uses a special magnifying lens to examine your retina and optic nerve for signs of damage and other eye problems. After the exam, your close-up vision may remain blurred for several hours.
Tonometry is the measurement of pressure inside the eye by using an instrument called a tonometer. Numbing drops may be applied to your eye for this test.
Pachymetry is the measurement of the thickness of your cornea. Your eye care professional applies a numbing drop to your eye and uses an ultrasonic wave instrument to measure the thickness of your cornea.
“Glaucoma cannot be prevented, but can be detected with periodic eye examinations every year if a family history is present, or less frequently without a family history of glaucoma.” says Dr. Benson.
There is no cure for glaucoma because the drain inside the eye cannot be replaced with new plumbing and therefore cannot improve the slow drainage of the fluid produced inside the eye. This leads to intraocular pressure, which is analogous to high blood pressure, that eventually leads to stroke or heart attack if untreated.