Glaucoma is a group of progressive diseases that can damage your eye’s optic nerve and cause vision loss, even blindness. There are many theories, but the exact cause of glaucoma is unknown. It is most often related to a build-up of pressure inside your eye. When this pressure, called intraocular pressure, or IOP, remains high over time, it begins to harm optic nerve fibers.
IOP increases when the fluid inside your eye, called aqueous humor, which normally flows out of your eye through a mesh-like drainage channel called the trabecular meshwork, gets blocked and cannot leave the eye. As a result, the fluid builds up and IOP increases. In some case, however, glaucoma can occur in people who have normal IOP.
Another theory suggests that glaucoma is caused by an inadequate amount of blood flow to the optic nerve.
About 3 million Americans have glaucoma. It’s expensive and damaging to vision. It costs the US economy $286 billion every year in direct costs and productivity loses, and it’s the leading cause of irreversible blindness in the world.
Open angle glaucoma is the most common type, affecting approximately 95 percent of patients. In this type of glaucoma, fluid does not drain properly due to changes in and along the drainage passageway. There are typically no early symptoms of open-angle glaucoma, so you can have it for years and not know it. It is often called “the silent thief of sight.”
With angle-closure glaucoma, your eye doesn’t drain like it’s supposed to because the drain space, or angle, which is located between your iris and cornea, becomes too narrow and can become blocked. This can occur suddenly, which is called acute angle-closure glaucoma, or over time, called chronic angle-closure glaucoma.
Anyone can develop glaucoma, but there are certain factors that increase your risk for developing it. You are more likely to get it if you are over age 40, have a family history of glaucoma, have diabetes, take certain steroid medications such as prednisone, have had an injury to your eyes, have high eye pressure, or are nearsighted or farsighted. There are other risk factors as well.
Glaucoma-related damage to the optic nerve generally starts with a loss of nerve tissue in a specific pattern called cupping. This is when the center of the optic disc, called the cup, becomes larger, leaving less room for the remaining optic nerve fibers. It’s common for you to experience blurry spots in your peripheral, or side, vision when this occurs. This is often the first symptom of glaucoma.
As your glaucoma progresses, it may begin to affect your central vision, which is needed to see details and for activities such as driving and reading. Advanced glaucoma can lead to permanent blurred or dimmed vision or even to blindness.
Your eye doctor may use several painless tests to diagnose glaucoma in addition to a dilated eye exam and visual field test. Tonometry measures eye pressure; gonioscopy examines the drainage area of the eye, and optical coherence tomography (OCT) creates a three-dimensional image of the optic nerve and retina to evaluate the degree of cupping and ocular damage.
Glaucoma is treated using medications, laser therapy, and surgery. Medications, which may include eye drops or pills, lower eye pressure by reducing the amount of aqueous humor produced in the eye. They also help increase the outflow of fluid from the eye..
A laser procedure called trabeculoplasty opens clogs in the trabecular meshwork so fluid can drain out of the eye. Laser iridotomy, which is used for angle-closure glaucoma, creates a tiny opening in the iris to allow the drainage angle to open.
During a glaucoma surgery called trabeculectomy, the doctor creates a new channel in your eye to allow the fluid to drain, which eases IOP. Another surgical procedure your doctor may choose involves implanting a tube to help drain fluid from your eye.
Glaucoma treatment cannot restore vision you may have already lost, but it can help prevent any further vision loss.
Because glaucoma has no early symptoms, people at high risk should see their eye doctor for a dilated eye exam and visual field test at least every one to two years or as directed by their doctor. Don’t let glaucoma steal your sight. See your eye doctor today!