According to the World Health Organization (WHO), glaucoma is the second leading cause of blindness around the world.
Glaucoma is a group of eye disorders that lead to progressive damage to the optic nerve. People with glaucoma can lose nerve tissue, resulting in vision loss. The optic nerve is a bundle of about 1 million individual nerve fibres that supplies visual information from the eye to the brain.
You may not notice any difference in your vision because glaucoma affects your peripheral vision (also known as your side vision) first. As your peripheral vision is not as sensitive as your central vision, it’s difficult to notice any early changes to your vision – but your sight is being damaged.
There is no treatment to restore sight loss caused by glaucoma but treatments, such as eye drops and laser surgery, can help prevent sight loss from happening.
Glaucoma is usually, but not always, the result of abnormally high pressure inside your eye. Over time, the increased pressure can erode your optic nerve tissue, which may lead to vision loss or even blindness. If it’s diagnosed early, you may be able to prevent additional vision loss.
What Are the Symptoms of Glaucoma?
The most common type of glaucoma is primary open-angle glaucoma. It has no signs or symptoms except gradual vision loss. For that reason, it’s important that you go for yearly comprehensive eye exams so your ophthalmologist, or eye specialist, can monitor any changes in your vision.
Acute-angle closure glaucoma, which is also known as narrow-angle glaucoma, is a medical emergency. See your doctor immediately if you experience any of the following symptoms:
severe eye pain
redness in your eye
sudden vision disturbances
seeing coloured rings around lights
sudden blurred vision
What Causes Glaucoma?
The back of your eye continuously makes a clear fluid called aqueous humour. As this fluid is made, it fills the front part of your eye. Then, it leaves your eye through channels in your cornea and iris. If these channels are blocked or partially obstructed, the natural pressure in your eye, which is called the intraocular pressure (IOP), may increase. As your IOP increases, your optic nerve may become damaged. As damage to your nerve progresses, you may begin losing sight in your eye.
What causes the pressure in your eye to increase isn’t always known. However, doctors believe one or more of these factors may play a role:
dilating eye drops
blocked or restricted drainage in your eye
medications, such as corticosteroids
poor or reduced blood flow to your optic nerve
high or elevated blood pressure
What Are the Types of Glaucoma?
Six major types of glaucoma exist. These are:
Primary open-angle glaucoma. Formerly known as chronic simple glaucoma, this is the most common form of glaucoma. Damage to the optic nerve is slow and painless. Those affected can lose a large portion of vision before they notice any vision problems.
One theory about its development is that the eye's drainage system becomes inefficient over time. This leads to an increased amount of fluid and a gradual build-up of pressure within the eye. Another theory about the cause of this type of glaucoma is that there is poor blood flow (perfusion) to the optic nerve. Other theories also exist.
Angle-closure glaucoma. This type of glaucoma, also called closed-angle glaucoma or narrow-angle glaucoma, is a less common form of the disease. It is a medical emergency that can cause vision loss within a day of its onset.
It occurs when the drainage angle in the eye (formed by the cornea and the iris) closes or becomes blocked. Many people who develop this type of glaucoma have a very narrow drainage angle. With age, the lens in the eye becomes larger, pushing the iris forward and narrowing the space between the iris and the cornea. As this angle narrows, the fluid in the eye is blocked from the drainage system. Therefore the fluid builds up and eye pressure increases.
Angle-closure glaucoma can be chronic (progressing gradually) or acute (appearing suddenly). The acute form occurs when the iris completely blocks fluid drainage. When people with a narrow drainage angle have their pupils dilated, the angle may close and cause a sudden increase in eye pressure. Although an acute attack often affects only one eye, the other eye may be at risk of an attack as well.
Secondary glaucoma. This type of glaucoma results from an injury or other eye disease. It may be caused by a variety of medical conditions, medications, physical injuries and eye abnormalities. Infrequently, eye surgery can lead to secondary glaucoma.
Normal-tension or low-tension glaucoma. In this form of glaucoma, eye pressure remains within the "normal" range, but the optic nerve is damaged nevertheless. It is not known why this happens.
Possibly, people with low-tension glaucoma have an abnormally sensitive optic nerve. Or they may have a reduced blood supply to the optic nerve caused by a condition such as atherosclerosis, a hardening of the arteries. Under these circumstances even normal pressure on the optic nerve can cause damage.
Pigmentary glaucoma. This rare form of glaucoma is caused by clogging of the drainage angle of the eye by pigment that has broken loose from the iris, reducing the rate of aqueous outflow from the eye. Over time, an inflammatory response to the blocked angle damages the drainage system.
You are unlikely to notice any symptoms with pigmentary glaucoma, though some pain and blurry vision may occur after exercise. Pigmentary glaucoma most frequently affects white males in their mid-30s to mid-40s.
Congenital glaucoma. Children born with congenital glaucoma have a defect in the angle of their eye, which slows or prevents normal fluid drainage. Congenital glaucoma usually presents with symptoms, such as cloudy eyes, excessive tearing, or sensitivity to light. Congenital glaucoma can run in families.
Who Is at Risk of Glaucoma?
The following factors can increase the risk for developing glaucoma:
People over 60 are at increased risk of glaucoma, and the risk of glaucoma increases slightly with each year of age. If you’re African-American, your increase in risk begins at age 40.
African-Americans or people of African descent are significantly more likely to develop glaucoma than Caucasians. People of Asian descent are at a higher risk of angle-closure glaucoma, and people of Japanese descent have a higher risk of developing low-tension glaucoma.
Chronic eye inflammation and thin corneas can lead to increased pressure in your eyes. Physical injury or trauma to your eye, such as being hit in your eye, can also cause your eye pressure to increase.
Some types of glaucoma may run in families. If your parent or grandparent had open-angle glaucoma, you’re at an increased risk of developing the condition.
People with diabetes and those with high blood pressure and heart disease have an increased risk of developing glaucoma.
Use of Certain Medicine
Using corticosteroids for extended periods may increase your risk of developing secondary glaucoma.
How Is Glaucoma Detected?
Glaucoma is diagnosed through a comprehensive eye examination by an ophthalmologist. Because glaucoma is a progressive disease, meaning it worsens over time, a change in the appearance of the optic nerve, a loss of nerve tissue, and a corresponding loss of vision confirm the diagnosis. Some optic nerves may resemble nerves with glaucoma, but the patients may have no other risk factors or signs of glaucoma. These patients should have routine comprehensive exams to monitor any changes.
Glaucoma testing includes:
Patient history to determine any symptoms the patient is experiencing and if there are any general health problems and family history that may be contributing to the problem.
Visual acuity measurements to determine if vision is being affected.
Tonometry to measure the pressure inside the eye to detect increased risk factors for glaucoma.
Pachymetry to measure corneal thickness. People with thinner corneas are at an increased risk of developing glaucoma.
Visual field testing, also called perimetry, to check if the field of vision has been affected by glaucoma. This test measures your side (peripheral) vision and central vision by either determining the dimmest amount of light that can be detected in various locations of vision, or by determining sensitivity to targets other than light.
Evaluation of the retina of the eye, which may include photographs or scans of the optic nerve, to monitor any changes over time.
Supplemental testing, which may include gonioscopy. This procedure offers a view of the angle anatomy, which is where eye fluid drainage occurs. Serial tonometry is another possible test. This procedure acquires several pressure measurements over time, looking for changes in the eye pressure throughout the day. In addition, devices can be used to measure nerve fiber thickness and to look for tissue loss on specific areas of the nerve fiber layer .
How Is Glaucoma Treated?
Glaucoma treatment is aimed at reducing pressure (intraocular pressure – IOP) in the eye. Regular use of prescription eye drops are the most common and often the first treatment. Some cases may require systemic medications, laser treatment or other surgery. While there is not yet a cure for glaucoma, early diagnosis and continuing treatment can preserve eyesight.
Several medicines designed to reduce IOP are available. These medicines are available in the form of eye drops or pills, but the drops are more common. Your doctor may prescribe one or a combination of these.
If a blocked or slow channel is causing increased IOP, your doctor may suggest surgery to make a drainage path for fluid or destroy tissues that are responsible for the increased fluid.
Treatment for angle-closure glaucoma is different. This type of glaucoma is a medical emergency and requires immediate treatment to reduce eye pressure as quickly as possible. Medicines are usually attempted first, to reverse the angle closure, but this may be unsuccessful. A laser procedure called laser peripheral iridotomy may also be performed. This procedure creates small holes in your iris to allow for increased fluid movement.
Will a Person with Glaucoma Go Blind?
If your increased IOP can be stopped and the pressure returned to normal, vision loss can be slowed or even stopped. However, because there’s no cure for glaucoma, you’ll likely need treatment for the rest of your life to regulate your IOP. Unfortunately, vision lost as a result of glaucoma cannot be restored.
Can Glaucoma Be Prevented?
You may not be able to prevent glaucoma. But these self-care steps can help you detect it early, limit vision loss or slow its progress.
Get regular eye care. Regular comprehensive eye exams can help detect glaucoma in its early stages before irreversible damage occurs. As a general rule, have comprehensive eye exams every four years beginning at age 40 and every two years from age 60. You may need more frequent screening if you're at high risk of glaucoma. Ask your doctor to recommend the right screening schedule for you.
Know your family's eye health history. Glaucoma tends to run in families. If you're at increased risk, you may need more frequent screening.
Exercise safely. Regular, moderate exercise may help prevent glaucoma by reducing eye pressure. Talk with your doctor about an appropriate exercise program.
Take prescribed eye-drops regularly. Glaucoma eye-drops can significantly reduce the risk that high eye pressure will progress to glaucoma. To be effective, eye-drops prescribed by your doctor need to be used regularly even if you have no symptoms.
Wear eye protection. Serious eye injuries can lead to glaucoma. Wear eye protection when using power tools or playing high-speed racket sports on enclosed courts.
Healthy Lifestyle to Adopt
These tips may help you control high eye pressure or promote eye health.
Eat a healthy diet. Eating a healthy diet can help you maintain your health, but it won't prevent glaucoma from worsening. Several vitamins and nutrients are important to eye health, including those found in dark, leafy greens and fish high in omega-3 fatty acids.
Exercise safely. Regular exercise may reduce eye pressure in open-angle glaucoma. Talk to your doctor about an appropriate exercise program.
Limit your caffeine. Drinking beverages with large amounts of caffeine may increase your eye pressure.
Sip fluids frequently. Drink only moderate amounts of fluids at any given time during the course of a day. Drinking a quart or more of any liquid within a short time may temporarily increase eye pressure.
Sleep with your head elevated. Using a wedge pillow that keeps your head slightly raised, about 20 degrees, has been shown to reduce intraocular eye pressure while you sleep.
Take prescribed medicine. Using your eye drops or other medications as prescribed can help you get the best possible result from your treatment. Be sure to use the drops exactly as prescribed. Otherwise, your optic nerve damage could get even worse.
Because some of the eye drops are absorbed into your bloodstream, you may experience some side effects unrelated to your eyes. To minimize this absorption, close your eyes for one to two minutes after putting the drops in. Or press lightly at the corner of your eye near your nose to close the tear duct for one or two minutes. Wipe off any unused drops from your eyelid.