What is glaucoma?
Glaucoma is a disease that is often associated with elevated intraocular pressure, in which damage to the eye (optic) nerve can lead to loss of vision and even blindness.
- Glaucoma is the leading cause of irreversible blindness in the world.
- Glaucoma usually causes no symptoms early in its course, at which time it can only be diagnosed by regular eye examinations (screenings with the frequency of examination based on age and the presence of other risk factors).
- Intraocular pressure increases when either too much fluid is produced in the eye or the drainage or outflow channels (trabecular meshwork) of the eye become blocked.
- While anyone can get glaucoma, some people are at greater risk.
- The two main types of glaucoma are open-angle glaucoma, which has several variants and is a long duration (chronic) condition, and angle-closure glaucoma, which may be a sudden (acute) condition or a chronic disease.
- Damage to the optic nerve and impairment of vision from glaucoma are irreversible.
- Several painless tests that determine the intraocular pressure, the status of the optic nerve and drainage angle, and visual fields are used to diagnose glaucoma.
- Glaucoma is usually treated with eyedrops, although lasers and surgery can also be used. Most cases can be controlled well with these treatments, thereby preventing further loss of vision.
- Much research into the causes and treatment of glaucoma is being carried out throughout the world.
- Early diagnosis and treatment is the key to preserving sight in people with glaucoma.
What is glaucoma?
Glaucoma is a disease of the major nerve of vision, called the optic nerve. The optic nerve receives light-generated nerve impulses from the retina and transmits these to the brain, where we recognize those electrical signals as vision. Glaucoma is characterized by a particular pattern of progressive damage to the optic nerve that generally begins with a subtle loss of side vision (peripheral vision). If glaucoma is not diagnosed and treated, it can progress to loss of central vision and blindness.
Glaucoma is usually, but not always, associated with elevated pressure in the eye (intraocular pressure). Generally, it is this elevated eye pressure that leads to damage of the eye (optic) nerve. In some cases, glaucoma may occur in the presence of normal eye pressure. This form of glaucoma is believed to be caused by poor regulation of blood flow to the optic nerve.
What are the symptoms for glaucoma?
The signs and symptoms of glaucoma vary depending on the type and stage of your condition. For example:
- Patchy blind spots in your side (peripheral) or central vision, frequently in both eyes
- Tunnel vision in the advanced stages
Acute angle-closure glaucoma
- Severe headache
- Eye pain
- Nausea and vomiting
- Blurred vision
- Halos around lights
- Eye redness
If left untreated, glaucoma will eventually cause blindness. Even with treatment, about 15 percent of people with glaucoma become blind in at least one eye within 20 years.
When to see a doctor
Seek immediate medical care
Promptly go to an emergency room or an eye doctor's (ophthalmologist's) office if you experience some of the symptoms of acute angle-closure glaucoma, such as severe headache, Eye pain and blurred vision.
Schedule eye exams
Open-angle glaucoma gives few warning signs until permanent damage has already occurred. Regular eye exams are the key to detecting glaucoma early enough to successfully slow or prevent vision loss.
The American Academy of Ophthalmology recommends glaucoma screening:
- Every four years beginning at age 40 if you don't have any glaucoma risk factors
- Every two years if you're at high risk or over 65
What are the causes for glaucoma?
Glaucoma is the result of damage to the optic nerve. As this nerve gradually deteriorates, blind spots develop in your visual field. For reasons that doctors don't fully understand, this nerve damage is usually related to increased pressure in the eye.
Elevated eye pressure is due to a buildup of a fluid (aqueous humor) that flows throughout your eye. This fluid normally drains into the front of the eye (anterior chamber) through tissue (trabecular meshwork) at the angle where the iris and cornea meet. When fluid is overproduced or the drainage system doesn't work properly, the fluid can't flow out at its normal rate and pressure builds up.
Glaucoma tends to run in families. In some people, scientists have identified genes related to high eye pressure and optic nerve damage.
The types of glaucoma include the following:
Open-angle glaucoma is the most common form of the disease. The drainage angle formed by the cornea and iris remains open, but the trabecular meshwork is partially blocked. This causes pressure in the eye to gradually increase. This pressure damages the optic nerve. It happens so slowly that you may lose vision before you're even aware of a problem.
Angle-closure glaucoma, also called closed-angle glaucoma, occurs when the iris bulges forward to narrow or block the drainage angle formed by the cornea and iris. As a result, fluid can't circulate through the eye and pressure increases. Some people have narrow drainage angles, putting them at increased risk of angle-closure glaucoma.
Angle-closure glaucoma may occur suddenly (acute angle-closure glaucoma) or gradually (chronic angle-closure glaucoma). Acute angle glaucoma is a medical emergency. It can be triggered by sudden dilation of your pupils.
In normal-tension glaucoma, your optic nerve becomes damaged even though your eye pressure is within the normal range. No one knows the exact reason for this. You may have a sensitive optic nerve, or you may have less blood being supplied to your optic nerve. This limited blood flow could be caused by atherosclerosis — the buildup of fatty deposits (plaques) in the arteries — or other conditions that impair circulation.
Glaucoma in children
It's possible for infants and children to have glaucoma. It may be present from birth or developed in the first few years of life. The optic nerve damage may be caused by drainage blockages or an underlying medical condition.
In pigmentary glaucoma, pigment granules from your iris build up in the drainage channels, slowing or blocking fluid exiting your eye. Activities such as jogging sometimes stir up the pigment granules, depositing them on the trabecular meshwork and causing intermittent pressure elevations.
What are the treatments for glaucoma?
The damage caused by glaucoma can't be reversed. But treatment and regular checkups can help slow or prevent vision loss, especially if you catch the disease in its early stages.
Glaucoma is treated by lowering your eye pressure (intraocular pressure). Depending on your situation, your options may include prescription eyedrops, oral medications, laser treatment, surgery or a combination of any of these.
Glaucoma treatment often starts with prescription eyedrops. These can help decrease eye pressure by improving how fluid drains from your eye or by decreasing the amount of fluid your eye makes. Depending on how low your eye pressure needs to be, more than one of the eyedrops below may need to be prescribed.
Prescription eyedrop medications include:
Prostaglandins. These increase the outflow of the fluid in your eye (aqueous humor), thereby reducing your eye pressure. Medicines in this category include latanoprost (Xalatan), travoprost (Travatan Z), tafluprost (Zioptan), bimatoprost (Lumigan) and latanoprostene bunod (Vyzulta).
Possible side effects include mild reddening and stinging of the eyes, darkening of the iris, darkening of the pigment of the eyelashes or eyelid skin, and blurred vision. This class of drug is prescribed for once-a-day use.
Beta blockers. These reduce the production of fluid in your eye, thereby lowering the pressure in your eye (intraocular pressure). Examples include timolol (Betimol, Istalol, Timoptic) and betaxolol (Betoptic).
Possible side effects include difficulty breathing, slowed heart rate, lower blood pressure, impotence and fatigue. This class of drug can be prescribed for once- or twice-daily use depending on your condition.
Alpha-adrenergic agonists. These reduce the production of aqueous humor and increase outflow of the fluid in your eye. Examples include apraclonidine (Iopidine) and brimonidine (Alphagan P, Qoliana).
Possible side effects include an irregular heart rate, high blood pressure, fatigue, red, itchy or swollen eyes, and dry mouth. This class of drug is usually prescribed for twice-daily use but sometimes can be prescribed for use three times a day.
- Carbonic anhydrase inhibitors. These medicines reduce the production of fluid in your eye. Examples include dorzolamide (Trusopt) and brinzolamide (Azopt). Possible side effects include a metallic taste, frequent urination, and tingling in the fingers and toes. This class of drug is usually prescribed for twice-daily use but sometimes can be prescribed for use three times a day.
- Rho kinase inhibitor. This medicine lowers eye pressure by suppressing the rho kinase enzymes responsible for fluid increase. It is available as netarsudil (Rhopressa) and is prescribed for once-a-day use. Possible side effects include eye redness, eye discomfort and deposits forming on the cornea.
- Miotic or cholinergic agents. These increase the outflow of fluid from your eye. An example is pilocarpine (Isopto Carpine). Side effects include headache, eye ache, smaller pupils, possible blurred or dim vision, and nearsightedness. This class of medicine is usually prescribed to be used up to four times a day. Because of potential side effects and the need for frequent daily use, these medications are not prescribed very often anymore.
Because some of the eyedrop medicine is 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. You may also press lightly at the corner of your eyes near your nose to close the tear duct for one or two minutes. Wipe off any unused drops from your eyelid.
If you have been prescribed multiple eyedrops or you need to use artificial tears, space them out so that you are waiting at least five minutes in between types of drops.
Surgery and other therapies
Other treatment options include laser therapy and various surgical procedures. The following techniques are intended to improve the drainage of fluid within the eye, thereby lowering pressure:
- Laser therapy. Laser trabeculoplasty (truh-BEK-u-low-plas-tee) is an option if you have open-angle glaucoma. It's done in your doctor's office. Your doctor uses a small laser beam to open clogged channels in the trabecular meshwork. It may take a few weeks before the full effect of this procedure becomes apparent.
- Filtering surgery. With a surgical procedure called a trabeculectomy (truh-bek-u-LEK-tuh-me), your surgeon creates an opening in the white of the eye (sclera) and removes part of the trabecular meshwork.
- Drainage tubes. In this procedure, your eye surgeon inserts a small tube shunt in your eye to drain away excess fluid to lower your eye pressure.
- Minimally invasive glaucoma surgery (MIGS). Your doctor may suggest a procedure to lower your eye pressure. These procedures generally require less immediate postoperative care and have less risk than trabeculectomy or installing a drainage device. They are often combined with cataract surgery. There are a number of techniques available, and your doctor will discuss which procedure may be right for you.
After your procedure, you'll need to see your doctor for follow-up exams. And you may eventually need to undergo additional procedures if your eye pressure begins to rise or other changes occur in your eye.
Treating acute angle-closure glaucoma
Acute angle-closure glaucoma is a medical emergency. If you're diagnosed with this condition, you'll need urgent treatment to reduce the pressure in your eye. This generally will require both medication and laser or other surgical procedures.
You may have a procedure called a laser peripheral iridotomy in which the doctor creates a small opening in your iris using a laser. This allows fluid (aqueous humor) to flow through it, relieving eye pressure.
What are the risk factors for glaucoma?
Because chronic forms of glaucoma can destroy vision before any signs or symptoms are apparent, be aware of these risk factors:
- Having high internal eye pressure (intraocular pressure)
- Being over age 60
- Being black or Hispanic
- Having a family history of the condition
- Having certain medical conditions, such as diabetes, heart disease, high blood pressure and sickle cell anemia
- Having certain eye conditions, such as nearsightedness
- Having had an eye injury or certain types of eye surgery
- Early estrogen deficiency, such as can occur after removal of both ovaries (bilateral oophorectomy) before age 43
- Taking corticosteroid medications, especially eyedrops, for a long time
Is there a cure/medications for glaucoma?
If eyedrops alone don't bring your eye pressure down to the desired level, your doctor may also prescribe an oral medication, usually a carbonic anhydrase inhibitor. Possible side effects include frequent urination, tingling in the fingers and toes, depression, stomach upset, and kidney stones.