Glaucoma

What is Glaucoma?

A glaucoma is a group of eye conditions that damage the optic nerve, the health of which is vital for good vision. This damage is often caused by abnormally high pressure in your eye.

Glaucoma is one of the leading causes of blindness for people over the age of 60. It can occur at any age but is more common in older adults.

Many forms of glaucoma have no warning signs. The effect is so gradual that you may not notice a change in vision until the condition is at an advanced stage.

Because vision loss due to glaucoma can't be recovered, it's important to have regular eye exams that include measurements of your eye pressure so a diagnosis can be made in its early stages and treated appropriately. If glaucoma is recognized early, vision loss can be slowed or prevented. If you have the condition, you'll generally need treatment for the rest of your life.

What are the Symptoms of Glaucoma?

The signs and symptoms of glaucoma vary depending on the type and stage of your condition. For example:

Open-angle glaucoma

• 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 per cent of people with glaucoma become blind in at least one eye within 20 years.

What are the Causes of 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 the inside of your eye. This internal fluid normally drains out through a tissue called the 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 eye pressure increases.

Glaucoma tends to run in families. In some people, scientists have identified genes related to high eye pressure and optic nerve damage.

What are the types of Glaucoma?

Open-angle glaucoma:

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:

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-closure glaucoma is a medical emergency.

Normal-tension glaucoma:

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 (plaque) 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 develop in the first few years of life. The optic nerve damage may be caused by drainage blockages or an underlying medical condition.

Pigmentary glaucoma:

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 Risk Factors?

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, Asian or Hispanic
• Having a family history of glaucoma
• Having certain medical conditions, such as diabetes, heart disease, high blood pressure and sickle cell anaemia
• Having corneas that are thin in the center
• Being extremely nearsighted or farsighted
• Having had an eye injury or certain types of eye surgery
• Taking corticosteroid medications, especially eyedrops, for a long time

What is the Prevention for Glaucoma?

These self-care steps can help you detect glaucoma in its early stages, which is important in preventing vision loss or slowing its progress.

• Get regular dilated eye examinations: Regular comprehensive eye exams can help detect glaucoma in its early stages before significant damage occurs. As a general rule, the American Academy of Ophthalmology recommends having a comprehensive eye exam every five to 10 years if you're under 40 years old; every two to four years if you're 40 to 54 years old; every one to three years if you're 55 to 64 years old; and every one to two years if you're older than 65. If you're at risk of glaucoma, you'll need more frequent screening. 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 eyedrops regularly: Glaucoma eyedrops can significantly reduce the risk that high eye pressure will progress to glaucoma. To be effective, eyedrops 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 in enclosed courts.

What is the Diagnosis of Glaucoma?

Your doctor will review your medical history and conduct a comprehensive eye examination. He or she may perform several tests, including:

• Measuring intraocular pressure (tonometry)
• Testing for optic nerve damage with a dilated eye examination and imaging tests
• Checking for areas of vision loss (visual field test)
• Measuring corneal thickness (pachymetry)
• Inspecting the drainage angle (gonioscopy)

What is the Treatment?

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.

Eyedrops

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 eye drops below may need to be prescribed.

Prescription eyedrop medications include:

• These increase the outflow of the fluid in your eye (aqueous humor), thereby reducing your eye pressure.

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).

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 the outflow of the fluid in your eye.

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 the eye. 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 the fluid increase. 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. 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.

Oral medications

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.

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 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, 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 MIGS 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 MIGS 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.

NEXT STEP

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• The name of the test or procedure
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• What results to expect and what they mean
• The risks and benefits of the test or procedure
• What the possible side effects or complications are
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• Who will do the test or procedure and what that person’s qualifications are
• What would happen if you did not have the test or procedure
• Any alternative tests or procedures to think about
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