Glaucoma

Glaucoma is a group of eye diseases 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 the elderly.

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

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

Symptoms

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

 Open angle glaucoma

• Blind spots in peripheral or central vision, often in both eyes
• Tunnel vision in the advanced stages

Acute angle closure glaucoma

• Headache
• Eye pain
• Nausea and vomiting
• Blurry vision
• Halos around lights
• Redness

 If left untreated, glaucoma will eventually cause blindness. 

 

When to see a doctor

Go to the emergency room or eye doctor's office immediately if you experience any of the symptoms of acute angle-closure glaucoma, such as severe headache, eye pain, and blurred vision.

 

Causes

Glaucoma is the result of damage to the optic nerve. As the nerve gradually deteriorates, blind spots develop in your field of vision. For reasons that doctors don't fully understand, this nerve damage is usually related to increased pressure in the eye.

 

Increased eye pressure is caused by a buildup of fluid (aqueous humor) that flows inside your eye. This internal fluid normally drains through a tissue called the ciliary body at the angle where the iris and cornea meet. When fluid is overproduced or the drainage system is not working properly, the fluid cannot flow out at the normal rate, and eye pressure increases.

 

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

 

Glaucoma types include

 

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 filtering filter is partially blocked. This causes pressure in the eye to gradually build up. This pressure damages the optic nerve. It happens so slowly that you may lose your vision before you are aware of a problem.

 

Angle closure glaucoma

Angle-closure glaucoma occurs when the iris bulges forward and narrows or blocks the angle formed by the cornea and iris. As a result, fluid cannot circulate through the eye and pressure builds up. Some people have narrow angles, and are at increased risk of angle-closure glaucoma.

 Angle-closure glaucoma can occur suddenly (acute angle-closure glaucoma) or gradually (chronic angle-closure glaucoma). Acute angle-closure glaucoma needs urgent treatment.

 

Normal pressure glaucoma

In normal-tension glaucoma, your optic nerve is damaged even though your eye pressure is within normal limits. You may have a sensitive optic nerve, or you may have less blood supplied to your optic nerve. This limited blood flow can be caused by atherosclerosis or other conditions that affect circulation.

 

Paediatric glaucoma

It is possible for infants and children to have glaucoma. It may be present from birth or develop in the first few years of life. Damage to the optic nerve may be caused by angle-closures or an underlying medical condition.

 

Pigment dispersion glaucoma

In pigmentary glaucoma, pigment granules from the iris end up in the corner of the eye, slowing or preventing fluid from draining from the eye. Activities such as running sometimes stir up the pigment granules, depositing them in the filtration membrane and causing intermittent increases in pressure.

 

Risk factors

Because chronic forms of glaucoma can destroy vision before any signs or symptoms appear, it's helpful to be aware of these risk factors:

 

• High eye pressure
• Age over 60
• Family history of glaucoma
• Certain medical conditions, such as diabetes, heart disease, high blood pressure, and sickle cell anemia
• Thin corneas
• High myopia
• Eye injury or certain types of eye surgery
• Long term steroid use

 

Prevention

 

Get eye exams with fundoscopy. Regular comprehensive eye exams can help detect glaucoma in its early stages, before significant damage occurs. As a general rule, a complete eye exam is recommended 

• every five to 10 years if you are under 40, 
• every two to four years if you are 40 to 54 years old, 
• every one to three years if you are 55 to 64 years old. and 
• every one to two years if you are over 65 years old. 

If you are at risk for glaucoma, you will need more frequent testing. 

 

Diagnosis

Your doctor will review your medical history and perform a complete eye exam. They may perform several tests, including:

•  Eye pressure check
• Fundoscopy
• Visual field examination
• Corneal thickness measurement
• Examination of the angle

 

Treatmenr

The damage caused by glaucoma cannot be reversed. But treatment and regular checkups can help you slow or prevent vision loss, especially if you diagnose the disease in its early stages.

 Glaucoma is treated by lowering the pressure in your eyes (intraocular pressure). Depending on your condition, your options may include drops, oral medications, laser therapy, surgery, or a combination of these.

 

Eye drops

Glaucoma treatment often starts with eye drops. These can help lower eye pressure by improving the rate at which fluid drains from your eye or by reducing the amount of fluid your eye produces. 

 

Drug categories include:

 

Prostaglandins. These increase the outflow of fluid in your eye (aqueous fluid), thereby reducing the pressure in your eyes. Drugs in this class include latanoprost (Xalatan), travoprost (Travatan), tafluprost (Saflutan), bimatoprost (Lumigan). 

Possible side effects include mild redness and stinging of the eyes, change in iris color, lengthening of eyelashes, and blurred vision. This class of medication is prescribed for once-daily use.

 

Beta blockers. These reduce the production of fluid in your eyes, thereby lowering pressure (intraocular pressure). They include timolol (Timoptol) and betaxolol (Betoptic).

 Possible side effects include difficulty breathing, slowed heart rate, lower blood pressure, impotence, and fatigue. This class of medication may be prescribed once or twice a day depending on your condition.

 

Alpha-adrenergic agonists. These reduce the production of aqueous humor and increase its drainage. Examples include apraclonidine (Iopidine) and brimonidine (Alphagan).

Possible side effects include heart rhythm disturbances, high blood pressure, fatigue, redness, itchy or swollen eyes, and dry mouth. This class of medication is usually prescribed for use twice a day, but sometimes it may be prescribed for use three times a day.

 

Carbonic anhydrase inhibitors. These drugs reduce the production of fluid in your eyes. 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 medication is usually prescribed for use twice a day, but sometimes it may be prescribed for use three times a day.

Rho kinase inhibitor. This medication lowers eye pressure by inhibiting the rho kinase enzymes responsible for increasing aqueous humor. It is available as netarsudil (Rhopressa) and is prescribed for once-daily use. Possible side effects include eye redness and discomfort. 

Myotic or cholinergic agents. These increase the outflow of fluid from your eyes. An example is pilocarpine (Isopto Carpine). Side effects include headache, eye pain, smaller pupils, possible blurred vision, and nearsightedness. This class of drugs is usually prescribed for use up to four times a day. Because of potential side effects and the need for frequent daily use, these drugs are not prescribed very often anymore.

 

Because some of the medication is absorbed into your bloodstream, you may experience some side effects that are not related to your eyes. To minimize this absorption, close your eyes for one to two minutes after putting the drops in. You may also press gently on the corner of your eyes near your nose to close the tear duct for one or two minutes. Wipe any unused drops from your eyelids.

 If you have been prescribed a combination of drops or need to use artificial tears, leave a gap of a few minutes between instillations.

 

Oral medication

If your blood pressure doesn't reach the desired level, your doctor may also prescribe oral medication, usually a carbonic anhydrase inhibitor. Possible side effects include frequent urination, tingling in your fingers and toes, depression, stomach upset, and kidney stones.

 

Surgery and other treatments

Other treatment options include laser therapy and various surgical procedures.