Glaucoma is an eye condition that develops when too much fluid pressure builds up inside of the eye. It tends to be inherited and may not show up until later in life.
The increased pressure, called intraocular pressure, can damage the optic nerve, which transmits images to the brain. If damage to the optic nerve from high eye pressure continues, glaucoma will cause loss of vision. Without treatment, it can cause total permanent blindness within a few years.
Because most people with this have no early symptoms or pain from this increased pressure, it is important to see your ophthalmologist regularly so that glaucoma can be diagnosed and treated before long-term visual loss occurs.
If you are over the age of 45 and if you have a family history of glaucoma, you should have a complete eye exam with an ophthalmologist every one to two years. If you have health problems such as diabetes or a family history or are at risk for other eye diseases, you may need to visit your eye doctor more frequently.
Glaucoma usually occurs when intraocular pressure increases. This happens when the fluid pressure in the eye's anterior chamber, the area between the cornea and the iris, rises.
Normally, this fluid, called aqueous humor, flows out of the eye through a mesh-like channel. If this channel becomes blocked, fluid builds up, causing it. The direct cause of this blockage is unknown, but doctors do know that it is most often inherited, meaning it is passed from parents to children.
Less common causes of glaucoma include a blunt or chemical injury to the eye, severe eye infection, blockage of blood vessels in the eye, inflammatory conditions of the eye, and occasionally eye surgery to correct another condition. It usually occurs in both eyes, but it may involve each eye to a different extent.
Types of Glaucoma: There are two main types of glaucoma:
Open-angle this also called wide-angle glaucoma: This is the most common type of this. The structures of the eye appear normal, but fluid in the eye does not flow properly through the drain of the eye, called the trabecular meshwork.
Angle-closure glaucoma also called acute or chronic angle-closure or narrow-angle this: This type of it is less common, but can cause a sudden buildup of pressure in the eye. Drainage may be poor because the angle between the iris and the cornea (where a drainage channel for the eye is located) is too narrow. Or, the pupil opens too wide, narrowing the angle and blocking the flow of the fluid through that channel.
This is the second leading cause of blindness in the United States, and the leading cause of blindness in African-Americans. It currently affects as many as 2.5 million Americans, but up to half of people with it don't know that they have the condition. This tends to run in families and is five times more common in African-Americans than in Caucasians. The risk of glaucoma also increases with age in people of all ethnic backgrounds.
Although open angle glaucoma and acute glaucoma both cause blindness, their symptoms are very different.
Open angle glaucoma: In this form of glaucoma, vision is lost painlessly and so gradually that most people do not realize they have a problem until substantial damage has occurred. Peripheral vision
(at the edges) is usually lost first, especially the field of vision near your nose. As larger areas of your peripheral vision fade, you may develop tunnel vision, vision that has narrowed so you see only what is directly in front of you, like looking through a railroad tunnel. If glaucoma is not treated, even this narrowed vision disappears into blindness.
Once gone, areas of lost vision cannot be restored.
Symptoms of acute this occur suddenly and can include blurred vision, pain and redness in the eye, severe headache, halos around lights at night, a haziness in the cornea (the clear front portion of the eye in front of the pupil), nausea and vomiting, and extreme weakness.
For most people, there are usually few or no symptoms of this. The first sign of glaucoma is often the loss of peripheral or side vision, which can go unnoticed until late in the disease. Detecting this early is one reason you should have a complete exam with an eye specialist every one to two years. Occasionally, intraocular pressure can rise to severe levels. In these cases, sudden eye pain, headache, blurred vision, or the appearance of halos around lights may occur.
If you have any of the following symptoms, seek immediate medical care:
Seeing halos around lights.
Causes and Risk factors:
- Narrowing of vision (tunnel vision).
- Vision loss.
- Redness in the eye.
- Eye that looks hazy.
- Nausea or vomiting.
- Pain in the eye.
Anyone can get glaucoma, but no one knows the exact cause or causes of the condition. Doctors can seldom explain why one person gets glaucoma and another does not. However, research has shown that people with certain risk factors are more likely than others to develop it. A risk factor is anything that increases a person's chance of developing a disease.
Factors Contributing to it: Although the causes of glaucoma have not been found, studies have found a number of factors that may increase the risk of glaucoma. These risk factors may act together to increase the risk even more. The risk of this is higher in the following people:
African Americans over age 40.
- Everyone over age 60, especially Mexican Americans.
- People with a family history of glaucoma.
- People with diabetes.
A comprehensive dilated eye exam can reveal more glaucoma risk factors, such as:
High eye pressure.
- Thinness of the cornea.
- Abnormal optic nerve anatomy.
In most cases, open angle glaucoma is diagnosed by a doctor during a routine eye examination. When looking at the back of the eye (fundus) using a special telescope, he or she may notice changes in the appearance of the optic nerve. If glaucoma is suspected, your doctor will confirm the diagnosis with one or more additional tests:
Tonometry: Measures the pressure within the eye. This may be done by pressing an instrument against your eyeball, or by blowing a puff of air against your eye. Your eye pressure is measured in millimeters of mercury, commonly abbreviated as "mmHg." Normal eye pressure is between 8 mmHg and 22 mmHg.
Visual-field testing is the best way to find early signs of loss of peripheral vision. Most often, visual fields are checked using an automated machine. You look straight ahead into the machine and press a button when you see a blinking light. The machine then draws a picture of where you are able to see the blinking lights.
Your doctor will not diagnose glaucoma unless your optic nerve shows evidence of damage. However, some people will be found to have elevated eye (intraocular) pressure but no evidence of optic nerve damage. In this case, you may be told that you are a "glaucoma suspect" or have "pre-glaucoma," but do not yet have the disease. It is important to remember that not everyone with elevated pressures will develop glaucoma and that not everyone with this has elevated eye pressures.
Angle closure glaucoma usually is diagnosed in a person who has developed a red, swollen eye and difficulties with vision. The eye pressure is usually quite high. Some people may be told by their eye doctor that they are at risk of angle closure glaucoma because their angle looks narrow.
This treatment may include prescription eye drops, laser, or microsurgery.
Eye drops for this: These either reduce the formation of fluid in the front of the eye or increase its outflow. Side effects of glaucoma drops may include allergy, redness of the eyes, brief stinging or visual blurring, and irritated eyes. Some this medications may affect the heart and lungs. Be sure to tell your doctor about any medication you are currently taking or are allergic to.
Laser surgery for glaucoma: Laser surgery for glaucoma slightly increases the outflow of the fluid from the eye in open-angle glaucoma or eliminates fluid blockage in angle-closure glaucoma. Types of laser surgery for glaucoma include trabeculoplasty, in which a laser is used to pull open the trabecular meshwork drainage area; iridotomy, in which a tiny hole is made in the iris, allowing the fluid to flow more freely; and cyclophotocoagulation, in which a laser beam treats areas of the ciliary body, reducing the production of fluid.
Microsurgery for glaucoma: In an operation called a trabeculectomy, a new channel is created to drain the fluid, thereby reducing intraocular pressure that causes glaucoma. Sometimes this form of glaucoma surgery fails and must be redone. For some patients, a glaucoma implant is the best option. Other complications of microsurgery for glaucoma include some temporary or permanent loss of vision, as well as bleeding or infection.
Open-angle glaucoma is most commonly treated with various combinations of eye drops, laser trabeculoplasty, and microsurgery. Traditionally in the U.S., medications are used first, but there is increasing evidence that some people with this may respond better with early laser surgery or microsurgery.
Medicine and medications:
Currently, five classes of drug are available for use in patients with glaucoma or elevated intraocular pressure. No perfect medicine has been developed - all have some side-effects. Moreover, in some patients, medication fails to reduce IOP adequately. It is important therefore to balance efficacy, tolerability and side effects on a patient-by-patient basis.
The most frequently used medical therapies include:
Ophthalmic Beta-Blockers lower pressure in the eye by reducing aqueous production. These drugs are divided into two classes: 1) nonselective beta-blockers (timolol, levobunolol, metipranolol, carteolol). 2) Beta 1 selective (betaxolol). The Alcon product in this class is BETOPTIC S® (betaxolol HCl) ophthalmic suspension 0.25%.
Carbonic Anhydrase Inhibitors also lower pressure in the eye by decreasing aqueous production. Carbonic anhydrase inhibitors are available as topically (dorzolamide and brinzolamide) or orally (acetazolamide, methazolamide). The topical forms are associated with fewer systemic side-effects than the oral forms and are better tolerated by many patients.
Alpha-Agonists are still another class of medicine that lower pressure primarily by reducing the aqueous production. In addition, they also may have an effect on increasing the rate at which the fluid drains from the eye. The most frequently prescribed drugs in this class are the relatively selective alpha 2 agonists (apraclonidine, brimonidine) IOPIDINE® 0.5%
Miotics have been used for over 100 years to lower eye pressure. Miotics decrease IOP by increasing aqueous outflow through the trabecular meshwork. However, because of their ocular adverse effects (increased myopia, eye and brow pain, decreased vision and retinal problems). The use of miotics is declining. Examples of miotics include pilocarpine and carbachol. Alcon brands include ISOPTO® CARPINE (pilocarpine HCl) ophtalmic solution, PILOPINE HS® (pilocarpine HCl) gel and ISOPTO® CARBACHOL (carbachol) ophthalmic solution.
Prostaglandin analogs work by increasing the uveoscleral outflow. Only one (latanoprost) is currently available in the US. It has the advantage of effectiveness in lowering eye pressure with once daily dosing. However, some patients experience an irreversible change in iris color and the long-term significance of this effect is currently unknown.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.