What is glaucoma?
The term "glaucoma" is used to describe a group of eye diseases that lead to permanent vision lossand blindness, as a result of optic nerve damage.It is the leading cause for preventable irreversible blindness worldwide.However, with early detection, diagnosis and appropriate treatment, you can often protect your eyes against serious vision loss.
The optic nerve is a bundle of millions of nerve fibers. It connects the retina to the brain.
The retina is the light sensitive tissue of the eye. A healthy optic nerve is necessary for good vision.
How does the optic nerve get damaged in glaucoma?
Several large studies have shown that eye pressure is a major risk factor for optic nerve damage. In most people, this increased pressure inside the eye is a result of blockage of the circulation of aqueous fluid in the eye, or its drainage. When this fluid builds up in the eye, the pressure inside the eye rises to a level that may damage the optic nerve and cause vision loss. That is why controlling eye pressure is important in glaucoma patients.
Nevertheless, not every person with increased eye pressure will develop glaucoma. Some people can tolerate higher levels of eye pressure better than others. Also, a certain level of eye pressure may be high for one person but normal for another. Whether you develop glaucoma depends on the level of pressure your optic nerve can tolerate without being damaged.
Can I develop glaucoma without an increase in my eye pressure?
Yes. Glaucoma can develop without increased eye pressure. This form of glaucoma is known as normal-tension or low-tension glaucoma.
In some patients, optic nerve damage may be caused by poor blood supply to the vital optic nerve fibres, a weakness in the structure of the nerve, and/or a problem in the health of the nerve fibres themselves.
Who is at risk of glaucoma?
Anyone can develop glaucoma. Everyone over the age of 60, and people with a family history of glaucoma has an increased risk of developing glaucoma. A comprehensive dilated eye exam can reveal more risk factors, such as high eye pressure, thinness of the cornea, and abnormal optic nerve anatomy. In some people with certain combinations of these high-risk factors, medicines in the form of eye drops reduce the risk of developing glaucoma by about half.
What are the symptoms of glaucoma?
Initially, open angle glaucoma has no symptoms. It causes no pain. Vision stays normal. Glaucoma can develop in one or both eyes. Without treatment, people with glaucoma will gradually lose their peripheral (side) vision. As glaucoma remains untreated, people may miss objects to the side and at the corner of their eye. They seem to be looking through a tunnel. Over time, central (straight ahead) vision may also decrease until all vision is lost.
In closed angle glaucoma, fluid in the front chamber of the eye is unable to drain and leave the eye. People with this type of glaucoma may have a sudden increase in the eye pressure. In such event, symptoms may include severe eye pain, nausea, blurred vision and eye redness. This is a medical emergency and patient with these symptoms need to seek medical treatment immediately. Without treatment to restore the flow of fluid, the eye can become blind. Usually, laser treatment and medications can help to clear the blockage, lower eye pressure, and protect vision.
How is glaucoma detected?
A comprehensive dilated eye exam is necessary for the diagnosis of glaucoma. This may include the following:
Visual acuity test. This eye chart test measures how well you see at various distances.
Visual field test (Perimetry). This test measures your peripheral (side) vision. Loss of peripheral vision is a sign of glaucoma. It can also be used to monitor progression of the disease.
Dilated eye exam. Eye drops are placed in your eyes to widen (dilate) the pupils, before your doctor uses a special magnifying lens to examine your retina and optic nerve for signs of damage and other problems. After the exam, your close-up vision may remain blurred for several hours.
Tonometry is the measurement of the pressure inside the eye. This measurement is important because high eye pressure is a known major risk factor for the development and progression of glaucoma.
Retinal nerve-fiber layer thickness scan, using machine such as the optical coherence tomography (OCT), can help to discriminate between healthy and glaucomatous optic nerve, and to evaluate disease progression.
Can glaucoma be cured?
No. Unfortunately there is no cure for glaucoma. Vision lost from the disease cannot be reversed or restored. Hence, diagnosis & treatment for early stage glaucoma is important to delay progression of the disease.
How is glaucoma treated?
Glaucoma treatments include medications, laser therapy, surgery or a combination of any of these. While these treatments may save remaining vision, they do not improve sight already lost from glaucoma.
Medications can be in the form of eye drops or pills, which lower the eye pressure. Some medications cause the eye to produce less fluid, others lower the eye pressure by helping fluid drain from the eye. Because glaucoma often has no symptoms, people may be tempted to stop using them, or may forget to use them. It is very important to realize that glaucoma medications need to be taken regularly as instructed by your eye care professional, as long as they help control your eye pressure.
Laser trabeculoplastytreatment helps fluid drain out of the eye by using laser burns to stretch the drainage meshwork, hence lowering the eye pressure. It is performed in the doctor’s office or the eye clinic. In most cases, you will need to continue taking glaucoma medications after this procedure. In addition, the laser effects can wear off over time and you may need further treatment.
Conventional glaucoma surgery makes a new opening for the fluid to leave the eye. This is often done after medications and laser treatment have failed to control eye pressure. It is about 60-80 per cent effective at lowering eye pressure. Sometimes after conventional surgery, your vision may not be as good as it was before. Potential side effects include cataract, problems with the cornea, inflammation, infection inside the eye or low eye pressure.
What can I do if I’m treated for glaucoma?
Be sure to take your glaucoma medications everyday and see your eye care professional regularly as scheduled.
After applying an eye drop, close your eye OR press the inner angle of the lower lid lightly with your finger for at least 1 minute. Either of these steps keeps the drops in the eye and helps prevent the drops from draining into the tear duct, which can increase the risk of side effects.If you are using more than one eye drop, be sure to wait at least 5 minutes before applying the second drop.
You can also help protect the vision of family members or friends who may be at high risk for glaucoma, and people with a family history of glaucoma. Encourage them to have a comprehensive dilated eye exam at least once a year. Remember that lowering eye pressure in the early stages of glaucoma slows progression of the disease and helps save vision.