What is glaucoma?

Glaucoma is the term used for a large group of diseases that all result in progressive damage to the optic nerve. The optic nerve is the major nerve that connects the eye to the brain. Damage to the nerve prevents the images received by the eye from reaching the brain. If left untreated, glaucoma can lead to partial or complete blindness.

How common is glaucoma?

Glaucoma is one of the leading causes of preventable, irreversible blindness in the world. In 2000, an estimated 90.8 million people worldwide were affected with glaucoma. According to the Third Philippine National Survey of Blindness it is the third leading cause of bilateral blindness (after cataract and error of refraction) and the leading cause of irreversible bilateral blindness in the Philippines.

What causes glaucoma?

The exact biochemical and cellular mechanisms for the development of damage to the optic nerve are still being researched. Two of the main theories are: 1) increased intraocular pressure (pressure inside the eye) causing compression of the optic nerve or compressing its blood supply and 2) vascular abnormalities causing lack of blood flow to the optic nerve.

Who are likely to develop glaucoma?

Many risk factors that can lead to glaucoma have been identified. Persons with one or more of these risk factors are more likely to develop the disease than those who have no risk factors. The major risk factors are increased age, race (different types of glaucoma are more prevalent in certain racial groups), a family history of glaucoma, and increased intraocular pressure. Other risk factors include certain medical conditions especially those affecting the blood vessels such as diabetes and hypertension, certain eye conditions such as extreme myopia (near-sightedness) or hyperopia (far-sightedness), previous eye trauma, and current or previous prolonged use of steroids whether as eye drops, oral, nasal spray or inhaled. Smoking has also been implicated a risk factor for glaucoma (and other serious eye diseases as well) due to its deleterious effects on the blood vessels.

What causes increased intraocular pressure?

Fluid circulates inside the front part of the eye (anterior chamber) in order to nourish certain structures and to wash away toxins. This fluid is constantly being produced and constantly being drained. Sometimes the fluid drainage pathway located in the anterior chamber angle malfunctions or becomes blocked. Despite this fluid production continues as usual. This causes fluid to build up within the eye and the intraocular pressure to increase.

Flow of aqueous fluid image courtesy of Mark Erickson of JirehDesign.com.

What is peripheral vision?

Glaucoma usually affects the peripheral vision first. Everything that we can see makes up our field of vision. The field of vision is made up of central vision and peripheral vision. Central vision is what you see in the area where your eyes are focused. Peripheral vision is what you can see to the right, left, above and below the area where your eyes are focused. You can try testing part of your left eye’s peripheral vision right now by looking straight at the center of your computer screen and then waving your hand back and forth near your left ear. You should still see your hand even though you are not looking directly at it.

What are the symptoms of glaucoma?

In most cases there are no symptoms. Because the optic nerve damage occurs over a long period of time the visual loss develops very gradually and most patients don’t notice that they have already lost quite a lot of their peripheral vision. It is only in the very late stage of the disease that central vision becomes blurred. Because there are usually no symptoms that can serve as an early-warning device, people who have any of the risk factors for glaucoma should be examined regularly by their eye doctor.

In some cases of a particular type of glaucoma called angle closure glaucoma, the intraocular pressure can rise very suddenly in one eye causing sudden blurred vision, eye redness, eye pain, headache on the side of the affected eye, seeing rainbows around lights (iridescent vision) and nausea or vomiting. If this happens, immediate consult with an eye doctor is warranted because delayed treatment is likely to produce a worse outcome.

How is glaucoma detected?

Your eye doctor will check your eye pressure and will look at the optic nerve and anterior chamber angle inside your eye. Your eye doctor may need to put some eye drops to dilate your pupil to get a better look at your optic nerve. If your eye doctor has any suspicions that you might have glaucoma you may be asked to have some diagnostic tests done including a visual field test. Your doctor will analyze all of the eye examination findings together with the test results to be able to make the diagnosis of glaucoma. Eye pressure measurements alone are not enough to detect or diagnose glaucoma.

What does it mean if my doctor tells me I am a “glaucoma suspect”?

Glaucoma is diagnosed by analyzing the results of all of the eye examinations and tests together. You may have suspicious findings in only 1 or 2 examinations or tests but have normal findings in the rest of the examinations or tests. In this case you may be diagnosed as a glaucoma suspect and, more often than not, your doctor may decide to simply observe and monitor you over a period of time. Occasionally, eye doctors may decide to already begin treatment in those glaucoma suspects who they consider high-risk.

How is glaucoma treated?

Glaucoma cannot be cured but it can be controlled. Successful control of glaucoma will prevent further damage to the optic nerve and further loss of vision but it cannot restore lost vision. In terms of treatment, the most important risk factor is increased intraocular pressure because this is the risk factor that doctors are able to control. Intraocular pressure can be lowered using one or more eye drops, oral medications, laser treatment, surgery or a combination of the different types of treatment. Your doctor will discuss the best treatment option in your specific case.

For how long will I have to be treated and have check-ups for glaucoma?

Because glaucoma can only be controlled and not cured patients with glaucoma need to have checkups for the rest of their lives. Glaucoma suspects also need to have regular checkups to see if they are converting from being glaucoma suspects to actually having glaucoma. Daily eye drops may need to be used indefinitely but surgical or laser procedures can have long lasting effects so that patients only need to come for periodic check-ups without having to have daily treatment.

Will I go blind from glaucoma?

Only a small percentage of glaucoma sufferers become completely blind. Majority of glaucoma sufferers keep at least some vision throughout their lives although they may have blind spots (scotomas) in their peripheral vision.

Will my children also develop glaucoma when they are older?

Having a family member with glaucoma is one of the major risk factors for developing the disease. If you have glaucoma, ask your eye doctor if you should have your children and other close blood relatives checked and at what age they should get checked.

What can I do to protect my vision?

Studies have shown that early detection and treatment of glaucoma, before it causes major vision loss, is the best way to control the disease. So, if you have any of the risk factors for the disease, make sure you have your eyes examined periodically by your eye doctor.

Where can I find more information?

For more information on the different types of glaucoma, tests and treatments please go to www.Glaucoma.com.ph

References:

1. Goldberg I. How common is glaucoma worldwide? In: Glaucoma in the 21st Century. London, UK. 2000, Mosby International Ltd.

2. Cubillan LDP, Olivar- Santos E. Third national survey of blindness. Philippine Journal of Ophthalmology. 2005; 30:100-114.

3. Ritch R, Shields MB, Krupin T (Eds). The Glaucomas, 2nd Edition. St. Louis, Missouri, USA, 1996, Mosby-Year Book, Inc.

4. Epstein DL, Allingham RR, Schuman JS (Eds). Chandler and Grant’s Glaucoma, 4th Edition. Baltimore, Maryland, USA, 1997, Williams & Wilkins.

5. South East Asian Glaucoma Interest Group. Asia-Pacific Glaucoma Guidelines. Sydney, Australia, 2003-2004, SEAGIG.