What is Glaucoma ?
Glaucoma is a group of diseases that damage the eye’s optic nerve and can result in vision loss and blindness. It's often associated with a build-up of pressure inside the eye. However, with early detection and treatment, you can often protect your eyes against serious vision loss.
The optic nerve
The optic nerve is a bundle of more than 1 million nerve fibres. It connects the retina to the brain. (Refer diagram above.) The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.
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 permanent loss of vision. Without treatment, glaucoma can cause total permanent blindness within a few years.
Because most people with glaucoma have no early symptoms or pain from this increased pressure, it is important to see your eye doctor regularly so that glaucoma can be diagnosed and treated before long-term visual loss occurs.
If you are over age 40 and have a family history of glaucoma, you should have a complete eye exam with an eye doctor every one to two years. If you have health problems such as diabetes or a family history of glaucoma or are at risk for other eye diseases, you may need to visit your eye doctor more freque
The optic nerve is a bundle of more than 1 million nerve fibres. It connects the retina to the brain. (Refer diagram above.) The retina is the light-sensitive tissue at the back of the eye. A healthy optic nerve is necessary for good vision.
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 permanent loss of vision. Without treatment, glaucoma can cause total permanent blindness within a few years.
Because most people with glaucoma have no early symptoms or pain from this increased pressure, it is important to see your eye doctor regularly so that glaucoma can be diagnosed and treated before long-term visual loss occurs.
If you are over age 40 and have a family history of glaucoma, you should have a complete eye exam with an eye doctor every one to two years. If you have health problems such as diabetes or a family history of glaucoma or are at risk for other eye diseases, you may need to visit your eye doctor more freque
4 main types of glaucoma :
1. Chronic open-angle glaucoma – this is the most common type of glaucoma and develops very slowly.
3. Secondary glaucoma – this mainly occurs as a result of an eye injury or another eye condition, such as uveitis (inflammation of the middle layer of the eye).
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2. Primary angle-closure glaucoma – this is rare and can occur slowly (chronic) or may develop rapidly (acute) with a sudden, painful build-up of pressure in the eye.
4. Developmental glaucoma (congenital glaucoma) – a rare but sometimes serious type of glaucoma which occurs in very young children, caused by an abnormality of the eye.
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Categories of Glaucoma
- Open-angle glaucoma
- Angle-closure glaucoma
- Normal-tension glaucoma
It is possible for infants and children to have glaucoma. It may be present from birth or developed in the first few years of life. The optic nerve damage may be caused by drainage blockages or an underlying medical condition.
Pigmentary glaucomaIn 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.
Signs and Symptoms
For most people, there are usually few or no symptoms of glaucoma. The first sign of glaucoma is often the loss of peripheral or side vision, which can go unnoticed until late in the disease. This is why glaucoma is often called the "sneak thief of vision."
Detecting glaucoma 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, headaches, blurred vision, or the appearance of halos around lights may occur.
If you have any of the following symptoms, seek immediate medical care:
Detecting glaucoma 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, headaches, 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
- Vision loss
- Redness in the eye
- Eye that looks hazy (particularly in infants)
- Nausea or vomitting
- Pain in the eye
- Narrowing of vision (tunnel vision)
Causes and Risk Factors
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 build-up of a fluid (aqueous humour) that flows throughout your eye. This fluid normally drains into the front of the eye (anterior chamber) through tissue (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 pressure builds up.
Glaucoma tends to run in families. In some people, scientists have identified genes related to high eye pressure and optic nerve damage.
Because chronic forms of glaucoma can destroy vision before any signs or symptoms are apparent, be aware of these risk factors:
Elevated eye pressure is due to a build-up of a fluid (aqueous humour) that flows throughout your eye. This fluid normally drains into the front of the eye (anterior chamber) through tissue (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 pressure builds up.
Glaucoma tends to run in families. In some people, scientists have identified genes related to high eye pressure and optic nerve damage.
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 or Hispanic
- Having a family history of the condition
- Having certain medical conditions, such as diabetes, heart disease, high blood pressure and sickle cell anaemia
- Having certain eye conditions, such as nearsightedness
- Having had an eye injury or certain types of eye surgery
- Early oestrogen deficiency, such as can occur after removal of both ovaries (bilateral oophorectomy) before age 43
- Taking corticosteroid medications, especially eye drops, for a long time
How is Glaucoma diagnosed?
Glaucoma is detected through a comprehensive dilated eye exam that includes the following:
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Treatment
There is no cure for glaucoma. Vision lost from the disease cannot be restored.
The goal of glaucoma treatment is to lower pressure in your eye (intraocular pressure). Depending on your situation, your options may include eye drops, laser treatment or surgery.
Eye drops
Glaucoma treatment often starts with prescription eye drops. These can help decrease eye pressure by improving how fluid drains from your eye or by decreasing the amount of fluid your eye makes. Prescription eye drop medications include:
Surgery and other therapies
Other treatment options include laser therapy and various surgical procedures. Possible complications include pain, redness, infection, inflammation, bleeding, abnormally high or low eye pressure, and loss of vision. Some types of eye surgery may speed the development of cataracts.
The following techniques are intended to improve the drainage of fluid within the eye, lowering pressure:
Alternative medicine
Some alternative medicine approaches may help your overall health but none are effective glaucoma remedies. Talk with your doctor about their possible benefits and risks.
The goal of glaucoma treatment is to lower pressure in your eye (intraocular pressure). Depending on your situation, your options may include eye drops, laser treatment or surgery.
Eye drops
Glaucoma treatment often starts with prescription eye drops. These can help decrease eye pressure by improving how fluid drains from your eye or by decreasing the amount of fluid your eye makes. Prescription eye drop medications include:
- Prostaglandins
- Beta blockers
- Alpha-adrenergic agonists
- Carbonic anhydrase inhibitors
- Miotic or cholinergic agents
Surgery and other therapies
Other treatment options include laser therapy and various surgical procedures. Possible complications include pain, redness, infection, inflammation, bleeding, abnormally high or low eye pressure, and loss of vision. Some types of eye surgery may speed the development of cataracts.
The following techniques are intended to improve the drainage of fluid within the eye, lowering pressure:
- Laser therapy
- Filtering surgery
- Drainage tubes
- Electrocautery
Alternative medicine
Some alternative medicine approaches may help your overall health but none are effective glaucoma remedies. Talk with your doctor about their possible benefits and risks.
- Herbal remedies
- Relaxation techniques
- Marijuana
Extra Info
- What research is being done?
NEI also is supporting studies to learn more about who is likely to get glaucoma, when to treat people who have increased eye pressure, and which treatment to use first.
- How common is glaucoma?
Chronic open-angle glaucoma affects up to two in every 100 people over 40 years old and around five in every 100 people over 80 years old.
You are also at increased risk of developing open-angle glaucoma if you are of black-African or black-Caribbean origin.
Some types of glaucoma, such as acute angle-closure glaucoma, are much less common. However, people of Asian origin are more at risk of getting this type of glaucoma compared with those from other ethnic groups.
- Why Does Pressure Rise in the Eye to Cause Glaucoma?
Normally, this fluid, called aqueous humour, flows out of the eye through a mesh-like channel. If this channel becomes blocked, fluid builds up, causing glaucoma. The direct cause of this blockage is unknown, but doctors do know that it can be 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. Glaucoma usually occurs in both eyes, but it may involve each eye to a different extent.