An overview of Glaucoma

Glaucoma is a group of eye conditions that damage the optic nerve. The optic nerve sends visual information from your eye to your brain and is vital for good vision. Damage to the optic nerve is often related to high pressure in your eye. But glaucoma can happen even with normal eye pressure.

Glaucoma can occur at any age but is more common in older adults. It is one of the leading causes of blindness for people over the age of 60.

Many forms of glaucoma have no warning signs. The effect is so gradual that you may not notice a change in vision until the condition is in its later stages.

It's important to have regular eye exams that include measurements of your eye pressure. If glaucoma is recognized early, vision loss can be slowed or prevented. If you have glaucoma, you'll need treatment or monitoring for the rest of your life.

Five major types of glaucoma exist. These are:

Open-Angle (Chronic) Glaucoma
Open-angle, or chronic, glaucoma has no signs or symptoms except gradual vision loss. This loss may be so slow that your vision can suffer irreparable damage before any other signs become apparent. According the National Eye Institute (NEI)Trusted Source, this is the most common type of glaucoma.

Normal Tension Glaucoma
In some cases, people without increased eye pressure develop damage to their optic nerve. The cause of this isn’t known. However, extreme sensitivity or a lack of blood flow to your optic nerve may be a factor in this type of glaucoma.

Congenital Glaucoma
Children born with congenital glaucoma have a defect in the angle of their eye, which slows or prevents normal fluid drainage. Congenital glaucoma usually presents with symptoms, such as cloudy eyes, excessive tearing, or sensitivity to light. Congenital glaucoma can run in families.

Secondary Glaucoma
Secondary glaucoma is often a side effect of injury or another eye condition, such as cataracts or eye tumors. Medicines, such as corticosteroids, may also cause this type of glaucoma. Rarely, eye surgery can cause secondary glaucoma.

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

Elevated eye pressure happens as the result of a buildup of fluid that flows throughout the inside of the eye. This fluid also is known as the aqueous humor. It usually drains through a tissue located at the angle where the iris and cornea meet. This tissue also is called the trabecular meshwork. The cornea is important to vision because it lets light into the eye. When the eye makes too much fluid or the drainage system doesn't work properly, eye pressure may increase.

The back of your eye continuously makes a clear fluid called aqueous humor. As this fluid is made, it fills the front part of your eye. Then, it leaves your eye through channels in your cornea and iris. If these channels are blocked or partially obstructed, the natural pressure in your eye, which is called the intraocular pressure (IOP), may increase. As your IOP increases, your optic nerve may become damaged. As damage to your nerve progresses, you may begin losing sight in your eye.

What causes the pressure in your eye to increase isn’t always known. However, doctors believe one or more of these factors may play a role:

1. dilating eye drops

2. blocked or restricted drainage in your eye

3. medications, such as corticosteroids

4. poor or reduced blood flow to your optic nerve

5. high or elevated blood pressure

The most common type of glaucoma is primary open-angle glaucoma. It has no signs or symptoms except gradual vision loss. For that reason, it’s important that you go to yearly comprehensive eye exams so your ophthalmologist, or eye specialist, can monitor any changes in your vision.

Acute-angle closure glaucoma, which is also known as narrow-angle glaucoma, is a medical emergency. See your doctor immediately if you experience any of the following symptoms:

1. severe eye pain

2. nausea

3. vomiting

4. redness in your eye

5. sudden vision disturbances

6. seeing colored rings around lights

7. sudden blurred vision

Glaucoma can’t be prevented, but it’s still important to catch it early so you can begin treatment that will help prevent it from getting worse. The best way to catch any type of glaucoma early is to have an annual preventive eye care appointment. Make an appointment with an ophthalmologist. Simple tests performed during these routine eye checks may be able to detect damage from glaucoma before it advances and begins causing vision loss.

Some people have a higher than normal risk of getting glaucoma. This includes people who:

1. are over age 40

2. have family members with glaucoma

3. are of African, Hispanic, or Asian heritage

4. have high eye pressure

5. are farsighted or nearsighted

6. have had an eye injury

7. use long-term steroid medications

8. have corneas that are thin in the center

9. have thinning of the optic nerve

10. have diabetes, migraines, high blood pressure, poor blood circulation or other health problems affecting the whole body

Talk with an ophthalmologist about your risk for getting glaucoma. People with more than one of these risk factors have an even higher risk of glaucoma.

The only sure way to diagnose glaucoma is with a complete eye exam. A glaucoma screening that only checks eye pressure is not enough to find glaucoma.

During a glaucoma exam, your ophthalmologist will:

1. measure your eye pressure

2. inspect your eye's drainage angle

3. examine your optic nerve for damage

4. test your peripheral (side) vision

5. take a picture or computer measurement of your optic nerve

6. measure the thickness of your cornea

Open-angle glaucoma
This is the most common form of glaucoma. The drainage angle formed by the iris and cornea remains open. But other parts of the drainage system don't drain properly. This may lead to a slow, gradual increase in eye pressure.

Angle-closure glaucoma
This form of glaucoma occurs when the iris bulges. The bulging iris partially or completely blocks the drainage angle. As a result, fluid can't circulate through the eye and pressure increases. Angle-closure glaucoma may occur suddenly or gradually.

Normal-tension glaucoma
No one knows the exact reason why the optic nerve becomes damaged when eye pressure is normal. The optic nerve may be sensitive or experience less blood flow. This limited blood flow may be caused by the buildup of fatty deposits in the arteries or other conditions that damage circulation. The buildup of fatty deposits in the arteries also is known as atherosclerosis.

Glaucoma in children
A child may be born with glaucoma or develop it in the first few years of life. Blocked drainage, injury or an underlying medical condition may cause optic nerve damage.

Pigmentary glaucoma
In pigmentary glaucoma, small pigment granules flake off from the iris and block or slow fluid drainage from the eye. Activities such as jogging sometimes stir up the pigment granules. That leads to a deposit of pigment granules on tissue located at the angle where the iris and cornea meet. The granule deposits cause an increase in pressure.

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