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What causes glaucoma?

Pressure-induced optic nerve damage is called glaucoma.

The eye is constantly producing a clear liquid called aqueous humor within. This fluid nourishes the eye and holds the eye in shape. The fluid is then drained out through an area called the anterior chamber angle or drainage angle. If the drainage angle does not work well (due to genetic abnormality/ trauma/ inflammation etc), the rate at which the eye produces the aqueous humor then becomes greater than the rate the eye can drain it – causing high pressure in the eye.

This increased pressure begins to damage the optic nerve which lies at the back of the eye. The optic nerve comprises approximately one million nerve fibres cells connecting the back of the eye to the brain. Damage to these cells results in irreversible damage to your eyesight.

Types of glaucoma

Primary Open Angle Glaucoma (POAG)

This is the most common form of glaucoma. There are no obvious symptoms to alert you until the disease is very advanced.

Angle-Closure Glaucoma

This type involves a blocked drainage angle. If angle closure occurs suddenly, the eye pressure may rise abruptly causing ACUTE pain, redness and loss of vision. Acute angle closure is an ophthalmological emergency requiring urgent treatment.

Who is at risk? Although anyone may develop glaucoma, some people are at a higher risk. Risk factors include:

• A family history of glaucoma (first-degree relatives)

• Diabetes

• A previous history of eye injury

• Past or present prolonged use of cortisone drugs (steroids)

What are the symptoms?

Glaucoma is known as the ‘sneak thief of sight’ as there are often no obvious visual symptoms in its early stages.

Primary Open Angle Glaucoma (POAG)

· There are no early-stage symptoms for POAG.

· Early detection with an eye test is the only way to detect visual field changes and damage to the optic nerve.

· Late stages are characterised by peripheral visual field defects progressing to tunnel vision

Acute Angle-Closure Glaucoma

• Severe eye pain associated with nausea and vomiting.

• Headache.

• Sudden onset of blurred vision or seeing halos around light.

How is glaucoma detected?

Glaucoma cannot be self-detected. Only an optometrist or an ophthalmologist can determine whether you have glaucoma or not. During a glaucoma exam your eye health practitioner will:

• Measure your eye pressure, also known as intraocular pressure (IOP).

• Inspect your eye’s drainage angle.

• Examine your optic nerve for damage.

• Test your central and peripheral (side) vision.

• Take a picture or computer measurement of your optic nerve.

• Measure the thickness of your cornea.

It is important to remember that the combined results of the above tests will determine the diagnosis of glaucoma and that no single test is diagnostic.

How is glaucoma treated?

Although there is no cure for glaucoma it can usually be controlled so that further loss of sight can be prevented or slowed. Treatment for glaucoma consists of eyedrops, laser treatment, surgery or a combination of the three.

Glaucoma and your family

In many cases, glaucoma is an inherited (genetic) disease that is passed on within families, and there is an increased risk with direct relatives. First-degree relatives (parents, siblings, and children) are at greater risk – having an almost 1 in 4 chance of developing glaucoma in their own lifetime. The best way to protect your sight from glaucoma is to have a comprehensive eye exam, which includes an optic nerve check. If you have a family history of glaucoma it is recommended that you have your eyes tested for glaucoma every 2 years from the age of 40 years.

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