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Glaucoma is a serious condition where the optic nerve is damaged due to increased pressure in the eye – it can lead to blindness.

A woman having her eyes tested for glaucoma

Glaucoma occurs when abnormally high pressure inside the eye due to too much liquid in the eyeball, damages the optic nerve at the back of the eye. It is caused by a blockage in part of the eye, which prevents fluid draining out of the eye and causes intraocular pressure (increased pressure in your eye).

This can lead to loss of peripheral vision, and eventually to blindness. Glaucoma is reportedly the leading cause of blindness worldwide. 

Glaucoma usually doesn’t produce symptoms until vision is already severely damaged. But if diagnosed early, it can be controlled and permanent damage prevented.

There are four main types:

  • Chronic open-angle glaucoma
  • Acute angle-closure glaucoma
  • Secondary glaucoma
  • Developmental glaucoma

Risk factors include family history, adults over 40, or those with diabetes and poor vision.

What are its symptoms?

Glaucoma symptoms will vary in severity and presentation from case to case, depending on the type of glaucoma you have.

1. Chronic open-angle glaucoma symptoms:

  • No noticeable symptoms because the condition develops slowly
  • Vision is lost from the outer rim of the eye, working inwards towards the centre

2. Acute angle-closure glaucoma symptoms:
Develops quickly and symptoms are severe. These include:

  • Intense pain
  • Redness of the eye
  • Headache
  • Tender eye area
  • Halos or rainbow-like rings around lights
  • Misty vision
  • Loss of vision in one or both eyes that progresses quickly

Acute angle-closure glaucoma is a medical emergency so see your doctor immediately if you experience the above symptoms.

3. Secondary glaucoma symptoms:
Secondary glaucoma is caused by other conditions, such as uveitis (inflammation of the middle layer of the eye). It can also be caused by eye injuries and certain treatments, such as medication or operations.

4. Developmental glaucoma symptoms:
This a rare condition affecting babies. Its symptoms include:

  • Large eyes due to the pressure in the eyes causing them to expand
  • Light sensitivity
  • Eye appears cloudy
  • Watery eyes
  • Jerky movements of the eyes
  • Having a squint

If you notice any of these symptoms, visit your doctor or optometrist as soon as possible.

How is it diagnosed?

There is no single glaucoma test, so a glaucoma diagnosis is usually made on the basis of the symptoms meeting several criteria.

Your doctor will review your medical history and thoroughly examine your eye.

A diagnosis may include several tests. These include:

  • Measuring your internal eye pressure, after numbing your eye with drops. This simple, painless procedure is usually the initial screening test for glaucoma.
  • Test for optic nerve damage: Your doctor will use instruments to look directly through the pupil to the back of your eye. This can reveal slight changes that may indicate the beginnings of glaucoma.
  • Visual field test: evaluates your peripheral vision.
  • Visual acuity: Your doctor will test your ability to see from a distance.
  • Measuring cornea thickness: Your eyes are numbed for this test, which determines the thickness of each cornea, an important factor in diagnosing glaucoma.

What are your treatment options?

Glaucoma treatment may include:

  • Prescription eye drops: These either reduce the formation of fluid in the front of the eye or increase its outflow.
  • Laser surgery: This slightly increases the outflow of the fluid from the eye in open-angle glaucoma or eliminates fluid blockage in angle-closure glaucoma.
  • Microsurgery: In an operation called a trabeculectomy, a new channel is created to drain the fluid, so reducing intraocular pressure. Complications include some temporary or permanent loss of vision, as well as bleeding or infection.

Can it be prevented?

In many cases, taking certain precautions can prevent glaucoma. These include:

  • Have a full eye test every three to five years after age 40 and every year after age 60.
  • Follow a healthy diet: This won’t prevent glaucoma, but will improve overall health.
  • Treat elevated eye pressure with glaucoma eye drops.
  • Eye injuries can lead to glaucoma. Wear goggles when you use power tools or play high-speed games like squash. Always wear sunglasses outside.

For more info
South African Glaucoma Society

South African National Council for the Blind

Ophthalmological Society of South Africa

IMAGE CREDIT: 123rf.com

The accuracy of this information was checked and approved by physician Dr Thomas Blake in May 2015