Eye Health

Updated 27 January 2014

Glaucoma in a nutshell

Glaucoma can occur in one of two forms: acute or chronic.


Glaucoma is an eye disorder where abnormally high pressure inside the eye due to too much liquid (known as aqueous humor) in the eyeball, damages the optic nerve at the back of the eye. This damage can lead to loss of your peripheral vision, and eventually to blindness. It is important to treat glaucoma as early as possible.

Acute glaucoma can lead to instant blindness. It is rare.

Chronic glaucoma is more common and progresses slowly and “silently” over years. When you first recognise symptoms of chronic glaucoma, the damage to the optic nerve may be very advanced.

The pressure inside the eye rises when drainage of the watery liquid produced inside the eye is blocked, instead of being drained by the network of tiny channels in the eye. With blockage, the volume of liquid in the eye increases like water behind a dam wall, causing pressure on and irreversible damage to the fragile optic nerve at the back of the eye.

See your doctor if:

Even if you only suspect that you have either acute or chronic glaucoma.

Recognise acute glaucoma by its dramatic symptoms:

  • Sudden, severe, deep pain in one eye affecting the whole side of the head. The severe pain can cause nausea and vomiting.
  • Partial loss of vision
  • Coloured haloes are seen around bright lights.
  • The pupil does not constrict in response to shining a light into it.
  • Treat this as an emergency. If the pressure in the eye is not reduced within hours with specific eye drops and other medication, permanent loss of vision can occur. When the pressure has dropped, emergency surgery must be performed to prevent the pressure from building up again. Treatment is usually successful if the problem is caught early enough.

Recognise chronic glaucoma like this:

It has no symptoms or very subtle symptoms. The progression is so gradual that you may not recognise the progressive patchy loss of your peripheral field of vision. The central part of the vision is not affected until very late. Damage almost always goes unnoticed until it is too late.

The only way to detect it early is during regular eye examinations.

Visit your ophthalmologist at least once a year if:

  • You are over 50 years of age;
  • You have a blood relative with glaucoma;
  • You are severely short-sighted, or
  • You ever had a blow to the eye.

Treatment is initially by means of eye drops to bring the pressure in the eye down. Surgery may be needed to help the outflow of aqueous humor. Although treatment can be very successful, the progression of chronic glaucoma is often difficult to stop.

Read more about other eye conditions

Useful resources:
South African Optometric Association
Tel: 011 805 4517
Retina South Africa
Tel: 011 622 4904
South African National Council for the Blind 
Tel: 012 452 3811
Ophthalmological Society of South Africa


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Megan Goodman qualified as an optometrist from the University of Johannesburg and is currently practising at Tygerberg Academic Hospital in Cape Town. She has recently completed a Masters degree in Clinical Epidemiology at Stellenbosch University. She has a keen interest in ocular pathology and evidence based medicine as well as contact lenses.

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