Glaucoma: The silent stealer of vision
Posted on 16 February 2017
Updated: 15 February 2017
This eye condition can lead to blindness and frequently presents no symptoms, which is why early detection through regular screenings is vital.
Glaucoma is an eye condition where the pressure inside the eye is too high. Over time, the sustained high pressure damages the optic nerve fibres.
The optic nerve, which is like a data cable coming out of the back of your eye, carries visual information to your brain. When glaucoma damages the nerve cells or ‘wires’ in the cable, the flow of visual information to the brain is disrupted.
Without treatment, people with this disease will slowly lose their peripheral (side) vision, and over time their central vision will also be affected. Once the damage has been done, the lost vision can’t be restored.
What is open-angle glaucoma?
‘There are numerous types but the most common in South Africa is open-angle glaucoma,’ says Dr Alan Sara, supporting ophthalmologist at Mediclinic Howick.
This is when the angle in the eye where the iris (the coloured part of the eye) meets the cornea (the transparent layer over the front of the eye) is as wide and open as it should be, but the eye’s drainage canals have become clogged, causing an increase in internal eye pressure.
What are the symptoms?
‘One of the big problems with open-angle glaucoma is that initially there are no symptoms,’ says Dr Sara. ‘There’s no pain, no redness, and no noticeable loss in vision at first.’
Does age play a role?
‘The prevalence and incidence of open-angle glaucoma increases with age, so it’s important that people from the age of 60 get their intraocular [eye] pressure measured regularly, either by an ophthalmologist or an optician,’ says Dr Sara. People at higher risk should usually be examined every 1-2 years.
How is it treated?
‘Most patients’ condition can be managed well with prescription eye drops to lower the pressure in the eye,’ says Dr Sara. Some of these eye drops cause the eye to produce less fluid, while others lower the pressure by helping fluid drain from the eye.
‘In severe cases, or for patients who don’t respond adequately to eye drops, surgery may be indicated,’ Dr Sara adds. Such surgery involves either inserting a small one-way valve, or cutting a little flap in the eye that allows the fluid to drain out.
Research is currently underway on a drug-dispensing contact lens that may be easier to use than eye drops.