Glaucoma – The leading cause of irreversible blindness in Canada

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BY: SHAUN RAWANA O.D., B.Sc

What is Glaucoma?

Glaucoma has been nicknamed the “sneak thief of sight”.  Glaucoma often goes undetected and causes irreversible damage to the eye.  Although there are several different forms of Glaucoma, it is generally characterized as an increase in pressure within the eye. This increased pressure can “push” against the optic nerve and damage it.  The damage is progressive with loss of the peripheral vision first, followed by a reduction in central vision and possible blindness.

Who is at risk of developing glaucoma?

People more likely to develop glaucoma include:

  • People of African descent (4x more likely than Caucasian)
  • Those with a family history of the disease (20% of sufferers have a close relative with the condition)
  • Those over the age of 50; over 40 if of African descent
  • Those who are very nearsighted (myopic)
  • Those who suffer a direct trauma to the eye
  • Those who are diabetic
  • Those with high blood pressure
  • Those with heart problems

How many people have glaucoma?

About 250 thousand people have glaucoma, with only 50% aware they have condition according to the Canadian National Institute for the Blind. This accounts for approximately 10% of all cases of blindness; however when glaucoma is diagnosed early and treated adequately, it rarely leads to blindness.

How is glaucoma detected?

Unfortunately, there is no simple test for glaucoma that is 100% effective.  Measurement of the pressure within the eye alone is not adequate to detect glaucoma.  Only a complete eye exam with fundus biomicroscopy and other specialized tests can detect glaucoma. These tests are often conducted on an annual to bi-annual basis and may include stereoscopic photos of the optic nerves, visual field analysis and ocular coherence tomography, which provides a cross-section of the optic nerve head and nerve fiber layer.

What are the types of glaucoma?

The most common form of glaucoma is called open-angle where fluid circulates freely in the eye and tends to rise slowly over time. Vision is gradually lost with no acute symptoms.  A less common form is called acute or angle closure glaucoma which develops suddenly with severe eye pain and redness. This form of glaucoma causes a rapid rise in pressure which is caused by a blockage of the fluid drainage angle.

What are the signs and symptoms?

In the vast majority of cases, especially in the early stages, there are few signs and symptoms. In the later stages of the disease, symptoms can occur and may include:

  • Loss of peripheral (side) vision
  • Difficulty adjusting to the dark
  • Difficulty focusing on close work
  • Rainbow coloured rings or halos around lights
  • Frequent need to change eyeglass prescriptions

Call your doctor immediately if you notice any sudden loss of vision, especially if it is accompanied by pain or redness in the eye. Vision may be lost within 24 hours if left untreated.

Can the loss of vision from glaucoma be cured?

Glaucoma is a life-long illness. Nerve tissue that has been destroyed cannot be restored, but proper medical and surgical treatments can help stop the disease from progressing.

What is the best defence against blindness from glaucoma?

Blindness from glaucoma can be prevented by early detection and appropriate treatment.  As such, the best defence is regularly scheduled comprehensive eye exams.   Ask your doctor how often you should be examined. If you have been diagnosed with glaucoma, it is important to discuss and understand all your options for treatment.

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