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Glaucoma – the sneak thief of sight.

Glaucoma – the sneak thief of sight.

Glaucoma is known as ‘the sneak thief of sight’. It is a disease in which the optic nerve head is slowly damaged by increased pressure in the eye. It is the leading cause of preventable blindness in Australia with one in eight Australians over the age of eighty developing glaucoma. The scary part of glaucoma is that it usually has few or no initial symtoms – living up to it’s ‘sneak thief of sight’ name. Because of this 50% of Australians with glaucoma are undiagnosed and untreated!

What is Glaucoma?

Glaucoma - the sneak thief of sight

In most cases, glaucoma is due to higher than normal pressure inside the eye, which is called intraocular pressure or IOP. The eyeball is filled with fluid to maintain it’s round shape. If too much fluid is being produced, or more commonly not enough is draining out, then the ‘pressure’ in the eye can increase. This rise in pressure can push down on the optic nerve head and gradually kills off the nerve fibres which carry information from the eye to the brain. The damage to the optic nerve head progresses slowly and gradually causes permanent loss of vision, starting with your peripheral vision. The vision loss is irreversible and usually goes unnoticed until it is too late. Treatment can not get back the vision that has been lost, but it can stop or slow down the progression and save what sight is left.

What are the most common types of Glaucoma?

There are many different types of glaucoma but we’ll look at the two most common types – open-angle glaucoma and angle-closure glaucoma.

Open-angle glaucoma is the most common type of glaucoma. Damage to the optic nerve occurs slowly due to raised intraoccular pressure. There are no symptoms until the condition has progressed significantly and vision has been affected. The vision loss is very slow and gradual and affects peripheral vision first and central vision later. Often the unaffected eye compensates for the affected eye so that the person remains unaware until significant damage to the nerve has occured.

Angle-closure is less common. It occurs with the closure of the drainage angle between the iris and cornea which blocks the outflow of eye fluid causing an increase in pressure. This increase in pressure damages the optic nerve in the same way that open-angle glaucoma does. With acute angle-closure glaucoma sudden symptoms do occur. These can include blurry vision, intense eye pain, headaches, halos around lights, nausea and vomiting. If you have these symptoms you need to immediately see your optometrist or visit the emergency department of hospital so that permanent eye loss can be prevented.

Who is at risk?

As our population becomes older, the proportion of glaucoma patients is increasing. Anyone can get glaucoma but there are some people who have a higher risk. These include individuals with:

  • diabetes or a family history of diabetes
  • short sightedness
  • long sightedness
  • migraine
  • traumatic eye injuries
  • high blood pressure
  • use of cortisone drugs

How is Glaucoma diagnosed?

Your optometrist will use a tonometer to measure your intraocular pressure (IOP). Usually eye drops will be used. An abnomally high IOP reading indicates a problem with the amount of fluid in the eye. Other methods of monitoring glaucoma involve the use of high-tech digital imaging such as an optical coherence tomography (OCT) or scanning laser polarimetry (SLP). These are used to create a baseline measure of the optic nerve and internal structures of the eye, which is used to compare to any furture readings.

A visual fields test is used to determine if there is any vision loss due to glaucoma. This test involves staring straight ahead into a machine and clicking a button when lights appear in your peripheral vision. Once again this test can be repeated at regular intervals as a way of moniteering any progressive visual loss from glaucoma.

How can I prevent prevent vision loss due to Glaucoma?

Unfortunatley the damage caused from glaucoma is irreversable and treatment cannot recover vision that has been lost. It can however prevent further vision loss. This is why regular eye examinations from your optometrist are so important – to detect glaucoma as early as possible to start early treatment with as little damage to your vision as possible.

Once detected actual treatment can involve medication, eye drops, laser treatment or surgery depending on the severity. Often because glaucoma is painless, people are not compliant with their recommended eye drops or medication, which is a major reason for blindness caused by glaucoma.

This week is World Glaucoma Week. For more information visit Glaucoma Australia.

Regular eye examinations are the most important way of preventing vision loss due to glaucoma. Call us on 07 5578-4611 or book online to have your eye health assessed.

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