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What is Glaucoma?

​Glaucoma is the name for a group of eye conditions where an increase in fluid pressure inside the eye gradually damages the optic nerve causing vision loss.

Because the loss of vision happens slowly, a person with glaucoma may not notice any changes to their vision until a significant reduction in sight has occurred. Without treatment, this loss continues until the eye is blind. It may surprise you to know that you often can't feel any increase in the pressure of your eye. The only way to know is to get your Optometrist to measure it.


The other reason that glaucoma is often called "the silent thief of sight" is that it damages your peripheral vision. We are all aware of what blurred vision may be like, but we cannot accurately measure our side vision or be aware if it has changed. Every Visique Optometrist can measure your peripheral vision and monitor it for change.

Even if you think you've got perfect vision or that your current contact lenses or glasses are suited to your eyes, it's important to get your eye health checked at least every two years.

"Too many people suffer with eye conditions without knowing just how bad their eyesight has got. All too often we examine people in our community who don't realise how badly their eyesight has deteriorated.

A customer I saw earlier this year came to the practice after he failed a routine driver's licence renewal eye test. At 45 years of age, he hadn't noticed that his eyesight had changed much at all. After examining him we found he had advanced Glaucoma in his left eye and early signs of the disease in his right eye. Glaucoma affects the eye very slowly, so it's common for people not to notice how much of their vision they've lost.

Our customer said he had no idea how badly his sight had deteriorated, let alone that he had glaucoma: While it's devastating that we caught the disease too late and that he'll never be able to drive again, the fact that the disease has now been detected means he will hopefully maintain some sight with the help of laser treatment. He wished that he had tested for Glaucoma earlier."

Andrea Kaijser, Optometrist at Visique Shattky on Russell Optometrists.


There are three main types of glaucoma:

  1. Chronic glaucoma is the most common type where the drainage channels slowly become blocked over many years.

  2. Acute glaucoma occurs when there is a sudden blockage of the drainage system. This is painful and causes permanent damage to sight if not treated promptly.

  3. Secondary glaucoma is where injury, inflammation or tumour blocks the drainage channels.

​Anyone may develop glaucoma, but the risk tends to increase with age (about 2 in 100 New Zealanders over 40 years of age have glaucoma) and is more likely if there is a family history of glaucoma.


​While glaucoma cannot currently be prevented, early treatment can help protect your eyes against vision loss.


Because there are often no symptoms at first, regular eye examinations with your Visique Optometrist, especially for those over 40 years of age, can help detect glaucoma in its early stages.

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The 8 warning signs of Glaucoma

You can prevent glaucoma with regular eye exams and by watching for any of these eight subtle warning signs...


Eye pain and headaches

The onset of sudden eye pain and headaches behind the eyes and brow are primary signs of late stage acute glaucoma. The term “acute” refers to the sudden and irreversible damage to the optic nerve. If you experience eye pain, seek treatment immediately to prevent more severe vision loss and even blindness.


Eye ball changes

It’s difficult to see the damage of glaucoma with the naked eye. However, patients with acute glaucoma typically have red eyeballs with large pupils that are nonreactive to light. The cornea (the transparent eye covering that shields the pupil, iris, and anterior chamber) may also appear slightly cloudy and swollen.


Night halos

Acute glaucoma often causes a coloured rainbow effect or night vision issues such as halos (or starbursts) and blurred vision around lights. This can be problematic for drivers with glaucoma who feel extreme pressure and sudden blindness as the pupil opens, especially at night or in low-lit environments.


Tunnel vision

Chronic glaucoma typically presents with a slow narrowing of the peripheral vision (causing tunnel vision) and interrupting the edges of the field of view in both eyes. Many glaucoma patients don’t realise there’s an issue until their sight is limited to what’s directly in front of them in the advanced stages of the disease.


Blurred vision

Acute glaucoma will cause a gradual decline in sharpness of vision (or visual acuity). Severe blurring isn’t evident until the latter stages of the disease. Tragically, often by that time, significant vision damage is irreversible, even with surgery.


Eye swelling and redness

Acute glaucoma shows few signs. However, red eye and headaches may indicate swollen irises due to eye pressure build-up. By the time the eyes become obviously red and swollen, immediate emergency treatment will be necessary. Eye redness can also occur from the chronic use of eye drops.



Nausea and vomiting often result when vision is distorted. However, acute glaucoma causes nausea and vomiting accompanied by severe eye pain, which slightly distinguishes symptoms from the stomach flu or other gastro-intestinal ailments.


Sudden visual disturbance

Unfortunately, sudden visual disturbance in one or both eyes can signal several eye problems — including retinal damage. However, the sudden onset of visual disturbance in low lighting is more typical to acute glaucoma.

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