Glaucoma is the name of a group of eye diseases that damage the optic nerve. The optic nerve transfers visual information from the eye to the brain and if it’s damaged, it can result in sight loss and even blindness. There are three main types of glaucoma: primary, secondary, and developmental (glaucoma in babies and children).
Glaucoma is a complicated disease and diagnosis is not always easy. Several different tests will be needed to confirm how and why damage to the optic nerve has occurred. In many cases, glaucoma is associated with high pressure within the eye.
To understand how glaucoma affects us, it’s useful to understand the structure of the eye, and why keeping eye pressure within the normal range is so important.



Most types of glaucoma develop gradually, so in the early stages there are no symptoms. Significant vision can be lost before someone has any signs of glaucoma.

If you look for images of what vision with glaucoma looks like, you’ll often see photos that show a black tunnel or big black patches dotted around. This isn’t accurate, and in fact, glaucoma sight loss can be quite subtle, especially at the start. Some people with glaucoma notice misty or blurry patches in their vision, particularly if they close one eye, and that’s how we tend to describe glaucoma sight loss.

For people with more advanced glaucoma, daily activities such as reading, driving or moving about become more difficult. For more information about the common types of glaucoma, visit primary glaucomas or secondary glaucomas.

The only way to tell if you have most types of glaucoma is through an eye examination.



For most people, the signs of glaucoma are first spotted by an optometrist at a routine eye test.

Conditions such as glaucoma, macular degeneration and even diabetes and high cholesterol can be detected during eye tests. So it’s important to get your eyes tested at least every two years.

It is particularly important to get your eyes tested if you have a close relative with glaucoma, if you are African-Caribbean, Asian, diabetic, have low blood pressure, or are short-sighted. All these factors mean you are at an increased risk of developing glaucoma.


The optometrist will carry out different tests to check the health of your eye. Some of these are key to detecting signs of glaucoma.

This tests whether your peripheral vision (i.e. the vision away from the centre, or everything you’re not looking directly at) is healthy, or whether there are gaps. Looking into a machine, you are asked to press a button every time you see a dot of light. If you have glaucoma, you may have some gaps in your field of vision so you may miss some of the flashing lights.

This is usually an “air puff” test. A small puff of air is directed at your eye and bounces back onto the machine, which measures the pressure within the eye (intraocular pressure or IOP). If you have glaucoma or ocular hypertension, your eye pressure will normally be raised.

The optometrist looks at the back of the eye and may take a photograph. This is to check the health of the optic nerve. If you have glaucoma, the optic nerve will look different.



Depending on the risks the optometrist has identified, and where you live, you may be referred directly to an ophthalmologist (an eye doctor) at a hospital.

When you see the glaucoma specialist, they will conduct more tests, including repeating some of those you have already had. The specialist will also look at other risk factors, such as ethnicity or family history of glaucoma. They will then decide whether you have glaucoma, or are at an increased risk, and whether you need to start treatment or not.

Glaucoma can usually be effectively controlled and treated. That’s why it is important that a diagnosis is made early and any treatment begins quickly, to protect your vision. Any vision lost to glaucoma is lost forever.


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