Glaucoma is a family of eye conditions that typically impairs your peripheral (side) vision and affects about 2% of the population over the age of 40 years old. It is a condition that normally affects both eyes, but not always at the same time and to the same extent. The causes of Glaucoma are generally quite well understood which means Glaucoma Treatment is better than it ever has been. Glaucoma symptoms can sometimes be non-existent as the disease normally happens slowly over many years. There are however different types of Glaucoma such as closed angle Glaucoma that have much more pronounced symptoms.

Although some people assume Glaucoma always causes blindness, this is in fact not true. Providing the disease is caught early, most people never notice an impairment to their vision. Even people with quite advanced Glaucoma can often function very well in everyday life as their central vision is normally unaffected. Tasks such as reading, writing and recognising faces all involve your central vision, which is only affected in very advanced Glaucoma. Even patients with quite pronounced peripheral vision loss often manage with very few problems as their better eye is able to compensate for the visual field loss in the more affected eye.

Glaucoma normally describes a condition in which the Optic nerve in your eye is damaged by increasing pressure (Intra-ocular pressure) which leads to loss of peripheral vision (side vision). The function of your optic nerve is to collect all the information provided by your retina and then send it to your brain (visual cortex) where the image is processed into the image that you ‘see’. The optic nerve is extremely fragile and is easily damaged with increasing pressure in the eye. In order to understand Glaucoma it is helpful to understand how your eye pressure is maintained and how problems can occur.

Detecting/Diagnosing Glaucoma

As mentioned above, the symptoms of Glaucoma are often non-existent (this is different for closed angle Glaucoma) and so it is therefore vitally important that you get your eyes tested regularly. It is also worth mentioning that if Glaucoma is detected early then there is a good chance that you will never notice any loss of vision at all. The vast majority of people who develop Glaucoma will only be required to put eye drops in once or twice per day. Other than that, they may be unaware that they have the condition. There are other glaucoma treatments such as surgery, but these are normally not required if the disease is picked up early enough.

How your optician detects Glaucoma

There are 3 main techniques that your optician will use to detect Glaucoma and they are as follows:

  • Tonometry: This test measures the pressure in your eye and you may remember it as the test that puffs air in your eye. There are also other techniques, some of which involve placing a small probe on your eye, after they have been numbed using eye drops. The normal range of IOPS (eye pressure) is between about 10-21 mmHg (this is what eye pressure is measured in). If the pressure is beyond this, your optician may refer you for Glaucoma investigation. It is important to mention that you could have eye pressure that is over 21mmHg but still not have Glaucoma. This is referred to as ocular hypertension and means that although your pressure is high it is not causing your optic nerve any damage.
  • Visual Field test: This is the test where you are asked to look for little flashes of light in your peripheral vision. It shows up any blind spots/visual field loss in your peripheral vision and occurs when your optic nerve has been damaged.
  • Assessing your Optic nerve: Your optician will assess the optic nerve during an eye examination and certain changes may indicate Glaucoma. You may remember your optician shining a bright light in your eye during the eye test – this is when the health of your eye is being assessed.

If your optician in concerned about any of the above results he/she may well refer you to an ophthalmologist.


This information is provided purely as a guide and in no way constitutes medical advice. If you are in doubt about the health of your eyes you should consult your doctor or optometrist.

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