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National Glaucoma Awareness Week: how big is your blind spot?

9 Jun 2008

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National Glaucoma Awareness Week: 9th - 15th June 2008

Around 95% of the sensory input used in driving comes from vision, yet there is a condition that can rob you of nearly half of your vision before you know anything about it. How can that be? Surely, if a person was, literally, nearly half blind, they would know all about it – wouldn’t they?

Every one of us has a natural blind spot – it is the point in the retina where the optic nerve leaves the eye and goes off to the brain, yet none of us are aware of the gap in our vision. This is because one eye will fill in for the other and the brain will put back the missing piece for us. Even if we close one eye so that there is no information from the closed eye, the brain still uses the rest of the visual information it has to replace the missing part of the field of vision.

Glaucoma damages the off centre parts of the field of vision first and leaves the central detailed vision until the late stages of the condition, so a person who had moderately advanced glaucoma might still be able to read the bottom line of the sight chart perfectly well. This off centre damage is not noticed, partly because we use our central vision most of the time and partly because, if there is no damage in the same area of the field in the second eye, the brain can complete its trick of using one eye to fill in for the other. The danger comes, especially in driving, when the damaged areas in each eye overlap: instead of an accurate combined visual picture, the brain is guessing in that overlapping damaged area. As a consequence, the driver relies on what his brain tells him and is completely unaware of what is happening. There could be a child running out with a ball, a cyclist, pedestrian, animal, even a car in the blind area and they would be none the wiser until something terrible happened.

Glaucoma is a controllable, treatable condition but, as good as modern treatments are, they cannot give back what has already been lost to glaucoma. Early detection is the key to controlling visual loss and to driving safely. Many people with glaucoma can be perfectly safe drivers, the difference is that they are checked every so often to make sure that there is no significant blind spot where disaster may hide.

Half of those who have glaucoma in the UK don’t know about their condition or the risk to their sight and driving safety. Regular comprehensive routine eye examinations are the key to early detection and the preservation of vision and the driving license.

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Notes to Editors:

For more information about National Glaucoma Awareness Week call: 01233 64 81 70 or e-mail:

National Glaucoma Awareness Week is run by the International Glaucoma Association. For more information about glaucoma and other sight-related eye conditions call the IGA SightLine on 01233 64 81 70

• Glaucoma affects 2% of the population over the age of forty

• Half of those who have glaucoma are unaware of their condition

• Glaucoma is the leading cause of preventable blindness in the UK today

• 95% of the sensory input to the brain required for driving comes from vision

• Glaucoma accounts for 13-14% of the people on the blind register in England and Wales

• Damage caused by glaucoma cannot be recovered

• Glaucoma can be treated effectively and further visual loss prevented in most cases

• Early detection is the key to the control of glaucomatous visual loss
• Everybody should have an eye test at least every 2 years but people who are over the age of 60 and people at higher risk should have an eye test every year

• Detection requires the use of three tests: 
1. Ophthalmoscopy (a visual examination of the optic nerve head using an ophthalmoscope or slit lamp microscope)
2. Tonometery (a measurement of the pressure within the eye – the intraocular pressure)
3. Perimetry (a check of the field of vision for damage caused by glaucoma)
4. Treatment of glaucoma will usually be with eye drops, but may include laser or surgery if necessary

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