Vision - short sightedness
vision; sight; short-sighted; short-sightedness; short; near; near-sightedness; myopia; glasses; contact; lenses; lens; retina; cornea; eyes;
Myopia is commonly known as short-sightedness or near-sightedness. It means that the eye is unable to focus the light from objects that are far away, making them seem blurry.
Light coming into a normal eye is focussed onto the retina at the back of the eye.
- The light is bent by the cornea (the clear part of the front of the eye) and the lens inside the eye.
- If the image is focussed on the retina, we see a clear image.
- When a person has myopia, the eye is too long and the image is focussed in front of the retina, so it appears blurry.
The causes of myopia appear to be a combination of:
- inheritance - it is more common if a young person's family members are short-sighted
- environment - it is more common if the person has spent a lot of time focussing on near objects as a child, such as reading or watching a computer screen.
Myopia usually starts to develop when a person is between about the ages of 8 and 14 years, and may get worse until the person is about 20 years old. Up to about 30% of young people in Australia around the age of 20 years are short-sighted.
can you tell if you are short-sighted?
A full vision test by an ophthalmologist or optometrist is needed to be sure what the eye problems are, but some signs of myopia are:
- difficulty reading the blackboard at school
- screwing up eyes to see distant objects
- poor posture while reading
- difficulty playing ball games.
Myopia is usually diagnosed by reading a standard chart, such as a Snellen chart, from a distance of 3 or 6 metres. These charts have large letters at the top and smaller letters below.
- If a person can read all of the letters clearly, this is called 6/6 vision.
- If the bottom lines are fuzzy, but the person can read a higher (larger) line, their vision may be 6/12 or 6/18, or worse (6/12 means that the person can read a line of letters at 6 metres that a person with normal vision can read at 12 metres).
Your optometrist or ophthalmologist will also check other aspects of eye health and vision when checking for myopia.
It is suggested that all students should have their vision checked when they start school, when they move to secondary school, or if they are having any problems seeing clearly. More frequent checks are a good idea if anyone in the family is short-sighted or has other vision problems.
- For children and teenagers, the image can be made clear by the use of spectacles ('specs') which have a concave lens or contact lenses.
- For adults, surgery on the cornea may be useful. This is not done on younger people whose eyes have not fully developed.
Wearing glasses if they are needed will improve your vision, but it appears that if you do not wear your glasses this does not cause your eyes to become weaker.
- It is important to wear the glasses when on the road (eg. for driving), but if you refuse to wear them at school, it probably will not affect how well you do academically, although you may have to sit close to the board to see what is written clearly.
BUPA Health 'Myopia (short-sightedness)'
Optometrists Association Australia 'Myopia'
The information on this site should not be used as an alternative to professional care. If you have a particular problem, see a doctor, or ring the Youth Healthline on 1300 13 17 19 (local call cost from anywhere in South Australia).