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Vision - short sightedness (myopia)

vision; sight; short-sighted; short-sightedness; short; near; near-sightedness; myopia; glasses; contact; lenses; lens; eye; retina; cornea;

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.

More information

There is more information about short-sightedness in children on this website:

Raising Children Network  
 
http://raisingchildren.net.au/

 

Contents of this topic

normal vision
        Normal vision

short sightedness
        Short-sightedness

Causes of myopia

The causes of myopia appear to be a combination of:

  • inheritance - it is more common if a young person has family members who 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 child 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.

How can you tell if your child is 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 board at school
  • screwing up eyes to see distant objects
  • poor posture while reading
  • lack of interest in playing ball games.

Testing for short-sightedness

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.

Correcting short-sightedness

  • For children and teenagers, the image can be made clear by the use of glasses (with 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

It appears that if a young person will not wear his glasses, this does not cause the eyes to become weaker.

  • Many young people will not wear their glasses until they are convinced themselves that they need them.
  • It is important to wear the glasses when on the road (eg. for driving), but if they refuse to wear them at school, it probably will not affect how well they do academically.

References and further reading

Better Health Channel (Victoria)

Medline Plus (USA) 
http://www.nlm.nih.gov/medlineplus/ 

Optometrists Association Australia
http://www.optometrists.asn.au/

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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 Parent Helpline on 1300 364 100 (local call cost from anywhere in South Australia).

This topic may use 'he' and 'she' in turn - please change to suit your child's sex.

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