What is Myopia?
Myopia is what most people call short-sightedness. Short-sighted people do not see distant objects clearly. The eye’s lens and cornea normally focus light into an image on the retina. In a myopic eye the light is focused in front of the retina and so the image is blurred.
Does a short-sighted person see close objects more clearly than a person with normal vision?
No. Short-sighted people see close objects equally as well or often slightly worse. When their myopia is corrected, they see objects equally as well.
How can I tell if I am shortsighted?
Shortsighted people have difficulty in seeing distant objects clearly. They find it hard to read road signs and scoreboards. Recognising people in the distance and playing ball games also may be a problem for many short-sighted people. Often a person will not realise that they cannot see clearly but an eye examination by an optometrist will reveal the problem.
How can I tell if my child is shortsighted?
A complete eye test is the only sure way of determining whether your child’s vision is normal. Some clues to myopia in a child are:
- Squinting eyes to see distant objects.
- Difficulty in reading the blackboard at school.
- Poor posture while reading.
- Lack of interest in playing outdoor games.
What causes Myopia?
Myopia is caused by a mismatch between the power of the optical components of the eye and the length of the eye (the ‘axial length’). Either the power is too high, or the length is too long, or both. Usually the cornea (the front surface of the eye) is curved more steeply than average, increasing its optical power. The exact causes of the mismatch between power and axial length are unknown. There is some genetic influence (if your parents are short-sighted, you have a greater chance of being short-sighted yourself), and there is some evidence for environmental factors, such as excessive amounts of near work, having some influence.
Can Myopia be cured?
No, but properly prescribed spectacles or contact lenses will enable the person to see clearly. The lenses diverge incoming light rays, so that they will be properly focused on the retina. There are also a number of techniques available for re-shaping the cornea (the front surface of the eye), in order to reduce its power and thus correct the myopia. One technique (known as orthokeratology or ‘Ortho-K’) uses rigid contact lenses to change the shape of the cornea. Other techniques use laser surgery to remove tissue from the cornea, leaving it with a flatter surface.
Can Myopia be prevented?
There is no certain prevention for myopia. However, in some cases, treatment can be prescribed to stop or slow its progression.
How common is Myopia?
It is a very common condition. With approximately 15% of the population being short-sighted. Usually myopia starts to develop in teenage years and may get worse in early adulthood.
Can Myopia cause other problems?
High levels of myopia can cause other, more serious problems. People with high levels of myopia often have very large, elongated eyes, and their retinas may be stretched and thinner than normal. This increases the risk of the retina developing holes and tears and the risk of retinal detachments. If you are myopic you should have regular eye examinations, and talk to your optometrist about the potential for problems.