Short Sightedness - Myopia
'Normal'
Vision
The front surface of the eye, known as the Cornea, acts as a lens through which light is collected. With good eyesight, the image that you are viewing is normally brought into focus on the back of the eye which is called the retina.
Eyesight difficulties tend to occur when that image is not able to be correctly focused on the retina and your vision becomes blurred.
When you look at something, light from that object passes into the eye
through your cornea then through the lens towards the retina at the back
of the eye. In 'normal' or healthy eyes the lens and cornea focus these
light rays onto a small area of your retina and this enables you to view
objects clearly
However, your vision can sometimes lose clarity which can be due to a
variation in these 'normal' parameters.
These variations are split into two main categories: short and long sightedness.
Short-sightedness
(Myopia)
Myopia, which is the clinical name for short sightedness, is when objects close up are seen in clear focus whilst those at a distance can be blurry or out of focus.
People who have short sighted vision can undertake close up tasks such as reading quite comfortably, but find it not so comfortable to focus on things in the distance such as driving or watching television.
People with short sighted vision sometimes suffer from eyestrain and headaches, especially after long periods of driving or concentrating on TV.
Short
sightedness is caused by an abnormality in the shape of the eyes.
In the case of a 'myopic eye' the shape of the eye being too long from back to front, or cornea or lens being too strong.
This leads to a mismatch between focussing power and
eye length resulting in the light rays from the object not reaching the
retina and the resultant images not being in focus.
Short sightedness is a common condition and is present in about a third
people to varying degrees.
About 5% of people have severe symptoms and are considered 'high myopes'.
The cornea controls up to 80% of the focussing power of the eye.
It is this part of the eye that can be altered through laser eye surgery to alter its refractive properties and thereby reduce the myopia.
Example
of a Short Sight Prescription
| Eye |
Sphere
|
CYL
|
AXIS
|
|---|---|---|---|
|
Right Eye
|
-2.50
|
-0.50
|
120
|
|
Left Eye
|
-2.50
|
-0.25
|
45
|
Laser
Eye Treatment
Laser eye treatment to correct short-sightedness is possible up to -14.00.
If you suffer from Myopia then your glasses will make things look smaller when held out in front of you (a negative power lens is thinner in the middle). Laser eye surgery reduces the thickness of the cornea in the central zone, reducing its focusing power. This allows Images to be brought into correct focus. Laser eye correction treatment for Myopia is very simple and effective.
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