Long Sightedness - Hyperopia
'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.
Long-sightedness
(Hyperopia)
Hyperopia or long sightedness, is when items which
are near up appear blurred or when reading or other close work is
possible but not comfortable because of fatigue and eyestrain.
However, with long sightedness distant objects are seen as perfectly
clear.
Occasionally Hyperopia can be the cause of headaches.
Most people can get round this blurred effect by straining the muscles within the eye to achieve a sharper and clearer focus. However, over time, this straining of the muscles can tire the eyesight system and headaches will occur.
Hyperopia is caused by a distortion from normal in the shape of the eyes - either the shape of the eye being too short from back to front, or the strength of the lens or cornea being slightly weak.
This causes an in-balance between the focussing power and the length of the eye. This results in the light rays not meeting at the retina and the images not being seen clearly.
The cornea controls up to 80% of the focussing power of the eye and it is this part of the eye that can be altered through laser eye surgery to alter its refractive properties and thereby reduce the hyperopia in the eyes.
Example
of a Long Sight Prescription
| Eye |
Sphere
|
CYL
|
AXIS
|
|---|---|---|---|
| Right Eye |
+2.00
|
-0.50
|
120
|
| Left Eye |
+2.50
|
-0.25
|
45
|
Laser
Eye Treatment
It is possible with Laser Eye Surgery to successfully correct long sightedness of up to +8.00.
Some long sightedness occurs between the ages of 45 to 65 years and is caused by the lens within the eye gradually loses some of its flexibility. This is a normal age related change called presbyopia, or age-related long-sightedness. This prevents the eyes from seeing near objects clearly and therefore reading glasses are needed. Surgeons can reduce your dependency for wearing reading glasses using Monovision correction.
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