Astigmatism
Astigmatism is a common eye defect which is characterized by the blurred vision due to the inability of the optic to focus on point object. If the curve of the cornea is too large, Astigmatism occurs. The vision id blurred because light rays coming through cornea and lens are not focused on one sharp retina point. Thus, it is much more complicated than the myopia and hypermetropia.
Generally, there are two main types of this disease, namely irregular and more common irregular. Irregular Astigmatism can be cured by lenses, while regular one can be corrected by eyeglasses and toric lenses.
Causes :
Astigmatism is usually present at the birth. But the situation may compelled by following reasons.
1- Damaged corneal surface.
2-Injury or scar to the eye.
3- Constant interference of large objects in the cornea.
4- Premature birth, as cornea doesn’t get enough time to develop fully.
5- Down’s syndrome. About 1 from 5 suffering form it is supposed to have Astigmatism.
6- Keratoconus, a degenerative disorder of the eye where the cornea gradually thins and changes to a more conical shape, can also cause astigmatism.
Symptoms :
1-Blurred or distorted vision at all distances.
2-Photophobia - sensitivity to light.
3- Headache.
4- Excessive squinting.
5- The person is constantly closing his/her eyes.
6- Fatigue.
7- Asthenopia.
8- Eye strain - occurs more often when the eye has to focus for long periods, as in reading from paper or a computer monitor.
9- Difficulty in seeing contrast colors.
10- Distorted or double vision.