Astigmatism is a kind of refractive error which is caused by irregularities in shape of cornea of a person. In such condition, your eye will fail to focus light equally on your retina and as a result, you will have distorted or blurred vision.
It can either be present right from the birth, or may develop slowly in their life. Astigmatism is certain eye condition that normally occurs with myopia or hyperopia and is easily diagnosed with simple eye test.
Astigmatism is just a refractive error and not any eye disease. You search online for any eye doctor near me who will be able to tell whether you have the problem.
Due to astigmatism usually the person will have blurred vision or distorted a little extent at all distances. Few of its symptoms can be –
- Eye strain
- Eye irritation
What causes astigmatism?
Usually, astigmatism is caused due to irregularly shaped cornea. If the cornea is having shape like egg instead of symmetrically round shape with one meridian significantly more curved as compared to the meridian perpendicularly to it.
The flattest and steepest meridians of your eye with astigmatism will be called principal meridians. In few cases, astigmatism will be caused by distortion of lens shape inside your eye which is known as lenticular astigmatism.
It is important that you must schedule your child’s eye exam to avoid any vision problems in their school due to uncorrected astigmatism.
Three kinds of astigmatism
Astigmatism can be of three primary types:
- Myopic astigmatism
Either one or both the principal meridians of your eye are nearsighted even if in differing degrees.
- Hyperopic astigmatism
Either one or both the principal meridians will be farsighted.
- Mixed astigmatism
One principal meridian may be nearsighted, and other is farsighted.
Also, astigmatism can be classified as a regular or irregular. For regular astigmatism, principal meridians are at 90ᵒ. In case of irregular astigmatism, principal meridians may not be at 90ᵒ or perpendicular.
Most of the astigmatism will be regular corneal astigmatism, that gives front surface of eye oval shape.
Sometime irregular astigmatism may be due to eye injury which has triggered scarring on cornea, from some types of either eye surgery or any keratoconus, certain disease which causes gradual thinning of cornea.
During routine eye exam, any astigmatism can be detected by using same instruments or techniques used for detecting nearsightedness and farsightedness.
Also, your eye doctor will be able to estimate astigmatism by throwing a shining light into the eye while introducing a series of lenses manually between light and the eye.