Contact Lens Basics

Astigmatism And Contact Lenses


The symmetrical shape of the cornea and lens of the eye results in clear vision but if they are not symmetrical then occurs astigmatism. In astigmatism, the cornea gets shaped like a football or back of a spoon. This irregular shape causes loss of vision. In astigmatism there is a difference in curvature in different medians of the eye thus resulting in the difference in the power of the eye along each median. Principal meridians are the flattest meridians of an eye which are perpendicular to each other. There are five types of astigmatism based on nearsightedness and farsightedness. These are:

A) Simple myopic astigmatism: In this condition, one meridian is nearsighted and the other is free of nearsighted or farsighted.

B) Compound myopic astigmatism: Although both the meridians are nearsighted. One is more nearsighted than the other.

C) Simple hyperopic astigmatism: One meridian is farsighted and other is free of nearsighted or farsighted.

D) Compound hyperopic astigmatism: Although both meridians are farsighted but one is more farsighted than the other.

E) Mixed astigmatism: In this condition, one meridian is nearsighted and the other is farsighted.

Usually, astigmatism is so mild that it does not require corrective lenses. Some of the symptoms of moderate or severe astigmatism are:

A) Eyestrains
B) Headache
C) Squinting
D) Fatigue
E) Blurred vision at all distances
F) Requirement of holding the reading material close

Astigmatism is being increasingly reported in children than the adults. Unlike adults children are unaware of this condition and it is detected after some time period. Astigmatism can be corrected with the help of spectacles or contact lenses. If your contact lens prescription constitutes of three parts instead of one, it means that your doctor has diagnosed astigmatism in one or both of your eyes. Many people have misconception that only rigid contact lenses can correct astigmatism but now there are several soft lenses like toric lenses which can correct this condition as they have a special correction built in to them which contains a prescription for both, farsightedness and nearsightedness. However, rigid contact lenses are better than the soft lenses in case of severe astigmatism. However, Astigmatism can also be corrected with refractive surgery.