Astigmatism:
It is a common eye problem that causes blurry or blurred vision due to an irregular shape of the cornea (the clear front covering of the eye), often occurring with other vision conditions such as nearsightedness and farsightedness.
Causes:
In a normal eye, the cornea and lens are regular in shape, as this helps focus light on the retina at the back of the eye. In the case of astigmatism, the cornea or lens is irregular in shape, causing the light not to be refracted properly (refractive error). Doctors do not know the causes for the difference in the shape of the cornea or lens from one person to another, but the possibility of infection with it is hereditary, or after a disease or injury in the eye or surgery therein. It can also happen due to a relatively rare condition called keratoconus where the cornea becomes thinner gradually and in a conical shape.
Symptoms:
- Blurry vision or areas of distorted vision at any distance.
- Eyestrain
- Headache
- Squinting to try to see clearly
- Eye discomfort
These symptoms are not necessarily evidence of astigmatism, so an eye examination should be done to find out the cause of the symptoms.
Diagnosis:
The ophthalmologist will test your vision by reading the letters on the eye chart, which will determine the clarity of vision at certain distances. The doctor may also use several devices during the examination:
- Phoropter where several lenses are placed in front of the eye to measure which of these lenses gives clearer vision.
- Autorefractive device to identify and measure astigmatism or other refractive errors.
- Corneal curve scale.
Treatment:
Mild to moderate astigmatism can usually be corrected with glasses or contact lenses. Glasses or lenses correct astigmatism by compensating for uneven curvatures in the cornea and lens, or by performing refractive surgery (LASIK), where a laser reshapes the cornea to adjust how light travels, through the most appropriate correction that fits each person's vision needs.
Prevention:
There is no way to prevent astigmatism, so it is important to have regular eye exams for children and adults.