Astigmatism is a common and usually minor condition of the eye that causes blurred or distorted vision.
Astigmatism is usually diagnosed after a routine eye test, which often involves testing your ability to focus your eyes.
People who have astigmatism experience blurred or distorted vision at all distances. Astigmatism occurs when light entering the eye comes into focus at multiple points, either in front of or behind the retina, instead of precisely on the retina. This can be caused by a cornea that is irregularly shaped, and differs from the rounded shape of a normal cornea. Sometimes it can be caused by an irregularly shaped lens inside the eye. People with mild astigmatism can experience slightly blurred or distorted vision at all distances, but people with severe astigmatism can have vision affected so much, that it prevents them from performing their daily activities.
Astigmatism can make a multitude of tasks more difficult – from close work like reading, to distance vision tasks like driving or watching television. Because of this, many people with astigmatism suffer sore or tired eyes from over-straining them. Headaches are also a common symptom of astigmatism.
Causes of Astigmatism
Astigmatism is a refractive error caused by an imperfection in the eye – usually in the cornea (the clear front ‘window’ of the eye), but sometimes in the lens. The imperfection changes the way your eye focuses the light rays that pass into it. This can happen when:
- The cornea is an oval ‘rugby ball shape’, rather than a round ‘soccer ball shape’
- The lens is an oval ‘rugby ball shape’, rather than a round ‘soccer ball shape’
When either of these imperfections occur, it causes the light that enters your eye to focus in two places, instead of one. This makes objects at all distances look blurry.
Astigmatism, is thought to be an inherited condition, so you’re more likely to be astigmatic if one or both of your parents has the condition. Astigmatism can also occur as a result of an eye injury that causes scarring on the cornea, and may come about as a result of the eye condition keratoconus too.
Astigmatism can be diagnosed easily by your eye care professional. Treatments for astigmatism are designed to change the way that light rays are bent when they enter the eye so that they come into a point of focus precisely on the retina.
When astigmatism causes objects to appear blurred or distorted, treatments can restore clear vision, making daily activities much easier.
These treatments may include prescription eyeglasses or contact lenses that compensate for the eye’s inability to focus.
Refractive errors like astigmatism were traditionally corrected with glasses and contacts. In the case of astigmatism, and particularly severe astigmatism, there used to be no other option, as laser eye surgery was generally unsuitable.
Another treatment option is refractive surgery, where the cornea is reshaped to change the way it bends entering light rays. Astigmatism can also be treated by implanting a prescription lens inside the eye where it works with the rest of the eye’s natural focusing system to refocus light rays precisely on the retina.
However, thanks to the advanced laser eye surgery at Exeter Eye called iLASIK, many people with astigmatism can now enjoy permanent vision correction and freedom from glasses and contacts. If you are not suitable for Laser vision correction, another option may be refractive cataract surgery with a toric lens (which cancels out the astigmatism in the cornea) or a Symfony toric lens.