Astigmatism is a refractive error – meaning that the light that is coming into the eye is not focused perfectly on the “film” in back of the eye (called the retina – which is a layer of nerve tissue). The retina is much like a movie screen or the film in your camera – the image must be focused PERFECTLY on the retina for the eye to see clearly. If the image is focused in front of the retina or behind the retina – much like a movie screen or camera film – the image will be blurry. This unfocused image is sent by the retina to the brain – where it is perceived as blurry, cloudy or distorted vision.
Astigmatism is a refractive error caused when the front surface of the eye (the cornea) or the lens (which is located inside the eye behind the colored part of the eye – called the iris) is irregularly shaped and oblong – much like a football. This irregular shape causes the light to be focused on 2 seperate points – either in front of or behind the retina. This causes distortion of the vision and blur at all distances. So objects at a distance and also nearby are blurry and/or distorted. The higher the degree of astigmatism – the more distortion and blur you will have.
Several methods can focus the light perfectly on the retina for you. Glasses, contact lenses (called astigmatic or toric contacts) or laser vision correction are aids that are available to help focus the light and images on the retina – which will get you to see clearly again!
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Visionary Eyecare's Blog: "The Eye Journal" 