Astigmatism is a distortion in the front corneal curvature of the eye. Rather than being spherical like a ball, the eye more closely resembles an oval shape grape. Small amounts will cause uncomfortable eyes that fatigue quickly and that could lead to headaches due to trouble focusing from the astigmatism. Higher amounts of astigmatism can cause blurred and distorted vision.
How is Astigmatism Tested?
A common test used to detect astigmatism is referred to as the “Astigmatism Fan”. With this particular examination a patient is presented with Black Radial lines arranged in a half circle and placed behind a white background. The patient views the fan one eye at a time and is queried about colour. If grey is noticed anywhere on the fan, an astigmatism is likely to be present.
The same concept of examination is explored with the “Astigmatism Block Chart”. Square blocks with black lines presented at varying orientations are presented, and if the patient appreciates a grey area that is different astigmatism is suspected.
How Do We Treat Astigmatism?
Not all astigmatism requires treatment. Most people have a small degree of astigmatism, which can be explained as an extension of their myopia or hyperopia. Patients will require astigmatic correction when the degree of astigmatism causes visual blur or when they experience symptoms of eyestrain, fatigue and headache related to trouble focusing due to astigmatism.
Treatment is often with spectacles or contact lenses. Depending on the severity and degree of astigmatism, refractive surgery can also be considered.
Often the discovery and correction of astigmatism is critical in the management of amblyopia (lazy eye).