Astigmatism

Astigmatism is a vision problem that causes blurred or ‘distorted’ vision. It is quite common and often occurs together with myopia or hyperopia in the same eye.

For clear vision, the cornea and the lens must properly focus (or refract) light to one point on the retina. Normally, the cornea is smooth and equally curved in all directions. However, with astigmatism, the cornea is usually 'warped', meaning it curves more in one direction. Thus, the irregular shape prevents light from focusing properly on the back of the eye, the retina. Instead, the light is focused on two points at the back of the eye, rather than just one. As a result, a person's vision may be blurred at all distances, as objects appear somewhat indistinct and slanted.

Astigmatism is often present from birth, as some people are born with warped corneas. However, astigmatism can also be due to pressure of the eyelids on the cornea, corneal scars, or keratoconus, to name but a few. Of important note is that astigmatism does have a hereditary component, i.e. if one or more parents have astigmatism there is a greater risk that their children will have it as well.

The most common symptoms of astigmatism are headaches and fatigue. Squinting, eye discomfort and irritation are also frequent. Astigmatism can also cause images to appear doubled, particularly at night. As well, patients tend to have inconsistent difficulty focusing on various objects, including printed words and lines at all distances.

Treatment

An optometrist or ophthalmologist can easily diagnose astigmatism. Once diagnosed, the treatment for astigmatism depends on several factors, including the patient's age, activities, and occupation. Glasses and contact lenses, which allow the light to be focused properly on the retina, are the most common method used to correct most astigmatism. However, many patients with astigmatism can achieve better vision with specifically designed toric contact lenses. Laser surgery is another option, which obviates the need for glasses and contact lenses; however, it can only be used to correct low to moderate astigmatism.