Astigmatism is a condition that causes blurred vision due either to the irregular shape of the cornea.

Astigmatism is not a vision problem, but a structural problem with the eye. The human eye is usually shaped in a sphere, like a basketball, but with astigmatism, the cornea of the eye is curved instead into an oval shape, more like a rugby ball. Astigmatism causes light to bounce unevenly off the flat and steep curve of the oval shaped eye, thus allowing light to more than one point in the eye. This impairs focusing ability, causing blurred vision.

The specific cause of astigmatism is unknown. It can be hereditary and is usually present from birth. Astigmatism is very common. Most people have some degree of astigmatism. Slight amounts of astigmatism usually don’t affect vision and don’t require treatment. It often occurs together with long-sightedness or short-sightedness. However, larger amounts cause distorted or blurred vision, eye discomfort and headaches.

Astigmatism is easily diagnosed by a standard ophthalmic exam with refraction test. Special tests are not usually required. Children or others who cannot response to questions can have the degree of their vision problem measured by a test that uses reflected light (retinoscopy).

The possible complications of unequal astigmatism may cause Amblyopia (commonly known as Lazy Eye).