Astigmatism

Astigmatism, unlike normal vision, occurs when the cornea is shaped like a football (more curved in one direction than the other) and often occurs in combination with myopia (nearsightedness) and hyperopia (farsightedness). This causes light to focus in more than one point on the retina, resulting in blurry and distorted vision.

Light focuses in more than one point on the
retina causing blurry and distorted vision at all distances
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Symptoms of astigmatism:

Blurry, distorted vision at all distances

Causes of astigmatism:

Heredity
Lid swellings such as chalazia
Corneal scars
Keratoconus

Diagnosing astigmatism:

Your eye doctor can conduct a refractive evaluation to determine whether your eyes focus light rays exactly on the retina at distance and near. A visual acuity test will determine your ability to see sharply and clearly at all distances. Your eye doctor will also check your eye coordination and muscle control, as well as your eyes' ability to change focus. All of these are important factors in how your eyes see.

Treatment of astigmatism:

Glasses and contact lenses are used by many for the temporary treatment of astigmatism. However, there are a number of vision correction procedures that can surgically reduce or eliminate astigmatism.

Other types of refractive errors include: nearsightedness, farsightedness and presbyopia.