Eye Health Matters > Vision Correction-Astigmatism

Astigmatism is an uneven surface of the cornea or lens, causing blurred or distorted vision - such as letters or shapes appearing to be compressed, stretched, or tilted. It is treated with corrective lenses or surgery.

Most commonly, astigmatism occurs because the cornea is oval or egg-shaped instead of round. Light entering the astigmatic eye disperses instead of focusing to a single point on the retina.

Very few people have perfect vision and most have some degree of astigmatism, which is usually present at birth and is believed to be hereditary. It can also result from injury or conditions such as keratoconus, pterygium, or chalazion.

Astigmatism tends to occur with other refractive disorders. Half of those with myopia (nearsightedness) are also astigmatic.

Symptoms

The most common symptom is blurred vision in both near and distant vision. Mild cases may have blurred vision only at certain distances, or see fine but experience headaches or eye strain (from squinting). If you have astigmatism, you may see better in some directions than others (vertically, horizontally or diagonally) or recognize some letters or shapes more easily than others (O versus X).

Although we are usually born with astigmatism, it is often not diagnosed until a child begins to read. Other symptoms can include:

• The need to squint
  
• Headaches
  
• Eyestrain
  
• Eye fatigue
  

Astigmatism cannot be prevented. However, your degree of astigmatism can increase with age, and regular eye exams can determine the need for increased strength of corrective lenses. If your astigmatism seems to be rapidly getting worse, you may be experiencing the onset of a more serious eye disease such as keratoconus, in which the center of the cornea thins and develops a cone-shaped bulge that blurs and distorts vision.

Parents and those who work with children should be aware that astigmatism could contribute to poor performance in school. Routine eye tests conducted in schools may not detect astigmatism, so regular exams by a qualified eye doctor are recommended. Astigmatism can be corrected with spectacle lenses, contact lenses, and laser eye surgery.