Refractive Errors of the Eye

What Is a Refractive Error and How Is It Corrected?

The cornea and the lens of the eye bend incoming light and focus it on the retina. When this system is out of balance, the image is blurred. Myopia, hyperopia, astigmatism and presbyopia can occur alone or together.

All of them can be corrected with glasses, contact lenses, excimer laser or refractive lens implants. The method is chosen together, based on age, occupation, the type of error and the structure of the eye.

Short-Sightedness (Myopia)

Distance vision is blurred, near vision is clear. It results from the eye bending light too strongly or from the eyeball being too long.

Lots of close work, long screen time and little time outdoors can increase the risk of myopia in children.

Long-Sightedness (Hyperopia)

Most babies are born long-sighted, and this lessens as they grow; usually no treatment is needed. If it is high, or there is a clear difference between the eyes, it should be treated. In school-age children these signs may suggest hyperopia:

• Reluctance to study, tiring quickly
• Skipping lines when reading
• Red eyes or tics

Astigmatism and Presbyopia

• Astigmatism: light rays do not meet at a single point. It is usually due to the shape of the cornea or lens and is particularly bothersome at a screen and when driving at night. It usually changes little; if it does change, other eye conditions should be ruled out.
• Presbyopia: from around 40, the eye's natural lens loses its flexibility and near vision becomes difficult. The reading prescription increases until about 55.