My WebMD Sign In, Sign Up

Ask Your Question

WebMD Answers

120 Characters remaining
120 Characters remaining
  • First, try and keep your question as short as possible.
  • Include specific words that will help us identify questions that may already have your answer.
  • If you don't find your answer, you can post your question to WebMD Experts and Contributors.


Posted: | Report This Report Question |

Answers From Experts & Organizations (1)

7,995 Answers
373,970 Helpful Votes

Most of the focusing power in the eye occurs along the front surface of the eye, at the cornea (the clear 'window' in the front of the eyeball), or within the lens, which sits behind the cornea inside the eye. The ideal cornea has a symmetrically curved surface. Astigmatism is caused by a cornea or a lens that is not symmetrical.

The cornea is the transparent window in front of the colored part of the eye. It bends (refracts) light rays to focus the light onto the retina in the back of the eye. When the cornea is oblong shaped (like an oval rather than a round teaspoon), it is not possible for the light rays to be focused at a single point. As a result, people with significant astigmatism may have distorted or blurry vision.

Astigmatism is measured in diopters. More than 1 diopter typically requires correction with glasses or soft contact lenses. 

Astigmatism can run in families and often occurs in combination with other refractive problems such as nearsightedness or farsightedness.

This answer should not be considered medical advice...down arrowThis answer should not be considered medical advice and should not take the place of a doctor’s visit. Please see the bottom of the page for more information or visit our Terms and Conditions.up arrow

| Report This Report Answer
Archived: March 20, 2014

Was this helpful?


Thanks for your feedback.

230 of 248 found this helpful
Read the Original Article: Understanding Astigmatism - the Basics