Eye conditions
With normal undistorted vision, the cornea should be smooth and equally curved in all directions. When astigmatism is present, the cornea is warped and curves more in one direction than the other.
Normally, light enters the eye and is focused precisely on the retina. With Astigmatism, the warped cornea causes the light rays to bend improperly. They are not refracted equally in all directions and one focus point on the retina is not attained. Some light rays are not focused on the retina but are focused in front of or behind the retina. The result of multiple focal points is distorted vision. Objects appear somewhat indistinct and slanted. Vision with Astigmatism can be compared to what one sees when looking through a glass bottle, with images appearing too tall, too thin, too wide, or blurred.
What causes astigmatism?
Astigmatism is most often caused by a defect in the curvature of the cornea but may also occur from an unequal bending of light by the lens inside the eye. Astigmatism is usually inherited and may be present at birth. Astigmatism can occur in conjunction with nearsightedness or farsightedness and usually remains unchanged through life.
What are the symptoms?
Common symptoms include:
- Blurred and distorted vision
- Headaches
- Eye strain
Astigmatism is diagnosed with a routine eye examination. A visual acuity test is performed to determine the focusing power of the eye at different distances. A process called refraction is used to measure the refractive error of the eye and determine the prescription for corrective lenses.
Is there a cure for astigmatism?
A small amount of astigmatism is common and does not need correction. However, in cases where the problem is more severe, glasses and contact lenses are used to correct vision. To correct astigmatism, glasses or contact lenses are ground to neutralise the defective curvature of the cornea. Hard or gas permeable contact lenses generally improve astigmatism better than soft contact lenses.
Astigmatism can also be corrected with refractive surgery. Radial keratotomy, corneal transplantation and laser surgery are procedures used to correct the path of light as it enters the eye. The cornea is reshaped to allow light to focus properly on the retina. With refractive surgery, the eye regains its proper focusing ability and astigmatism is corrected.
If you are experiencing blurred or distorted vision or other eye problems, you should arrange an eye exam.