Most people have heard the word “astigmatism.” What does it mean? The word was first coined by an English scientist in 1849. It derives from Greek and best translates as “no spot” or “no point.” To explain this term we first have to talk about how light is focused in the eye. When light strikes a point on an object, the light rays bounce off of it in all directions. As these light rays spread apart or diverge, some of the rays strike your eye. The outside surface of the eye (the cornea) and the crystalline lens inside the eye refocus the light rays into an image of that point on the retina. This is what happens when the light rays are equally focused by a round or spherical eye. Many eyes however, focus light more strongly in one direction than another because the cornea is more curved in one direction. Instead of focusing the point object into an image of a point, it is drawn into a line. That eye has astigmatism (“no point”) and produces image blur.
There are several ways to correct astigmatism. The easiest way is with glasses. A lens corrects astigmatism by being shaped such that it is also curved in one direction more than another in order to compensate for the shape of the eye. Contact lenses also can correct astigmatism. One may use either soft contact lenses called “toric” lenses or rigid gas permeable contacts (hard lenses). Surgical means of correcting contact lenses include laser vision correction, astigmatic keratotomy and implantation of intraocular lenses. People are often under the mistaken idea that laser vision correction cannot correct astigmatism. This is untrue. Laser vision correction is commonly used to treat astigmatism and is very successful.
People undergoing cataract surgery may opt for lens implants that allow them to see both near and far without glasses. If they have astigmatism, this is something that can be treated at the same time as their cataract surgery. This is done either by placing relaxing incisions in the eye or by implanting astigmatism-correcting lens implants inside the eye. The relaxing incisions are very effective and add only a few minutes to the surgery time. There effect is to make the cornea more spherical.
If you are interested in correcting your astigmatism, or any other error in your vision please call us for an appointment.
For more information, please call Helm Vision at 661-259-3937.
