Many people think that if they have an astigmatism, they have a special eye condition. However, astigmatism is a very common vision problem. An astigmatism is a refractive error in vision, just like being farsighted or nearsighted. It is caused by having an eye which is not shaped round or spherical, but more like an egg or football. This causes light to bend in different directions and not focus on the back of the eye properly. A recommendation for vision correction will be made, if you are found to have an astigmatism during your vision exam. Astigmatism is normally corrected with eyeglasses or contact lenses. Some patients may even get their astigmatism corrected with laser eye surgery.
Glasses and contact lenses can correct most amounts of astigmatism. When small amounts of astigmatism are present, often correction with eyeglasses or contacts may not even be required.
In eyeglasses, astigmatism correction is ground into the lens. A lens with astigmatism correction will have different amounts of curvature in different meridiens of the lens. The difference in curvature between the front and back surface of the lens has light bending properties. This causes light to move in different directions in order to focus on the retina (back of the eye), resulting in clear vision. After reading your prescription, your optician who is making your new glasses will interpret the numbers (cylinder & axis) and determine where the astigmatism aligns within your eyes, and which direction your eyeglass lenses should be rotated in order for you to see clearly.
Just like an eyeglass lens, contact lenses can also correct astigmatism. With most contact lenses, astigmatism can’t be corrected for as finitely as it can with eyeglasses lenses. Therefor, with larger amounts of astigmatism, vision in contact lenses may not be as clear as eyeglasses. When wearing contacts, how the lenses fit and move plays a key role in how clear vision is. Typically, larger amounts of astigmatism are not correctable in soft contact lenses, unless specially manufactured soft contacts are ordered. Hard contact lenses, do a better job at correcting larger amounts of astigmatism, and are often used in the treatment of correcting astigmatism caused by the eye disease keratoconus.
Laser Eye Surgery
Another method to correct astigmatism is by undergoing refractive surgery, often called laser eye surgery. The surgeon will change the shape of the cornea to correct for the deviation of light (astigmatism) through the use of lasers. Not everyone is a candidate for laser eye surgery. Surgery can also come with unwanted side effects that can be both short and long term.
If you have questions regarding astigmatism, ask your optometrist at your next eye examination appointment.
Article Written By: Trina Vanaalst