Astigmastism is the correct spelling. Astigmatism is a condition that can impact both farsighted and nearsighted people and is caused by an irregular shaped cornea (corneal astigmatism). Astigmatism can also result from an irregularly shaped lens behind the cornea and is known as a lenticular astigmatism. Astigmatism can be corrected with contact lenses, lasik or with eyeglasses.
Symptoms of astigmatism usually included some degree of blurred vision. When left uncorrected, astigmatism can result in eye strain, headaches and distorted vision at all distances; near, far and in between.
Both young and old can be impacted by astigmatism, as it is a genetic trait and people are born with it. Children more likely than adults are less likely to speak up about blurred vision, so without an eye exam, which eye doctors recommend at least once a year, the condition may go unnoticed. Doctors estimate that at least 28 percent of children are born with astigmatism.
If left untreated, vision problems resulting from astigmatic conditions can exacerbate over time.
What causes astigmatism is a football-shaped cornea, rather than one shaped like a baseball, which is the cornea’s normal shape. In most cases of astigmatism, the oval shape of the eye directs light toward two points in the back of the eye--instead of just one--as the cornea has both a steeper curve and a flatter one.
Corneal astigmatism is typically easy to correct, while lenticular astigmatism is more complicated depending on the extent of the irregularity.
Astigmatism can also result from corneal scarring or inflammation caused by an eye injury, certain eye surgeries and a condition known as keratoconus, or gradual thinning of the cornea.
Astigmatism is typically easy to correct with eyeglasses or contact lenses, depending on the degree of corneal curvature.
Astigmatism and Contact Lenses
All too many people think that contact lenses are not for astigmatism or that just gas permeable contacts (GPs, RGPs ) can correct astigmatic conditions. Not true. Soft toric contact lenses are more than suitable for correcting astigmatism and for many even more effective than eyeglasses. Contact lenses sit right on the eye and are not subject to the distance between the surface of the cornea and eyeglass lenses—which can cause further refraction of light.
For persons with serious astigmatism, gas permeable lenses or eyeglasses are usually the best choice. Your eye care professional or eye doctor can advise you here.
For people with astigmatism, there will be three numbers in your prescription. The general form for writing these numbers is S x C x Axis.
The S refers to the "spherical" portion of the prescription, which is the degree of nearsightedness or farsightedness:
A plus sign in front of the number means you are farsighted and a minus sign means you are nearsighted. These numbers represent diopters, the unit used to measure the correction, or focusing power of the lens your eye requires. Diopter is often abbreviated "D."
For example, if your prescription says -1.00, you have one diopter of nearsightedness. This is a fairly mild amount of nearsightedness. If you are -4.25, that means you have 4 and 1/4 diopters of nearsightedness. This is more nearsighted than -1.00, and requires stronger (thicker) lenses. Similarly, +1.00 would be a small amount of farsightedness and +5 would be more.
The C refers to the "cylinder" or astigmatism, and can be a negative or a positive number. It measures in diopters the degree of astigmatism that you have. The bigger this number, the more astigmatism you have.
The Axis is a number anywhere between 0 and 180 degrees. It reveals the orientation of the astigmatism. It’s not enough to specify how much astigmatism there is; you have to know where the difference in curvature is taking place.
Here are two examples of what an astigmastism prescription could look like:
-2.00 +1.50 x 180
+3.50 +3.00 x 45
The first prescription means that the person has 2 diopters of nearsightedness with 1.5 diopters of astigmatism and an axis of 180 degrees.
The second prescription means that the person has 3.5 diopters of farsightedness, 3 diopters of astigmatism and an axis of 45 degrees.*
*Statements contained herein have not been reviewed by the FDA (Food and Drug Administration). Yourlens.com does not provide medical advice. User assumes all liability for content. Talk to your licensed eye care professional or eye doctor regarding vision correction, eye or vision disorders, eye discomfort, contact lens types and materials and for general information on eye care products and eye health.