In people with the eye disorder astigmatism, the light coming into the eye becomes focused in two places instead of being pinpointed down to a single spot at the back of the eye. This can induce blurry vision, headaches and eye strain. Astigmatism is usually caused by a misshapen cornea but is occasionally due to a misshapen lens of the eye. Astigmatism grows slowly over time and often begins in childhood. According to the website All About Vision, 28 percent of children have some degree of astigmatism, although it remains undiagnosed in many until adulthood.
Regular Astigmatism
In regular astigmatism, the cornea is oblong, shaped like a football, instead of a sphere. The cornea may be steeper at the top and bottom or at the sides, but in all cases the steepest part and flattest part will be at 90 degrees from each other, explains All About Vision. Someone with regular astigmatism will see a single dot as two perpendicular lines instead. Treatment for regular astigmatism tends to be fairly simple. The affected individual will typically receive a prescription for eyeglasses or contact lenses. While in the past, only hard contact lenses could be used to correct astigmatism, a type called soft toric lenses are now available for astigmatism treatment. Refractive surgery, such as laser-assisted in-situ keratomileusis, or Lasik surgery, can also be used, explains MayoClinic.com. Photorefractive keratectomy and laser-assisted subepithelial keratomileusis, or Lasek, are other surgical options for treatment.
Irregular Astigmatism
In irregular astigmatism, the cornea has many bumps and waves that may reflect light unevenly. The result of this misshapen cornea is that the person sees a dot as many random lines instead. Irregular astigmatism can only be corrected using hard contact lenses or refractive surgery, according to the EyeStar Lasik Institute, of Istanbul, Turkey. Eyeglasses will not help a person with irregular astigmatism, the institute explains. Treatment for severe irregular astigmatism may include refractive surgery, but this surgery is generally custom designed for the particular individual, taking into account the specific irregularities of the cornea.
Subtypes
While there are only two true types of astigmatism, regular astigmatism has five subtypes, according to Eyestar Lasik Institute. In simple myopic astigmatism, one eye is nearsighted while the other is normal. Simple hyperopic astigmatism, on the other hand, results in one farsighted eye and one normal eye. In compound myopic astigmatism, both eyes are nearsighted and in compound hyperopic astigmatism, both are farsighted, but in both of these subtypes, one eye may be more affected than the other. Mixed astigmatism occurs when one eye is nearsighted and the other is farsighted.
