Two types of astigmatism
Two kinds of astigmatism are widely known: corneal astigmatism and lenticular astigmatism, both of which can be corrected by eyeglasses, contacts or refractive surgeries. While the former type results from irregular shaped cornea, the latter type is caused by irregular lens shape.
Both adults and children can suffer from astigmatism. Common symptoms of astigmatism include blurry vision, headache, eye strain and distorted distance vision. Eye exams are critical to detect underlying astigmatism on children. The Ohio State University School of Optometry has ever found that 28% out of 2,523 children had astigmatism, which surely affected their school performance. What’s worse, most children are less self-aware about their vision problems.
Most of the astigmatism patients are born with that, which may get worse over time. Eye injuries, improper eye surgeries and keratoconus can also damage the corneal shape. The corneal shape of astigmatism patients is not perfectly spherical. Instead, it likes an oblong football, which causes light rays to focus on two points in the eye back. For regular astigmatism, its two meridians are located 90 degrees apart, so that it is easy to correct. However, irregular astigmatism has meridians that are other than 90 degrees apart, which brings more complexity for correction.
Prescriptions of eyeglasses or contact lenses for astigmatism correction usually have three parts. The first part is designed to provide common visual clarity. For example, convex lenses are used to correct hyperopia. A second part is particularly for astigmatism. And the third part is prescribed to bend certain light rays as a compensation for the cornea’s oval shape.
Nowadays, both rigid gas permeable contacts and soft toric lenses are available for astigmatism patients. Soft toric lenses can provide most comfort for most of people, while RGP contact are more competent for heavy astigmatism. If you can not get enough vision satisfaction from eyeglasses or contacts, refractive surgeries such as LASIK are the best choice.
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