Correcting Astigmatism with Contact Lenses
What is astigmatism?
Astigmatism is the result of a misshaped cornea. Rather than being spherical like a ball, the cornea in people with astigmatism is oblong, shaped more like a football. Because of this shape, light rays can't refract properly against the retina.
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Instead of focusing the rays on one spot, the odd shape causes light to refract in multiple locations on the retina, causing the blurred vision, regardless of distance, that is symptomatic of astigmatism.
Astigmatism for a long time was a vision problem that could not be fully corrected with contact lenses. A case of mild astigmatism could be improved with soft contact lenses, but there weren't options for more severe cases.
Understanding Toric contact lenses.
Toric contact lenses don't look any different than other soft or rigid gas permeable contact lenses, but the development of Toric contact lenses opened up a whole new world of vision for people with astigmatism.
The lenses consist of a number of different curvatures in various meridians or sections on the lens.
Since astigmatism is a problem involving unbalanced meridian sections (due to the odd shape of the cornea) bringing the meridian sections back into balance is what helps produce clear vision.
Because the position of the various curvatures is key to improving the wearer's vision, toric soft contact lenses cannot rotate - they must be held in a certain position in order to be effective. This is accomplished several ways. One way is to add weight to the bottom of the lens by building up or thickening that section. Another way is to make the top part of the lens lighter, by thinning this section.
Rigid gas permeable lenses are another option.
Another solution to correct astigmatism using contact lenses is to use rigid gas permeable lenses. Thy are not as flimsy as soft lenses which enables them to hold their shapes, even after blinking.
While regular gas permeable lenses work effectively at correcting mild to moderate astigmatism, in cases where the astigmatism is severe, it's may be necessary to prescribe gas permeable toric contact lenses.
Toric lenses are custom shaped so that the inside of the lens more closely matches the shape of the astigmatism. Because of the customized fit, toric lenses remain in position and rotation isn't an issue. Toric contact lenses generally cost more than due to the custom fit.
If you work with an ophthalmologist you can trust, he or she will likely first try to prescribe regular contact lenses to treat your astigmatism.
Again, mild and moderate astigmatism can usually be sufficiently corrected with standard contact lenses. A severe astigmatism may resort to toric style contact lenses.
Toric lenses are available as daily wear, extended wear, silicone hydrogel and disposable brands. They even come in an assortment of eye color options!