Toric contact lenses correct a common eye condition called astigmatism. The American Optometric Association describes astigmatism as a vision problem caused either by an irregular shaped cornea, which is the clear outer layer of the eye, or because the crystalline lens inside the eye is misshapen. The irregularity keeps light from focusing correctly on the the retina and causes blurry vision. Toric contact lenses, which are made from soft or rigid material, correct the way light enters the eye.
Toric Soft Lenses
The most common type of toric lens is a soft contact. The lenses are made from gel-like plastic and are similar to regular soft contact lenses except toric soft lenses contain a a second curve. The additional part of the lens helps direct light to focus correctly on the retina and correct the blurriness of astigmatism.
Unlike regular spherical soft contact lenses, toric lenses must sit a specific way on the eye so the lenses are weighted with a ballast so that they do not rotate.
Rigid Gas Permeable Contact Lenses
Rigid, or RGP, are gas permeable lenses made from a harder material than soft toric lenses. They are smaller, more durable and easier to clean than soft lenses but generally take longer to get used. RGP lenses do not change shape like soft lenses do when the eye blinks. This provides a clearer and crisper vision than soft toric lenses. In addition to correcting astigmatism, gas perm lenses are prescribed for keratoconus and other conditions in which the cornea needs to be reshaped.
Options for Toric Lenses
Soft toric and gas perm lenses are available in several choices or in combinations of options, depending on a person's prescription. Toric soft lenses, which have color options, are prescribed as disposable or frequent replacement. Disposable, soft toric lenses are made to be thrown away after a day, a week or a month, based on the type prescribed. They are then replaced with a new pair.
Both soft toric lenses and gas permeable lenses are made as multifiocal contact lenses, which correct for distance and near vision at the same time in the same way as bifocal eyeglasses.
