An eye with normal vision has a cornea with a perfectly round shape, while an astigmatic cornea has the shape of a rugby ball. Toric contact lenses help divert light rays entering the eye, so that they form a sharp image on the retina. A toric contact lens combines cylindrical and spherical features, which means that it has two powers, one to correct astigmatism and one for near- or farsightedness.
Because of its two different powers, a toric contact lens must stay in place regardless of the eye’s movement. Because of this, it has a definite up and down, with a thicker, heavier bottom. The weight, as well as the blink of the eye, keeps the thicker part of the lens pointing downwards.
Like most other contact lenses, toric lenses are available as soft or rigid gas-permeable (RGP) lenses and for extended or daily wear. Those wishing to enhance their eye colour can get tinted toric lenses in a variety of colours. While soft toric lenses are more popular than RGP toric lenses, mainly due to their comfort and the fact that they are a lot easier to get used to, rigid gas-permeables have the advantage of retaining their shape on the cornea better and hence providing slightly sharper vision.
Rigid gas-permeables are very durable and cost effective, but some people find them hard to get used to. They are less suitable for sports activities than soft lenses, as soft contacts cling to the eye and are unlikely to ever fall out. People with only a mild degree of astigmatism, however, may not need toric lenses, in which case RGP contact lenses are often more suitable thanks to their ability to conform the cornea.
It is quite common to have astigmatism in one eye only, using one toric lens and one ordinary, spherical contact lens. Wearers requiring correction for both reading and distance vision in addition to astigmatism will be prescribed multifocal toric lenses.
Astigmatism is a hereditary condition, but young children rarely complain until they start to struggle with school work, as they often don’t realise that there is something wrong with their eye sight before that. The condition is not at all dangerous, though, and most people can very easily find a vision correction method which suits them perfectly.
Toric contact lenses are more expensive to manufacture than other lenses, and slightly more complicated to fit. This means that they are also more expensive to buy. Yet, many wearers feel that toric lenses are the best available vision correction option around as they in most cases provide crisp, comfortable, almost perfect vision.