Astigmatism simply means that one curve of your cornea is a little different to the other – slightly more egg-shaped rather than a perfect sphere. If you (like most people) have a small amount of astigmatism it probably won’t impact on your choice of contact lens.
However, more than 0.5 of astigmatism can mean that your vision just isn’t as clear with soft contact lenses as it is with your glasses. This is where toric lenses come in. They are more curved in one contour than the other, like the image below.
How do toric contact lenses work?
These lenses have thicker and thinner zones with different curves. They have to be matched exactly to the shape of your cornea just like glasses lenses. With glasses, the frame holds the lens in the correct position to correct your astigmatism. Toric contact lenses are specially weighted and shaped to stay in one position on your eye and not swing around each time you blink. Once you insert the lens, after a few initial blinks the lens settles into the correct position to provide clear vision.
Toric contact lenses are soft contact lenses that are worn each day and replaced either daily, fortnightly or monthly. They are specially shaped and weighted to correct astigmatism. These lenses are removed each night, and either disposed of or cleaned and stored in contact lens solution. They are not worn overnight. Daily disposables are convenient and comfortable, but they don’t always provide adequate vision and it is often necessary to get a custom lens in order to achieve a stable fit that provides consistently good vision.