Astigmatism is a relatively common eye problem, historically corrected primarily by eyeglasses. However, contact lenses now exist which can correct nearly all types of astigmatism, and they may be a better option, depending on your needs and preferences.
There are two types of astigmatism: corneal astigmatism and lenticular astigmatism.
A corneal astigmatism is when the cornea (a clear, round dome-shaped portion of your eye that covers both the iris and pupil) isn’t evenly curved, causing it to refract light incorrectly onto the retina at the back of the eye.
A lenticular astigmatism is when the lens of the eye, which sits just behind the cornea, is misshapen.
In both cases, the result is blurry vision (both with objects close and objects far from away.) More severe cases can also lead to eye strain, chronic headaches, squinting, and poor night vision.
Astigmatism is often inherited, and most people who suffer from it were born with it. However, it can also occur after an eye disease, injury, or surgery.
In most cases, astigmatism is easily treated with corrective lenses. Many people wear glasses for this, which feature special cylindrical prescription lenses that offset the problem. Most of these people just need a single vision lens, though people over the age of 40 are more likely to need bifocal or progressive lenses.
However, contact lenses are an increasingly popular method of treatment for many people who have moderate astigmatism. In fact, there is reason to believe that contact lenses are better at correcting astigmatism than glasses since contacts can provide clear vision with an unobstructed, wider range of view (as a result of them sitting directly on the eyes, while glasses sit in front of the eyes.)
However, it is not all that simple. Hard lenses generally performed better at correcting astigmatism compared with soft lenses, at least in cases where it is more pronounced. However, more recent developments with soft contacts have led to increased efficacy and comfort.
When looking into contact lens options for correcting astigmatism, you are likely to encounter two specific types of lenses: gas permeable lenses and toric lenses.
Toric contact lenses are soft lenses specifically designed to correct astigmatism. They are either made out of a conventional material or a special, breathable silicone hydrogel, and are different from standard soft contacts in two major ways.
First, they have different powers in different meridians of the lens. This is to correct the different amounts of nearsightedness or farsightedness in the eyes which characterize astigmatism.
They also include a special feature that allows the lens to rotate to the proper orientation on the cornea so its various power meridians align correctly with the various meridians of the eye. This operates via a small weight on the edge of the lens that keeps it aligned, even as you blink (which can cause lenses to rotate). This also helps ensure that when you put them on, they start off aligned correctly.
Because no two cases of astigmatism are identical, it may require more than one pair of toric lenses to find the brand and design that is the best for you, in terms of function and comfort. Fitting these lenses is more complicated than fitting regular soft lenses, so they tend to cost more, and the same is true for replacement lenses. Getting an exact fit is extremely important, so there is no way around this.
These days, lenses (in particular soft lenses) for correcting astigmatism are readily available, from various brands and in numerous styles. This includes even daily disposable lenses.
There are toric lenses that are designed to be worn for up to 30 days, including overnight, and bifocal toric lenses that can also correct presbyopia (farsightedness due to age).
Rigid gas permeable lenses (alternatively referred to as RGP of GP contact lenses), are a popular type of contact lenses specifically used for correcting astigmatism.
Being rigid lenses, they will maintain their spherical shape over the eye instead of conforming to the abnormal shape of an eye with astigmatism (which is an issue with soft lenses.)
The properly shaped, uniform front surface of gas permeable lenses effectively takes the place of the misshapen cornea, becoming the primary refracting surface of the eye without needing to control the rotation of the lens (as with toric lenses). For more severe or unusual cases, gas permeable lenses can also include a toric design, but in most cases that is unnecessary.
An additional option are large-diameter gas permeable lenses called scleral lenses. These provide effective astigmatism correction even when there are highly irregular corneal surfaces.
In many cases, people who go with gas permeable contact lenses have markedly sharper vision with them as opposed to with soft toric contact lenses. However, because they are thicker and more rigid, they typically take more time to adapt to, and some people cannot get used to them at all.
Gas permeable lenses also take more time and expertise to fit than soft lenses, and must be custom-made to the parameters prescribed by your eye care professional. So getting fitted with these lenses (and replacing them) costs more than soft lenses.
In some extreme cases, you can use hybrid lenses which have a gas permeable lens in the center for purposes of vision correction with a soft lens skirt surrounding it for comfort and stability.
For additional, or more detailed questions about contact lenses to correct astigmatism, consult with our eyecare optometrist, who specializes in fitting contact lenses for astigmatism. Our doctor will be able to provide a full exam and advise you on whether contact lenses for astigmatism are the best choice for you.
Contact lenses are a great choice for correcting your astigmatism, and there are many options available to ensure both effectiveness and comfort. Contact us today if you have any questions, or wish to schedule an appointment for an eye exam.