Astigmatism is a common and generally treatable imperfection in the curvature of the eye that causes blurred distance and near vision. 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
How many types of astigmatism are there?
There are two types of astigmatism: corneal and lenticular. These different types of astigmatism can be caused by different factors. Corneal astigmatism is a condition in which the front part of the eye, known as the cornea, is not curved equally. Therefore, when light enters the eye, it does not bend perfectly onto the back of the eye, which results in blurred vision. Lenticular astigmatism is not caused by an irregularly shaped cornea, but by an irregularly shaped lens behind the cornea. In a similar manner to corneal astigmatism, lenticular astigmatism also blurs your vision. Astigmatism, along with its accompanying symptom of blurry vision, causes severe eye strain in advanced cases.
How can astigmatism be corrected?
Astigmatism can sometimes be treated more effectively with contact lenses than glasses mainly because contact lenses sit on the eye whereas glasses are in front of it. Astigmatism can be corrected with either hard contact lenses or soft contact lenses. 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.
What are toric contact lenses?
A soft contact lens, also known as a toric lens, fits similarly to a single vision spherical lens. The difference is that you have to make sure that the toric contact lens is not rotating on your eye since it contains two different powers to correct astigmatism. Toric contact lenses may take longer to settle on your eyes than regular contact lenses. Patients with extremely irregular astigmatism may require scleral lenses, which are hard lenses with a larger diameter. An eye care provider must make sure that the contact lens has good coverage, good centration, good movement and does not rotate on your eye.
What are gas permeable lenses?
Rigid gas permeable 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.) 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.
What are the best glasses for astigmatism
Spectacles for astigmatism have special cylindrical lenses to counteract the way light passes through the cornea. While we generally recommend contact lenses for patients with astigmatism, there are also spectacle lens designs that correct for astigmatism.
As a general rule patients with astigmatism are going to have better success with the following tips.
- Choose high index lenses
- Wraparound or curved frames may bend the light, so best to stick with flatter frames
- Anti reflective lens coatings are generally recommended for astigmatism in order to reduce the amount of light entering the eye
- Always keep the lenses of your glasses clean
What should you do if you have astigmatism?
If you have astigmatism you should schedule an appointment with an optometrist that specializes in contact lenses. Because contact lenses provide the best correction for astigmatic patients, it is important to discuss the different options that may be available in order to fully understand the pro’s and con’s of each type of contact lens.
