Have you been told you have ‘astigmatism’? Here are the top FAQs asked about this common refractive error.
1. What is astigmatism?
Astigmatism is a common type of refractive error that causes blurred vision, usually at all distances.
Astigmatism occurs when the curvature of the cornea, the clear dome at the front of the eye, is not perfectly spherical in shape, rather more oval.
Eye doctors will often explain astigmatism as the front of the eye being more oval-shaped like a football, as compared to a spherical soccer ball.
The misshapen cornea results in two different points for the light to be focused on— leading to blurry vision.
2. What are signs of astigmatism?
The symptoms of astigmatism can be subtle, often going undetected until a comprehensive eye exam is conducted.
The most common symptoms of astigmatism include:
- Distorted vision
- Blurred vision
- Eyestrain
- Headaches
- Fatigue
3. How common is astigmatism?
Astigmatism is a common refractive error, occurring in about 1 in 3 of all people.
Astigmatism is often present at birth but it can also develop over time, and most often occurs with myopia (nearsightedness) or hyperopia (farsightedness).
The rate of astigmatism significantly increases from 14.3% in the under 15-year-old age group to 67.2% in the age group of over 65-years old.
4. What’s the difference between astigmatism, myopia and hyperopia?
All three of these refractive errors cause blurred or distorted vision, but they differ in their underlying causes, which are related to the shape of the cornea and length of the eye.
Astigmatism occurs as a result of a non-spherical cornea.
Myopia occurs when the cornea focusing power is too high, or the length of the eye being too large – both cause the light entering the eye to be focused in front of the retina, instead of directly on it.
Hyperopia occurs when the corneal power is too weak, or the length of the eye being too small – both cause the light entering the eye to be focused behind the retina, instead of directly on it.
If you notice blurry vision, schedule an appointment with an eye doctor near you to learn more about astigmatism.
SEE RELATED: Astigmatism – Is It Serious?
5. How is astigmatism corrected?
Mild to moderate cases of astigmatism are typically corrected with prescription glasses or toric contact lenses.
Low levels of astigmatism, such as up to -1.00D, can often be corrected with spherical contact lenses.
Toric contact lenses are specially designed to correct the higher level of astigmatism. Toric lenses are available in both soft and hard contact lenses, depending on the amount of the presenting astigmatism.
For higher levels of astigmatism or irregular astigmatism, hard RGP lenses or scleral lenses are generally recommended.
Refractive laser surgery, such as LASIK or PRK, are procedures that change the shape of the cornea. These procedures may be recommended for patients over the age of 20, if eyewear is insufficient in treating their astigmatism or if they simply prefer not to wear eyeglasses or contact lenses.
Although laser surgery is safe and effective, there are risks and side effects, such as dry eye and distorted vision.
6. Why can’t I wear standard soft contact lenses with high astigmatism?
Standard soft contact lenses are unable to achieve vision correction for high astigmatism due to the irregular shape of the cornea.
Standard soft lenses do not provide enough stability on the eye, and are therefore inefficient in correcting vision, and may cause eye discomfort as well. As a result, standard soft contact lenses are usually only recommended for mild to moderate levels of astigmatism.
Standard hard lenses can often correct a higher degree of astigmatism, but these lenses are smaller in size and are also less stable on the eye.
Scleral contact lenses are often recommended for high astigmatism due to their larger size and their unique design that allows them to vault over the cornea and sit directly on the sclera, the white part of the eye.
7. Why are scleral lenses ideal for high astigmatism?
Scleral contact lenses are customized to each individual, taking into account both the shape of the eye and cornea, as well as the optical prescription and amount of vision correction necessary.
Scleral rigid gas permeable lenses cover a larger surface area of the eye, offering increased stability and sharper, clearer vision.
Scleral lenses are uniquely designed to vault over the cornea and sit directly on the sclera— allowing them to completely avoid the irregularly shaped cornea and provide clear and comfortable vision.
Moreover, the space between the cornea and the surface of the scleral lens creates a well that is filled with hydrating solution prior to lens insertion. This reservoir of fluid provides constant hydration to the eye all day, for maximum comfort.
8. Will I outgrow my astigmatism?
Many babies are born with astigmatism, and in many cases, it generally disappears by the time the child turns 5 years old.
However, if the astigmatism has yet to disappear by the time the child reaches school age, in most cases, the astigmatism is permanent,
Astigmatism levels typically increase as a child grows, usually only stabilizing by around 25 years of age.
9. Can eye surgery cause astigmatism?
Yes.
Cataract surgery has been shown to cause post-surgical astigmatism or worsen existing astigmatism, as the corneal shape can change following corneal surgery.
If you notice blurry vision, schedule an appointment with an eye doctor near you to learn more about astigmatism.
LEARN MORE: Guide to Eye Health
Astigmatism refers to a non-spherical cornea and causes blurred vision.
Here are 9 frequently asked questions and answers about this very common refractive error.
