Astigmatism is a common vision condition that causes blurred vision. It occurs when the cornea (the clear front cover of the eye) is irregularly shaped or sometimes because of the curvature of the lens inside the eye. … Most people have some degree of astigmatism.
Astigmatism is a refractive error, like farsightedness and nearsightedness, meaning it is not an eye disease; it’s just a problem with how the eye focuses light.
In an eye with astigmatism, light fails to come to a single focus on the retina to produce clear vision. Instead, multiple focus points occur, either in front of the retina or behind it (or both).
Astigmatism usually causes blurred or distorted vision to a certain degree at all distances.
Symptoms of uncorrected astigmatism are eye strain and headaches, especially after reading or other prolonged visual tasks.
Squinting also is also a very common telltale sign that one has developed astigmatism.
What Causes Astigmatism?
Astigmatism is caused by an irregularly shaped cornea. Instead of the cornea having a symmetrically round shape (like a baseball), it is shaped more like an American football, with one meridian being more curved than the meridian perpendicular to it.
The steepest and flattest meridians of an eye with astigmatism are called the principal meridians.
In some cases, astigmatism is caused by the shape of the lens inside the eye. This is called lenticular astigmatism, to differentiate it from the more common corneal astigmatism.
Types of Astigmatism
There are three primary types of astigmatism:
- Myopic astigmatism. One or both principal meridians of the eye are nearsighted. (If both meridians are nearsighted, they are myopic in differing degree.)
- Hyperopic astigmatism. One or both principal meridians are farsighted. (If both are farsighted, they are hyperopic in differing degree.)
- Mixed astigmatism. One principal meridian is nearsighted, and the other is farsighted.
Astigmatism can also be known and classified as regular or irregular. In regular astigmatism, the principal meridians are 90 degrees apart (perpendicular to each other). In irregular astigmatism, the principal meridians are not perpendicular. Most astigmatism is regular corneal astigmatism, which gives the front surface of the eye an oval shape.
Irregular astigmatism can result from an eye injury that has caused scarring on the cornea, from certain types of eye surgery or from keratoconus, a disease that causes a gradual thinning of the cornea.
Astigmatism Correction Options
Astigmatism, like nearsightedness and farsightedness, usually can be corrected with eyeglasses, contact lenses or refractive surgery.
If you have questions, you can talk to our team for recommendations. We sell the best lenses and coatings in our Maple Location. To book an appointment for an eye exam to see an optometrist, call us at 905-832-6262.
Our Maple optometrist Location: Eyes on Eyes Optical
9929 Keele St, Unit 110, Maple, ON L6A 1Y5, Tel: 905-832-6262