Astigmatism occurs when the curvature of the surfaces of your eye are irregular, resulting in a refractive error.
Your eye has two curved surfaces – the cornea and the lens – which bend, or refract, light. In a perfectly functioning eye, both the cornea and lens have two curves that match each other, resulting in a sharp image. However, if the curves are mismatched in either the cornea or lens, your retina will receive a blurry image. A fault in the cornea is called corneal astigmatism while a fault in the lens is called lenticular astigmatism.
Both of these types come under the bracket of regular astigmatism, which is by far the most common form of astigmatism.
Irregular astigmatism involves the cornea or lens which is curved in multiple directions, curved asymmetrically, or uneven in other ways. Irregular astigmatism is difficult to correct with glasses or soft contact lenses, and usually appears as a result of keratoconus or an injury to the eye. The rest of this article focuses on regular astigmatism.
Astigmatism can usually be corrected with glasses or contact lenses. Both involve the use of artificial lenses to give you clear vision.
Previously, it was not possible to buy soft contact lenses for astigmatism, and the only option was the use of rigid lenses. Now, however, a special form of soft lens called ‘toric’ lenses are available.
For stronger forms of astigmatism, the cost of contact lenses can increase, and the range of frames you can wear may be restricted. If you opt for eyeglasses or contact lenses, it is important to have your eyes regularly tested because the shape of your eyes change gradually over time, and your prescription might change.
Laser eye surgery is often an option, but can be more expensive and may carry the risk of regression (recurrence) in high degrees of astigmatism. Phakic intraocular lens implantation and refractive lens exchange are the other surgical options to address the astigmatism.
The main symptom of astigmatism is blurry vision, which can come with:
Astigmatism, along with long and short-sightedness, can be diagnosed by an optometrist during a comprehensive eye exam.
The doctor will be able to determine from this what degree of astigmatism you have, and therefore what your corrective options are.
