What is Astigmatism?
- by Carole Adams
Eye care specialists use a variety of tests to accurately diagnose astigmatism, and other vision conditions. These include visual acuity assessments and an instrument known as a keratometer.
Astigmatism affects both distance and near vision depending on how your eyes are shaped and function.
Astigmatism can be caused by an irregularly shaped cornea or lens. This condition is known as corneal or lenticular Astigmatism by eye care specialists. Its irregular shape prevents light rays focusing on your retina at the back of your eyes, resulting in blurry vision and strain to the eyes.
Your cornea or lens will usually take the shape of an oval ball. This allows light to enter evenly, and be focused sharply on your retina at the rear of your eye. Astigmatism prevents light from focusing on the retina directly. Instead, it forms two focal spots that overlap and cause blurry vision.
Astigmatism is hereditary and can be present at birth. However, it can also develop after an injury, surgery or certain eye conditions like keratoconus. The most reliable way to diagnose astigmatism is through a comprehensive eye exam. During your exam, your eye doctor will use a phoropter instrument to test your visual acuity and then measure corneal curvature using a corneal topographer.
Eye care specialists can accurately detect astigmatism by performing a series tests. They will inspect your cornea (the clear front portion of your eye) and lens to determine if there is an irregular shape. If so, this indicates corneal astigmatism. A lens with an uneven shape would indicate lenticular.
Normal corneal and lens structures should look like baseballs. This allows light to enter evenly, and focus on a focal point on the retina for clear vision. Astigmatism can cause your eyes to look like footballs or eggs. Light doesn't focus in one place and appears wavy and fuzzy.
Astigmatism is often not detected by children. This makes regular eye exams, starting at age 6, even more important. Astigmatism that is not corrected can affect near and far vision, as well as put the child at risk of an eye disorder called amblyopia.
It's important that you take your child to an eye specialist for a complete exam if they are squinting, rubbing their eyes or have blurry vision. They will examine every part of the eye, including its interior. They will also perform a visual acuity assessment, refractions and cross-cylinders (during which they will look through 360-degree lines to get the crispest vision), in order to diagnose and give advice on astigmatism.
Astigmatism can be corrected with contact lenses or eyeglasses. By bending the light rays so that they land on the retina at a single focal point, they ensure accurate optics. RGP rigid gas permeable lenses are more durable than soft lenses and offer better optics. Surgery may be considered depending on the severity. For astigmatism, this is usually done with LASIK laser eye surgery.
Treatment options for astigmatism include eyeglasses or contact lenses, or surgery depending on your lifestyle and requirements. Your eye care professional will guide you in selecting the right one.
Normal eye anatomy includes two perfectly curved surfaces, your lens and cornea, which work together to focus light onto the retina for clear sight. Astigmatism changes these curved surfaces to have irregular curves, which leads to blurry or distortion images. It is one of the three common refractive mistakes along with myopia (nearsightedness), and hyperopia (farsightedness).
Contact lenses or eyeglasses can improve your vision by compensating irregularities in corneal curvatures and lenticular curves that contribute to astigmatism. Refractive surgery is another option. The most common procedure is LASIK, which uses laser technology for reshaping corneas. LASEK and PRK procedures apply alcohol directly to corneas before they are reshaped using laser technology.
Eye care specialists use a variety of tests to accurately diagnose astigmatism, and other vision conditions. These include visual acuity assessments and an instrument known as a keratometer. Astigmatism affects both distance and near vision depending on how your eyes are shaped and function. Causes Astigmatism can be caused by an irregularly shaped cornea or…