Astigmatism is a common refractive error that results from an imperfection in the eye’s curvature. In normal eyes, the cornea (the front part of the eye’s surface) and the lens are smooth and evenly shaped in all directions. With astigmatism, the cornea or lens is irregularly shaped in some areas, causing blurred vision. Astigmatism is not an eye disease; it is simply a variation in the way the eye is shaped. A person can experience moderate to severe astigmatism depending on how many corneal or lens disturbances are present. Read on to learn more about the treatment of astigmatism, as well as its symptoms, causes, and diagnosis.
There are a number of options for patients seeking effective astigmatism treatment, from time-tested eyeglasses to the latest in laser technology. Choosing the right treatment for you will depend on a number of factors, including your lifestyle, medical history, and degree of refractive error.
Glasses and Contact Lenses
Before the advent of refractive surgery, eyeglasses and contact lenses were the only way to correct astigmatism, and many people still prefer them. Eyeglasses are a reliable astigmatism treatment that comfortably correct for the cornea’s irregular curve. Contact lenses are another option and can vary greatly in type. Hard, soft, extended wear, disposable, rigid gas permeable, and bifocal contact lenses are all appropriate choices for astigmatism treatment.
LASIK, which stands for “Laser-Assisted In Situ Keratomileusis,” is an astigmatism treatment that uses a cold-beam excimer laser to reshape the cornea so it can properly focus images on the retina. The LASIK procedure involves cutting a small flap in the cornea and moving it out of the way before reshaping the underlying tissue. The cornea heals quickly, and many patients notice a significant improvement in vision within the first day of recovery. Because of its short recovery time and convenience (it is an outpatient procedure, and usually takes only 10-15 minutes), LASIK is the most frequently performed of all refractive surgeries.
Another innovation in astigmatism treatment is custom LASIK surgery, or Wavefront™ LASIK, which takes three-dimensional measurements of how your eyes process images and uses them to guide the laser during surgery. This method is much more precise than traditional LASIK and makes for a more accurate astigmatism treatment than glasses or contacts.
PRK, which stands for “Photorefractive Keratectomy,” was the first form of refractive surgery available in the United States and is still a preferred astigmatism treatment for patients with large pupils or very thin corneas. The PRK process involves removing the epithelium (outer layer of the cornea) and using a cool ultraviolet light to reshape the surface of the cornea. This method is less invasive than LASIK because it does not actually reshape the cornea’s interior. It does require a longer recovery time, however, but for those willing to make the commitment, PRK is an excellent and time-tested astigmatism treatment.
Although the term LASEK sounds a lot like "LASIK," the procedure is actually more similar to PRK. This form of astigmatism treatment is appropriate for patients whose corneas are too thin or too flat for traditional refractive surgery. In LASEK, the epithelium, or outer layer of the cornea, is cut using a tiny blade called a trephine. An alcohol solution is then applied to loosen the epithelial cells. The epithelial flap remains pulled back during surgery until the cornea has been reshaped. Unlike in PRK, the corneal flap is never fully removed. Your doctor may recommend LASEK as an alternative astigmatism treatment to LASIK if your corneas are very thin or if you have dry eyes.
The most common symptom of astigmatism is blurred vision at any distance. People with astigmatism often experience distortions of vertical, horizontal, or diagonal lines, as well as frequent headaches and fatigue, squinting, eye discomfort, and irritation. These symptoms are not exclusive to astigmatism and will vary depending on whether the patient has mild, moderate, or severe astigmatism. If you experience any of these symptoms, you should contact a qualified ophthalmologist for a comprehensive eye examination.
Causes of Astigmatism
In the human eye, the cornea focuses images by refracting incoming light onto the retina (back of the eye). In the ideally-shaped eye, the cornea has a smooth, even curvature and is shaped like a round ball. With astigmatism, the cornea is shaped more like an oval, or football, causing light to scatter as it passes through. The result is a blurred image on the retina, making it difficult for people with astigmatism to see clearly at any distance.
Contrary to common belief, reading in poor light, squinting, or sitting too close to the television are not causes of astigmatism. Astigmatism is usually present from birth and can either stay the same or worsen over time. Eye injury, disease, or surgery can also be causes of astigmatism.
Astigmatism is usually diagnosed during routine eye exams, wherein your ophthalmologist will check your eye’s refraction (ability to properly focus light rays on the retina) and visual acuity using a standard eye chart. The eye’s refraction can be measured in a number of ways; some doctors will simply ask a series of questions about your current vision and conduct a visual acuity test, while others will use a keratometer or keratoscope to assess the curvature of your cornea and determine the presence of moderate or severe astigmatism.
Moderate to Severe Astigmatism
Many experts believe that all people are born with a degree of astigmatism that may worsen or stay the same throughout their lifetime. For most people, the degree of astigmatism experienced is so mild that it does not require corrective lenses. However, for those with moderate to severe astigmatism, eyeglasses or contact lenses must be worn unless their vision is corrected with refractive surgery.
Degree of Refractive Error
The term refractive error refers to the degree to which images received through the eye's cornea and lens are not focused on the retina. In other words, it is the degree of “blurriness” that a person experiences when trying to focus on images at varying distances. The numbers on a person’s eyeglass or contact prescription reflect this measurement. With astigmatism, the degree of refractive error is noted under “C,” or “cylinder,” which measures the eye’s irregular curvature. A person’s prescription can vary greatly depending on whether he or she has moderate or severe astigmatism, and it must remain stable before LASIK or other refractive surgery can be performed.
Contact an Ophthalmologist
If you experience any of the symptoms of moderate or severe astigmatism, it is important that you schedule a comprehensive eye exam as soon as possible. A qualified ophthalmologist can explain in detail the varying degrees, symptoms, and causes of astigmatism and provide you with an appropriate prescription. To find an ophthalmologist in your area, use our eye care specialists database.