Astigmatism is an extremely common refractive error that affects both children and adults. It occurs when the cornea—the clear, protective outer layer of the eye—is not perfectly round. Instead of a uniform spherical shape, an astigmatic cornea may have an irregular curvature, similar to an egg. This variation affects the way light is focused on the retina, leading to blurry or distorted vision at both near and far distances. Astigmatism often occurs alongside nearsightedness (myopia) or farsightedness (hyperopia).
Symptoms of Astigmatism
Common symptoms include:
- Blurred or distorted vision at all distances
- Difficulty seeing clearly while driving at night
- Frequent squinting
- Eyestrain and fatigue
- Headaches
Mild astigmatism may not cause noticeable symptoms, but more significant cases often impact daily activities and require vision correction.
Causes of Astigmatism
Most astigmatism develops naturally due to the shape of the cornea, influenced by the eyelids and surrounding facial structures. However, other factors can contribute to astigmatism, including:
-
Eye injury or trauma that alters the shape of the cornea.
-
Pterygium, a growth on the eye from prolonged sun exposure.
-
Frequent eye rubbing, often due to allergies, which can warp the cornea over time.
-
Keratoconus, a progressive eye disease that causes thinning and bulging of the cornea.
If your astigmatism has worsened over time, your eye doctor may ask about habits like excessive eye rubbing and may recommend treatments for underlying irritation or allergies.
Diagnosing Astigmatism
Astigmatism is easily detected through a routine eye exam. Your optometrist or ophthalmologist will conduct several tests, including:
-
Visual acuity testing using an eye chart to assess clarity of vision.
-
Refraction testing to determine the best prescription for correcting vision.
-
Keratometry to measure the curvature of the cornea.
These tests help determine the degree of astigmatism and the best course of action for correction.
Treatment Options for Astigmatism
The most common treatments include:
-
Eyeglasses: A simple and effective way to correct astigmatism by adjusting the way light enters the eye.
-
Toric Contact Lenses: Specially designed contact lenses that compensate for the irregular curvature of the cornea.
-
Orthokeratology (Ortho-K): A non-surgical option where rigid contact lenses worn overnight temporarily reshape the cornea for clearer daytime vision.
-
Refractive Surgery (LASIK or PRK): Permanent surgical reshaping of the cornea to correct astigmatism. Eligibility depends on eye health and a stable prescription.
Managing Astigmatism
With proper corrective lenses or surgery, most individuals with astigmatism can achieve 20/20 vision or close to it. If you experience symptoms or notice worsening vision, schedule an appointment with an eye care professional. Early detection and appropriate treatment ensure optimal vision and long-term eye health.
Sincerely,
Dr. Mark Cannon, Optometrist
Cannon EyeCare (at Market Optical)
Seattle, Washington