What Does Astigmatism Mean?
- Fysiobasen
- Oct 11
- 3 min read
Astigmatism, often referred to as “irregular cornea” or “skewed cornea,” is a common refractive error that affects how light is focused in the eye. The cornea—the clear, front part of the eye—helps focus light on the retina to produce clear vision. When the cornea is unevenly curved, light bends incorrectly, leading to blurred vision at both near and far distances. Astigmatism can occur alongside other vision problems such as nearsightedness (myopia) or farsightedness (hyperopia), and its severity varies.
Causes of Astigmatism
Astigmatism occurs when the natural curve of the cornea is uneven. In a healthy eye, the cornea is evenly rounded like a basketball, allowing light to focus sharply on the retina. In astigmatism, the cornea may be shaped more like a football—oval rather than round—causing light to scatter and focus unevenly.
Effect: Uneven curvature of the cornea causes blurred vision by refracting light irregularly.
Astigmatism can be present at birth or develop later in life. It may not always cause obvious symptoms but often becomes noticeable with demanding visual tasks, such as reading or night driving.
Symptoms of Astigmatism
Common symptoms include:
Blurred vision at both near and far distances
Headaches from prolonged eye strain
Eye fatigue during tasks like reading or screen use
Double vision in more severe cases
Effect: Blurred vision, headaches, and eye strain are key indicators of astigmatism.
How Is Astigmatism Diagnosed?
Astigmatism is usually detected during a routine eye exam. Optometrists often use a refractometer to measure how light bends in the eye. Additional tests like keratometry or corneal topography can map the shape of the cornea for precise diagnosis.
Effect: Specialized instruments help determine the degree and type of astigmatism.
Treatment Options
Astigmatism can be corrected in several ways depending on its severity:
1. Glasses
Prescription glasses with special cylindrical lenses compensate for irregular light refraction.
Effect: Glasses correct refractive errors by redirecting light to focus properly on the retina.
2. Contact Lenses
Specialized toric lenses are designed to correct astigmatism by providing an even refraction across the cornea.
Effect: Toric lenses often provide more natural vision correction and can be comfortable for daily use.
3. Surgery
For severe cases or patients seeking permanent correction, procedures such as LASIK or keratotomy reshape the cornea to improve vision.
Effect: Surgical procedures can permanently correct corneal irregularities.
Can Astigmatism Get Worse?
Astigmatism may progress with age, although not always. It can also coexist with other refractive errors like myopia or hyperopia, making vision correction more complex. Regular eye exams are crucial for monitoring changes and adjusting treatment.
Effect: Astigmatism can worsen over time, but it is manageable with proper care.
Summary
Astigmatism is a common refractive error caused by an unevenly shaped cornea, leading to blurred vision and eye strain. Though it can worsen with age, it is effectively treatable with glasses, contact lenses, or surgery. Regular eye check-ups are essential to maintain clear vision and long-term eye health.
Sources
American Optometric Association. (2023). Astigmatism. AOA.org. https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/astigmatism
National Eye Institute. (2022). Astigmatism. NEI.nih.gov. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/astigmatism
Rosenfield, M., & Logan, N. S. (2009). Optometry: Science, techniques and clinical management (2nd ed.). Elsevier Health Sciences.
Yanoff, M., & Duker, J. S. (2018). Ophthalmology (5th ed.). Elsevier.
Read, S. A., Collins, M. J., & Carney, L. G. (2007). A review of astigmatism and its possible genesis. Clinical and Experimental Optometry, 90(1), 5–19. https://doi.org/10.1111/j.1444-0938.2006.00195.x
