Astigmatism is a common vision condition caused by an irregular curvature of the cornea or lens, leading to improper light refraction and blurry vision. While most people have slight imperfections in eye shape, pronounced curvature differences can result in noticeable visual disturbances. Unlike nearsightedness or farsightedness, astigmatism can cause blurred vision at all distances and often occurs alongside these other refractive errors.
Causes of Astigmatism
A normal cornea has a smooth, round curve, much like a basketball. However, in astigmatism, the cornea or lens may be shaped more like a football, leading to uneven refraction of light. The curvature of the cornea is often uneven, with some areas being steeper or flatter than others. There are two main types of astigmatism:
- Corneal Astigmatism: Caused by an irregularly shaped cornea.
- Lenticular Astigmatism: Caused by an irregularly shaped lens.
Astigmatism is usually present from birth, but it can change over time. It may also develop after an eye injury, surgery, or due to a condition called keratoconus, in which the cornea thins and becomes cone-shaped, progressively worsening vision. In minor cases, individuals may not even notice a change in vision.
Diagnosis of Astigmatism
A comprehensive eye exam is essential for detecting astigmatism. During the exam, an eye doctor will assess your vision and use specialized instruments to measure the curvature of your cornea and lens. Diagnostic tools include:
- Visual Acuity Tests: Checking how clearly you can read letters at a distance.
- Keratometer: A device that shines light on the cornea to measure its curvature and determine proper contact lens fit.
- Corneal Topography: A video imaging technique that maps the cornea’s surface for a detailed assessment.
- Refraction Tests: Placing different lenses in front of your eyes to determine the exact refractive error.
Treatment Options
Astigmatism is highly treatable, with multiple correction options available:
- Eyeglasses: The simplest and safest way to correct astigmatism by adjusting the way light enters the eyes.
- Contact Lenses: Special toric lenses are designed to counteract corneal irregularities and improve focus.
- Orthokeratology (Ortho-K): A non-invasive treatment using a series of rigid contact lenses to temporarily reshape the cornea for clearer vision without daytime eyewear. Although orthokeratology does not permanently change the shape of the cornea, it may allow for glasses- and contact-free vision for extended periods.
- Refractive Surgery (LASIK, PRK): Permanent surgical options that reshape the cornea with a laser to correct vision. These surgeries remove a small amount of corneal tissue to improve how light is refracted.
When to See an Eye Doctor
If you experience blurry or distorted vision, elongated vision, or difficulty reading at any distance, schedule an eye exam to determine if astigmatism is the cause. Early detection and treatment can significantly improve visual clarity and overall eye health. Contact us today to set up an appointment and take the first step toward clearer vision.