Astigmatism is a common eye condition that causes blurry or fuzzy vision. It occurs when there is an imperfection in the natural curvature of the eye—instead of a smooth, baseball-like shape, the curvature more closely resembles a football. The irregular shape may be present in the eye’s front surface (cornea) or the lens inside the eye. Astigmatism may also be categorized as vertical, in which the shape of the eye is taller than it is wide, or horizontal, in which the eye is wider than it is tall.
One in every three people in the United States has some measure of astigmatism. The blurry vision associated with this condition results from uneven light refraction. In a normally shaped eye, light passes through—or refracts—to the retina at the back of the eye in an even manner and produces a clear, precise image. Astigmatism causes light rays to be bent unevenly and produce overlapping images, what we know as blurry vision.
Can Astigmatism Cause Other Symptoms?
The hallmark sign of astigmatism is blurred or distorted vision. However, some people may also experience:
- Frequent squinting
- Eye pain or irritation
- Increased trouble seeing at night
What Causes Astigmatism?
Astigmatism may be present at birth or develop later in adulthood. While the precise cause of this condition is sometimes unclear, astigmatism is often hereditary, meaning it is passed down from parent to child.
Astigmatism may also result from:
- Eye injuries
- Eye diseases, including keratoconus
- Eyelid pressure
- Surgical complications
Astigmatism is a type of refractive error—an eye disorder that makes it hard to see clearly—that can occur alongside other refractive errors like nearsightedness (myopia) or farsightedness (hyperopia).
Sitting too close to a television or computer screen or reading in poor light does not cause astigmatism, despite popular belief (although these behaviors may worsen existing blurry vision or eye pain).
How Is Astigmatism Diagnosed?
Diagnosing astigmatism begins with a thorough eye examination, which is conducted by an optometrist (an eye specialist who can diagnose disorders) or an ophthalmologist (an eye specialist who can provide surgical treatment). Several tests may be performed to rule out or confirm a diagnosis of astigmatism, including:
- Refraction testing – This test assesses how well light focuses within the eye to produce a clear or blurry image.
- Visual acuity testing – A very common exam, visual acuity testing involves reading letters of various sizes on a distance chart and receiving a performance-based measurement (20/20, 20/40, etc.).
- Keratometry – This test uses a special tool called a keratometer to measure the curvature of the cornea.
What Are the Treatment Options for Astigmatism?
It’s possible for mild cases of astigmatism to improve over time without treatment. For many people, though, treatment is necessary to address eye discomfort and improve vision clarity.
The first step of astigmatism treatment is often wearing corrective lenses. Available in eyeglass or contact lens form, corrective lenses counteract astigmatism by refocusing light to the retina in the back of the eye.
Moderate to severe cases of astigmatism may be treated surgically. There are several surgical approaches to correcting astigmatism, including laser-assisted procedures like photorefractive keratectomy (PRK) surgery. This treatment uses a laser to gently adjust the curvature of the cornea.
We Can Help
Florida Medical Clinic’s diverse physician team includes ophthalmologists who routinely treat astigmatism and other complex eye conditions. To schedule an appointment at one of our locations in North Tampa, New Tampa, Land O’Lakes, or Zephyrhills, request a visit with one of our providers.
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