Astigmatism is a common and treatable refractive error caused by an irregular curvature of the eye's cornea or lens. Instead of being perfectly round like a basketball, the eye's surface may be shaped more like a football. This irregular shape causes light to focus on multiple points in the eye rather than a single point on the retina, resulting in blurred or distorted vision at all distances. It frequently occurs alongside nearsightedness (myopia) or farsightedness (hyperopia).
How Optometrists Diagnose Astigmatism
A comprehensive eye exam is the only way to accurately diagnose and measure astigmatism. Your optometrist will use several precise instruments and tests to assess the shape and focusing power of your eyes.
- Visual Acuity Test: You'll read letters on a chart to determine the clarity of your vision at various distances. This initial test identifies if a vision problem exists.
- Keratometry/Topography: This test measures the curvature of the front surface of your cornea. It maps the cornea's shape to identify the degree and axis of any irregular curvature, which is crucial for determining the exact prescription.
- Phoropter and Retinoscopy: Using a phoropter, your optometrist will place a series of lenses in front of your eyes and ask which lenses provide the clearest vision. They may also use retinoscopy, shining a light into your eye to observe how it reflects off the retina, to obtain an objective starting measurement for your prescription.
Management and Correction Options for Astigmatism
Once diagnosed, astigmatism can be effectively managed with several options. Your optometrist will recommend the best solution based on the severity of your astigmatism, your lifestyle, and your overall eye health.
Eyeglasses
Glasses are the simplest and most common way to correct astigmatism. Lenses for astigmatism are called "toric" lenses. They have different powers in different meridians of the lens to precisely compensate for the irregular curvature of your eye. A study in the journal Optometry and Vision Science confirms that properly prescribed toric lenses provide excellent visual acuity and comfort.
Contact Lenses
Specialized soft toric contact lenses or rigid gas permeable (RGP) lenses are excellent options. Toric soft lenses are designed to maintain a specific orientation on the eye to correct the astigmatism. RGPs provide a smooth, uniform surface over the cornea, effectively neutralizing the irregular shape. Your optometrist will ensure a proper fit and teach you safe handling techniques.
Refractive Surgery
For eligible candidates seeking a permanent correction, procedures like LASIK or PRK can reshape the cornea. It is important to note that an optometrist often plays a key role in the pre-operative evaluation to determine candidacy and in post-operative care to monitor healing and vision.
Why Professional Assessment is Essential
Self-diagnosis or using non-prescriptive readers will not correct astigmatism and can lead to eye strain and headaches. Regular comprehensive eye exams are vital, as astigmatism can change over time. Furthermore, an exam rules out other potential causes of blurred vision. If you experience symptoms like blurry vision, eye strain, headaches, or difficulty with night driving, schedule an appointment with your optometrist for a precise diagnosis and a personalized management plan.