Astigmatism is a common vision condition where the eye does not focus light evenly onto the retina, leading to blurry or distorted vision. This occurs because the eye’s front surface, the cornea, or the internal lens, has an irregular curve. Glasses effectively correct astigmatism.
What is Astigmatism?
Astigmatism is an imperfection in the eye’s curvature. This irregular shape means that light entering the eye bends unevenly, causing it to focus on multiple points instead of a single, sharp point on the retina. This results in blurry or distorted vision at all distances.
Common symptoms of astigmatism include blurred vision, eye strain, headaches, and difficulty seeing clearly at night. While the exact cause is often unknown, astigmatism is frequently inherited. It can also develop after an eye injury or certain eye surgeries. A comprehensive eye exam is necessary for diagnosis.
How Glasses Correct Astigmatism
Glasses correct astigmatism by using specialized “cylindrical” lenses. Unlike standard spherical lenses that have the same curvature across their surface, cylindrical lenses possess different curvatures in different directions. This unique design allows them to compensate for the irregular shape of the eye’s cornea or lens.
These lenses are precisely crafted to bend light more in one specific direction than another, counteracting the eye’s uneven focusing power. The optometrist or ophthalmologist determines the exact power and orientation (axis) of this cylindrical correction needed for each eye during an eye examination. This prescription ensures that light rays converge correctly onto a single point on the retina, providing clear vision. Glasses are a highly effective method for correcting most levels of astigmatism.
Beyond Glasses: Other Correction Options
While glasses are a primary method for correcting astigmatism, other options are available for those seeking alternatives. Contact lenses, specifically “toric” contact lenses, are designed to correct astigmatism. These lenses have a unique shape and weighted areas to ensure they stay properly oriented on the eye, providing consistent vision correction by having different refractive powers across the lens. Toric lenses are available in various materials, including soft and rigid gas permeable (RGP) options.
Refractive surgeries offer a more permanent solution by reshaping the cornea. LASIK (Laser-Assisted In Situ Keratomileusis) is a common procedure where a laser reshapes the cornea to improve how light focuses on the retina, effectively treating corneal astigmatism. PRK (Photorefractive Keratectomy) also uses a laser to reshape the cornea, but it involves removing the outermost layer of the cornea before the laser treatment. SMILE (Small Incision Lenticule Extraction) is a newer, less invasive laser surgery that creates and removes a small disc of corneal tissue through a tiny incision to correct vision, including astigmatism. Consulting an eye care professional is important to determine the most suitable correction method for individual needs.