Astigmatism is a common vision condition that affects millions of people worldwide. It stems from an imperfection in the curvature of the eye’s cornea, the clear front surface, or sometimes the lens inside the eye.
What Astigmatism Is
Astigmatism is an optical defect where the eye’s cornea or lens is not perfectly spherical. Instead of having a uniformly curved surface like a basketball, it is shaped more like a rugby ball or the back of a spoon, with one meridian being steeper than the other. This irregular shape causes light rays entering the eye to bend unevenly. As a result, incoming light fails to focus on a single point on the retina, leading to blurred or distorted vision.
How Vision Is Affected
The irregular curvature of the eye in astigmatism causes light to scatter across multiple points on the retina rather than converging precisely at one focal point. This results in vision that can be blurry, fuzzy, or distorted at all distances. Common visual experiences include seeing images stretched or elongated, such as a round clock face appearing oval. People with astigmatism often report difficulty seeing fine details and may experience ghosting, where objects appear to have shadows or double images.
Individuals with astigmatism frequently notice glare around lights and halos, particularly during nighttime driving. The effort to clarify blurry images can lead to symptoms like frequent squinting, eye strain, and headaches. These visual challenges can make everyday tasks more difficult.
Why Astigmatism Happens
Astigmatism primarily occurs due to an irregularly shaped cornea, known as corneal astigmatism, which is the most frequent type. Less commonly, the lens inside the eye can have an irregular shape, leading to lenticular astigmatism. While the exact cause is not always known, astigmatism is often present from birth and can be hereditary.
It can also develop later in life following an eye injury, certain eye diseases like keratoconus where the cornea thins and bulges, or as a complication after eye surgery. Astigmatism is broadly classified as regular, where the curvature is consistent but uneven, or irregular, which involves an uneven curvature in multiple directions, often due to scarring. Regular astigmatism is more common and typically correctable with standard lenses.
Ways to Correct Astigmatism
Correcting astigmatism aims to improve vision clarity and eye comfort by counteracting the eye’s uneven curvatures. Corrective lenses, such as eyeglasses, are common and non-invasive methods. These lenses bend light properly onto the retina, compensating for the irregular shape. Another effective option is contact lenses, specifically toric contact lenses, which are uniquely shaped to correct astigmatism.
For those seeking a more permanent solution, refractive surgeries like LASIK, PRK, and SMILE can reshape the cornea using lasers. These procedures reduce or eliminate the need for glasses or contacts. An eye care professional can determine the most suitable corrective approach based on an individual’s specific condition.