Astigmatism is a common visual condition where the eye has an imperfection in the curvature of its lens or cornea, the clear front surface of the eye. This irregular shape prevents light from focusing correctly on the retina, causing light rays to bend unevenly. As a result, vision can appear blurred or distorted at various distances, rather than forming a single, clear image.
Adult-Onset Astigmatism
Astigmatism can develop or worsen later in life. This change often occurs due to age-related alterations in the eye’s structure. For instance, the cornea, the eye’s outermost layer, can change shape over time, leading to corneal astigmatism.
These corneal changes may include age-related thinning or conditions like keratoconus. Keratoconus is a condition where the cornea progressively thins and bulges into a cone-like shape, leading to irregular astigmatism that distorts vision. Additionally, changes in the eye’s natural lens can cause lenticular astigmatism. This is often associated with cataracts, where the lens becomes cloudy and alters its curvature.
Cataract surgery, while correcting cloudiness, can also influence astigmatism; it may induce new astigmatism or, with specialized intraocular lenses, correct pre-existing astigmatism. Other eye surgeries, such as corneal transplants or refractive procedures like LASIK or PRK, can similarly induce or alter astigmatism as part of the healing process. Astigmatism’s axis can also shift with age, becoming more common in individuals over 40.
Recognizing the Signs
When astigmatism develops or progresses later in life, several symptoms can emerge that impact daily visual tasks. A primary indicator is blurred or distorted vision, affecting both close-up and distant objects. This can make reading fine print challenging or distant road signs unclear.
Individuals might also notice difficulty with night vision, experiencing halos or starbursts around lights, making driving after dark troublesome. Other common signs include eye strain or fatigue, especially after prolonged visual activities like computer work or reading. Headaches, often around the eyes or forehead, and frequent squinting are also reported. These symptoms may develop gradually and subtly, sometimes leading people to attribute them to general aging rather than a specific eye condition.
Detection and Correction
Detecting astigmatism involves a comprehensive eye examination. The examination includes tests to assess how the eye focuses light. A visual acuity test, reading letters on an eye chart, evaluates vision sharpness. A refraction test uses a phoropter, allowing the eye doctor to determine the precise lens prescription for clear vision.
Specialized instruments like a keratometer measure the curvature of the cornea, while corneal topography provides a detailed map of the corneal surface, identifying irregularities. Once diagnosed, astigmatism is manageable and correctable. Eyeglasses with “toric” lenses, which have different refractive powers, are a common solution. Similarly, specialized toric contact lenses correct the irregular curvature, providing clear and stable vision.
For some individuals, refractive surgery options such as LASIK or photorefractive keratectomy (PRK) can reshape the cornea to permanently correct astigmatism, reducing or eliminating the need for glasses or contact lenses. Suitability for these procedures depends on individual eye health and astigmatism stability. Even when astigmatism develops later in life, various effective correction methods can significantly improve vision and enhance daily quality of life.