Which condition often leads to blurry vision due to an irregularly shaped cornea?

Astigmatism is a refractive error caused by an irregular curvature of the cornea or the lens, which distorts the way light enters the eye. In a normally shaped cornea, light rays are focused evenly onto the retina, providing clear vision. However, when the cornea is shaped more like a football — having different curvatures in different meridians — light is refracted unevenly. This results in blurred or distorted vision, making it difficult for individuals to see clearly at any distance. Astigmatism can often be corrected with prescription eyeglasses, contact lenses, or refractive surgery.

In contrast, cataracts primarily involve the clouding of the lens, glaucoma affects the optic nerve often due to increased intraocular pressure, and macular degeneration involves deterioration of the central portion of the retina. These conditions lead to different visual impairments that do not primarily stem from an irregular shape of the cornea, which is the defining characteristic of astigmatism.