What condition is caused by irregularity in the curvature of the cornea or lens, producing a distorted image?

Astigmatism is characterized by an irregular curvature of the cornea or lens, which leads to the distortion of visual images. In a normally shaped cornea or lens, light rays focus clearly onto the retina. However, when the curvature is uneven, light rays bend incorrectly, resulting in blurred or distorted vision at various distances. This condition can affect the ability to see fine details and can occur in combination with other refractive errors, but its primary distinguishing feature is that the shape of the cornea or lens is not uniformly round.

Myopia, hyperopia, and presbyopia are related to different issues with vision. Myopia, often referred to as nearsightedness, occurs when the eyeball is too long or the cornea has too much curvature, causing distant objects to appear blurry. Hyperopia, or farsightedness, happens when the eyeball is too short or the cornea is not curved enough, making it difficult to see close objects clearly. Presbyopia is an age-related condition where the lens loses flexibility, making it hard to focus on close objects, rather than an issue of curvature. Thus, astigmatism stands out as the condition specifically associated with irregular curvature leading to distorted images.