What is astigmatism?

Astigmatism is a refractive error that occurs when the cornea or lens of the eye is not perfectly curved. Instead of being spherical, an irregular shape causes light entering the eye to focus on multiple points rather than one, resulting in blurred or distorted vision at various distances. This condition can be present from birth or can develop over time, and it affects how well a person can see details both up close and far away.

Understanding astigmatism is essential because it is one of the most common vision problems and often coexists with other refractive errors such as myopia (nearsightedness) and hyperopia (farsightedness). The other options do not accurately define astigmatism, highlighting the uniqueness of this refractive error compared to different ocular conditions such as color blindness or age-related eye diseases.