Which type of lens is used specifically to correct astigmatism?

The lens specifically designed to correct astigmatism is the cylinder lens. Astigmatism is an optical condition caused by an irregular curvature of the cornea or lens, leading to distorted or blurred vision at various distances. Cylinder lenses have a varying curvature in one meridian and are flat in the perpendicular meridian. This unique shape allows them to address the principal meridians affected by astigmatism, providing a clearer vision by compensating for the uneven focal points.

Single vision lenses are typically used to correct nearsightedness or farsightedness but do not address the specific aberrations caused by astigmatism. Plus lenses are designed to correct farsightedness, while ADD lenses are primarily used for presbyopia, which is the age-related loss of near vision, rather than for astigmatism.