What term describes a lens with different curvatures on different axes to correct astigmatism?

A lens designed with different curvatures on different axes specifically to correct astigmatism is known as a toric lens. Astigmatism arises when the cornea or lens of the eye is not perfectly spherical, leading to distorted vision. The toric lens incorporates two distinct optical powers, which address the varying degrees of curvature needed for each axis of the eye. This design enables clearer vision by compensating for the irregular shape of the eye that causes astigmatism.

Spherical lenses, on the other hand, have a uniform curvature throughout and are meant to correct nearsightedness or farsightedness but are ineffective for astigmatism. Aspheric lenses offer a more complex surface profile that improves visual quality, particularly in higher prescriptions, but they are not specifically tailored with dual curvatures as toric lenses are. Bifocal lenses, designed for individuals with presbyopia, have two distinct optical powers for distance and near vision but do not directly address astigmatism. Therefore, the unique design of a toric lens makes it the appropriate choice for correcting astigmatism.