Contact Lenses Bifocal Astigmatism

contact lenses
(contact lens) contact: a thin curved glass or plastic lens designed to fit over the cornea in order to correct vision or to deliver medication
(contact lens) A thin lens, made of flexible or rigid plastic, that is placed directly on to the eye to correct vision, used as an alternative to spectacles, or, if coloured, to change one's eye color cosmetically
A thin plastic lens placed directly on the surface of the eye to correct visual defects
(Contact lens) A small plastic disc containing an optical correction that is worn directly on the cornea as a substitute for eyeglasses.

astigmatism
(optics) defect in an optical system in which light rays from a single point fail to converge in a single focal point
A defect in the eye or in a lens caused by a deviation from spherical curvature, which results in distorted images, as light rays are prevented from meeting at a common focus
(astigmatic) of or relating to a defect in the eye or in a lens caused by a deviation from spherical curvature which prevents light rays from meeting at a common focus and so results in distorted images
(ophthalmology) impaired eyesight resulting usually from irregular conformation of the cornea; common in nearsighted people

bifocal
having two foci; "bifocal eyeglasses"
Bifocals are eyeglasses with two distinct optical powers. Bifocals are most commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism.
(usually of a pair of eyeglasses) Having lenses each with two parts with different focal lengths, one for distant vision and one for near vision
(bifocals) eyeglasses having two focal lengths, one for near vision and the other for far vision