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Prism correction. Prism lenses (here unusually thick) are used for pre-operative prism adaptation. Eye care professionals use prism correction as a component of some eyeglass prescriptions. A lens which includes some amount of prism correction will displace the viewed image horizontally, vertically, or a combination of both directions.
An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are not prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides.
Prism and Base Prism refers to a displacement of the image through the lens, often used to treat strabismus and other binocular vision disorders. The prism value is measured in prism diopters , and Base refers to the direction of displacement.
The prism cover test ( PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. [1] It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
A Fresnel lens ( / ˈfreɪnɛl, - nəl / FRAY-nel, -nəl; / ˈfrɛnɛl, - əl / FREN-el, -əl; or / freɪˈnɛl / fray-NEL [1]) is a type of composite compact lens which reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections.
Optics began with the development of lenses by the ancient Egyptians and Mesopotamians, followed by theories on light and vision developed by ancient Greek philosophers, and the development of geometrical optics in the Greco-Roman world.