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  2. Bifocals - Wikipedia

    en.wikipedia.org/wiki/Bifocals

    Bifocals with separate lenses. In this case, the Swedish ethnologist Jan-Öjvind Swahn [ sv]. Bifocals are eyeglasses with two distinct optical powers. Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hyperopia, and/or astigmatism .

  3. Adjustable-focus eyeglasses - Wikipedia

    en.wikipedia.org/wiki/Adjustable-focus_eyeglasses

    Adjustable-focus eyeglasses. Adjustable focus eyeglasses are eyeglasses with an adjustable focal length. They compensate for refractive errors (such as presbyopia) by providing variable focusing, allowing users to adjust them for desired distance or prescription, or both. Current bifocals and progressive lenses are static, in that the user has ...

  4. Eyeglass prescription - Wikipedia

    en.wikipedia.org/wiki/Eyeglass_prescription

    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. PL is an abbreviation for plano or plain, meaning no prescription

  5. Peli Lens - Wikipedia

    en.wikipedia.org/wiki/Peli_Lens

    The Peli Lens is a mobility aid for people with homonymous hemianopia. It is also known as “EP” or Expansion Prism concept and was developed by Dr. Eli Peli of Schepens Eye Research Institute in 1999. It expands the visual field by 20 degrees.

  6. Corrective lens - Wikipedia

    en.wikipedia.org/wiki/Corrective_lens

    A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia. Glasses or "spectacles" are worn on the face a short distance in front of the eye.

  7. Progressive lens - Wikipedia

    en.wikipedia.org/wiki/Progressive_lens

    Progressive lenses are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. They are characterised by a gradient of increasing lens power, added to the wearer's correction for the other refractive errors.

  8. Glasses - Wikipedia

    en.wikipedia.org/wiki/Glasses

    The most common type of corrective lens is "single vision", which has a uniform refractive index. For people with presbyopia and hyperopia, bifocal and trifocal glasses provide two or three different refractive indices, respectively, and progressive lenses have a continuous gradient. [1]

  9. Presbyopia - Wikipedia

    en.wikipedia.org/wiki/Presbyopia

    Presbyopia can be corrected using glasses, contact lenses, multifocal intraocular lenses, or LASIK (PresbyLASIK) surgery. The most common treatment is glass correction using appropriate convex lens. Glasses used to correct presbyopia may be simple reading glasses, bifocals, trifocals, or progressive lens.

  10. Belay glasses - Wikipedia

    en.wikipedia.org/wiki/Belay_glasses

    Belay glasses are eyeglasses with prismatic lenses that are used by belayers in rock climbing to avoid the neck strain associated with belaying.

  11. Prism (optics) - Wikipedia

    en.wikipedia.org/wiki/Prism_(optics)

    Prism spectacles with a single prism perform a relative displacement of the two eyes, thereby correcting eso-, exo, hyper- or hypotropia. In contrast, spectacles with prisms of equal power for both eyes, called yoked prisms (also: conjugate prisms, ambient lenses or performance glasses) shift the visual field of both eyes to the same extent.