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  2. Refractive error - Wikipedia

    en.wikipedia.org/wiki/Refractive_error

    Depending on the eyeglasses, they serve many functions. [37] Reading glasses These are general over-the-counter glasses which can be worn for easier reading, especially for defective vision due to aging called presbyopia. Single vision prescription lenses They can correct only one form of defective vision, either far-sightedness or near ...

  3. Astigmatism (optical systems) - Wikipedia

    en.wikipedia.org/wiki/Astigmatism_(optical_systems)

    Astigmatism causes difficulties in seeing fine detail. Astigmatism can be often corrected by glasses with a lens that has different radii of curvature in different planes (a cylindrical lens), contact lenses, or refractive surgery. [5] Astigmatism is quite common. Studies have shown that about one in three people suffers from it.

  4. Aberrations of the eye - Wikipedia

    en.wikipedia.org/wiki/Aberrations_of_the_eye

    It has only recently [when?] become possible to measure the aberrations of the eye and with the advent of refractive surgery it might be possible to correct certain types of irregular astigmatism. The appearance of visual complaints such as halos , glare and monocular diplopia after corneal refractive surgery has long been correlated with the ...

  5. Bifocals - Wikipedia

    en.wikipedia.org/wiki/Bifocals

    Adaptation to the small field of view offered by the reading segment of bifocals can take some time, as the user learns to move either the head or the reading material rather than the eyes. Computer monitors are generally placed directly in front of users and can lead to muscle fatigue due to the unusual straight and constant movement of the ...

  6. Toric lens - Wikipedia

    en.wikipedia.org/wiki/Toric_lens

    One of the lens surfaces is shaped like a "cap" from a torus (see figure at right), and the other one is usually spherical. Such a lens behaves like a combination of a spherical lens and a cylindrical lens. Toric lenses are used primarily in eyeglasses, contact lenses and intraocular lenses to correct astigmatism.

  7. Limbal relaxing incisions - Wikipedia

    en.wikipedia.org/wiki/Limbal_relaxing_incisions

    Limbal relaxing incisions (LRI) are a refractive surgical procedure to correct minor astigmatism in the eye. Incisions part way through the cornea are made at one side or at opposite edges of the cornea, following the curve of the iris, causing a slight flattening of the cornea in that area. [1]

  8. Corrective lens - Wikipedia

    en.wikipedia.org/wiki/Corrective_lens

    Single vision lenses correct for only one distance. If they correct for far distance, the person must accommodate to see up close. If the person cannot accommodate, they may need a separate correction for near distances, or else use a multifocal lens (see below). Reading glasses are single vision lenses designed for near work and include over ...

  9. Refractive surgery - Wikipedia

    en.wikipedia.org/wiki/Refractive_surgery

    Refractive surgery is an optional eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses.This can include various methods of surgical remodeling of the cornea (keratomileusis), lens implantation or lens replacement.