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  2. Corrective lens - Wikipedia

    en.wikipedia.org/wiki/Corrective_lens

    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.

  3. Presbyopia - Wikipedia

    en.wikipedia.org/wiki/Presbyopia

    Presbyopia is a typical part of the aging process. [4] It occurs due to age related changes in the lens (decreased elasticity and increased hardness) and ciliary muscle (decreased strength and ability to move the lens), causing the eye to focus right behind rather than on the retina when looking at close objects. [4]

  4. Jackson cross cylinder - Wikipedia

    en.wikipedia.org/wiki/Jackson_cross_cylinder

    Astigmatism. Based on. circle of confusion. The Jackson cross cylinder ( JCC) is an instrument used by ophthalmologists, orthoptists and optometrists in their routine eye examination, particularly in determination of corrective lens power in patients with astigmatism. It is also used for testing near point of the eye.

  5. Intraocular lens - Wikipedia

    en.wikipedia.org/wiki/Intraocular_lens

    Intraocular lens. An Intraocular lens ( IOL) is a lens implanted in the eye usually as part of a treatment for cataracts or for correcting other vision problems such as short sightedness and long sightedness; a form of refractive surgery. If the natural lens is left in the eye, the IOL is known as phakic, otherwise it is a pseudophakic lens (or ...

  6. Refractive error - Wikipedia

    en.wikipedia.org/wiki/Refractive_error

    Multifocal lenses The multifocal lenses can correct defective vision in multiple focus, for example: near-vision as well as far-vision. This are particularly beneficial for presbyobia. Contact lenses. Alternatively, many people choose to wear contact lenses. One style is hard contact lenses, which can distort the shape of the cornea to a ...

  7. Near point - Wikipedia

    en.wikipedia.org/wiki/Near_point

    In visual perception, the near point is the closest point at which an object can be placed and still form a focused image on the retina, within the eye 's accommodation range. The other limit to the eye's accommodation range is the far point . A normal eye is considered to have a near point at about 11 cm (4.3 in) for a thirty year old. [1]

  8. 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 ...

  9. Optics and vision - Wikipedia

    en.wikipedia.org/wiki/Optics_and_vision

    A corrective lens is a lens worn in front of the eye, mainly used to treat myopia, hyperopia, astigmatism, and presbyopia. The goal is to bring vision up to 20/20 vision or as close to this as possible. Glasses or "spectacles" are corrective lenses worn on the face a short distance in front of the eye.

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