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Phoropter

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Phoropter
10/6/2012 Optical Refractor/Phoropter
Introduction
An optical refractor or a phoropter is an optical instrument with many adjustable lenses and settings that quickly determine the patient’s exact refractive error and prescribe the exact vision correction needed when people have trouble seeing (blurred vision). Eye doctors or optometrists rely on some questions and a phoropter to determine the condition their patient has. Firstly the optometrist asks the patient what objects are blurry: far objects, near objects, or the full image. And that determines what kind of lens the optometrist will work with.
What are the eye conditions? If seeing: * Light rays
Light rays
Retina
Retina
Retina
Retina
Light rays
Light rays
Focal point
Focal point
Far blurry objects (near-sightedness) use spherical corrective lenses with negative power.
EYE
EYE

(Near-sightedness) correction
(Near-sightedness) correction
Negative spherical lens
Negative spherical lens
Focal point
Focal point

(Near-sightedness)

* Retina
Retina
EYE
EYE
Light rays
Light rays
Light rays
Light rays
Positive spherical lens
Positive spherical lens
(Far-sightedness) correction
(Far-sightedness) correction
Near blurry objects (far-sightedness) use spherical corrective lenses with positive power. *

Focal point
Focal point
Retina
Retina
Focal point
Focal point

(Far-sightedness)

* Retina
Retina
Light rays
Light rays
Light rays
Light rays
Full blurry image (astigmatism) uses cylindrical corrective lenses.
Retina
Retina

EYE
EYE
Cylindrical lens
Cylindrical lens
Focal point
Focal point
Focal points
Focal points

(Astigmatism) correction
(Astigmatism)



Bibliography: * Douglas A. Kerr, The Refractor/Phoropter, [online] http://dougkerr.net/Pumpkin/articles/Refractor.pdf, December 7, 2010. * Myron Moe, Taking the Mystery Out of Refraction, [online] http://www.abo-ncle.org/themes/default/assets/images/papers/moe.pdf, July 6, 1999. February 14, 2012. * Malaya Optical, What Is Astigmatism? , [online] http://www.malayaoptical.com/eye-problems/what-is-astigmatism, May 12, 2011. * Jean Zuni, Phoropters, [online] http://www.scribd.com/doc/19428106/Phoropter-Handouts, September 4, 2009.

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