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refraction
refraction
refraction (ri-frak-shŏn) n. the change in direction of light rays when they pass obliquely from one transparent medium to another, of a different density. Refraction occurs as light enters the eye and passes through the cornea, lens, etc., to come to a focus on the retina.
error of r. (
refractive error) an abnormality of the eye, such as astigmatism or long- or short-sightedness, in which a blurred image forms on the retina due to abnormal focusing.
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refractive (ri-
frak-tiv) adj.
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System improves accuracy of refractions before, after LASIK
Magazine article from: Ophthalmology Times; 11/1/2004; ; 700+ words
; ...WaveScan and manifest refractions were measured...The preoperative refraction in this patient...and cycloplegic refractions, we found that the manifest refraction was slightly more...the wavefront refractions, the manifest...
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Accuracy of refraction measurement by wavefront devices should be examined
Magazine article from: Ophthalmology Times; 11/15/2006; ; 700+ words
; ...generated comparable refractions, while another...finding a reliable refraction with these instruments...using manifest refraction again?" he posed...contradictory." Comparing refractions In light of these...they compared the refractions obtained with the...with the manifest ...
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A nonlinear model of the shoaling and refraction of interfacial solitary waves in the ocean. Part II: Oblique refraction across a continental slope and propagation over a ...
Magazine article from: Journal of Physical Oceanography; 11/1/2001; ; 700+ words
; ABSTRACT The refraction of internal solitary waves can be due to...linear internal-wave theory predicts small refraction of the wave front, the nonlinear EKdV model shows that the refraction of large amplitude internal waves is significantly...
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Reflections on refraction: a source of ancient imprecision still humbles astronomers.
Magazine article from: Science News; 10/13/1990; ; 700+ words
; Reflections on Refraction An invisible sprite plays pranks on...natural trickster -- atmospheric refraction -- toys with their shapes and colors...Center in Greenbelt, Md. Atmospheric refraction prevents greater precision, he reports...
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Birefringence. (use of double refraction in photo lighting technique)
Magazine article from: PSA Journal; 2/1/1992; ; 700+ words
; ...effect causes the double refraction. The double refraction varies with different items...is caused by the unequal refraction of different wavelengths...Without cross polarization the refractions are barely visible. Also...
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Researchers examine effect of horizontal strabismus surgery on refraction
Magazine article from: Ophthalmology Times; 10/15/2008; ; 700+ words
; ...aware of this possibility of a change in their refraction, and the final refraction should be made after surgery, especially in...affect the refractive index and, therefore, the refraction. Changes in refraction after strabismus surgery...
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Gravity Wave Refraction by Three-Dimensionally Varying Winds and the Global Transport of Angular Momentum
Magazine article from: Journal of the Atmospheric Sciences; 9/1/2008; ; 700+ words
; ...neglects horizontal propagation as well as refraction by horizontally inhomogeneous basic...established whether horizontal propagation and refraction are indeed negligible for atmospheric...internal gravity waves that allows wave refraction and horizontal propagation in spherical...
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U.S., Ukrainian, Greek Inventors Develop Eye Aberration Refraction Measurement Method
News Wire article from: US Fed News Service, Including US State News; 12/11/2007; 514 words
; ...have developed an eye aberration refraction measuring method. According to the...provided for measuring aberration refraction of an eye with a first device for measuring the total aberration refraction of the eye and a second device for...
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The issue of refraction.(Letters to the Editor)(Letter to the editor)
Magazine article from: Review of Optometry; 5/15/2006; 622 words
; ...Practice Guidelines list refraction as a component of a comprehensive...states that "inclusion of refractions in examinations or the assumption...with the HIPAA regulation. Refractions must be reported separately, if performed." Certainly, refraction cannot be bundled into a...
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Exact-power IOLs show high precision for toric refraction
Magazine article from: Ophthalmology Times; 4/1/2007; ; 700+ words
; ...When the SE is compared with the end refraction, with the toric retraction values of...measured between the preoperative toric refraction and the postoperative SE for each lens...the spherical equivalent and the toric refraction of the standard IOL and the exact labeled...
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refraction
Book article from: The Columbia Encyclopedia, Sixth Edition
refraction in physics, deflection of a wave on passing obliquely from one transparent...light waves, can be refracted, as can sound waves. The Nature of Refraction Refraction is commonly explained in terms of the wave theory of light and is...
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atmospheric refraction
Book article from: A Dictionary of Astronomy
atmospheric refraction The displacement in apparent direction of a celestial object caused by the refraction of its light in passing through the Earth's atmosphere. Refraction increases the observed altitude of an object. For an object on the...
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refraction, atmospheric
Book article from: A Dictionary of Astronomy
refraction, atmospheric See atmospheric refraction .
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seismic refraction
Book article from: A Dictionary of Earth Sciences
seismic refraction See REFRACTION .
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cleavage refraction
Book article from: A Dictionary of Earth Sciences
cleavage refraction The change in orientation (analogous to wave refraction ) of cleavage planes as they are traced into and through layers of varying lithology and therefore differing competence . Angles between the cleavage plane and the bedding...
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