re·frac·tion noun \ri-ˈfrak-shən\
: the deflection from a straight path undergone by a light ray or a wave of energy in passing obliquely from one medium (as air) into another (as water or glass) in which its velocity is different
a : the refractive power of the eye b : the act or technique of determining ocular refraction and identifying abnormalities as a basis for the prescription of corrective lenses
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