Editing Myopia (section)

===Glasses and contacts===
{{multiple image
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| image1 = Nearsighted color fringing -9.5 diopter - Canon PowerShot A640 thru glasses - overview.jpg
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| image2 = Nearsighted color fringing -9.5 diopter - Canon PowerShot A640 thru glasses - closeup detail.jpg
| width2 = 200
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| footer = Prismatic color distortion shown with a camera set for near-sighted focus, and using −9.5 [[diopter]] eyeglasses to correct the camera's myopia (''left''). Close-up of color shifting through corner of eyeglasses. The light and dark borders visible between color swatches do not exist (''right'').
}}

[[Corrective lens]]es [[Refraction|bend]] the light entering the eye in a way that places a focused image accurately onto the retina. The power of any lens system can be expressed in [[diopter]]s, the [[Multiplicative inverse|reciprocal]] of its [[focal length]] in meters. Corrective lenses for myopia have negative powers because a divergent lens is required to move the [[far point]] of focus out to the distance. More severe myopia needs lens powers further from zero (more negative). However, strong eyeglass prescriptions create distortions such as prismatic movement and [[chromatic aberration]]. Strongly myopic wearers of [[contact lens]]es do not experience these distortions because the lens moves with the cornea, keeping the optic axis in line with the visual axis and because the vertex distance has been reduced to zero.