An electrically-powered, automated, ophthalmic device designed to measure the refractive error of the eye (the inaccuracies of focusing of light upon the retina) by measuring how light is changed when it enters the patient's eye(s). A beam of light is emitted from the device into the patient's eye and reflected back out where it is detected and measured for sphere, cylinder and axis, as well as high order aberration measurements; typically measured in dioptres (the reciprocal of the focal length of the lens expressed in metres). Using this information, the device, also known as an aberrometer, will automatically calculate the lens prescription needed to correct the patient's vision.
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