What Is an Eye Refraction Exam?


Quick Answer

A refraction test is the part of an eye exam that shows what strength prescription a patient needs. A person who does not have 20/20 vision has a refractive error, which means light does not bend properly when passing through the eye. An accurate prescription corrects this.

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What Is an Eye Refraction Exam?
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Full Answer

During a refraction test, the doctor shines light into the patient's eyes and measures the amount of light reflected by the retina. Next, he places the patient in front of a machine called a phoroptor. This machine has holes for the patient to look through and read a row of letters placed 20 feet away. The doctor inserts a different strength lens in front of each hole until he finds the one that correct the patient's vision to 20/20. This is the strength of eyeglass lenses prescribed for the patient.

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