Automated refractor

An automated refractor, or autorefractor, is a computer-controlled machine used during an eye examinationto provide an objective measurement of a person's refractive errorand prescriptionfor glassesor contact lenses. This is achieved by measuring how light is changed as it enters a person's eye.

The automated refraction technique is quick, simple and painless. The patient takes a seat and places their chin on a rest. One eyeat a time, they look into the machine at a picture inside. The picture moves in and out of focus and the machine takes readings to determine when the image is on the retina. Several readings are taken which the machine averages to form a prescription. No feedback is required from the patient during this process.

Within seconds an approximate measurement of a person's prescriptioncan be made by the machine and printed out.

In some offices this is used to provide the starting point for the optometristin subjective refraction tests. Here, lensesare switched in and out of a phoropterand the patient is asked "which looks better" while looking at a chart. This feedback refines the prescription to one which provides the patient with the best vision.

Automated refraction is particularly useful when dealing with non-communicative people such as young children or those with disabilites.

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It uses material from the http://en.wikipedia.org/wiki/Automated+refractor Wikipedia article Automated refractor.