Autorefractor

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An autorefractor or automated refractor is a computer-controlled machine used during an eye examination to provide an objective measurement of a person's refractive error and prescription for glasses or 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 eye at a time, they look into the machine at a picture inside. The picture moves in and out of focus as 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 prescription can be made by the machine and printed out.

In some offices this is used to provide the starting point for the optometrist in subjective refraction tests. Here, lenses are switched in and out of a phoropter and 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 disabilities.

Retinoscopy performed by an experienced clinician has been found to provide a more accurate estimation of refractive error than autorefraction.^[1]

[edit] References

[edit] External links

• Trusit Dave "Automated refraction - Design and applications" in "Optometry Today" 04/06/04 [1]

• Autorefractors in the market