Eye doctors use a variety of diagnostic tests and procedures to examine their patient's eyes. In addition to color blindness exams and cover tests, ophthalmologists administer refraction tests to determine eyeglass prescriptions and measure visual acuity. During a refraction test, the doctor can use a phoropter to manually determine lens prescription or an autorefractor to automatically measure refractive error.
What is an autorefractor?
An autorefractor, or automated refractor, is a computer-controlled device that is used during an eye exam to check how the eye processes light. Autorefractors measure refractive error in just seconds and automatically determines a person's eyeglass or contact lens prescription.
Reasons for autorefractor testing
Autorefractors are used by eye doctors to help determine whether a patient needs prescription eyewear or contact lenses. Modern autorefractors are extremely accurate and easy to use. They help save time during eye examinations by cutting down on the interaction between patient and doctor.
Testing with an autorefractor takes just a few seconds and is painless. These devices are extremely useful when dealing with children who have a hard time sitting still, as well as for adults with developmental disabilities that have difficulty communicating with the doctor during an eye exam.
Performing an autorefractor test
Autorefractor testing is extremely simple. As a patient, you rest your chin on a chin rest and look at an image inside the autorefractor machine, one eye at a time. The image moves in and out of focus until readings determine that the image is precisely on the retina. The machine takes several detailed readings, which it averages out to form a prescription. The entire testing process is automatic so you are not required to determine when your eye is properly focused – your doctor gets this feedback from the machine.
If necessary, autorefractor testing may be followed by a manual exam by your eye doctor to refine prescription strength.