If you've ever had an in-depth vision check, you probably got a close-up look at an autorefractor. This isn't the instrument with all the dials that your optometrist or ophthalmologist uses to hone in on your ideal prescription for glasses or contact lenses. Instead, the autorefractor uses computer-controlled machinery to determine the eye's ability to take in light. Here's an overview of this important tool that helps you achieve better vision with glasses or lenses.
WHAT'S AN AUTOREFRACTOR?
Designed to measure visual acuity, an autorefractor reveals how well you see. The process involves evaluating how your eye reacts to light. Providing valuable data, the autorefractor gives a good starting point to the ophthalmologist or optometrist who's determining the prescription for your glasses or contacts.
HOW IT WORKS
This computerized device measures and determines the shape of the retina. Located at the back of the eye, the retina is similar to a movie screen. It's a smooth surface full of nerve cells and receptors that transform light when it enters the eye. This transformation allows the brain to interpret the light coming from an image and see it. The autorefractor displays an image for each eye to see, increasing the object's size until the eye brings it into focus. Multiple iterations of this process give the doctor an accurate snapshot of the eye's ability to focus on an image.
THE AUTOREFRACTOR FROM A PATIENT'S POINT OF VIEW
Image via Flickr by Pacific Air Forces
Patients typically sit down for an autorefractor reading. Leaning forward, they place their chin in a comfortable holder that positions their eyes in the right spot. The technician asks them simply to look straight ahead, and the machine does the rest.
Because the patient doesn't have to provide any spoken responses about how well he or she sees, this is an ideal way to identify vision problems in children and in adults who have special needs. Thanks to its speed of operation, the autorefractor doesn't require the patient to sit still for very long, another bonus when working with young kids. Finally, the autorefractor is a useful instrument because it's completely painless.
HOW THE AUTOREFRACTOR HELPS DOCTORS
The information from the autorefractor gives ophthalmologists and optometrists a good idea of what your vision needs are. When they ask you to look at a chart through different lenses, they're further refining their understanding of how well you see. But the autorefractor gave them a good idea of what lens strength to offer you.
Some autorefractors perform other tasks in addition to determining your prescription. With added functionality, an autorefractor can do double duty as a keratometer, which evaluates the cornea's shape. Doctors need to have this information to determine whether a patient has corneal problems or astigmatism. Keratometer data also helps doctors find the right fit for a patient who wants contact lenses.
As technology evolves, autorefractors are becoming more portable. One of the latest innovations is an autorefractor that connects to a smartphone. With this device, there's no need for a chin rest or other support infrastructure to complete the evaluation. Enhanced portability means that patients in more corners of the world have the chance to get their vision tested so that they can receive the right glasses to help them see.