There are a few tests that you may have noticed at an eye exam and questioned what they are for. Having beams of light shined into your eye may be one of them. This is one way we determine the refractive error of your eye, and it’s called a retinoscopy exam. Whether you’re near or farsighted, or you have astigmatism, examining the reflection of light off your retina is one test your eye doctor can employ to see if you need eyeglasses.
The main thing your doctor is looking for during this exam is how accurately your eyes can focus. When light shines into your eye using a retinoscope, a reddish light reflects off your retina, through your pupil. We call this the red reflex. The degree at which the light reflects off your retina, which is what eye care professionals call your focal length, is exactly what tells us how well your eye can focus. And if we notice that you can’t focus properly, we hold a variety of lenses with varying prescriptions in front of the eye to see which one fixes the refractive error.
Your retinoscopy exam is generally conducted in a dark or dimmed room. To make your eyes easier to examine, you’ll usually be instructed to focus on something behind the doctor. Not having to read any eye charts means that a retinoscopy exam is also a very useful tool to determine the prescriptions of the speech-impaired, or young children.