There may be some assessments that you have seen at an eye exam and wondered how they work. Having a bright light shined into your eyes could be one of them. This is one way eye doctors test the refractive error of your eye, and it’s known as retinoscopy. 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 use to see if you need vision correction.
How well your eyes are able to focus during the retinoscopy exam is the main thing we look for. When light shines into your eye using a retinoscope, a reddish light reflects off your retina, through your pupil. This is known as the red reflex. The angle at which the light refracts off your retina, also called your focal length, is precisely what tells us how well your eye can focus. And if we see that you are not focusing properly, we hold up a few prescription lenses in front of the eye to determine which one will correct the refractive error.
The retinoscopy exam is conducted in a darkened room. The patient will usually be told to focus on an object behind the doctor. Because a patient isn’t instructed to read eye charts during a retinoscopy exam, it means that it’s also a really great way to determine an accurate prescription for kids who might struggle with speech, or others who might be speech-impaired.