A Closer Look at Retinoscopy

There may be some tests that you have seen at an eye exam and wondered what they measure. Having a bright light shined into your eye could be an example. 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 a way your eye doctor can see if you need eyeglasses.

Essentially, what we are doing during a retinoscopy exam is checking how accurately your eye focuses. We do this looking for what we call your red reflex. The retinoscope aims a beam of light into your eye, and a red or orange light reflects through your pupil and off your retina. The degree at which the retinoscope's light refracts off your retina, which is what eye care professionals call your focal length, is the thing that tells us how well your eye can focus. If it becomes clear that you aren't focusing well, that's when we use a set of lenses. We hold up different prescription lenses in front of the eye to see which one will correct the refractive error.

These exams are performed in a darkened room. To make your eyes easier to examine, you'll usually be instructed to look at an object behind the doctor. Because a retinoscopy exam doesn't require you to read eye charts, it's also a particularly useful way to determine an accurate prescription for kids who might struggle with speech, or others who might be speech-impaired.