Sometimes, especially when performing an eye exam on small children the eye doctor will focus a beam of light in the eyes. But why? Firstly, this test is called a retinoscopy examination, and if you struggle with accurate vision, this is a preliminary way the eye doctor could find out. Whether you’re near or farsighted, or you have astigmatism, examining the way light reflects off your retina is a test your eye doctor can use to see if you need eyeglasses.
Basically, what we are looking for during the retinoscopy exam is checking to see how your eye focuses. We begin the exam by looking for what we call the red reflex. The retinoscope aims light into your eye, and a reddish light reflects through your pupil and off your retina. The retinoscope measures your focal length, or in other words, to determine the angle of refraction of light off your retina. And this is what lets us know how well your eye is able to focus. And if we see that you can’t focus properly, that’s when we use a set of lenses. We hold a variety of prescription lenses in front of the eye to determine which one fixes the refractive error.
All this happens in a dark room. To make your eyes easier to examine, you’ll usually be instructed to look at an object behind the doctor. Unlike eye examinations you may have had, you won’t be asked to read letters off charts. This means that a retinoscopy exam is also a very useful tool to determine the prescriptions of the speech-impaired, or young children.