On occasion, especially when performing an eye exam on a small child the optometrist will focus a beam of light in the eyes. So what does this do? This test is a retinoscopy examination, which is a preliminary way to assess the refractive error of your eye. Whether you're near or farsighted, or you have astigmatism, examining the way light reflects off your retina is a way your eye doctor can see if you need vision correction.
In short, what we are looking for during the retinoscopy exam is checking how well your eye can focus. We begin the exam by looking for what's known as your red reflex. The retinoscope aims light into your eye, and a reddish light reflects through your pupil and off your retina. The angle at which the light refracts off your retina, which is what eye care professionals call your focal length, is exactly what tells us how well your eye can focus. If it becomes clear that you can't focus properly, that's where the lenses come in. We hold up different lenses with varying prescriptions in front of the eye to determine which one corrects the error. And that is precisely how we find out the prescription your glasses or contact lenses need to be.
The retinoscopy exam is usually performed in a darkened room. To make your eyes easier to examine, you'll usually be asked to keep your eyes fixed on an object behind the doctor. Because a patient isn't required to read eye charts during a retinoscopy exam, it means that it's also a really great way to determine an accurate prescription for children or patients who have difficulty with speech.