There may be a few assessments that you may have noticed during an eye exam and questioned how they work. Having a bright light shined into your eyes could be an example. Such as test is used to help test the refractive error of your eye, and it's known as a retinoscopy exam. Whether you're near or farsighted, or you have astigmatism, examining the way light reflects off your retina is one test your optometrist can use to determine if you need vision correction.
The most important thing an eye doctor is looking for during this exam is how accurately your eyes can focus. When we use the retinoscope to shine light into your eye, a reddish orange light reflects off your retina, through your pupil. We call this the red reflex. The degree at which the light reflects off your retina, also called your focal length, is exactly what tells us how well your eye can focus. And if it's apparent that you aren't focusing properly, we hold a variety of lenses with varying prescriptions in front of the eye to determine which one will correct the refractive error.
All this happens in a dark room. To make your eyes easier to examine, you'll usually be instructed to keep your eyes fixed on something 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 the prescriptions of children or patients who have difficulty with speech.