There are various assessments that you have experienced at an eye exam and questioned how they work. Having beams of light shined into your eye may be an example. This test is called a retinoscopy examination, and it’s a basic way to measure the refractive error of your eye. It sounds fascinating, but by examining the way light reflects off your retina, the eye care professional can determine if you are nearsighted, farsighted or have astigmatism. This is how they may also get a pretty good reading on the prescription you would need to correct your vision.
How well your eyes are able to focus during the exam is really what we’re looking for. 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. We use the light to determine your focal length, or in other words, to measure the angle of refraction of light off your retina. And this is what tells us how well your eye is able to focus. And if we see that you can’t focus properly, we hold several prescription lenses in front of your eye to see which one corrects your vision. That lens power is the prescription you require to correct your vision with glasses or contact lenses.
All this happens in a dark room. To make your eyes easier to examine, you’ll generally be instructed 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 the prescriptions of kids who might struggle with speech, or others who might be speech-impaired.