There may be various assessments that you may have noticed at an eye exam and wondered what they are for. Having a bright light shined into your eyes could be an example. Firstly, this test is known as a retinoscopy examination, and it's a basic way to determine the refractive error of your eye. By merely looking at the way light reflects off your retina, the optometrist can determine if you are nearsighted, farsighted or have astigmatism. This is how they may also measure the prescription required to correct your vision.
How well your eyes are able to focus under the circumstance we create during the retinoscopy exam is the main thing we look for. We begin the exam by looking for what's known as your red reflex. The retinoscope sends a beam of light into your eye, and a red or orange 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 the thing that tells us how well your eye can focus. And if we notice that you can't focus well, that's where the lenses come in. We hold up a number of lenses with varying prescriptions in front of your eye to see which one fixes the refractive error. This is precisely how we find out what prescription your glasses or contact lenses need to be.
Your optometrist will perform your exam 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 instructed to read eye charts during a retinoscopy exam, it's also a particularly useful way to determine an accurate prescription for children or patients who have difficulty with speech.