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Refraction in an eye exam is the test measuring how well your eyes can focus light and determines the prescription you need for eyeglasses or contacts. This is the part where you look through a phoropter (the mask-like device with many lenses) while the doctor asks the famous "Which is better, 1 or 2?" routine to fine-tune the lenses that give you the clearest vision.
read more about refraction in an eye exam ...Yes, eye refraction exams are necessary. The primary purpose is to detect any refractive error and identify the exact lens power that corrects your vision to as close to 20/20 as possible. This test finds out if you're nearsighted, farsighted, have astigmatism, and precisely how strong your lenses should be to help you see clearly.
A refraction exam is painless, straightforward, and typically takes just a few minutes per eye. Here's what happens:
Initial measurement: The eye doctor often starts with an autorefractor (a computerized device that shines a light into your eye) or a handheld retinoscope. You'll gaze at a target while the device measures how light reflects off your retina. This gives a quick estimate of any nearsightedness, farsightedness, or astigmatism.
Looking through the phoropter: You'll sit facing the eye chart (usually 20 feet away) and rest your chin on a support. The doctor places the phoropter in front of your face. They test one eye at a time while the other is covered.
"Which is better, 1 or 2?": The doctor systematically changes lenses and asks which makes the letters clearer. By comparing your responses, they home in on the optimal lens power. This process fine-tunes the sphere (for nearsighted or farsighted correction), cylinder and axis (for astigmatism), and any additional reading power if needed. Don't worry if you're unsure about some choices. Eye doctors are skilled at guiding you through it.
Both eyes and double-check: After determining the prescription for one eye, they switch to the other and repeat. At the end, the doctor may show you the combined result with both eyes open so you can confirm it's comfortable.
The refraction portion typically takes 5 to 10 minutes total. The entire extensive eye exam usually runs 30 to 60 minutes, but refraction itself is only a small part of that. It doesn't hurt or have side effects. You're simply looking at letters and answering questions. There are no eye drops (unless a separate dilation is done later) and nothing touches your eye.
A extensive eye exam is a broad evaluation covering everything from the sharpness of your sight to the health of your eyes. A refraction test is one component of that exam, focused solely on finding out if you need vision correction and how much. It doesn't assess eye health conditions; it measures vision clarity and lens power.
You can have a medical eye exam for an issue like an infection that might not include a refraction test if there's no concern about changing your glasses. Conversely, you might go for a routine vision exam where the main goal is updating your glasses prescription. In that case, refraction is the centerpiece of the visit, though the doctor will still do basic health screenings.
Yes, you generally can drive after a refraction test as long as you have not had your pupils dilated. The refraction itself involves just looking at charts through lenses and has no after-effects. However, if your eyes were dilated (a separate procedure often done during the same visit), you might experience blurry near vision and increased light sensitivity for a few hours.
Normal result means 20/20 vision without glasses. No refractive error found and light focuses perfectly on your retina. An abnormal result means your vision is less than 20/20 unaided, indicating you have a refractive error. The result of the refraction test is the prescription that corrects your vision to as close to 20/20 as possible.
The doctor systematically changes lenses and asks which makes the letters clearer. By comparing your responses, they home in on the optimal lens power. This process fine-tunes the sphere (for nearsighted or farsighted correction), cylinder and axis (for astigmatism), and any additional reading power if needed. Don't worry if you're unsure about some choices. Eye doctors are skilled at guiding you through it.
If you are visiting for a routine comprehensive exam, you should generally remove your contact lenses at least two hours before the test. Contacts can slightly change the shape of your cornea, which may lead to an inaccurate prescription. However, if the appointment is specifically for a contact lens fitting or follow-up, you should wear them so the doctor can assess their fit and function.
Medicare does not cover routine refractions or routine vision exams. They consider it part of a non-medical service. Most medical insurance (HMOs, PPOs) also do not cover refraction or routine vision exams unless you have a separate vision benefit. They cover eye exams only if related to eye diseases or injuries. Vision insurance plans (like VSP or EyeMed) do cover routine eye exams including refraction.
Refraction 101: Go Forth and Refract. American Academy of Ophthalmology. https://www.aao.org/young-ophthalmologists/yo-info/article/refraction-101-go-forth-and-refract. Accessed March 12, 2026.
Refractive Errors. National Eye Institute. https://www.nei.nih.gov/eye-health-information/eye-conditions-and-diseases/refractive-errors. Accessed March 12, 2026.
Comprehensive Eye Exams. American Optometric Association. https://www.aoa.org/healthy-eyes/caring-for-your-eyes/eye-exams. Accessed March 12, 2026.
Refraction. MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/article/003844.htm. Accessed March 12, 2026.
Standard Eye Exam. MedlinePlus Medical Encyclopedia. https://medlineplus.gov/ency/article/003434.htm. Accessed March 12, 2026.
Eye Exam and Vision Testing Basics. American Academy of Ophthalmology. https://www.aao.org/eye-health/tips-prevention/eye-exams-101. Accessed March 12, 2026.
How to Read an Eyeglasses Prescription. American Academy of Ophthalmology. https://www.aao.org/eye-health/glasses-contacts/how-to-read-eyeglasses-prescription. Accessed March 12, 2026.
Fact Sheet: Refraction. American Academy of Ophthalmology. https://www.aao.org/Assets/bef9c80f-15d4-4efb-a078-ea3f9bc347c4/638743011019600000/refraction-fs-pdf?inline=1. Accessed March 12, 2026.