A routine eye exam is a preventive health visit that checks your vision clarity and screens for early signs of eye disease. It typically lasts 30 to 60 minutes, covers a series of painless tests, and ends with an updated prescription for glasses or contacts if you need one. Even if your vision feels fine, these exams can catch problems like glaucoma, cataracts, and even diabetes before symptoms appear.
What Happens During the Exam
A routine eye exam follows a fairly standard sequence, though the exact tests can vary depending on your age, health history, and what your eye doctor notices along the way.
It starts with a visual acuity test, the familiar letter chart on the wall. You sit 20 feet from the chart (or look at it through a mirror that simulates that distance), cover one eye at a time, and read the smallest line you can. The result is expressed as a fraction like 20/20 or 20/40. The top number is your distance from the chart. The bottom number is the distance at which someone with normal clarity could read that same line. So 20/40 means you need to be 20 feet away to read what a person with standard vision reads from 40 feet. Worth noting: 20/20 doesn’t mean “perfect vision.” It only measures distance clarity, not depth perception, peripheral vision, or how well your eyes work together.
If your acuity isn’t 20/20, a refraction test comes next. Your doctor places a device in front of your eyes and flips through a series of lenses, asking “which is better, one or two?” each time. This process narrows down the exact combination of lens power that gives you the sharpest vision and becomes the basis for a glasses or contact lens prescription. It identifies nearsightedness, farsightedness, and astigmatism.
Eye Pressure and Glaucoma Screening
One of the most important parts of the visit is tonometry, which measures the pressure inside your eyes. High pressure is a major risk factor for glaucoma, a condition that damages the optic nerve and can steal peripheral vision without any noticeable symptoms until significant damage has occurred.
There are two common methods. The air puff test (non-contact tonometry) shoots a small burst of air at your eye and measures how your cornea responds. It’s quick and doesn’t require numbing drops, which is why many offices use it as a first pass. The other option, applanation tonometry, uses a tiny probe that gently touches the surface of your numbed eye to get a more precise reading. Normal eye pressure falls between 10 and 21 mmHg. Readings above that range prompt further testing.
The Dilated Eye Exam
Your doctor may put drops in your eyes to widen your pupils. This allows a much clearer view of the structures at the back of the eye: the retina, the optic nerve, and the blood vessels that supply them. Without dilation, the pupil only offers a narrow window, roughly 5 to 10 degrees of view, making it difficult to spot subtle changes in tissue health.
Dilation is painless, but it does make your vision blurry and your eyes sensitive to light for a few hours afterward. In some cases, your pupils may still look dilated for up to 24 hours. Bringing sunglasses to your appointment helps, and you may want someone else to drive you home.
Many offices now also offer digital retinal imaging as a complement to (or occasionally a substitute for) dilation. A specialized camera captures a high-resolution photo of your retina in seconds. These images have high sensitivity and specificity for detecting problems, and they create a permanent record your doctor can compare year over year to track changes. For screening conditions like diabetic eye disease, retinal photography has actually shown higher accuracy than traditional examination with a handheld scope, even when performed by specialists.
What an Eye Exam Can Reveal Beyond Vision
The blood vessels in your retina are the only blood vessels in the body that a doctor can observe directly without surgery. That makes an eye exam surprisingly useful for detecting conditions that have nothing to do with your eyesight.
Diabetes shows up as tiny hemorrhages, swelling, or abnormal new blood vessel growth on the retina, sometimes before blood sugar levels have been flagged on routine lab work. High blood pressure causes visible narrowing and nicking of retinal arteries. Autoimmune conditions like lupus and rheumatoid arthritis can cause inflammation inside the eye. Even certain infections leave distinct patterns that an eye doctor can recognize. These findings don’t replace a visit to your primary care doctor, but they often serve as the first alert that something else is going on in your body.
How Often You Need One
The American Academy of Ophthalmology’s 2025 guidelines recommend the following schedule for adults without symptoms or known risk factors:
- Under 40: every 5 to 10 years
- 40 to 54: every 2 to 4 years
- 55 to 64: every 1 to 3 years
- 65 and older: every 1 to 2 years
If you have diabetes, a family history of glaucoma, or other risk factors, your doctor will likely recommend more frequent visits. People who wear contacts also typically need annual exams to keep their prescription current and check for contact-related complications.
Children’s Eye Exams
Kids follow a different screening timeline because their visual system is still developing, and catching problems early can prevent lasting issues like amblyopia (lazy eye).
A newborn’s eyes are checked at birth for basic indicators of health. Between 6 and 12 months, a second screening happens, usually during a well-child visit with a pediatrician. From 12 to 36 months, doctors look for healthy eye development and may use photoscreening, where a special camera photographs the eyes to detect alignment or focusing problems. Between ages 3 and 5, visual acuity should be tested as soon as the child can cooperate with an eye chart. If they can’t manage the chart yet, photoscreening fills the gap. From age 5 onward, regular acuity and alignment checks continue.
Young children obviously can’t sit through a “which is better, one or two?” refraction test, so their exams rely more on objective tools. The photoscreener, for instance, can detect nearsightedness, farsightedness, and unequal focus between the eyes without requiring any verbal feedback from the child at all.
Routine vs. Medical Eye Exams
You’ll sometimes see a distinction between a “routine” eye exam and a “medical” eye exam, and the difference matters mostly for insurance purposes. A routine exam focuses on updating your prescription and doing a general health screening of your eyes. It’s preventive. A medical eye exam is performed when there’s a specific complaint or a diagnosed condition, like flashes of light, sudden floaters, or a history of glaucoma. Medical exams involve more specialized testing, such as detailed visual field mapping or advanced imaging of the retina.
Optometrists handle most routine exams. They’re trained to prescribe corrective lenses and detect eye disease. Ophthalmologists, who are medical doctors with surgical training, typically handle medical eye exams and treat conditions that require intervention. In practice, many optometrists are also qualified to manage common eye diseases, so the line between the two isn’t always rigid.
The insurance distinction, however, is rigid. Vision insurance generally covers routine exams and lens prescriptions. Medical insurance covers exams for diagnosed eye conditions. If your doctor discovers a problem during what started as a routine visit, the billing may shift to medical insurance for any follow-up testing done that same day.