What to expect during an eye exam

It’s easy to take your vision for granted, especially if you’re not experiencing any unusual symptoms or discomfort. “Some eye conditions can become very advanced — and even cause blindness — without any pain or a lot of symptoms,” says Chantal Cousineau-Krieger, M.D., an ophthalmologist at the National Eye Institute. “An illness like glaucoma can happen so slowly that the person may not even notice until it is too late. This is why it is so important to get eye exams.”

“The frequency of eye exams depends on age,” says Dr. Cousineau-Krieger. The American Optometric Association (AOA) recommends that children get an eye exam at 6 months and 12 months of age, then again between 3 and 5 years old. They should also get an eye exam before entering first grade, then once a year after that until age 17. The AOA recommends that adults get an eye exam annually.¹

A comprehensive eye exam is especially important after age 40. That’s because the exam may find early signs of illness or changes in vision that start to appear at this age, according to the AOA.² And if you are 60 or older, your eyes should be checked every year for signs of age-related eye diseases.³

Of course, there are exceptions. Call your eye care provider right away if you have:

• An eye infection
• Eye pain
• An eye injury
• Sudden flashes of light
• Floaters
• Patterns of light

If you wear contact lenses, you should get an exam every year. If you have diabetes or a family history of eye disorders, ask your eye care provider how often you should have an eye exam.

The entire exam may take about an hour (or more).⁴ An optometrist or ophthalmologist will screen for early signs of eye disease and any other changes to your eye health.

To start, you’ll be asked questions about your general health history, eye health history, and family eye health history.

Then your eye care provider will do a few tests to evaluate your vision and eye health:

Each eye is tested individually for this. “There will be some kind of chart that the patient looks at and reads. It consists of either letters, numbers or symbols that get progressively smaller,” explains Dr. Cousineau-Krieger.

Typically, the Snellen eye chart or the Random E test will be used. For the Snellen eye chart, you will stand or sit 20 feet from the chart and be instructed to read each row as far as you can see. For the Random E test, the capital letter E gets smaller in size and changes direction. The test is completed when you can’t tell which direction the E is facing. When children have a visual acuity test, they may be given cards with symbols or letters to match with those on the chart.

Sometimes an overlay with multiple small perforations is placed over the eye. This is called a pinhole test. You will look through the pinhole to see if it helps you read the smaller letters. The pinhole test is a quick way to tell whether glasses will help you see things a little better, as explained by Dr. Cousineau-Krieger.

Eye care providers use a tool that looks like a microscope with a bright light on it to look inside and outside of your eyes. “It creates a cross section of the eye — so we get a magnified view of the structure of the eye,” Dr. Cousineau-Krieger says. “It is part of every eye exam.”

Dilating eye drops enlarge your pupils and keep them from getting smaller when the light shines into your eyes. It allows your eye care provider to look at the back of the eye for any signs of disease. It is a painless process, although you may have blurry vision and/or sensitivity to light for a few hours afterward. “A lot of people don’t want to get a dilated exam; but you really can’t assess the health of the eyes without dilating them,” says Dr. Cousineau-Krieger.

If any abnormalities are seen during the slit-lamp evaluation, further testing will be done. Most commonly, these tests may include a fundus photo — which is a photograph of the retina — or optical coherence tomography (OCT). OTC uses reflected light to create pictures of the back of your eye.

Eye pressure — also called intraocular pressure — is a measurement of the fluid pressure inside the eye. It’s like a blood pressure measurement. Your eye is numbed with eye drops for this test. Your eye care provider uses a tool called a tonometer to measure how your cornea resists slight pressure; this test helps determine your eye pressure. Having eye pressure that’s too low or too high can damage your vision.

During an eye exam, your eye care provider is typically looking for the following:

With cataracts, the lens of your eye, which bends (refracts) light rays that come into the eye, becomes cloudy. It is like looking through a foggy or dusty car windshield, making things look blurry, hazy or less colorful. More than half of all Americans ages 80 and above have either had cataracts or the surgery to remove them, according to the National Eye Institute.⁵

This disorder can develop in people with diabetes. High blood-sugar levels damage the blood vessels in the retina, causing them to leak or swell. Sometimes the blood vessels close, which stops blood from passing though. Other times abnormal new blood vessels grow on the retina. These changes can cause vision loss. In the early stages of diabetic retinopathy, you may be able to retain some or all your vision by lowering your blood sugar levels.⁶

In this condition, the macula, an area in the back of the eye, becomes damaged. This causes blurry central vision. In the early stages, there are usually no symptoms. In the later stages, you lose your central vision and are unable to see fine details, whether you are looking at something close or far. AMD is the leading cause of vision loss in people over age 50.⁷

This is the second leading cause of blindness worldwide, according to the Centers for Disease Control and Prevention (CDC).⁸ Glaucoma is a group of disorders that damage the optic nerve in the eye. Around 3 million Americans live with glaucoma, which can cause vision loss and even blindness. The most common form, open-angle glaucoma, results in increased eye pressure. Since there are often no early symptoms, half of all people with glaucoma don’t know they have the disease.

The bottom line: An eye exam is relatively simple and comfortable; it can catch vision conditions early so they can be treated. This prevents more serious damage and helps ensure that you have healthy vision for years to come.