Keep Your Vision Healthy: Understanding Eye Tests and Diagnoses

Regular eye exams can help prevent blindness and detect other health issues

Kimberly Hayes,

AARP

Reviewed by

Stan Sack, M.D.

Comments

En español

Published September 12, 2024

Eyeball with an eye chart and colorful dots around it

AARP (Source: Shutterstock; Getty Images)

More on Eye Health

It can be easy to dismiss changes to your eyesight as an inevitable fact of getting older. However, these changes can sometimes signify serious eye conditions that can lead to vision loss or even blindness, as well as reveal potentially dangerous health issues unrelated to sight. Getting regular eye exams can help to preserve your sight and detect diseases early.

At age 45, less than 1 percent of people are likely to have low vision, which means having impaired vision that may make everyday activities like reading and driving challenging and that cannot be fixed by standard means, including glasses, medication or eye surgery. By 75, that number jumps to nearly 5 percent, and then to 15 percent by the age of 85. But losing your vision with age doesn’t have to be a foregone conclusion. Detection of low vision and other potential eye issues through a dilated eye exam can be key to getting an early diagnosis and treatment.

Eye exams can also help to diagnose conditions unrelated to sight — hypertension, high cholesterol, diabetes, aneurysms and even brain tumors — because doctors are able to directly see nerves and blood vessels in the eyes. According to the American Academy of Ophthalmology (AAO), problems found in the eye are often the first indicators of diseases that could be elsewhere in your body.

a diagram of a normal eye with descriptions of the eye parts

AARP/Shutterstock

Understanding eye parts and vision

While small, your eyeball is a complex structure with numerous parts working in sync to allow you to see.

When you should get an eye test

Recommendations for the frequency of eye exams for older adults vary slightly and depend on your age, overall health and risk factors for eye disease.

The American Academy of Ophthalmology recommends that adults get a complete eye examination at age 40 (earlier if you have an eye disease or risk factors such as diabetes, high blood pressure or a family history of eye disease). After that exam, your eye care provider can tell you how often you should have your eyes checked in the future. If you are 65 or older, you should get your eyes checked every year or two, the group says.
The American Optometric Association (AOA) recommends that people at low risk for eye problems get an exam at least every two years between the ages of 40 and 64 and annually at 65 or older.
The National Institute on Aging has slightly different recommendations, advising that everyone over age 50 have an eye exam annually, or as recommended by their eye care provider, and every year or two after age 60.

More frequent eye exams than those noted above may be needed for people with certain risk factors. These include people who:

Are of Black, Native American or Hispanic descent
Are overweight or obese (a body mass index [BMI] of 30 or more)
Have health conditions, such as diabetes or high blood pressure, that can cause eye issues or vision loss
Have a family history of eye disease
Wear contact lenses or glasses
Have a history of eye surgery, an eye injury or previous eye damage from conditions such as strokes

It’s important to talk with your doctor or eye care professional to find out the best examination schedule for you.

Common eye disorders and diseases

A full eye exam can help diagnose numerous eye conditions and diseases that can cause vision loss and even blindness. These include:

Cataracts, where the eye lens can begin to cloud and impact your vision.
Diabetic retinopathy, a condition that causes damage to the blood vessels in the back of your eye.
Glaucoma, which is caused by fluid that builds up in the front of your eye, increases pressure and damages your optic nerve, which is the connection that allows your eyes to send signals to your brain.
Age-related macular degeneration, a progressive eye disease that affects the central vision and the ability to do such everyday tasks as driving, reading or watching TV.
Presbyopia. According to the American Optometric Association, this normal change in the eyes’ focusing ability develops between the ages of 41 and 60 and continues to progress over time. It can be fixed with prescription glasses, contact lenses or reading glasses.

Types of eye doctors and eye care professionals

Ophthalmologists. These have either a medical doctor (M.D.) or doctor of osteopathic medicine (D.O.) credential. They have completed four years of medical school and another four years of residency. They can perform eye surgery.
Optometrists. Optometrists attend four years of optometry school and have a doctor of optometry (O.D.) credential. Some also choose to do a one-year residency. They cannot perform eye surgery.
Opticians. Opticians do not conduct eye exams or surgery, but they can help you pick out eyeglasses, take eye and head measurements, and adjust your eyeglasses.

9 types of eye tests

A comprehensive eye exam shouldn’t take more than 45 to 90 minutes, according to the AAO. After getting a medical history, including a family history, what medications you take and whether you wear corrective lenses, your doctor may perform the following tests.

1. Eye chart test for visual acuity

For this test, you will read an eye chart to decipher how well you can see from various distances. One eye will be covered while the other is tested.

A phoropter test can help determine what type of corrective lens you need.

Getty Images

2. Phoropter test

During this test, your doctor will have you look at an eye chart through a phoropter, which contains different lenses and can help to determine the appropriate contact lenses or eyeglass prescription for you.

3. Pupil tests

By shining a bright light into your eye, your doctor can see how your pupils respond to light. Normally pupils will respond by getting smaller. If they don’t, or if they react unequally, you could have an underlying problem with your eyes.

4. Peripheral (side) vision test

A loss of vision at the sides of your eyes, which you may not even notice in your daily life, can be a symptom of glaucoma. This can be tested with a visual field test, where you look straight ahead at one fixed point and tell the doctor when you see light or an object off to the side.

5. Eye movement test (ocular motility)

The ocular motility test evaluates your eyes’ movement. The eye care specialist will look to see if your eyes are aligned and if the muscles work properly. You may be asked to look straight ahead while the doctor moves an object in several directions and asks you to follow it with your eyes while keeping your head still. The purpose is to determine weakness or other problems in your eye muscles that could lead to double vision.

a doctor performing a tonometry test on a woman

A tonometry test is also known as an eye pressure test.

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6. Eye pressure test (tonometry)

Tonometry, otherwise known as eye pressure testing, measures your intraocular eye pressure (IOP). The test could include a quick puff of air onto the eyeball or the application of a pressure-sensitive tip near your eye. Eye numbing drops may be used. Having elevated IOP could be a sign of glaucoma.

7. Slit- lamp exam (front of the eye exam)

A slit-lamp microscope is used to light up the front portions of your eye, which include your eyelid, cornea, iris and lens. This test can help to diagnose cataracts and identify injuries to the cornea, among other conditions.

8. Dilated pupil exam (retina and optic nerve test)

Your doctor may put dilating eye drops into your eye to widen your pupil during an eye exam.

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During your visit, the ophthalmologist will likely put dilating eye drops into your eye to widen your pupil, which is the black dot in the middle of your eye. This allows the doctor to examine your optic nerve and your retina, which is a light-sensitive layer of tissue at the back of your eyeball that converts images into electric signals and sends them to your brain through the optic nerve.

Learn more about diseases that a dialated pupil exam can detect.

9. Brain and cognitive testing

Eye symptoms can sometimes be an indicator of cognitive issues, according to the Cleveland Clinic. In certain circumstances, your doctor may do a cognitive assessment by making conversation with you to make sure that you know details about yourself and your environment.

Additional eye tests include specialized imaging techniques that help to provide early detection of problems in the back of the eye, as well as on its surface and inside the eye.

What happens after the eye exam?

If your eye care professional finds that you need corrective lenses, they will provide a digital or paper copy of the prescription. The prescription could also include your pupillary distance, which is the distance between the pupils of your eyes. You need that number to buy glasses online. You may have to ask for the pupil measurement, as it’s not always routinely provided.

Your doctor may also provide recommendations for treatment and follow-up testing for other eye conditions they detect.

If your pupils are dilated during the exam, you may be sensitive to daylight and device screens for a few hours and could have trouble focusing on items close to your face. You may want to wear sunglasses or temporary shades immediately after the visit. Arranging transportation is a good idea if you are concerned about driving after eye dilation.

VIDEO: These Meals Help Keep Your Eyes Healthy

Warning signs of eye problems

Anytime you notice changes in your vision, it is a good idea to visit an eye specialist. These changes can include:

Decreased vision, such as finding it harder to read fine print or text
Fading of color vision
Squinting or eyestrain
Headaches at the end of the day
Eye pain or prolonged itching
Drainage or redness of the eye
Double vision
Floaters (tiny specks that appear to float before your eyes)
Circles (halos) around light sources
Flashes of light

When vision loss is an emergency

According to the Cleveland Clinic, unexpected or sudden vision loss in one or both eyes (partial or total) is a medical emergency. In some situations, the vision loss can become permanent, and in others, the underlying condition causing the sudden vision loss can be deadly. Sudden vision loss can look like the following:

Blurring or fading
Darkening/dimming
A black curtain or sheet covering part or all of your vision in one or both eyes
Bright flashes or lights that cover part or all of your vision

Call 911 if you experience these sudden vision loss symptoms.

Migraines can also cause temporary vision loss. It’s important to talk to your eye care specialist or health care provider to see if you need emergency care in that scenario, according to the Cleveland Clinic.

Can I check my eyesight myself at home?

A home vision test is not a substitute for an exam by a professional eye care provider and will not diagnose any underlying health conditions you may be facing. However, it can be a first step in learning more about your eye health. The AAO offers what’s known as a Snellen chart for adults along with instructions on setting up the test and determining the results.

Other possible home tests include the Amsler grid test for macular degeneration. This can be used to check if lines on the grid look wavy or distorted, or if any of the areas of the grid appear to be missing. The American Macular Degeneration Foundation provides a printable grid with instructions.

Smartphone apps are available that offer vision tests and even provide prescriptions, but they may require attaching an additional device to your phone. Your eye care provider may be able to offer more information on their accuracy.

What does your eye color say about your health?

Your eye color may signal a predisposition to certain medical conditions, such as skin or eye cancer. Additionally, some diseases, medications and traumas can make your eyes seem to change color. These changes can happen in the iris, which is the colored part of the eye, or in another part of your eye that makes the eye color appear to change.

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Kimberly Hayes is an editor-writer for AARP and has written on health and social justice issues for numerous organizations, including the National Organization for Women, the Robert Wood Johnson Foundation and the Lawyers’ Committee for Civil Rights. She previously served as editor of Native American Report.

Dr. Stan Sack practiced pediatrics for 33 years in Massachusetts and Florida. He now works as a freelance health writer and editor. His articles have appeared in several outlets, including Keys Weekly, Rural Health Quarterly and AARP.

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