For many people, going to the eye doctor can feel a little confusing or even intimidating. With so many machines, bright lights, and unfamiliar terms, it’s easy to feel overwhelmed. But understanding what happens during an eye exam—and why—can help make the experience smoother and more reassuring.
Regular eye exams are important, not just for checking if you need glasses, but also for detecting serious eye conditions early, like glaucoma, macular degeneration and diabetic eye disease. In this article, we’ll break down the common tests and tools your eye doctor may use during your eye exam.
Why do eye exams matter?
Before diving into the tests that occur during an eye exam, let’s talk about why eye exams are so important. Even if you think your vision is perfect, eye exams can reveal hidden problems that don’t cause symptoms right away.
Early detection means better chances of treatment and preserving your sight. Your eye doctor can detect signs of more than 270 health conditions during your annual eye exam—including diabetes and high blood pressure, as well as eye conditions such as glaucoma and diabetic eye diseases. Eye conditions like these can damage your eyes slowly and silently.
What are common eye tests and what do they do?
Here are 12 of the most common tests your eye doctor might perform during a typical eye exam. Nine of the tests are done without pupil dilation, and three optimally use pupil dilation to get the best result.
1) External ocular examination
Your optometrist or ophthalmologist examines the visible external parts of the eye, such as the eyelids, eyelashes, tear ducts, sclera and cornea (the white part and clear surface of the eye, respectively), and the area around the eyes.
With this simple exam, signs of irritating conditions such as dry eye or allergies or even a blocked tear duct can be identified.
2) Visual acuity test
This is the eye test most people think of when they picture an eye exam. The technician will ask you to read a chart—the snellen “E” chart—with progressively smaller characters, one eye at a time first, then both eyes.
The visual acuity test can also be done with glasses or lenses for comparison to your uncorrected vision.
3) Extraocular motility and vergences (cover test)
The cover test checks how well your eyes work together. The eye doctor will ask you to focus on a small object while covering and uncovering each eye.
A cover test helps detect lazy eye (amblyopia), eye misalignment (strabismus), or problems with depth perception.
4) Visual field screening
During a visual field screening test, you’ll stare ahead at a fixed point and let your doctor know when an object enters your peripheral vision. The test could be done with a target, such as a finger or penlight, or in an automated machine.
A visual field screening checks your peripheral vision—how well you can see things out of the corners of your eyes. It’s important for detecting glaucoma, brain tumors, or stroke-related vision loss.
5) Pupillary evaluation
With a small penlight, your technician will observe the responses of both pupils, one at a time, by moving the light around or turning it on and off. You may also be asked to focus on a close object to check if your pupils contract as expected.
A pupillary evaluation can identify conditions affecting coordination between the eye and the brain.
6) Tonometry (puff test)
Glaucoma is a condition where pressure builds up in the eye and damages the optic nerve. One common way to test for glaucoma is to measure the pressure inside your eye with a tonometer.
The most often used puff of air tonometer used on eyes is a non-contact tonometer. There are also other types of tonometers that have a small probe that gently touches the eye. This is called contact tonometry. Don’t worry about this part of the eye exam—it’s quick and painless and will help your eye doctor determine if glaucoma is an issue or not.
7) Objective refraction
Objective refraction is an automated vision assessment using a machine. You’ll gaze at a simple scene through a viewer, and the machine can determine a starting point for your corrective lens prescription.
Objective refraction can speed up the process of determining your prescription.
8) Keratometry
You’ll look into a machine called a keratometer that measures the curvature of your corneas. This test is important to determine astigmatism, fit for contact lenses, follow up on eye surgery such as LASIK, or a part of an eye surgery work up/pre-op.
9) Subjective refraction
Starting from the results of your objective refraction test, the optometrist will have you look at a Snellen chart again, this time with corrective lenses (called a phoropter) placed in front of your eyes. They will adjust the lenses for each eye, one at a time, and ask you which of two settings is clearer.
By answering “one” or “two” through a series of choices, you’ll determine which prescription works best to correct your vision.
Is pupil dilation necessary for eye tests?
To get a better view inside your eyes for several tests, your doctor may use special eye drops to temporarily dilate your pupils. Is it necessary to dilate the pupils? To get good test results, absolutely! Dilating your eyes makes it easier to see the retina and optic nerve. Afterward, your vision will be blurry and light-sensitive for a few hours, so bring sunglasses—and someone to drive you home!
10) Slit lamp exam
A slit lamp exam uses a special microscope that shines a thin beam of light into your eye. It lets the eye doctor look at the front parts of your eye, including the eyelid, cornea, iris, and lens.
The slit lamp exam is essential for spotting signs of cataracts, infections, dry eye, and other issues. During a slit lamp exam your eye doctor gets an anterior view of the eye without dilation, but it’s possible that your pupils may be dilated so the structures in the eye are easier for your eye doctor to examine.
11) Ophthalmoscopy
Ophthalmoscopy is done with a hand-held lens or a headset with magnifying lenses and a light to examine the inside of each eye. Overall eye health can be assessed with an ophthalmoscopy test, as well as finding issues that contribute to “floaters” in your eyes.
12) Fundus exam (plus optional retinal image test)
The fundus examination continues from the ophthalmoscopy, also using a magnifying lens and a light—this time to examine the back surface of the eye.
Optionally, a retinal image test can be performed. This uses a high-resolution camera to take pictures of the back of your eye, including the retina, optic nerve, and blood vessels. This retinal image can then be referred to in future exams to watch for changes over time.
Both eye tests help detect diseases like diabetic retinopathy, macular degeneration, and more.
What tools does an eye doctor use during an eye exam?
Across the many tests mentioned in this article, a number of critical tools help your optometrist or ophthalmologist assess your eye health and need for correction. Here are some tools used in comprehensive eye exams:
1) Snellen chart
As mentioned earlier, this is the chart with large and small letters used in visual acuity tests. It helps measure how sharp your vision is from a distance. Using a Snellen chart is what gives you metrics like “20/20 vision”.
2) Phoropter
This is the big device with multiple lenses that the doctor flips in front of your eyes while asking, “Which is better, lens one or lens two?” A phoropter helps find your exact glasses or contact lens prescription. Because it depends on your perception, it’s important to focus on this test—no pun intended!
3) Autorefractor
An autorefractor automatically measures how light changes as it enters your eye, giving a rough idea of your prescription. An autorefractor is often used before the doctor fine-tunes your results with the phoropter.
4) Keratometer
A keratometer measures the curve of your cornea (the clear front surface of your eye). It’s important for fitting contact lenses and diagnosing conditions like astigmatism.
What to expect during your exam?
A full eye exam typically lasts between 30 and 60 minutes. You may not need every eye test listed above—your eye doctor will choose based on your age, vision, and medical history. Children, older adults, and people with certain health conditions may need more frequent exams.
Final thoughts: Stay on top of your eye health
Understanding the tests and tools used during an eye exam helps take the mystery out of the experience. Whether you’re updating your glasses prescription or checking for hidden problems, regular eye exams are a key part of staying healthy.
Quick tips for your next eye exam:
- Bring your current glasses or contact lenses.
- Make a list of any vision problems you’ve noticed.
- Know your family’s eye health history.
- Be ready to disclose any systemic health conditions and current medications/vitamins.
- Be ready for possible pupil dilation—bring sunglasses and avoid driving right after.
If it’s been more than a year since your last visit, consider scheduling an appointment today. Staying on top of your eye exams is made simpler with a vision insurance plan from VSP® Individual Vision Plans.
VSP vision insurance is widely accepted—with over 39,000 providers—and offers a solid range of vision benefits and advantages.
To get the most out of your vision plan:
- Learn about frequently asked questions regarding coverage and benefits.
- Use the VSP Find An Eye Doctor tool to find an in-network provider or participating doctor or clinic.
Whether you’re due for an annual eye exam or just need a new pair of glasses, knowing where to use your VSP vision benefits can help you save both time and money. Get started with the VSP Individual Vision Plan Selector today.
Information received through VSP Individual Vision Plans’ social media channels is for informational purposes only and does not constitute medical advice, medical recommendations, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
Reviewed by Dr. Valerie Sheety-Pilon:
Dr. Valerie Sheety-Pilon is Vice President of Clinical and Medical Affairs at VSP Vison Care where she helps drive strategic initiatives aimed at raising awareness about vision, eye health and its connection to overall wellness, while providing insight into medical advancements that seek to benefit patient care. She also provides oversight of VSP programs to address gaps in care for some of the most high-risk populations, including those living with diabetes.
With more than two decades of experience as a Doctor of Optometry, Dr. Sheety-Pilon has dedicated much of her time to clinical research across numerous ophthalmic subspecialties and has an established history of helping patients through novel therapeutic agents and clinical adoption of transformative technology in the areas of digital health, pharmaceuticals, and medical devices.
Prior to joining VSP Vision in 2019, Dr. Sheety-Pilon served as Adjunct Clinical Professor at Illinois College of Optometry, held various executive positions within the eye health industry, and has extensive experience managing and practicing within an ophthalmology and optometry practice.
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