What Is an Eye Exam?

What tests may be involved and what to expect

A comprehensive eye exam, also sometimes called a routine eye exam, consists of a series of tests to measure how well you can see and to look for any problems that might be affecting the overall health of your eyes. These can include ophthalmologic conditions, such as cataracts, but also unrelated medical issues that cause symptoms that affect the structures of the eyes, such as diabetes. It can be done by an ophthalmologist or an optometrist, depending on if there are any specific things about your eyes that need to be addressed. How often you should have an eye exam depends on a variety of factors, including your overall risk for specific problems.

What to expect during an eye exam
Illustration by Cindy Chung, Verywell

Purpose

During a comprehensive eye exam an eye doctor will assess:

  • Eye muscle movement
  • Visual acuity (how clearly you see)
  • Refractive error (how light waves pass through the cornea and lens of the eye)
  • Visual field (how much you can see on either side of you while not moving your eyes)
  • Color vision
  • The physical health of your eyes and the surrounding structures, including lashes and eyelids
  • The health of the retina
  • Risk of glaucoma

During an eye exam, signs or symptoms of a health problem unrelated to your eyes also may be discovered. According to the American Academy of Ophthalmology (AAO), this is because "the eye is the only place in the body where a doctor can have an unobstructed view of our blood vessels, nerves, and connecting tissue—without the need for surgery. Examples of diseases and conditions that can be discovered during a comprehensive eye exam include diabetes, high blood pressure, autoimmune diseases, sexually transmitted diseases, and cancer."

Who Should Have an Eye Exam and How Often

Although generally regarded as a yearly event, when and how often a person should have their eyes examined depends on factors such as age, general health, risk of eye disease, and other factors. For most people, the guidelines are as follows:

Children 3 and under: Although a little one this age won't need an eye exam, the pediatrician will keep a close watch for problems such as strabismus (when the eyes are not aligned) and amblyopia (lazy eye) at regular well-child checkups.

Children ages 3 to 5: Preschoolers should have their first eye exam when they reach a stage at which they're able to cooperate with the doctor (can identify simple shapes on an eye chart, for example).

School-age children and adolescents: All kids should have an eye exam before starting first grade and every one to two years thereafter (or per the advice of their eye doctor).

Adults are advised to have regular eye exams according to this schedule:

  • During their 20s and 30s: Every five to 10 years
  • From ages 40 to 54: Every two to four years. The AAO recommends having a baseline eye exam at age 40, which is when early signs of problems may show up. "A baseline screening can help identify signs of eye disease at an early stage when many treatments can have the greatest impact on preserving vision," the organization states. This is the age at which people often begin to develop hyperopia—farsightedness, or trouble seeing close-up—and may need to use reading classes.
  • From ages 55 to 64: Every one to three years
  • From age 65 and on: Every one to two years

You may need to have your eyes checked more often if you wear glasses and/or contact lenses, have a family history of eye disease, or have a chronic condition such as diabetes that increases your risk of eye problems.

Risks and Contraindications

There are no risks associated with having a comprehensive eye exam. Women who are newly pregnant and due for an eye exam may want to make their appointment for after the first trimester based on the "very, very small" risk, if any, posed by the drug that's used to dilate the pupils, according to the AAO. The organization advises moms-to-be who have their eyes dilated to close them after the drops are placed to reduce the amount of medication that's absorbed by the body.

Before the Test

When you're due for a comprehensive eye exam, you'll want to consider which type of doctor to see. There are two practitioners who focus on vision and eye health. Here's how they differ:

Ophthalmologists are medical doctors (MDs) or doctors of osteopathic medicine (DOs). They attend medical school for four years, do a residency for four years, and often do one- to two-year fellowships in order to specialize in a particular field of interest, such as pediatrics or strabismus. Ophthalmologists can treat all eye diseases and also perform surgery, in addition to providing general eye care.

Optometrists go to optometry school for four years in order to earn a doctor of optometry degree (OD). Besides basic care and vision assessment, they are qualified to handle nearly all types of medical issues related to ophthalmology. They can prescribe medication and treat eye diseases, although some states may limit the specific conditions an optometrist can treat. Optometrists are not able to do surgery.

Which you choose will mostly depend on which you prefer, but you'll probably want to be examined by an ophthalmologist if you have or are at high risk for certain problems like adult strabismus, glaucoma, or cataracts, or you have a medical condition that can affect eyesight, such as diabetes.

Timing

A comprehensive eye exam will take at least an hour, including the 20 to 30 minutes that it takes for pupils to fully dilate after drops are put in. If you plan to shop for and be fitted for glasses at your appointment, plan to be there longer.

Location

Comprehensive eye exams can be done at the private or group practice of an eye doctor or at a freestanding or hospital-based clinic. Often, an ophthalmologist or optometrist will have an eyeglass shop on the premises so that patients can choose frames and be fitted for glasses at the same time as their appointment, if desired. Many eyeglass stores employ optometrists to give customers eye exams as well. You can even have an eye exam and purchase glasses or contact lenses from a retail store such as Target or Walmart.

Cost and Health Insurance

Health insurance will pay for routine examinations for people who have ongoing medical problems that affect eyes, but for people whose eyes are healthy, coverage for routine eye care can be baffling.

Some plans will cover an eye appointment for a medical problem (a scratched cornea, say, or an infection), but not routine check-ups. Often, a health insurance plan will include a separate rider for comprehensive eye exams. Others may be a hybrid, covering medical visits and routine exams, but the latter only at specific intervals (every two years, for instance). And still other vision plans provide coverage for glasses and contact lenses or at least offer a discount.

If you're paying out-of-pocket, the average cost of a routine eye exam with a private doctor is around $150. In some regions of the country, it could be $115 or less, and in others, more than $300. Stores that sell eyeglasses, including dedicated frame shops and big-box stores like Costco, may offer complete eye exams at a price that's less than a private doctor would charge when you purchase glasses or contact lenses.

What to Bring

You will need to have your health insurance or vision insurance card with you.

If you only wear eyeglasses, be sure to do so the day of the exam. If you wear contact lenses, put them in for the appointment, but bring your lens case and glasses. The doctor will want to look at your eyes with and without your lenses to make sure they're fitting properly. You'll need to remove your lenses for certain tests, as well as to have your pupils dilated.

Whether you wear prescription lenses of any type, bring a pair of sunglasses to wear after your visit. Your vision will be blurry and your eyes will be highly sensitive to light until the effects of the drops wear off. You may even want to have someone to drive you home after your appointment, depending on how much your vision is affected by the dilation.

In addition, bring a list of all medications you take, including prescriptions and over-the-counter and herbal supplements. Certain substances can affect vision, and your doctor will want to take that into consideration while examining your eyes. Finally, if you have an eyeglass or contact lens prescription from another provider, bring a copy of that as well.

During the Exam

All or most of your eye exam will be conducted by the ophthalmologist or optometrist, although some practices have a clinical assistant, nurse, or technician perform certain tests.

Pre-Exam

If this is your first visit to the practice, you may have to fill out routine new-patient forms and hand over your vision insurance card to be copied. Beyond that, you will start and finish your appointment in an exam room.

You will be seated in a comfortable padded chair with various medical apparatus attached that the doctor will use to perform different tests and procedures to check your vision and the overall health of your eyes.

Your exam is likely to begin with a series of questions about your vision and general health. Your doctor may ask if you:

  • Have had any eye problems in the past or are having any now
  • Have had any general health problems in recent years
  • Were born prematurely
  • Wear glasses or contacts now and how well they're working for you
  • Have had any health problems recently
  • Take any medications regularly
  • Have allergies to any medications, food, or other substances
  • Have ever had eye surgery
  • Know of family members who have eye problems, such as macular degeneration or glaucoma
  • Know if you or anyone in your family has diabetes, high blood pressure, heart disease, or other health problem that can affect the whole body

After this discussion, testing begins.

Visual Acuity

A visual acuity test is a measure of the clarity of your vision—in other words, how well you can see. The most common way to test visual acuity is with an eye chart that may be posted on the wall or projected onto a wall or screen 20 feet away from where you will be standing or sitting. Your eye doctor will ask you to read the letters on the chart starting with the bottom row, where the letters are smallest. The smallest letters you are able to read will determine your acuity.

Your visual acuity may be written as 20/20 if your vision is normal. If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet. Someone with 20/60 vision would need to move up to 20 feet away to read what a person with normal vision could read from 60 feet away. If you have less than 20/20 vision you have myopia.

Pupillary Response Testing

The way the pupils dilate and constrict in response to light can reveal a lot about the health of the eyes and the body. The nerves that control the pupil travel through a long pathway. Certain pupillary reactions can reveal neurological problems. Sometimes the acronym PERRLA is used to describe the findings of a pupillary response test. It stands for: Pupils Equal Round Reactive to Light and Accommodation—the ability of the eyes to focus on objects that are close-up and far away.

The doctor will look for uniformity between both pupils and note their shape and size prior to starting the test. He'll then move a small flashlight back and forth between the eyes every two seconds (the "swinging flashlight test") to see if the pupils get smaller in response to direct light, and, if so, if one constricts when the other does or they constrict separately (which would be abnormal). The doctor also will ask you to follow a pen or index finger as he moves it in all directions to see how well your eyes are able to stay focused on it and how the pupils respond. Normally, the pupils constrict while fixated on an object that is being moved close or far away.

Confrontation Visual Field Test

A confrontation visual field test is a quick check of your field of vision, including your central and side (peripheral) vision. Your eye doctor or a technician will sit in front of you and ask you to cover one eye. She'll then move her hand in and out of your field of vision from the sides and have you tell her when you can see it.

This test measures the muscles that control eye movement. It is usually a simple test conducted by moving a pen or small object in different directions of gaze. Restrictions, weaknesses, or poor tracking of visual objects are often uncovered.

Cover Test

This simple test measures how well the eyes work together. The doctor will have you fix your gaze on an object, cover one eye, pause, and uncover it. He is evaluating your eye as it is uncovered and re-fixes on the target. The cover test helps to detect crossed eyes (strabismus), lazy eye (amblyopia), or a decrease in depth perception.

Color Blindness Test

You may be shown a series of images called Ishihara color plates to test your ability to distinguish shades of red from shades of green, or blues from yellows. Both types of color blindness are congenital (inherited) traits and very rare—so rare, in fact, that there are no official guidelines for including the Ishihara test in a routine eye exam, according to the AAO. Most often the test is used by eye doctors as part of an overall evaluation of certain symptoms that may indicate a problem with the retina or optic nerve, such as a general decline in vision or seeing persistent dark or white spots. You can find the Ishihara color blindness test online and try it yourself. If you have trouble distinguishing numbers formed by dots of color within a field of contrasting colors, let your doctor know.

Retinoscopy

Retinoscopy is a test that gives your eye doctor a way to measure refraction. Usually performed early in an exam, retinoscopy provides your doctor a starting point to estimate your prescription for glasses, if needed.

Refraction

Refraction is a subjective test to measure nearsightedness, farsightedness, astigmatism (irregularity in the curvature of the cornea that can cause vision to be blurry), and/or presbyopia. The doctor positions a phoropter, an instrument that has a lot of different lenses representing different degrees of vision correction on it, in front of your face. As you look through the instrument, the doctor will have you look at an image through two different lenses and state which is clearer.

This will be repeated using different lenses and combinations of lenses until the doctor determines which will correct your vision most adequately. The results of a refraction test are primarily what the doctor uses to develop your final eyeglass and/or contact lens prescription.

Slit Lamp Examination

To examine the front and back of your eye as part of an overall test of general health, the doctor will use an instrument called a slit lamp, or biomicroscope. It both magnifies the eye many times and illuminates it with a bright light so individual structures can be examined, including the lids and lashes, conjunctiva (the membrane that lines the eyelid and white of the eye), cornea, iris, lens, and anterior chamber. This will reveal any defects or diseases of the eye, such as cataracts.

Applanation Tonometry

Applanation tonometry is a method for measuring fluid pressure, or intraocular pressure (IOP), which can indicate the risk of developing glaucoma. To do this, the doctor will put a drop of anesthetic into each eye, followed by a small amount of fluorescein (yellow dye). He will then move a small device called a tonometer close enough to your eye to gently touch the cornea, which is why it's made slightly numb. The tonometer determines intraocular pressure by measuring the resistance of your cornea to indentation.

Some physicians prefer to measure eye pressure with the "air puff test" in which a non-contact tonometer (NCT) exerts a painless puff of air onto the cornea to measure the pressure. This, however, is considered to yield less accurate results.

Retinal Examination

Sometimes called funduscopy or ophthalmoscopy, this typically is the last step in a comprehensive eye examination. It starts with pupil dilation. Your eye doctor will place drops of a medication that will cause your pupils (the black circle in the very middle of the colored part of the eye) to increase in size. This gives the doctor a larger window through which to inspect the inside structures of the eye, including the retina, vitreous, optic nerve, blood vessels (choroid), and macula.

It takes 20 to 30 minutes for your pupils to fully dilate. You may stay in the exam chair while this is happening or be asked to return to the waiting room.

Once you're dilated, the doctor will put an instrument called a binocular indirect ophthalmoscope (BIO) on his head. This frees his hands so that he can operate a powerful lens on the BIO that emits light into your eye, allowing him a clear view of the entire back of the retina and the optic nerve. (When the pupil isn't dilated, only small portions of the retina and nerve are visible.) The dilated fundus examination is a crucial part of an eye exam, as many eye diseases can be detected with the test.

Interpreting Results

Your doctor will be able to share the results of your exam while you're still in the exam room.

Normal results from an eye exam include:

  • 20/20 vision
  • Good peripheral vision
  • Ability to distinguish various colors (if tested for)
  • Normal-appearing structures of the external eye
  • Absence of cataracts, glaucoma, or retinal disorders such as macular degeneration

Because so many different aspects of visual acuity and eye health are evaluated during a comprehensive eye exam, it's possible to have just one abnormal result among a long list of normal ones. A few examples include:

  • High eye pressure: The range of normal for eye pressure, which is measured in millimeters of mercury (mmHg), is between 10 and 21 mmHg. If yours is higher, it's an indication of glaucoma.
  • Decline in peripheral vision: If the visual field test reveals that you have lost some of the distance you can see above, below, or on either side of you without moving your eyes, it can be a sign of a problem with the part of the nervous system that controls sight or the beginning stages of glaucoma. Your eye doctor will monitor your field-of-vision results at subsequent routine eye exams.
  • Clouding of the lens of the eye: During a slit lamp exam, the doctor may notice that the lens of your eye isn't as clear as it should be, meaning you've developed a cataract in that eye.
  • Separation of the retina from the structures that surround and support it: This is a symptom that is also picked up during a slit lamp exam. It means that your retina has detached.
  • Loss of sharp vision: Again, as a result of the slit lamp exam, this finding can indicate macular degeneration, a leading cause of blindness. If this and certain other findings lead to a diagnosis of this condition, you'll need to see a specialist.

    Post-Exam

    If the visual acuity test showed that you need corrective lenses or a change to your current prescription, your doctor will write that out for you. You can use that to purchase contacts, pick out frames for an entirely new pair of glasses, or simply have your current eyeglass lenses swapped out at a shop of your choosing. You will also need to submit a copy of this prescription if you are buying from an online retailer. If you want to try contact lenses, you will need to schedule a separate exam to be fitted for them.

    You will then be free to leave. If you want to put contact lenses back in, ask if it's OK to do that. Note, though, that wearing contacts may be irritating while your pupils are still dilated. You also will want to put on the sunglasses you brought before you head outside, especially if it's really bright. Your vision may be a bit blurry for several hours. If you brought someone to drive you, let them, or take public transportation, a taxi, or a car service.

    Follow-Up

    If the visual acuity tests show that your distance vision is 20/30 or better (there is such a thing as 20/15 vision), that you are able to read at a normal distance, that you don't have astigmatism, and that your overall eye health is normal, you will not need to be tested until your next exam.

    If your doctor discovered a problem with the health of your eyes, such as glaucoma or cataracts, you will need more testing and/or treatment to address the issue directly. The same holds if your exam revealed signs of a non-ophthalmological disease or condition that can be detected via an eye exam. In that case, the doctor will refer you to your primary care physician or to a specialist.

    A Word From Verywell

    According to the U.S. Centers for Disease Control and Prevention, as many as 61 million adults in the United States are at high risk for vision loss, but only half see an eye doctor as recommended. Fewer than 15 percent of preschool children get an eye exam and less than 22 percent receive vision screening. Most eye problems can be detected before they cause symptoms or serious vision problems, so it makes sense to be proactive and have a checkup (or make sure your family members do) regularly. It only takes an hour or so of safe and painless testing to make sure that you and your loved ones are able to view the world clearly and with healthy eyes.

    Was this page helpful?
    Article Sources