What Are Dry Eye Tests?

What to Expect When Undergoing These Tests

Dry eye tests are done to help find out if you have dry eye syndrome. Dry eye syndrome is when you do not have enough tears or your tears are of poor quality. There are several tests used for dry eye syndrome. This article will describe the tests to expect, how to prepare, what happens during the tests, and how results are interpreted.

Young woman having a slit lamp exam.

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Purpose of the Tests

An eye doctor often will test for dry eye if you have complaints about dry eye–related symptoms. Tests for dry eye have several purposes, including:

  • They help the eye doctor to diagnose what type of dry eye you have, which will guide treatment.
  • The tests confirm that you actually have dry eye vs. another eye-related problem.
  • The tests can give specific information about the quality or quantity of your tears.

Eye doctors usually need more than one type of test to gain a better understanding of your dry eye. For this reason, it's common to undergo more than one dry eye test done during an exam.

Risks and Contraindications

There are no risks or contraindications associated with the tests for dry eye. These tests can be done on people of any age or condition and are well-tolerated.

Before the Tests

Before your dry eye tests, give some thought to your dry eye symptoms. This can provide the eye doctor with helpful information. Your eye doctor will use your information, along with the test results, to diagnose your dry eye. Some questions to ask yourself include:

  • When are my dry eye-related symptoms worse?
  • Is there anything I do that soothes my dry eye symptoms?
  • How long have I had these symptoms?
  • What medications do I use? Some over-the-counter (OTC) and prescription medications can lead to dry eye. Consider any supplements you use as well.

You can note these answers on paper or on an electronic device.

Timing

Tests for dry eye should only take a couple of minutes each. They may be part of a more general eye exam, which could take about a half hour. Or, you may have to return another day for a dry eye assessment. The eye doctor should be able to share the test results while you are in the office.

Location

Dry eye tests usually take place in an eye exam room. The room may be somewhat darkened.

What to Wear

You do not need to wear any special clothing for dry eye tests. If you wear contact lenses or eyeglasses, you will need to remove them before an eye exam or dry eye tests.

Food and Drink

You can eat and drink normally before your dry eye tests.

Costs and Health Insurance

Check with your eye doctor or insurance company in advance to find out what costs are involved with dry eye testing. If you have insurance, some tests for dry eye are considered part of the exam and are not billed for separately. This includes a slit lamp exam, staining the eye with fluorescein to look for dry eye, and Schirmer tear testing.

Other dry eye tests may be covered by insurance if they are considered medically necessary. This means that you have symptoms of dry eye that require an eye doctor to further examine you.

What to Bring

Bring any paperwork required by your eye doctor to your eye appointment. This includes a health insurance or vision insurance card (if you have insurance) and valid identification. If you have any notes about your dry eye symptoms, bring them as well.

Other Considerations

Find out in advance if the eye doctor will dilate your eyes during the exam. Dilation will always be part of a comprehensive eye exam, which can also include dry eye testing. Dilation is not needed if your dry eye testing takes place at another visit.

Eye doctors use a dilated eye exam to check the back of your eye for diseases like glaucoma and macular degeneration. Dilation makes your eyes more sensitive to light for a couple of hours. You usually will need someone to drive you home after a dilated eye exam.

During the Test

Pretest

There usually is no preparation needed for dry eye tests. If you are having a type of test called a Schirmer test, a technician or the eye doctor will give you drops to numb your eyes to prevent tearing and irritation.

Throughout the Test

Slit Lamp Exam and Fluorescein Staining

During an eye exam, the eye doctor will examine your eyes using a slit lamp. This is a microscope with a bright light to help the doctor examine in and around the eye.

Using the light from the slit lamp, your eye doctor will get a closer look at your cornea, or the front, dome-shaped part of your eye. This is where the doctor will check for signs of dry eye, damage to the cornea, or cataracts. The light from the slit lamp will be bright but will not cause eye damage.

Your eye doctor may use a fluorescein strip or insert drops of this yellow dye to check for damage to the cornea while also checking for signs of dry eye. The fluorescein strip is wet with saline (saltwater solution). Then the doctor touches the strip to your inner lid or the white of your eye. This does not hurt—there is no pain or stinging with this method.

But sometimes the fluorescein drops are used if a numbing drop is needed to do other tests, such as for eye pressure, since there is both a dye and anesthesia in these drops. (These are not the same as dilating drops.) Some people feel a slight stinging sensation when these drops go into the eye.

Schirmer Test

During a Schirmer test, the eye doctor will place a thin paper strip inside the lower eyelids of each eye. They will test both eyes at the same time.

For most Schirmer tests, you will keep your eyes closed for five minutes. Close your eyes gently, not tightly, to ensure the most accurate results.

When the five minutes are up, your eye doctor will remove the paper strips to see how moist they have become.

Tear Breakup Time Test

Also called tear film breakup time, or TBUT, this test measures how long the layers of tears on your eyes last after you blink.

With TBUT, the eye doctor will place fluorescein dye in your eye. Next, you will be instructed to blink so the dye can cover your eye. You will then look forward without moving your eyes or blinking. The eye doctor will measure how long your eye is covered by the dyed tear film.

Posttest

You will be able to leave the eye doctor's office after the tests are finished. As you leave the eye doctor's office, you will pay any fees and discuss scheduling for any follow-up appointments. A follow-up a few weeks or months later can help determine if the treatments you are using have helped your dry eye syndrome.

If your eyes were dilated as part of the examination, you will need someone else to drive you home. Eyes can remain dilated for three to four hours, or longer.

After the Test

After your dry eye tests, your eye doctor will share the results immediately. The doctor will also recommend treatment based on the results.

Do not rub your eyes for 30 minutes after a Schirmer test. For any test, ask your eye doctor or the practice staff when you can reinsert your contact lenses if you usually wear them.

Managing Side Effects

The tests used for dry eye should not cause any side effects. If your doctor used fluorescein dye, your eyes may appear slightly yellow from the stain. However, this should go away quickly.

Interpreting Results

The eye doctor should have the results from your dry eye tests as soon as the tests are completed.

A slit lamp exam could reveal a scratch, irritation, or dryness on the cornea (the clear dome covering the front of the eye) as well as other problems. Depending on the findings, the eye doctor will direct treatment, such as OTC eye drops, prescription eye drops, or controlling your environment to reduce dryness.

The results from a Schirmer test are measured in millimeters. A measurement of 10 millimeters of moisture on the paper strips after five minutes indicates normal tear production. A measurement of less than 5 millimeters indicates lower tear production. Your doctor will let you know if you may need certain dry eye treatments.

For the TBUT test, a breakup time of fewer than 10 seconds is considered abnormal and may indicate dry eye. You and your eye doctor will talk about any possible treatments.

Follow-Up

As your dry eye syndrome gets treated over several weeks or months, your eye doctor may want to repeat some of the tests. The tests can indicate if your dry eye has improved.

Your eye doctor will let you know how often the tests should be repeated. It may depend on how long it usually takes for your treatment, such as a prescription eye drop, to help relieve your symptoms.

Summary

Dry eye tests can help confirm if you have dry eye and what type of dry eye you have. There are several tests an eye doctor may perform. These include a slit lamp exam with staining, a Schirmer test, and a tear breakup time test.

A Word From Verywell

The symptoms of dry eye can range from mildly irritating to debilitating. Knowing what type of dry eye you have will make it easier to find potential treatments to improve it. Treatments for dry eye have expanded in recent years. That means you have more options to improve your symptoms.

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10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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