How is Dry Eye Diagnosed?

Dry eye (sometimes also called dry eye syndrome or dry eye disease) is a condition that occurs when you do not produce enough tears to properly lubricate your eyes. People with dry eye may experience painful symptoms such as a burning sensation, itchiness, redness, and irritation.

If you notice any changes in your vision or experience dry eye symptoms, it’s a good idea to get your eyes tested. An eye care specialist, such as an optometrist or ophthalmologist, can help you understand why your symptoms are occurring and give you a proper diagnosis.

There is no one way to diagnose dry eye. Instead, your eyecare specialist will use a variety of tests to reach a diagnosis. Testing measures may include a verbal questionnaire about your symptoms and a combination of eye exams that test the structure of your eyelids and tear film (the fluid layer between your eye and eyelid), your ability to make tears, and how long it takes your tears to dry.  

Generally, people with dry eye are able to manage their symptoms with eye drops and lifestyle changes. However, if the condition is left untreated, you may be at greater risk for eye infections and vision loss. This is why an early diagnosis is so important.  

Questionnaire

A key first step in diagnosing dry eye is a verbal questionnaire or a series of questions about your symptoms. Your eye care specialist will likely ask you which symptoms you have, how long you have had them, and the impact they have on your daily life. 

One of the most commonly used questionnaires is the Ocular Surface Disease Index (OSDI). This index has a total of 12 questions and asks you about:

• Symptoms (e.g., blurry vision or eye pain)
• Difficulty performing tasks (e.g., reading or driving at night)
• Response to the environment (e.g., eyes hurt or become watery when it’s windy or too dry) 

It is also common for your eye care specialist to ask you questions about your lifestyle and family history. This information can help them better understand your symptoms and prepare you for a comprehensive eye exam.

If you receive a dry eye diagnosis, your eye care specialist may use similar questionnaires during your routine check-ups to see if treatment is helping.

Comprehensive Eye Exam

After your provider learns about your symptoms, the next step is to perform an eye exam. In some cases, they may dilate your eyes or use eye drops to widen your pupils (which helps more light enter your eyes). 

During your comprehensive eye exam, your eye care specialist may perform several tests. The three most common measures are the slit lamp test, Schirmer’s test, and tear break up time (TBUT) test.

Slit Lamp Test

Your eye care specialist will use a slit lamp microscope, which is a tool that allows them to look at the front and back of your eyes. Once your eyes are dilated, they will shine a light into your eyes and use the microscope to take a closer look at the quality of your tears. 

While the light may be bright, it will not damage your eyes. Let your provider know if you are sensitive to the light or experience pain or twitching during your exam.

During the slit lamp test, your provider can identify if:

• Your cornea (the outer layer of the eye) has scratches or swelling 
• Your eyes are making enough tears
• Your eyelids are swollen or irritated
• You have trouble blinking 
• Your tear film is producing balanced amounts of water, oil, and mucus 

The results from the slit lamp test may indicate signs of dry eye. However, most eye care specialists will use additional tests to confirm a diagnosis.

Schirmer’s Test 

A Schirmer’s test can help your eye care specialist measure the quantity of your tears.  To perform this test, your provider will:

• Place a small strip of filter paper on the inside of your lower eyelids, gently underneath each eyeball
• Give you numbing eye drops to minimize any irritation from the paper strips
• Ask you to close your eyes
• Remove the paper strips after five minutes 
• Measure the wetness on the paper strips

Generally, the less wet the paper strips are, the fewer the number of tears you may be producing. You may have dry eye if your tears fill up less than five millimeters of fluid on each paper strip.

In some cases, your provider may opt to use a thread to measure your tears, rather than a piece of paper. The thread test is called a phenol red test, which is a variation of the Schirmer’s test.

Most people find this exam to be mildly uncomfortable. However, you should have no other side effects after the procedure. 

Tear Break Up Time (TBUT) Test

Your eye care specialists may use a tear break up time (TBUT) test to examine how long your tear film stays wet after you blink. 

During this exam, your provider will:

• Put a small amount of harmless colored dye in your eyes
• Tell you to keep blinking until the dye spreads across your eyes 
• Ask you to keep your eyes open and look forward without blinking
• Use a slit lamp to measure how long the dye stays across the eye 

You may have dry eye if the dye dries up in less than five seconds.

Other Exams 

Your eye care specialist may choose to perform additional tests to confirm a dry eye diagnosis. Some examples of other measures include:

• Fluorescein staining: Uses a dye to check for scratches or spots on the cornea caused by injury or inflammation to rule out dry eye
• Lissamine green staining: Checks for damage to your tear film and signs of inflammation in your eyelids 
• Tear film osmolarity: Takes a small sample of your tears to check the salt concentration (a higher salt concentration can indicate dry eye)

Screening for Related Conditions

Dry eye can sometimes be hard to detect. This is because dry eye symptoms can mimic other eye concerns. That said, your eye care specialist may also test you for the following conditions.

Some people with dry eye may also have other conditions that co-occur with dry eye. These co-occurring conditions may include:

• Sjögren’s syndrome: A condition that causes dry eyes and dry mouth
• Rheumatoid arthritis: An autoimmune disease that causes inflammation in the joints
• Lupus: An inflammatory condition that makes your immune system attacking healthy tissue 
• Type 1 and Type 2 Diabetes: A group of diseases that result in high blood sugar
• Scleroderma: A condition that leads to the thickening of the skin 
• Dermatomyositis: A rare disease that causes muscle weakness and skin rash 

If your eye care specialist suspects that another condition may be causing dry eye symptoms or co-existing with dry eye syndrome, they may refer you to other healthcare providers for proper testing and diagnosis. 

A Quick Review

 Dry eye is a common condition that affects the quality and quantity of your tears. This can lead to frustrating symptoms such as redness, irritation, and blurry vision. 

An eye care specialist (such as an optometrist or ophthalmologist) can perform a series of exams to identify the cause of your symptoms and provide you with a proper diagnosis. Testing measures typically include a verbal questionnaire and a comprehensive eye exam. 

Your provider may also do additional testing for eye infections and allergies or refer you to another specialist to either rule out or diagnose you with co-occurring conditions.

Don’t wait to get tested. With an early diagnosis, you can manage symptoms with eye drops and lifestyle changes and prevent serious complications such as vision loss.