What Causes Dry Eye?

You can get dry eye if your eyes don't make enough tears or dry too quickly. Medications, environmental factors, and lifestyle habits can also increase risk.

older woman experiencing eye pain

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Nearly 16 million Americans have dry eye, a frustrating condition that makes your eyes sting, burn, and feel scratchy. The condition happens when there’s a problem with your tears: either you don’t make enough of them or they dry up too fast—which makes it hard to keep your eyes lubricated (or, wet). 

In some cases, dry eye can be a side effect of other health conditions. Other risk factors and lifestyle habits can also increase your risk of developing the condition.

You Don’t Make Enough Tears

When you blink, a thin layer of tears called the “tear film” coats your cornea, the outer surface of your eye. Tears are made in the glands above your eyes and then travel through your tear ducts and nose. Tears help clear debris out of your eye and keep the surface moist. Think: windshield wipers that wipe off dirt or dust from your car window.

When your tears are functioning normally, your eyes are constantly making tears to help keep your eyes lubricated. However, problems with your tear glands can cause your eyes to produce fewer tears—which can increase your risk of developing dry eye.

There are several reasons your eyes may not be making enough tears. Some include: 

  • Getting older
  • Taking certain medications (e.g., antihistamines or antidepressants)
  • Wearing contact lenses
  • Exposure to environmental factors like dust, wind, air conditioning, or cigarette smoke
  • Not blinking enough

Your Tears Dry Too Quickly

Even if your eyes make plenty of tears, they may dry too quickly and prevent your tear film from keeping your eyes moist. This can happen if there’s a problem with the quality of your tears. 

Your tear film has three layers: the oily layer, the aqueous layer, and the mucus layer. 

  • Oily layer: The oily layer makes up the outside of the tear film. It is made in the eye’s meibomian glands (tiny oil glands) along the edge of the eyelids. The purpose of the oily layer is to prevent the tears from drying up too quickly. But sometimes, the oily layer can become hard and thicken, causing the glands to get clogged. As a result, the oily layer doesn’t function as it should, and your tears evaporate prematurely. 
  • Aqueous (watery) layer: The aqueous (or, watery) layer is the middle of the tear film. The majority of your tears come from the watery layer. This layer is made in the eye’s lacrimal glands (tears glands) in the eyelids and works to clean debris out of the eyes. Damage to this layer can affect the balance of your tear film and cause your tears to dry too quickly. 
  • Mucus layer: This is the inner layer of the tear film. The mucus layer helps the watery layer coat the eye’s surface and stay put. Mucus is made in the conjunctiva, the clear tissue that covers the white part of your eye and the inside of your eyelids. The mucus layer is the foundation of the tear film—thus, any issues with this layer can also affect the watery and oily layers from properly functioning. 

If there is any issue with one or more of these layers, your tear film won’t be able to keep your eyes lubricated. Damage to these layers can happen for several reasons, such as allergies, rubbing your eyes too much, hormonal changes, or inflamed eyelids or glands.

Is Dry Eye Hereditary?

Dry eye may be hereditary, but right now, the research on the link between dry eye and genetics is limited. 

Researchers conducted one study with nearly 4,000 pairs of twins and found that identical twins were more likely to share a dry eye diagnosis than fraternal twins. This suggests that genetics may play some role in dry eye. But further research is needed to build upon this theory. The authors of a different research study published a review that stated that there are too many gaps in current research to understand if and how genetics might play a role in dry eye.

Who Gets Dry Eye?

Anyone can get dry eye, but some people are more likely to develop dry eye than others. 

  • Age: People who are 50 or older tend to experience dry eye more often. This occurs because your eyes have to work harder to make tears as you age.
  • Sex: Dry eye is more common in people assigned female at birth—especially those who have gone through pregnancy and menopause. The hormone changes that happen for people assigned female at birth can make it harder for the body to make tears.

Risk Factors of Dry Eye 

Certain risk factors can increase your chances of dry eye.

Medications

Dry eye is a common side effect of many prescription and over-the-counter medicines. These medications include:

  • Diuretics (water pills) for high blood pressure
  • Beta-blockers for heart problems or high blood pressure
  • Allergy medicines (antihistamines)
  • Cold medicines
  • Sleeping pills
  • Anxiety and antidepressant medicines
  • Heartburn medicines
  • Non-steroidal anti-inflammatory drugs (NSAIDs) for pain and inflammation 

Health Conditions

Dry eye can be a symptom of many health conditions, including:

  • Diabetes: 54% of people with diabetes have dry eye. Low levels of insulin affect the function of the lacrimal gland—the gland that makes the watery parts of your tears. This can lead to a decrease in how many tears your eyes produce. High blood sugar can also cause inflammation in your eyes and interfere with the oils that prevent your tears from evaporating.
  • Sjögren’s syndrome: In this autoimmune disorder, the body’s white blood cells attack healthy tissues—including the glands that keep our eyes wet. Sjögren’s syndrome also co-occurs with other autoimmune conditions, such as rheumatoid arthritis and lupus. Living with any one of these three autoimmune diseases can increase your risk of dry eye. 
  • Eye allergies: You may have eye allergies if your immune system overreacts to something in the environment, like dust, dirt, or air pollution. When this happens, your immune system releases substances that cause the eyes to get itchy and watery.
  • Thyroid eye disease: Thyroid eye disease is a rare disease that causes inflammation and damage to the tissues around the eyes. Inflammation and damage happen slowly and can cause symptoms like pain, bulging eyes, inflamed eyelids, and dry eye as a result.

Lifestyle Habits

Certain lifestyle habits may be drying your eyes out without you realizing it. This includes looking at screens for long periods of time, reading (especially in poor lighting), and other activities that may lead you to blink less.

Wearing contact lenses can also increase your odds of receiving a dry eye diagnosis because the lenses can separate the tear film. As a result, your eyes may produce less water in the aqueous layer of your tear film.

Surgeries

Dry eye can be a side effect of certain eye surgeries. Mainly, refractive eye surgeries that correct nearsightedness and farsightedness, such as LASIK. Eye surgeries can decrease tear production and raise your risk of developing dry eye symptoms.

Environment

Exposing your eyes to irritants like chemical fumes, cigarette smoke, pollution, wind, dust, and dry air can make your tears dry up faster, leading to dry eye. Though most of these irritants are hard to avoid, you may find it helpful to wear sunglasses outside and stay away from environmental conditions that can increase your risk of developing symptoms.

A Quick Review

Dry eye affects millions of Americans. Some of the most common symptoms include stinging, burning, and a scratchy feeling in the eyes. This condition happens when there is an issue with the quantity or quality of your tears: Either your eyes don’t make enough tears or the tears they do make don’t protect your eyes well. 

You’re more likely to get dry eye if you're 50 or older or were assigned female at birth. Dry eye is also a side effect of certain medications, health conditions, surgeries, environmental factors, and lifestyle habits. 

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Sources
Health.com 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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