Dry eye tends to be more common in women. Illustration by The Epoch Times, Shutterstock
Dry eye syndrome affects millions of Americans every year.
Dry eye, also known as dry eye syndrome and keratoconjunctivitis sicca (chronic dry eye), is a common condition affecting nearly 16.4 million Americans, or about 6.8 percent of the U.S. adult population. It occurs when the eyes don’t produce enough tears or when the tears don’t function properly, leading to dryness, irritation, and discomfort.
Dry eye syndrome has two main causes: insufficient tear production and rapid tear evaporation. Illustration by The Epoch Times, Shutterstock
What Are the Symptoms and Early Signs of Dry Eye?
Symptoms of dry eye can vary in intensity and frequency. They often worsen during activities that require prolonged focus, such as reading, working on a computer, or watching television. While some people experience mild discomfort, others may have more persistent irritation.
Common Sensations and Discomfort
Many people with dry eyes describe a gritty, burning, or stinging sensation in their eyes as if something is stuck inside. Some also experience pressure behind the eyes or sharp, stabbing pain. A heavy feeling in the eyelids or difficulty keeping the eyes open can also occur, especially after prolonged use of screens.
Vision-Related Symptoms
Blurred vision—particularly when it fluctuates—can be an early sign of dry eye. Sensitivity to light is also common and may make it uncomfortable to be in bright environments. Frequent blinking or excessive tearing can paradoxically signal dryness, as the eyes may produce extra tears in response to irritation.
Changes in Eyelids and Tear Production
Dry eye can also affect the eyelids, leading to eyelid twitching, inflammation, or a lack of tears when crying. Some people may notice crusting or clumping of the eyelashes, particularly upon waking.
Additional Symptoms
Redness is a common sign of dry eye and may worsen with certain over-the-counter eye drops, which temporarily shrink blood vessels to reduce redness. However, once the effect wears off, the redness can return even stronger. Many people also experience discomfort while using digital devices, as prolonged screen time reduces blinking, which can increase dryness and irritation.
What Causes Dry Eye?
Tears are essential for keeping the eyes moist, removing particles, and ensuring clear vision. Dry eye syndrome has two main causes: insufficient tear production and rapid tear evaporation. These issues occur when the eyes can’t maintain a healthy tear film.
Tears form a three-layered film that protects and maintains the eye’s health:
- Oily layer (lipid layer): This outer layer of tears is produced by the meibomian glands (oil glands along the edge of the eyelids). It smooths the tear surface and prevents the two inner layers from evaporating too quickly, helping maintain clear vision.
- Watery layer (aqueous layer): This middle layer is produced by the lacrimal glands (tear glands located above the outer corners of the eyes). It hydrates the eye, removes bacteria and debris, and makes up the majority of visible tears.
- Mucus layer (basal layer): This innermost layer is produced by the conjunctiva (a thin, transparent membrane covering the white part of the eye and the inner eyelids). It helps tears adhere to the eye’s surface, spreads the watery layer, and provides lubrication to keep the eye moist.
When any of these layers are disrupted, the quality of the tear film is compromised, making the eye more susceptible to dry eye disease.
What Are the Types of Dry Eye?
Dry eye is classified into two main types, depending on the underlying cause. These types of dry eye include:
- Aqueous tear-deficient dry eye: This type occurs when your eyes don’t produce enough tears. It can result from various factors, including aging, hormonal changes, autoimmune diseases, and certain medications. It most commonly occurs in postmenopausal women for unknown reasons and is frequently associated with Sjögren’s syndrome, rheumatoid arthritis, or systemic lupus erythematosus.
- Evaporative dry eye: This type occurs when tears evaporate too quickly due to a lack of a proper oil layer on the surface of the watery part of the tears. It is often caused by meibomian gland dysfunction, a condition in which the glands in your eyelids that produce oil don’t work properly. The oil in tears helps prevent them from evaporating too quickly.
It is possible to have both aqueous tear-deficient dry eye and evaporative dry eye at the same time. This is called mixed dry eye.
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Who Is at Risk of Developing Dry Eye?
The following risk factors make a person more susceptible to developing dry eye:
- Age: Tear production decreases as people get older.
- Gender: Dry eye syndrome is more common in women, especially those over 50.
- Dry or polluted environments: Environmental factors such as dry air in heated rooms during winter, air-conditioned rooms in summer, smoky surroundings, and irritants like chemical fumes, cigarette smoke, and pollution can trigger dry eye symptoms. Strong winds (e.g., sleeping with a fan or using a sleep apnea mask), high temperatures, high altitudes, and low humidity can also contribute to dry eye.
- Certain conditions: Many underlying conditions can lead to dry eye. Notable autoimmune conditions include Sjögren’s syndrome, Graves’ ophthalmopathy, and connective tissue disorders. Other conditions that increase risk include diabetes, multiple sclerosis, blepharitis (eyelid inflammation), and facial paralysis, such as Bell’s palsy.
- Medications: Certain medications can contribute to dry eye, including antihistamines (anti-allergy medication), contraceptive pills, high blood pressure medicines, benzodiazepines, diuretics, hormone replacement therapy, inhaled corticosteroids, isotretinoin (used to treat severe acne), glaucoma drops, and antidepressants.
- Conjunctival scarring: Chemical burns and conditions like Stevens-Johnson syndrome (caused by a reaction to certain medications) can lead to conjunctival scarring, increasing the risk of dry eye.
- Certain herbal products: Herbal supplements like kava and echinacea have been linked to dry eye.
- Laser eye surgery (LASIK): Some individuals experience dry eyes after LASIK due to damage to the corneal nerves. While these nerves typically regenerate and symptoms improve over time, dryness may persist in some cases. People with preexisting dry eye syndrome should avoid LASIK, which can worsen the condition.
- Computer vision syndrome: Prolonged screen time reduces blink frequency, leading to dry eyes.
- Contact lenses: Contact lenses absorb tears, increasing the risk of dryness.
- Nutrient deficiencies: Deficiencies in vitamin A and omega-3 fatty acids can contribute to dry eye. These deficiencies may be caused by underlying medical conditions, such as digestive disorders.
- Alcohol: A 2021 study found that alcohol use is a risk factor for dry eye disease, but the effect was observed only in females.
- Poor sleep quality: A 2019 study found a strong link between poor sleep quality and more severe dry eye symptoms.