Dry eyes occur when your tears aren't able to provide adequate moisture for your eyes. Tears can be inadequate for many reasons. For example, dry eyes may occur if you don't produce enough tears or if you produce poor-quality tears.
Dry eyes feel uncomfortable. If you have dry eyes, your eyes may sting or burn. You may experience dry eyes in certain situations, such as on an airplane, in an air-conditioned room or after looking at a computer screen for a few hours.
Dry eyes treatments may make you more comfortable. Dry eyes treatments can include lifestyle changes and eyedrops. For more serious cases of dry eyes, surgery may be an option.
Signs and symptoms of dry eyes, which usually affect both eyes, may include:
- A stinging, burning or gritty sensation in your eyes
- Stringy mucus in or around your eyes
- Increased eye irritation from smoke or wind
- Eye fatigue after short periods of reading
- Sensitivity to light
- Difficulty wearing contact lenses
- Periods of excessive tearing
- Blurred vision, often worsening at the end of the day or after focusing for a prolonged period
When to see a doctor
See your doctor if you've had prolonged signs and symptoms of dry eyes, including red, irritated, tired or painful eyes.
The tear glands (lacrimal glands), located above each eyeball, continuously supply tear fluid that's wiped across the surface of your eye each time you blink your eyelids. Excess fluid drains through the tear ducts into the nose.
Dry eyes are caused by a lack of adequate tears. Your tears are a complex mixture of water, fatty oils, proteins and electrolytes. This mixture helps make the surface of your eyes smooth and clear, and it helps protect your eyes from infection.
For some people, the cause of dry eyes is an imbalance in the composition of their tears. Other people don't produce enough tears to keep their eyes comfortably lubricated. Eyelid problems, medications and other causes, such as environmental factors, also can lead to dry eyes.
Poor tear quality
The tear film has three basic layers: oil, water and mucus. Problems with any of these layers can cause dry eyes symptoms.
- Oil. The outer layer of the tear film, produced by small glands on the edge of your eyelids (meibomian glands), contains fatty oils called lipids. These smooth the tear surface and slow evaporation of the middle watery layer. If your oil glands don't produce enough oil, the watery layer evaporates too quickly, causing dry eyes. Dry eyes are common in people whose meibomian glands are clogged. Meibomian dysfunction is more common in people with inflammation along the edge of their eyelids (blepharitis), rosacea and other skin disorders.
- Water. The middle layer is mostly water with a little bit of salt. This layer, produced by the tear glands (lacrimal glands), cleanses your eyes and washes away foreign particles or irritants. If your eye produces inadequate amounts of water, the oil and mucus layers can touch and cause a stringy discharge.
- Mucus. The inner layer of mucus helps spread tears evenly over the surface of your eyes. If you don't have enough mucus to cover your eyes, dry spots can form on the front surface of the eye (cornea).
Decreased tear production
Dry eyes can occur when you're unable to produce enough tears. The medical term for this condition is keratoconjunctivitis sicca (ker-uh-to-kun-junk-ti-VIE-tis sik-uh).
You may not produce enough tears if you:
- Are older than 50. Tear production tends to diminish as you get older. Dry eyes are common in people older than 50.
- Are a postmenopausal woman. A lack of tears is more common among women, especially after menopause. This may be due in part to hormonal changes.
- Have a medical condition that reduces your tear production. Dry eyes are also associated with some medical conditions such as diabetes, rheumatoid arthritis, lupus, scleroderma, Sjogren's syndrome, thyroid disorders and vitamin A deficiency.
- Have had laser eye surgery. Refractive eye surgeries such as laser-assisted in-situ keratomileusis (LASIK) also may cause decreased tear production and dry eyes. Symptoms of dry eyes related to these procedures are usually temporary.
- Have tear gland damage. Damage to the tear glands from inflammation or radiation can hamper tear production.
Blinking spreads a continuous thin film of tears across the surface of your eyes. If you have an eyelid problem that makes it difficult to blink, tears may not be spread across your eye adequately or your tears may evaporate too quickly, causing dry eyes. Eyelid problems can include an out-turning of the lids (ectropion) or an in-turning of the lids (entropion).
Medications that cause dry eyes
Medications that can cause dry eyes include:
- Certain types of drugs used to treat high blood pressure, such as central-acting agents and diuretics
- Antihistamines and decongestants
- Birth control pills
- Certain antidepressants
- Pain relievers, such as ibuprofen (Advil, Motrin, others) and naproxen (Aleve)
- Isotretinoin-type drugs for treatment of acne
Other dry eyes causes
Other causes of dry eyes include:
- High altitude
- Dry air
- Tasks that require concentration, such as working at a computer, driving or reading
Factors that make it more likely that you'll experience dry eyes include:
- Increasing age
- Being a woman
- Taking medications that can cause dry eyes
- Having laser eye surgery
- Undergoing radiation therapy, such as is used to treat cancer, aimed at the eyes
- Eating a diet that is low in vitamin A, which is found in liver, carrots and broccoli, or low in omega-3 fatty acids, which are found in fish, walnuts and vegetable oils
Most people don't experience complications caused by dry eyes. Complications that can occur include:
- More frequent eye infections. Your tears protect the surface of your eye from infection. Without adequate tears, you may have an increased risk of eye infection.
- Scarring on the surface of your eye. If left untreated, severe dry eyes may lead to eye inflammation, scarring on the surface of your cornea and vision problems.