Signs and symptoms, which usually affect both eyes, may include:
- A stinging, burning or scratchy sensation in your eyes
- Stringy mucus in or around your eyes
- Increased eye irritation from smoke or wind
- Eye fatigue
- Sensitivity to light
- Eye redness
- A sensation of having something in your eyes
- 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. Your doctor can take steps to determine what's bothering your eyes or refer you to a specialist.
Dry eyes are caused by a lack of adequate tears. Your tears are a complex mixture of water, fatty oils, and mucus. 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 mucous 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-toe-kun-junk-tih-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) 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:
- Some drugs used to treat high blood pressure
- Antihistamines and decongestants
- Hormone replacement therapy
- Certain antidepressants
- Isotretinoin-type drugs for treatment of acne
Other causes of dry eyes include:
- Dry air
- Tasks that require enough concentration that you blink less often, 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
Generally, dry eyes don't cause serious problems. However, possible complications include:
- More-frequent eye infections. Your tears protect the surface of your eyes from infection. Without adequate tears, you may have an increased risk of eye infection.
- Scarring on the surface of your eyes. If left untreated, severe dry eyes may lead to eye inflammation, scarring on the surface of your corneas and vision problems.
- Decreased quality of life. Dry eyes can make it difficult to perform everyday activities.
If you experience dry eyes, pay attention to the situations that are most likely to cause your symptoms. Then find ways to avoid those situations in order to prevent your dry eyes symptoms. For instance:
- Avoid air blowing in your eyes. Don't direct hair dryers, car heaters, air conditioners or fans toward your eyes.
- Add moisture to the air. In winter, a humidifier can add moisture to dry indoor air.
- Consider wearing wraparound glasses or eyeglass shields to protect your eyes. Safety shields can be added to the tops and sides of eyeglasses to block wind and dry air from getting to your eyes. Ask about shields where you buy your eyeglasses. Swim goggles may create the same effect.
- Take eye breaks during long tasks. If you're reading or doing another task that requires visual concentration, take periodic eye breaks. Close your eyes for a few minutes. Or blink repeatedly for a few seconds to help spread your tears evenly over your eyes.
- Be aware of your environment. Ambient air at high altitudes, desert areas, and in airplanes can be extremely dry. When spending time in such an environment, especially when flying over long distances, it may be helpful to frequently close your eyes for a few minutes at a time to minimize evaporation of your tears.
- Position your computer screen below eye level. If your computer screen is above eye level, you'll open your eyes wider to view the screen. Position your computer screen below eye level so that you won't open your eyes as wide. This may help slow the evaporation of your tears between eye blinks.
- Stop smoking and avoid smoke. If you smoke, stop. Ask your doctor for help devising a quit-smoking strategy that's most likely to work for you. If you don't smoke, stay away from people who do. Smoke can worsen dry eyes symptoms.