What causes dry eyes? 6 possible conditions
Dry eyes occur when your eyes do not produce enough tears, or produce tears that can’t effectively keep your eyes moist. Tears are needed to help keep enough moisture in your eyes. They keep the eye surface smooth, wash away foreign materials, and also help to protect the eyes from infection.
Dry eyes may sting or burn and can be very uncomfortable. You may experience dry eyes all the time or only during certain situations. For instance, you may have dry eyes after staring at a computer for a long time, or when it is windy outside. Both eyes are usually affected at the same time.
Eye dryness will likely affect everyone at one point or another in his or her life. It is rarely serious and can usually be treated with simple, over-the-counter solutions.
There are many reasons why a person may experience dry eyes. A few common underlying causes are described in the sections below.
Inadequate Production of Tears
In most people, dry eyes are caused by low production of tears. A low production of tears is also called keratoconjunctivitis sicca, or dry eye syndrome. Some reasons why you might not produce enough tears include:
- old age (this is especially relevant for women: after menopause, your risk for dry eye syndrome increases significantly)
- deficiency of vitamin A (rare in the United States)
- other medical conditions such as diabetes, lupus, Sjogren’s syndrome, rheumatoid arthritis, allergies, infections, or a thyroid disorder
- damage to the tear glands from injury, inflammation, chemical burns, heat, or radiation
- laser surgery, such as LASIK (usually temporary)
Tears are made of a mixture of water, oils, and mucus. For some people, dry eyes are caused by an imbalance in the components of this mixture. For example, dry eyes can occur if the glands that produce oil for the eyes are clogged. The oily part of tears slows down evaporation. These glands are called the meibomian glands.
This problem might be referred to as having “low-quality tears.”
Certain drugs can cause dry eyes, including:
- high blood pressure medication
- allergy drugs, such as antihistamines
- birth control pills
- hormone replacement therapies
- certain acne treatments
Sometimes, elements of your environment or everyday life can lead to dry eyes, including:
- dry air
- exposure to smoke
- working at a computer
- riding a bicycle
- flying in an airplane
Other factors that may contribute to dry eyes include:
- difficulty blinking
- inflammation of the eyelids (blepharitis)
- inward or outward turning of the eyelids
- long-term use of contact lenses
You should call a doctor if your eyes are itchy, red, and irritated for a long period of time. You should also contact a doctor if you experience blurred or sudden decreased vision, or if you have pain in your eyes.
A doctor may refer you to a specialist, such as an optometrist or ophthalmologist, to determine what is bothering your eyes. The specialist will usually conduct a thorough examination of the eyes. He or she will measure the volume of your tears, and may also measure how quickly the tears evaporate from the surface of the eye.
Treatment is aimed at restoring a normal amount of tears in the eyes. You can typically care for your dry eyes at home or by using over-the-counter drugstore treatments.
The most common type of treatment is over-the-counter eye drops or artificial tear solutions. They are affordable, effective, and easy to apply. There are many types of eye drops available. Some contain electrolyes, such as potassium and bicarbonate, that are thought to promote healing on the surface of the eyes. Others contain thickening agents, which keep the lubricating solution on your eye surface for longer.
There are two main groups of artificial tears: those with preservatives and those without. Eye drops with preservatives are the more common type. These usually come in a multi-dose bottle—they contain chemicals that prevent bacterial growth in the open container. However, some people may find that the preservatives irritate their eyes. Eye drops without preservatives come in small, single-dose vials, and are less likely to irritate your eyes. They may, however, be more expensive.
It’s hard to determine which will work best for you. You may have to try a few different brands before you find the best eye drops for you.
Some common brand names include:
- Clear Eyes
Your local grocery or drugstore might also offer a store brand version.
You can rake a number of steps to help prevent and/or stop dry eyes, including:
- remembering to blink when staring at a computer or book for long periods of time
- increasing the humidity in the air
- avoiding air blowing into your eyes, such as from an air conditioner or fan
- wearing sunglasses outside
- avoiding people who smoke
- quitting smoking
Other ways to address dry eyes include using lubricating ointments or applying a warm compress to your eyes.
You probably will not need to see a doctor for dry eyes. But if you do, your doctor may prescribe medications, such as prescription eye drops like ophthalmic cyclosporine (Restatis) or topical corticosteroids.
Supplements containing omega-3 fatty acids, or dietary sources of omega-3 fatty acids (such as tuna), may be recommended by a doctor. These fatty acids are known to decrease dry eye symptoms in some patients. Discuss proper dosage with your doctor.
In some cases, a surgery to plug the drainage holes at the corners of the eyelids is recommended. These holes are where tears drain from the eye into the nose. The plugs, called lacrimal plugs, are inserted by an eye doctor. The plugs are not painful, not permanent, and are usually not felt by the patient.
If not treated, dry eyes can be painful, lead to infections, and cause ulcers or scars on the cornea, which is the front part of the eye. Loss of vision may occur. However, permanent vision loss from dry eyes is not common.
Dry eyes can also decrease a person’s quality of life and make it difficult to perform everyday tasks.
Dry eyes cannot always be prevented. Taking breaks when staring at a computer screen, using a humidifier, wearing sunglasses, and avoiding smoke might help prevent dry eyes if the symptoms are caused by environmental factors. You can prevent complications of dry eyes by using eye drops and ointments.
- Dry Eye. (n.d.). American Optometric Association. Retrieved September 14, 2012, from http://www.aoa.org/x4717.xml
- Dry Eyes. (2012, August 4). Mayo Clinic. Retrieved September 14, 2012, from http://www.mayoclinic.com/health/dry-eyes/DS00463
- Dry Eye Syndrome. (2010, November 8). National Institutes of Health. Retrieved September 14, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/000426.htm
- Facts About Dry Eye. (2009, August). American Eye Institute. Retrieved September 14, 2012, from http://www.nei.nih.gov/health/dryeye/dryeye.asp
See a list of possible causes in order from the most common to the least.
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