Dry Eye Syndrome
- What is it?
- Facts to Know
- Questions to Ask
- Key Q&A
- Lifestyle Tips
- Organizations and Support
What is it?
What Is It?
Dry eye syndrome is a group of disorders in which either you don't produce enough tears, or you have unstable tears or excessive tear evaporation.
Tears keep your eyes moist, lubricate the surface of the eye for eyelid closure and guard against infection. They also wash away allergens and protect the eye. Without tears, good vision is impossible. Dry eye syndrome is a group of disorders affecting the film of tears over the eye. The condition affects an estimated 5 to 30 percent of the population age 50 and older in the United States. In addition, tens of millions of Americans experience less severe symptoms of dry eye.
Dry eye syndrome is one of the most common reasons people visit an eye health professional. It occurs most often in the elderly.
The cause of dry eye syndrome is unknown. External factors may aggravate dry eye symptoms, including conditions common in many workplaces such as prolonged computer use and exposure to air conditioning, heating, dust and allergens.
But dry eye syndrome should not be confused with eye allergies, an even more pervasive problem that affects an estimated 20 percent of the U.S. population. Eye allergies are reactions to substances in the environment that can result in some of the same types of discomforts associated with eye dryness.
When you have dry eye syndrome, either you don't produce enough tears, or you have unstable tears or excessive tear evaporation. Both problems cause your eyes to sting or burn, feel scratchy, become irritated and tear excessively. It most commonly occurs in both eyes, but may affect one eye more than the other. People with dry eyes have difficulty wearing contact lenses. They also may develop mucus in or around their eyes. There can be pain and redness in the eye, a feeling of heavy eyelids or blurred, changing or decreased vision. People with more severe cases of dry eye often are also sensitive to light.
Although eye infections are more common in people with dry eye syndrome, irreversible vision loss from dry eye is rare. More commonly, people with dry eye have fluctuating vision and experience problems with tasks requiring visual concentration such as reading, using a computer and driving. Most people with dry eye find the condition to be an uncomfortable nuisance, with many characteristics of a "chronic pain" type of syndrome.
Understanding the Role of Tear Film
The tear film on your eyes actually consists of the following three major components:
- Lipid. The outer layer of the tear film is covered by an oily layer produced by meibomian glands in the lower and upper eyelids. This layer smoothes the eye's surface and keeps tears from evaporating too fast and helps them stay on the eye.
- Aqueous. The aqueous component is a watery layer that is produced by the lacrimal glands. This layer makes up most of what we normally consider tears. It nourishes the cornea (the clear tissue of the outer protective layer of the eye that transmits light) and the conjunctiva (a thin, clear layer of tissue that covers the white outer surface of the eye). This tear layer also cleanses the eye and washes away foreign particles or irritants that are wrapped up by the other major component—mucin.
- Mucin. The goblet cells of the conjunctiva, as well as the surface cells of the cornea and the conjunctiva, produce this protective lubricant of tears. It helps spread the watery layer of tears across the eye to keep the eye wet, and it traps and wraps up foreign pathogens and debris so they do not damage the ocular surface.
As we age, the eyes naturally produce fewer tears. However, sometimes the lipid and mucin layers produced by the eye are so unstable that tears can't remain on the eye long enough to keep it lubricated. Consequently, some people with dry eye may actually have tears running down their cheeks! Dry eye syndrome, also called keratoconjunctivitis sicca or dysfunctional tear syndrome, is the result. In some people, dry eyes result from an imbalance in the composition of their tears or an inability to produce enough tears to keep their eyes sufficiently lubricated. In addition, eyelid problems, environmental factors, certain medications and other causes can lead to dry eyes.
Dry eye occurs most often in older women. Information gathered from the Women's Health Study, a large cohort study in which 25,665 postmenopausal women provided information about the use of hormone replacement therapy (HRT), suggests that those who use HRT, particularly estrogen alone, are at increased risk of dry eye syndrome. A relatively uncommon but often more serious form of the disorder is associated with rheumatoid arthritis or dry mouth and is called Sjögren's syndrome. Sjögren's syndrome is an autoimmune disease that attacks the body's lubricating glands, such as the tear and salivary glands. Allergies can also contribute to eye dryness, causing additional eye discomforts such as itchiness, redness, swelling and wateriness.
Although dry eye syndrome has no cure, its symptoms can be treated. Over-the-counter artificial tears that lubricate the eye are the main treatment. Other treatments include eye ointments, antibiotics (both oral and drops) and avoiding environmental triggers such as hair dryers and rooms with low humidity. And a prescription medication called Restasis (cyclosporine ophthalmic emulsion 0.05%) works to increase the body's ability to produce its own natural tears by treating one of the underlying causes of the disease—inflammation.
In cases of moderate to severe dry eye, tears can be conserved by placement of a temporary or permanent punctal plug into the channel at the inner corner of the eyelid where tears drain into the nose and the back of the throat. And in some cases, a surgical procedure to close the tear ducts is in order.
Your ophthalmologist or optometrist can diagnose dry eye syndrome during an eye examination. A complete physical examination and blood tests may be necessary to diagnose any underlying diseases, such as Sjögren's syndrome. Make sure you tell your health care professional what medications you are taking because many drugs can aggravate dryness of the eyes. Among those that can contribute to dry eye syndrome are:
some high blood pressure medications, including diuretics
some heart medications
Parkinson disease medications
birth control pills
some pain relievers
The early symptoms of dry eye syndrome may include:
burning, stinging or scratchy sensation in the eye, especially in an environment with low humidity
a feeling that something is in the eye
trouble wearing contact lenses
a gritty feeling that may be persistent and painful
In mild cases, these symptoms may come and go. An individual may have some or all of these symptoms. As dry eye worsens, the symptoms tend to become more persistent. People who have severe cases of dry eye may find little or no relief for these symptoms from artificial tears, have eyes that are unusually sensitive to light and may experience severe eye pain or notice changing vision.
Because many patients with dry eye syndrome are unable to tolerate contact lenses, they may desire corrective surgery such as laser-assisted in situ keratomileusis (LASIK). But according to the U.S. Food and Drug Administration, LASIK eye surgery may lead to temporary or permanent dry eye syndrome, requiring intensive drop therapy or use of plugs or other procedures.
During your eye examination, your health care professional may look at your eyes with a slit lamp, a lighted, microscope-like instrument that illuminates the eyes. Your health care professional will focus on the front of your eye and check whether it remains moist or quickly develops dry spots. If the eye is deficient in tears, particularly in mucin or lipid parts of tears, dry spots appear quickly.
Your health care professional may also conduct one of the following tests for dry eyes:
Schirmer test. The Schirmer test, the main test for dry eyes, measures tear production. It is often conducted when your health care professional sees a lack of a tear pool during the initial slit lamp examination and finds dry areas in one of the stain tests. Your health care professional will take a special strip of filter paper, put a tiny fold in it and place it on the tear pool on the edge of the lower eyelid. The paper remains in place for five minutes, absorbing the tears. Some patients find this slightly uncomfortable. It does not affect vision. After five minutes, the paper strip is removed and the area of wetness measured in millimeters (mm). A wetness area of 10 mm or more is normal. A reading of less than 10 mm is below normal, but most patients can tolerate it and may have a few symptoms. A reading of less than 4 mm is considered severe, and most patients at this level have some symptoms.
Fluorescein stain test. Your health care professional will place eyedrops containing a fluorescent dye called fluorescein into your eyes and examine them with the slit lamp while shining a blue-colored light on the eyes. You may feel a slight burning sensation in the eyes after receiving the drops, but it will disappear within seconds. Fluorescein stain is used to evaluate tear film. In addition, the dye stains dry areas and shows any erosion on the eye's surface that occurs as a result of dryness. As your tears naturally replace themselves, over several minutes, the dye is washed out of the eye. The test, which is conducted in minutes, does not affect vision.
Rose Bengal stain test. This is another test in which dye is placed in the eyes. It tends to be a subtler test than the fluorescein stain, picking up lighter areas of dryness on the eye. It is used less frequently because it can be quite irritating in the presence of dry eye. The dye will stain areas of dryness on the eye. As with fluorescein stain, your tears will wash the dye out of your eyes. The test takes a matter of minutes and does not affect vision.
Lissamine green stain test. Lissamine green dye is actually a color additive in drugs, cosmetics and food. When used for dry eye testing, it has a staining profile nearly identical to Rose Bengal but does not cause ocular irritation. It stains the areas where there is poor protection of surface by the tear film.
Tear film normalization test. The doctor will check your vision. When you get to a line on the chart that is a little blurry, the doctor will place a watery eyedrop in your eyes. If the vision improves after a few seconds, then you most likely have dry eyes. If the vision does not improve, then you most likely do not have dry eyes.
Seek a second opinion if you are suspicious you may have dry eyes and your doctor does not agree. Dry eye syndrome remains one of the most underdiagnosed conditions eye doctors see.
The mainstays of dry eye treatment are over-the-counter artificial tears in the form of eyedrops. Health care professionals generally recommend you use them as often as needed to relieve symptoms, provided they don't contain preservatives. If you use a drop that does contain preservatives, you can use it up to four times a day. How often you use the drops can depend upon how bothersome your symptoms are, how dry your immediate environment is and even how humid the weather is. Some patients with dry eye may find that on a rainy day, they need only a drop of artificial tears for the entire day. On a dry, sunny and windy day, they may use a drop every hour.
Artificial tears primarily provide symptomatic relief and do not address the underlying causes of dry eye disease; however, they may be adequate for treating mild or episodic dry eye. Further, they are a "foundation" therapy for all levels of severity and are recommended as a treatment component as additional therapies are added. As a general rule, if you use artificial tears three or more times a day for dry eye symptoms, you should visit an eye health professional to discuss additional treatments.
If you are using artificial tears frequently but find they don't seem to relieve symptoms, the preservatives in the drops may be irritating the eye or creating an allergic reaction. In such cases, preservative-free eyedrop brands may be better for you.
Over-the-counter sterile eye ointments, such as Refresh P.M., sometimes are recommended for nighttime use to lubricate the eye during sleep and to treat the scratchy eye feeling that many dry eye sufferers have when they wake up. Such ointments are primarily used to coat the eye when it is exposed while sleeping. This occurs in cases of nocturnal lagophthalmos, which involves the inability to close the eyelids while sleeping.
In addition, avoiding anything that can exacerbate eye dryness—such as hair dryers, rooms with low humidity, air conditioning or heat in cars (especially when vents are positioned directly at your face), wind and cigarette smoke—is recommended.
If these measures don't relieve dry eye, your doctor may prescribe a drug called Restasis. Restasis (cyclosporine ophthalmic emulsion 0.05 percent) is the first U.S. Food and Drug Administration-approved treatment for patients with the tear deficiency of keratoconjunctivitis sicca (or dry eye disease), whose tear production is presumed to be suppressed due to ocular inflammation. Its primary ingredient is cyclosporin A, an immunosuppressive agent used in organ transplantation. The anti-inflammatory effect of topical cyclosporin A helps increase the eyes' natural ability to produce tears, which may be suppressed by inflammation due to chronic dry eye. The exact mechanism of action is not known, however. Restasis is generally recommended to people who use artificial tear eyedrops frequently without getting long-term symptom relief. Restasis should not be used by patients with active eye infections.
Another option for people with moderate to severe dry eye syndrome is prescription eye inserts that work like artificial tears. The hydroxypropyl cellulose inserts (Lacrisert) are placed between the lower eyelid and eyeball once a day. They dissolve slowly, releasing a lubricating substance into the eye.
In some cases, your doctor may also prescribe steroid drops to help reduce inflammation or antibiotics in the form of drops or pills.
In the case of dry eye syndrome due to eyelid problems, such as an anatomical problem or an incomplete blink, your health care professional may refer you to a plastic surgeon who specializes in the eyes. If your eyelids are inflamed due to blepharitis, your health care professional may recommend that you regularly clean your lids with a diluted baby shampoo solution.
People with dry eyes who wear contact lenses may benefit from special lenses that rest on the white part of the eye, creating a fluid-filled layer over the cornea that prevents it from drying out.
In cases of moderate to severe dry eye, a temporary or permanent plug about the size of a sesame seed can be inserted into some of the tear draining channels, or puncta, at the inner corner of the eyelids. Here tears normally drain through the tear duct into the nose and down the throat. Blocking these exit channels helps to keep the tears on the surface of the eye longer. Plugs are inserted by your health care professional in the office setting in minutes using a magnifying instrument to best see the puncta. These plugs may be made of silicone or collagen, are reversible and are usually a temporary measure. In cases of severe dry eye, permanent plugs may be considered. Some patients with silicone plugs initially may have a sensation that something is in the eye, but the feeling usually disappears over a few hours to a few days. Many people don't feel them at all after they've been inserted. Plugs can be dislodged by rubbing the eye, so your health care professional may recommend you refrain from doing so.
In severe dry eye cases, irreversible surgical closure of the puncta may be recommended.
There is no cure for dry eye syndrome and no way to prevent it. But, you can help prevent evaporation of your tears by avoiding anything that can cause dryness, such as hair dryers, rooms with low humidity and wind. Placing a humidifier in the room when indoor heat is used and wearing wrap-around glasses when outside may provide some relief from dry eye. Smoking is especially bothersome to dry eye sufferers and should be avoided. Additionally, dry eye can be aggravated by a number of external factors, many of which are common in workplace environments. These external factors include prolonged computer use and exposure to air conditioning, heating, dust, allergens and wind. If you cannot find relief from your dry eye symptoms, make an appointment with an eye care professional to discuss your symptoms.
Facts to Know
Facts to Know
Dry eye syndrome is a group of disorders affecting the tear film.
The exact prevalence of dry eye syndrome in the United States is not known, but it is estimated to affect 5 to 30 percent of the population age 50 and older. In addition, tens of millions of Americans experience less severe symptoms of dry eye.
Dry eye syndrome tends to occur most often in the elderly, especially women.
Although dry eye syndrome can affect vision, it rarely produces permanent vision loss.
Early symptoms of dry eye syndrome may include eye redness, blurry vision, burning, stinging or gritty sensation in the eye, especially in an environment with low humidity; a feeling that something is in the eye; trouble wearing contact lenses; a gritty feeling that can be persistent and painful; eye dryness; and excessive tearing.
As dry eye worsens, symptoms become more persistent. Patients with severe cases may also have eyes that are unusually sensitive to light and may experience severe eye pain or notice changing or fluctuating vision.
Dry eye can be a symptom of an autoimmune disease called Sjögren's syndrome that attacks the body's lubricating glands.
Dry eye syndrome has no cure, but it can be treated.
Over-the-counter artificial tears in eyedrop form are the main treatment for dry eye. Anyone experiencing dry eye symptoms or using artificial tears regularly without relief should see an eye care professional for a diagnosis.
Punctal plugs that block tear drainage channels can help conserve tears for dry eye suffers who get little or no relief from artificial tears.
Questions to Ask
Questions to Ask
Review the following Questions to Ask about dry eye syndrome so you're prepared to discuss this important health issue with your health care professional.
Am I at risk for developing dry eye syndrome?
Is a disease causing my dry eye syndrome?
Can any of the medications I take contribute to dry eye syndrome?
What can I do to reduce my discomfort from dry eye?
What kind of artificial tears are best for me?
How often should I use artificial tears?
Should I use preservative-free artificial tears?
Can artificial eye ointments help me?
Can punctal plugs help me?
What new medications may help my dry eye?
Is my job environment contributing to my dry eye symptoms?
How can I tell if my symptoms are not from allergies?
What is dry eye syndrome?
Dry eye syndrome is a group of disorders affecting the film of tears over the eye. When you have dry eye syndrome, either you don't produce enough tears or you have unstable tears and excessive tear evaporation.
What causes or contributes to dry eye?
Dry eye disproportionately affects more women than men and is often caused by hormonal changes due to aging and menopause. Dry eye also can be caused by certain medications such as antihistamines, antidepressants, diuretics, oral contraceptives or hormone replacement therapy. Additionally, dry eye can be caused by autoimmune disorders such as rheumatoid arthritis, lupus, rosacea, sarcoidosis, Sjögren's syndrome or other medical conditions such as diabetes, vitamin A deficiency and diseases such as Parkinson's disease.
Dry eye can be aggravated by a number of external factors, many of which are common in the workplace, including: computer use; heating and air conditioning; reading; exposure to dust and allergens; hot, dry or windy environments; high altitude; contact lens use; and driving.
Who is at risk for dry eye syndrome?
Dry eye affects an estimated 5 to 30 percent of the population age 50 and older. Although the cause of dry eye syndrome is unknown, it tends to occur more often in women, especially those who are pregnant or postmenopausal. In addition, tens of millions of Americans have less severe symptoms of dry eye.
How do I know if I have dry eye syndrome?
The early symptoms of dry eye syndrome include eye redness; a burning, stinging and/or gritty sensation in the eye, especially in an environment with low humidity; a feeling that something is in the eye; trouble wearing contact lenses; a gritty feeling that is persistent and painful; eye dryness; and excessive tearing. In mild cases, these symptoms may come and go. As dry eye worsens, the symptoms become more persistent. Severe cases of dry eye may also show symptoms of light sensitivity, severe eye pain or changing vision. Anyone experiencing these symptoms or using artificial tears regularly without relief should visit their eye care professional for a diagnosis.
What's a Schirmer test? Will it hurt?
A Schirmer test measures your tear production. It is often conducted when your health care professional sees a lack of a tear pool during the initial slit lamp examination and finds dry areas in one of the stain tests. Your health care professional will take a special strip of filter paper, put a tiny fold in it and place it on the tear pool on the edge of the lower eyelid. The paper remains in place for five minutes, absorbing the tears. The test produces no pain, but some patients find it slightly uncomfortable. It does not affect vision. After five minutes, the paper strip is removed and the area of wetness measured in millimeters (mm). A wetness area of 10 mm or above is normal. A reading of less than 10 mm is below normal, but most patients can tolerate it and may have a few symptoms. A reading of less than four mm is considered severe, and most patients at this level do have some symptoms.
Can dry eye syndrome be cured?
No, but it can be treated. The cause of dry eye is unknown. Dry eye can be associated with rheumatoid arthritis. It also is a symptom of Sjögren's syndrome, an autoimmune disease that attacks the body's lubricating glands, such as the tear and salivary glands. And, it can be a side effect of a variety of over-the-counter and prescription medications. Because there is no cure, health care professionals direct treatment at managing symptoms, but it is important to figure out why your eyes are dry.
What is the most common treatment for dry eye?
Over-the-counter artificial tears in the form of eyedrops are the mainstays of dry eye treatment. Your health care professional can recommend what brands may be best for you. As a general rule, if you use artificial tears three or more times a day for dry eye symptoms, you should visit your health care professional to discuss additional treatments.
Artificial tears don't seem to be relieving my dry eye symptoms. Will punctal plugs help me?
Possibly, but talk to your health care professional about what treatment might be right for you. In cases of moderate to severe dry eye, a temporary or permanent plug about the size of a sesame seed can be inserted into some of the channels, or puncta, at the inner corner of the eyelid where tears drain into the nose and back of the throat. This helps conserve tears. Plugs are inserted by your health care professional in the office in minutes using a magnifying instrument to best see the punctum. These plugs may be made of silicone or collagen, are reversible and are a temporary measure. In cases of severe dry eye, permanent plugs may be considered.
How can I prevent dry eye syndrome?
There is no way to prevent dry eye syndrome. But, you can help preserve your tears by avoiding anything that can cause dryness, such as hair dryers, rooms with low humidity and wind. Placing a humidifier in the room when indoor heat is used and wearing wrap-around glasses when outside may provide some relief from dry eye. Smoking is especially bothersome to dry eye sufferers and should be avoided.
Try these common-sense solutions for keeping eyes moist
All moisture tends to evaporate when exposed to air and certain climate conditions. To preserve as much of your eyes' natural moisture as possible, the Mayo Clinics suggests that you slow evaporation with these simple precautions:
Don't direct hair dryers, car heaters, air conditioners or fans toward your eyes.
Wear glasses on windy days and goggles while swimming.
Add moisture to the air. A humidifier can add moisture to dry indoor air in the winter. Or, some people wear glasses specially designed to form a moisture chamber around the eye. These glasses can be worn during the day to relieve dry eye symptoms or at night to help people who sleep with their eyes partially open.
Take an inventory of the medicines you take
Some medications, even those that you buy without a prescription, can make your eyes feel dryer. Culprits include antihistamines, nasal decongestants, tranquilizers and antidepressants. People with dry eye should let their health care providers know all the medications they are taking since some of them may intensify dry eye symptoms.
Don't forget to blink
Americans are spending more and more time in front of their computer screens, staring intently into the monitor. With so much information so readily available, we sometimes simply can't tear away from it all. Don't become blindly absorbed. Take time to blink; it helps spread your tears more evenly. Most people blink about once every five seconds.
Pay attention to your diet
It's important not only to keep your eyes lubricated, but your body as well. Certain foods and drinks dehydrate your body—and your eyes. Chocolate, colas, coffee and tea all contain caffeine, which robs your body of moisture. To keep fluids flowing, drink plenty of water (six to eight glasses daily if possible).
Practice good eye care habits
Practicing good eye-care habits helps not only with dry eye, but with your overall eye health. Some things to do: wear sunglasses with maximum ultraviolet protection (block 99 to 100 percent of UV-A and UV-B); eat a diet that includes at least five fruits and vegetables per day; and wear proper eye-safety equipment when doing eye-hazardous activities at work and home or when participating in eye-hazardous sports.
Organizations and Support
Organizations and Support
American Academy of Ophthalmology
Address: P.O. Box 7424
San Francisco, CA 94120
National Eye Health Education Program
Address: National Eye Institute Information Office
31 Center Drive MSC 2510
Bethesda, MD 20892
Schepens Eye Research Institute
Address: 20 Staniford Street
Boston, MA 02114
Medline Plus: Dry Eye Syndrome
Address: Customer Service
US National Library of Medicine
8600 Rockville Pike
Bethesda, MD 20894
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"Dry eye syndrome." Medline. The National Institutes of Health. December 2010. http://www.nlm.nih.gov/medlineplus/ency/article/000426.htm. Accessed January 2011.
"Dry eyes." Uptodate.com. Updated May 2010. http://www.uptodate.com/patients/content/topic.do?topicKey=~poGK.SiIim6wBmG. Accessed January 2011.
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"Vision Researchers Update Congressional Staff about Important Advances in Understanding and Treating Chronic Dry Eye." The National Alliance for Eye and Vision Research. February 2006. http://www.eyeresearch.org. Accessed September 2008.
"What are the risks (of LASIK eye surgery) and how can I find the right doctor for me?" The U.S. Food and Drug Administration. July 2007. http://www.fda.gov. Accessed September 2008.
"Classification and diagnosis of Sjögren's syndrome." Uptodate. May 2008. https://vnet.christianacare.org. Accessed October 2008.
Bensinger, R, MD, FAAO, spokesman for the American Academy of Ophthalmology, and chief of ophthalmology at Swedish Hospital, Seattle, WA. Direct interview. November 6, 2000.
"Dry Eye Syndromes, Your Questions Answered." The Schepens Eye Institute, Harvard Medical School. http://www.eri.harvard.edu. Accessed September 2002.
"Fact Sheet: The Cornea and Corneal Disease." National Eye Institute. http://www.nei.nih.gov. June 2001. Accessed September 2002.
"Frequently Asked Questions About Dry Eye." Prevent Blindness America. http://www.preventblindness.org. Updated May 2003. Accessed September 2003.
"Hydroxypropyl Cellulose (Ophthalmic)." Medlineplus Health Information, National Library of Medicine. Updated Sept. 2002. http://www.nlm.nih.gov. Accessed September 2002.
Petrauskas, JL, MSPH. "Digging in the Ocular Desert." EyeNet Magazine Online. American Academy of Ophthalmology. http://www.aao.org. July 2000. Accessed September 2003.
"Studies Show Promise for Drug to Treat Dry Eye Syndrome." American Academy of Ophthalmology. http://www.medem.com. News release April 11, 2000. Accessed September 2002.
"Dry Eye Syndrome" EyeMDLink. Updated Oct. 2001. http://www.eyemdlink.com. Accessed September 2002.
"Conjunctival Histologic Findings of Dry Eye and Non-Dry Eye Contact Lens Wearing Subjects" The CLAO Journal. Jan. 2001. http://www.clao.org. Accessed September 2002.
Cross WD et al. "Clinical and Economic Implications of Topical Cyclosporin A for the Treatment of Dry Eye." Managed Care Interface. 2002;15 (9):44-49.
Sullivan DA et al. "Androgen Deficiency, Meibomian Gland Dysfunction, and Evaporative Dry Eye." Annals New York Academy of Sciences. 2002; 966:211-222.
"LASIK Safe, Effective in Patients With Dry Eyes" Medscape Medical News. Aug. 16, 2002. http://www.medscape.com. Accessed September 2002.
"Hormone Replacement Therapy and Dry Eye Syndrome" JAMA. Vol. 286 No. 17, Nov. 7, 2001. http://jama.ama-assn.org. Accessed September 2002.
"New Dry Eye Therapy Launched" Sjögren's Syndrome Foundation. 2003. http://www.sjogrens.com. Accessed September 2003.
Schaumberg DA, et al. "Prevalence of Dry Eye Syndrome Among US Women" Aug. 2003. American Journal of Ophthalmology, 136:(2):318-326.
Market Scope. Report on the Global Dry Eye Market. St. Louis, Missouri: Market Scope, July 2004.
"Dry Eye Fact Sheet." The Schepens Eye Institute, Harvard Medical School. http://www.theschepens.org. Accessed June 2006.
Last date updated: 2011-03-30