- Risk Factors
- Signs & Symptoms
What is dry eye syndrome?
A disturbance of the tear film characterizes dry eye syndrome, a very common and usually benign condition. This abnormality may result in disruption of the ocular surface, causing a variety of symptoms and signs and interference with quality of life. Dry eye syndrome is a common eye condition that occurs when your eyes do not produce enough tears, or the quality of your tears is poor, resulting in eye discomfort, irritation, and inflammation.
To help keep the eyes comfortable and vision optimal, a normal, thin film of tears coats the eyes. Three main layers make up this tear film.
- The innermost layer is the thinnest. It is a layer of mucin (or mucus). The cells in the conjunctiva (the clear skin that lines the eye) produce a very thin layer of mucus. The mucus helps the overlying watery layer to spread evenly over the eye.
- The middle (or aqueous) layer is the largest and the thickest. This layer is essentially a very dilute saltwater solution. The lacrimal glands under the upper lids and the accessory tear glands produce this watery layer. The function of this layer is to keep the eye moist and comfortable, as well as to help flush out any dust, debris, or foreign objects that may get into the eye. Defects of the aqueous layer are the most common cause of dry eye syndrome, also referred to as dry eye or keratoconjunctivitis sicca (KCS).
- The most superficial layer is a very thin layer of lipids (fats or oils). The meibomian glands and the glands of Zeis (oil glands in the eyelids) produce these lipids. The main function of this lipid layer is to help decrease the evaporation of the watery layer beneath.
Dry eye syndrome can affect any race and is more common in women than in men. Another term used for dry eye is ocular surface disease.
Tears are essential to lubricate and protect the surface of the eye, and when they are inadequate, it can lead to a range of symptoms, including:
- Dryness, grittiness, or a feeling like something is in your eye
- Burning or stinging sensations
- Redness or irritation
- Blurred vision
- Excessive tearing (a reflex response to dryness)
What is chronic dry eye syndrome?
Chronic dry eye syndrome is a persistent condition of dry eyes that may wax and wane over an extended period. Chronic dry eye syndrome is a common condition that can affect people of all ages, but it is more common in older adults, women, and those with certain medical conditions. It can be caused by a variety of factors, including hormonal changes, medications, environmental factors, and underlying medical conditions.
Removing environmental influences or reducing contact lens wear does not provide relief.
What causes dry eye syndrome?
Dry eye syndrome is a common disorder of the normal tear film that results from decreased tear production, excessive tear evaporation, and an abnormality in the production of mucus or lipids normally found in the tear layer, or a combination of these. Aqueous (watery) tear deficiency is caused by either poor production of watery tears or excessive evaporation of the watery tear layer. Poor production of tears by the tear glands may be a result of the following:
- hormonal changes, or
- various autoimmune diseases, such as primary Sjögren's syndrome, rheumatoid arthritis, or systemic lupus erythematosus.
- Evaporative loss of the watery tear layer is usually a result of an insufficient overlying lipid layer.
If blinking decreases or if the eyelids cannot be closed, the eyes may dry out because of tear evaporation. While reading, watching TV, or performing a task that requires close attention with the eyes, a person may not blink as often. This decreased blinking allows excessive evaporation of the tears. Certain health conditions, such as stroke or Bell's palsy, make it difficult to close the eyes. As a result, the eyes may become dry from tear evaporation.
Abnormal production of mucin by the conjunctiva may occur. This can result from chemical (alkali) burns to the eye or because of different autoimmune diseases, such as Stevens-Johnson syndrome and cicatricial pemphigoid. This abnormal production leads to poor spreading of the tears over the surface of the eye. The surface of the eye can dry out and even become damaged despite the presence of sufficient watery tears.
Insufficient lipid layers are the result of meibomian gland dysfunction, rosacea, or following oral isotretinoin medication. Meibomian glands are the oil glands in the eyelids that produce the lipid layer. If these oil glands become blocked or if the oil is too thick, there may not be enough oil to cover the watery tear layer to prevent its evaporation.
In addition, if an infection is present along the eyelids or the eyelashes (called blepharitis) the bacteria may break down the oil, so there may not be enough oil. This may lead to evaporative loss of tears and dry eyes.
What are the risk factors for dry eye syndrome?
Dry eye syndrome is more common with increasing age, female sex, and Asian ethnicity.
Other common risk factors include:
- Menopause can increase the risk of dry eye syndrome.
- Paradoxically, postmenopausal women on hormone replacement therapy, especially estrogens alone, have a higher prevalence of dry eyes than postmenopausal women who don't take hormones.
- Occupational and environmental factors increasing risk include low humidity, high room temperature, wind exposure, pollution, poor air quality, smoking, and decreased blink rates due to sustained computer use or reading.
- Diseases associated with dry eyes include vitamin A deficiency (historically known as xerophthalmia), acne rosacea, autoimmune/connective tissue disease, hepatitis C infection, HIV infection, Sjögren's syndrome, sarcoidosis, diabetes mellitus, and androgen or estrogen deficiency.
- Wearing contact lenses increases the risk of dry eye syndrome. Refractive surgery, especially LASIK, frequently causes dry eyes.
- A diet low in omega-3 fatty acids or a diet with a relatively high amount of omega-6 fatty acids relative to omega-3 fatty acids can also increase the risk of dry eye syndrome.
- Various types of medications, including systemic chemotherapy, diuretics, antidepressants, antihistamines, and beta-adrenergic blockers, may cause dry eyes as a side effect of the medication.
- Irregularities of the conjunctival surface as seen with pingueculae or pterygia can cause dry eye symptoms. Abnormalities of the blink mechanism or mechanical lid abnormalities can also produce DES symptoms.
- Prolonged screen time such as extended use of digital devices like computers, smartphones, and tablets can lead to dry eyes due to reduced blinking.
What are symptoms and signs of dry eye syndrome?
A person with dry eye syndrome may experience including:
- Dryness: A feeling of dryness or grittiness in the eyes is one of the most common symptoms of dry eye syndrome.
- Gritty/scratchy, or filmy feelings: The eyes may become more uncomfortable and fatigued.
- Burning or itching: Vision may be temporarily blurred or distorted, especially when reading or doing tasks that require visual focus.
- Redness of the eyes (conjunctivitis): The eyes may appear red, and there may be a sensation of burning or stinging.
- Blurred vision: Vision may be temporarily blurred or distorted, especially when reading or doing tasks that require visual focus.
- Foreign body sensation: The eyes may appear red and have discomfort.
- Light sensitivity: The eyes may become more sensitive to bright lights, making it uncomfortable to be outside or in brightly-lit areas.
- Mucous discharge: In some cases, dry eye syndrome can cause a thick, stringy discharge from the eyes.
- Contact lens discomfort: People who wear contact lenses may experience increased discomfort or difficulty wearing their lenses.
Dry eye symptoms seem to worsen in dry or windy climates and with higher temperatures and lower humidity. Symptoms may also be worse with prolonged use of the eyes (for example, while reading and watching TV) and toward the end of the day.
Sometimes a symptom of dry eye syndrome may be intermittent excessive tearing. With dry eyes, when the eyes become slightly dry and irritated, they may initiate reflex tearing with the production of a large number of tears all at once to try to get moist and comfortable again. Unfortunately, the eyes can only handle so many tears at any one time; the rest pour over the eyelids and down the cheeks. A short time later, the eyes will become slightly dry and irritated again and the whole process may repeat itself.
How do healthcare professionals diagnose dry eye syndrome?
During an eye examination, an eye care specialist (ophthalmologist) will most likely be able to diagnose dry eye syndrome just by hearing the patient's complaints about his or her eyes. A healthcare professional can confirm the diagnosis of dry eyes by observing signs of dry eyes.
As part of the eye examination, a doctor may do the following:
- Examine the front of the eyes is examined using a special microscope, called a slit lamp
- Inspect the amount and thickness of the tear film
- Assess the stability of the tear film by checking the tear breakup time
- Inspect the eyelids for signs of inflammation
- Examine the Meibomian glands of the lids and their openings into the tear film
- Assess the conjunctiva to determine if it is too dry or inflamed
- Check the cornea to see if it has dried out or become damaged. If both the cornea and conjunctiva are involved, the condition is known as keratoconjunctivitis.
An ophthalmologist may use different dyes during a patient's eye examination. An eye care specialist will place the dyes into the tears in the form of a drop. Fluorescein is a yellow dye that stains the cornea where epithelial (surface) cells have been worn away because of the lack of an adequate protective tear film. Rose Bengal is a red dye that stains the cornea and the conjunctiva where the cells are dead or dying as well as where healthy cells are inadequately protected by the tear film. Lissamine Green is a green dye that can help differentiate between normal and abnormal surface cells of the cornea and conjunctiva.
Schirmer tests measure the number of tears produced by the eyes. The ophthalmologist places the end of a thin strip of filter paper just inside the lower eyelid. After a minute, the doctor removes the filter paper, and the amount of wetting is measured. Less wetting of the filter paper is more indicative of dry eye syndrome.
The osmolarity (salt content) of the tears may be measured. This is a new test that aids in the diagnosis of dry eye syndrome, in which tear osmolarity is increased over normal levels.
Another new test on the tears can detect the presence of MMP-9 (matrix metalloproteinase 9), a substance which, when present in the tears, is a reliable marker for the presence of early ocular surface disease and dry eye. This test may be helpful to identify patients with ocular surface inflammation and autoimmune disease and may facilitate the decision to institute anti-inflammatory treatment in these patients. If autoimmune diseases or Sjögren's syndrome are suspected as a cause of a patient's dry eye syndrome, blood tests may be performed. These blood tests check for the presence of different autoantibodies that may be associated with dry eye syndrome.
Rarely, a doctor may perform a biopsy of the salivary glands. Certain disease processes, such as Sjögren's syndrome, affect both the salivary glands, which produce saliva in your mouth, and the lacrimal glands, which produce tears.
What are over-the-counter medical treatments for dry eye syndrome?
Although no cure exists for dry eye syndrome, many medical treatments are available. Treatment is dependent on the severity of the condition; some people may only require a humidifier or occasional eye drops while others may require surgery to help decrease dry eyes.
Over-the-counter lubricating eye drops, commonly referred to as artificial tears, may help relieve dry eyes. Some examples of these products include 20/20 Tears, Celluvisc, Comfort Tears, Dry Eyes, Murine, Refresh, Genteal, Soothe, TheraTears, Systane, and Tears Naturale. Most of these are available in preservative-free packaging, which reduces the possibility of irritation from preservatives. One should avoid tear substitutes containing a vasoconstrictor such as naphazoline, tetrahydrozoline, phenylephrine, and oxymetazoline. A doctor may also prescribe medications to help a patient with dry eye syndrome.
What types of medications (prescriptions) are used for dry eye syndrome?
A major portion of the ophthalmologist's decision about prescription treatment of DES is based on determining whether the problem is primarily evaporative or aqueous-deficient, or a combination of both. There is a great deal of overlap between the evaporative and aqueous-deficient dry eye.
Certain prescription medications may help with dry eye syndrome. An eye care professional may prescribe eye lubricants, such as Lacrisert, an artificial tear insert. The insert is similar to a contact lens, and the patient will need to insert the eye lubricant one to two times per day. Cellulose is contained in the insert and acts to stabilize and thicken the film of tears over the eyes and to prolong the time the tear film works. Corneal abrasion may occur if the artificial tear insert isn't inserted properly.
Certain prescription medications may help with dry eye syndrome. Cyclosporine A 0.5% (Restasis) helps decrease any inflammation on the surface of the eye. This inflammation decreases the ability of the eyes to maintain a healthy tear film. Used twice a day, cyclosporine 0.5% helps people make more, healthier tears on their own. Lifitegrast 5% (Xiidra) is another approved prescription eye drop that reduces inflammation in the tear glands. Corticosteroid drops (Lotemax, Alrex, FML, Vexol), either alone or used in conjunction with cyclosporine or Lifitegrast, reduce the signs and symptoms of dry eye. Although the FDA has not yet approved this group of drops for the medical treatment of dry eye syndrome, many ophthalmologists use them. Corticosteroid drops, if used in excess, may have some side effects, but new formulations with fewer side effects have become available. Like all medications, patients should only use these under a doctor's supervision and according to her or his instructions. Nonsteroidal anti-inflammatory drops (Voltaren, Acular, Nevanac, and Xibrom) likewise reduce the inflammation associated with dry eye syndrome.
People with blepharitis or meibomian gland dysfunction need antibiotics. The patient will use antibiotic ophthalmic drops or ointments, such as erythromycin, azithromycin, and bacitracin, among others, for about seven to 10 days to decrease the number of bacteria that break down the lipid layer of the tear film. In ointment form, these also lubricate the eyes overnight. Oral antibiotics, particularly azithromycin and doxycycline or another tetracycline, not only help to decrease the number of bacteria but also help to make the oil more fluid so it flows out of the oil glands more easily. This is often used if a person has rosacea. Many people have rosacea of the eyelids, suffer from dry eye syndrome, and do not have the typical changes of rosacea on the rest of the face.
Other physician-prescribed medications may include drops prepared by a compounding pharmacy such as autologous serum or hormonal drops.
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Can surgery treat dry eye syndrome?
Different minor surgical procedures may help decrease dry eye syndrome. Near the inner corner of each eyelid are tiny openings, called punctae, that are the beginning of the normal tear drainage system. From there, tears normally flow through nasolacrimal ducts into the nose.
Here are some examples of surgical procedures used to treat dry eye syndrome:
- Punctal occlusion helps by decreasing the normal drainage of the tears from the ocular surface and down the tear drainage system, into the back of the nose, and down the throat. This occlusion is usually done by a very simple office procedure and only takes a few minutes.
- An eye care professional can place different punctual plugs or lacrimal canalicular plugs at or just inside these openings to block the normal drainage of tears down the tear drainage system. Just like a stopper placed in the drain of a sink keeps the water from flowing down the drain, these plugs keep the tears from flowing down the tear drainage system. Therefore, the eyes stay more moist and comfortable, even if one has fewer tears.
- Ophthalmologists can remove these plugs very easily, if necessary. Sometimes, in severe cases of dry eye syndrome, eye care professionals permanently close these openings, usually by cautery (burning) or laser. This accomplishes the same thing as the plugs, but it is very difficult, if not impossible, to reverse.
- If a person has difficulty closing the eyes for any reason, such as Bell's palsy, the eyes may dry out because of tear evaporation. Lateral tarsorrhaphy is a procedure during which the lateral (outside) one-third of the eyelids are sewn together to decrease the ability of the eye to open widely and to help the eyes close more easily. If a stroke or nerve damage keeps the eyelids from closing properly, a doctor may implant a small gold weight into the upper eyelid to help it close.
- Thermal pulsation therapy uses a device to apply heat to the inner eyelids to liquefy and release blockages in the meibomian glands, which can improve the quality of the tear film.
- Intense pulsed light therapy uses a handheld device to apply light and heat to the lower eyelids, which can stimulate the meibomian glands and increase tear production.
- Autologous serum eye drops are eye drops made from a person's blood serum that can help lubricate and heal the surface of the eye.
- Salivary gland transplantation is a rare procedure in which a person's salivary gland tissue is transplanted into the lower eyelid to increase tear production.
Can self-care treatments and remedies help alleviate dry eyes?
To help alleviate the symptoms of dry eye syndrome, certain self-care tips at home may help.
- A humidifier puts more moisture into the air. With more moisture in the air, tears evaporate more slowly, keeping the eyes more comfortable. Both furnaces in the winter and air conditioning in the summer decrease the humidity in the air.
- Excessive air movement dries out the eyes. Avoid having excessive air movement by decreasing the speed of ceiling fans and/or oscillating fans.
- Large amounts of dust or other particulate matter in the air may worsen the symptoms of dry eye. In those situations, an air filter may be helpful.
- Warm compresses and eyelid scrubs/massage with baby shampoo help by providing a thicker, more stable lipid layer. This is especially helpful if a person has meibomian gland dysfunction, rosacea, or blepharitis.
- The heat (careful, warm compresses should not be too hot; the compress should be comfortable if placed on your wrist) warms up the oil in the oil glands, making it flow more easily; the mild massaging action helps get the oil out of the glands.
- The cleansing action decreases the number of bacteria that break down the oil.
- Blink regularly: Remind yourself to blink often when using a computer or reading for an extended period, as this helps to spread tears across the surface of the eye.
- Artificial tears and lubricating eyedrops and gels (available over the counter) help provide more moisture and lubrication for the surface of the eye.
- Individuals typically use lubricating eyedrops about four times a day, but they can be used as often as needed.
- Doctors recommend preservative-free solutions for those who wish to use tears more than six times a day.
There is no single over-the-counter drop that is best for everybody. Each individual will determine which drop provides the most relief from symptoms. Some drops may have a long time effect than others.
- Lubricating eye ointments are much thicker than eye drops and gels. Because ointments are so thick, they last much longer than eye drops and gels. However, because of their thickness, ointments may blur vision if people use them during the day. Therefore, people typically use ointments to lubricate the eyes overnight during sleep.
- If the eyes are dry mainly while reading or watching TV, taking frequent breaks to allow the eyes to rest and become moist and comfortable again is helpful. Closing the eyes for 10 seconds every five to 10 minutes will increase comfort, as well as blinking more frequently.
- Taking a fish oil (or another high-quality source of omega-3 fatty acids) supplement every day can often help alleviate symptoms of dry eye.
What are other therapies that treat dry eye syndrome?
Sometimes, people sleep with their eyes slightly open. If a person sleeps this way, he or she might want to tape the eyes shut at night.
Moisture chambers are plastic shields (similar to swim goggles) that help keep the eyes from drying out by decreasing the evaporation of tears in the eye. A person may use the moisture chambers just at night if he or she sleeps with his or her eyes slightly open, or they may be used all day, if necessary.
What is the prognosis of dry eye syndrome?
Although dry eye syndrome can be very symptomatic, it is seldom a cause of significant visual loss. Most cases are benign and easily treated with artificial tears. Although ulcers of the cornea can occur, they are extremely rare.
More than 3 million American women over the age of 50 have moderate to severe dry eyes, while more than 1.5 million American men over the age of 50 are similarly afflicted. Millions of others have mild dry eyes. In the majority of these people, this health condition is benign and easily treated with artificial tears.
Many wearers of contact lenses experience dry eyes at some point with many discontinuing or limiting lens wear. Dry eye is a significant finding in patients having undergone refractive surgery, especially LASIK.
In addition to affecting ocular health, the discomfort and irritation of dry eyes can cause deterioration of general well-being, emotional health, and social functioning. Studies have demonstrated that people with dry eye syndrome are three times more likely than those without dry eyes to have difficulty with reading, computer work, watching TV, and driving. Direct costs of dry eyes, such as frequent physician visits, diagnostic tests, and charges for medication and surgery impact our healthcare resources. In addition, there are immeasurable indirect costs related to decreased productivity and efficiency and lost work time.
What are the health complications of dry eye syndrome?
Most people with dry eye syndrome have nothing to worry about aside from an annoying inconvenience. Although the symptoms might make activities of daily living (for example, reading, watching TV, driving) miserable, no long-term vision loss is to be expected.
For those with more severe dry eye syndrome, significant drying of the surface of the eye can lead to an increased risk of serious infections. Ultimately, scarring, thinning, and even perforation of the cornea may occur. As a result, vision, or even the eye itself, may be permanently damaged or function lost.
Is it possible to prevent dry eye syndrome?
Avoiding environmental causes of dry eye can be helpful in prevention. If the eyes are dry mainly while reading or watching TV, taking frequent breaks to allow the eyes to rest and become moist and comfortable again is helpful. Closing the eyes for 10 seconds every five to 10 minutes will increase comfort, as well as blinking more frequently.
Taking a fish oil (or other high-quality sources of omega-3 fatty acids) supplement every day can often help alleviate symptoms of dry eye.
Foster, C. Stephen, et al. "Dry Eye Syndrome." Medscape.com. 25 Jan. 2012. <http://emedicine.medscape.com/article/1210417-overview>.
Kangari, Haleh, Mohammad Hossein Eftekhari, Sara Sardari, Hassan Hashemi, Jamshid Salamzadeh, Mohammad Ghassemi-Broumand, and Mehdi Khabazkhoob. "Short-term Consumption of Oral Omega-3 and Dry Eye Syndrome." Ophthalmology 120.11 November 2013: 2191-2196.
Lemp, Michael A. "Epidemiology and classification of dry eye." Advances in Experimental Medicine and Biology 438 (1998): 791-803.
Moss, S. E., et al. "Prevalence of and risk factors for dry eye syndrome." Archives of Ophthalmology 118.9 (2000): 1264-1268.
Uchino, M., et al. "Prevalence and risk factors of dry eye disease in Japan: Koumi study." Opthalmology 118.12 (2011): 2361-2367.
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