Keratoconjunctivitis sicca
Encyclopedia
Keratoconjunctivitis sicca (KCS), also called keratitis
sicca, xerophthalmia
or dry eye syndrome (DES) is an eye disease caused by eye dryness
, which, in turn, is caused by either decreased tear
production or increased tear film evaporation. It is found in humans and some animals. The phrase "keratoconjunctivitis sicca" is Latin
, and its literal translation is "dry inflammation of the cornea
and conjunctiva
".
There may also be a stringy discharge from the eyes. Although it may seem strange, dry eye can cause the eyes to water. This can happen because the eyes are irritated. One may experience excessive tearing in the same way as one would if something got into the eye. These reflex tears will not necessarily make the eyes feel better. This is because they are the watery type that are produced in response to injury, irritation, or emotion. They do not have the lubricating qualities necessary to prevent dry eye.
Because blinking coats the eye with tears, symptoms are worsened by activities in which the rate of blinking is reduced due to prolonged use of the eyes. These activities include prolonged reading, computer usage, driving, or watching television. Symptoms increase in windy, dusty or smoky (including cigarette smoke) areas, in dry environments, high altitudes including airplanes, on days with low humidity, and in areas where an air conditioner (especially in a car), fan, heater, or even a hair dryer is being used. Symptoms reduce during cool, rainy, or foggy weather and in humid places, such as in the shower.
Most people who have dry eyes experience mild irritation with no long-term effects. However, if the condition is left untreated or becomes severe, it can produce complications that can cause eye damage, resulting in impaired vision or (rarely) in the loss of vision.
Symptom assessment is a key component of dry eye diagnosis - to the extent that many believe dry eye syndrome to be a symptom-based disease. Several questionnaires have been developed to determine a score that would allow for dry eye diagnosis. The McMonnies & Ho dry eye questionnaire is often used in clinical studies of dry eyes. It has 14 questions, resulting in a score from 0 to 45. Scores above 14.5 are consistent with dry eyes.
undergoes pathologic changes, namely squamous metaplasia
and loss of goblet cell
s. Some severe cases result in thickening of the corneal surface, corneal erosion, punctate keratopathy
, epithelial
defects, corneal ulcer
ation (sterile and infected), corneal neovascularization
, corneal scarring, corneal thinning, and even corneal perforation
.
produces an unstable tear film, resulting in symptoms of keratitis sicca.
does not produce sufficient tears to keep the entire conjunctiva
and cornea
covered by a complete layer. This usually occurs in people who are otherwise healthy. Increased age is associated with decreased tearing. This is the most common type found in postmenopausal women.
Causes include idiopathic
, congenital alacrima, xerophthalmia, lacrimal gland ablation
, and sensory denervation. In rare cases, it may be a symptom of collagen vascular diseases, including rheumatoid arthritis
, Wegener's granulomatosis
, and systemic lupus erythematosus
. Sjögren's syndrome
and autoimmune diseases
associated with Sjögren's syndrome
are also conditions associated with aqueous tear deficiency. Drugs such as isotretinoin
, sedatives, diuretics, tricyclic antidepressants, antihypertensive
s, oral contraceptive
s, antihistamines, nasal decongestants, beta-blockers, phenothiazines, atropine, and pain relieving opiates such as morphine can cause or worsen this condition. Infiltration of the lacrimal glands by sarcoidosis
or tumors, or postradiation fibrosis of the lacrimal glands can also cause this condition.
About half of all people who wear contact lenses complain of dry eyes. There are two potential connections between contact usage and dry eye. Traditionally, it was believed that soft contact lenses, which float on the tear film that covers the cornea, absorb the tears in the eyes. However, it is also now known that contact usage damages corneal nerve sensitivity, which subsequently may lead to decreased lacrimal gland tear production and dry eye. The effect of contact on corneal nerve sensitivity is well established for hard contacts as well as soft and rigid gas permeable. The connection between this loss in nerve sensitivity and tear production is the subject of current research .
Dry eyes also occurs or gets worse after LASIK
and other refractive surgeries
, in which the corneal nerves are cut during the creation of a corneal flap
. The corneal nerves stimulate tear secretion. Dry eyes caused by these procedures usually resolves after several months, but it can be permanent. Persons who are thinking about refractive surgery should consider this.
An eye injury or other problem with the eyes or eyelid
s, such as bulging eyes or a drooping eyelid
can cause keratoconjunctivitis sicca. Disorders of the eyelid can impair the complex blinking motion required to spread tears.
Abnormalities of the lipid tear layer caused by blepharitis
and rosacea
, and abnormalities of the mucin tear layer caused by vitamin A
deficiency, trachoma
, diphtheric keratoconjunctivitis, mucocutaneous disorders and certain topical medications are causes of keratoconjunctivitis sicca.
Persons with keratoconjunctivitis sicca have elevated levels of tear nerve growth factor
(NGF). It is possible that this ocular
surface NGF plays an important role in ocular surface inflammation associated with dry eyes.
examination can be performed to diagnose dry eyes and to document any damage to the eye.
A Schirmer's test
can measure the amount of moisture bathing the eye. This test is useful for determining the severity of the condition. A five-minute Schirmer's test with and without anesthesia using a Whatman #41 filter paper 5 mm wide by 35 mm long is performed. For this test, wetting under 5 mm with or without anesthesia is considered diagnostic for dry eyes.
If the results for the Schirmer's test are abnormal, a Schirmer II test can be performed to measure reflex secretion. In this test, the nasal mucosa is irritated with a cotton-tipped applicator, after which tear production is measured with a Whatman #41 filter paper. For this test, wetting under 15 mm after five minutes is considered abnormal.
A tear breakup time (TBUT) test measures the time it takes for tears to break up in the eye. The tear breakup time can be determined after placing a drop of fluorescein
in the cul-de-sac.
A tear protein analysis test measures the lysozyme
contained within tears. In tears, lysozyme accounts for approximately 20 to 40 percent of total protein content.
A lactoferrin analysis test provides good correlation with other tests.
The presence of the recently described molecule Ap4A, naturally occurring in tears, is abnormally high in different states of ocular dryness. This molecule can be quantified biochemically simply by taking a tear sample with a plain Schirmer test. Utilizing this technique it is possible to determine the concentrations of Ap4A in the tears of patients and in such way diagnose objectively if the samples are indicative of dry eye.
can often co-exist and paying particular attention to cleaning the eyelids morning and night with mild shampoos and warm compresses can improve both conditions.
, especially in the winter, can help by adding moisture to the dry indoor air.
, hepatocyte growth factor
, fibronectin
, neurotrophic growth factor
, and vitamin A
—all of which have been shown to play important roles in the maintenance of a healthy ocular surface epithelial milieu. Autologous serum eye drops contain these essential factors. However, there is some controversy regarding the efficacy of this treatment. At least one study has demonstrated that this modality is more effective than artificial tears in a randomized control study.
, mineral oil
, and similar lubricants. They serve as a lubricant and an emollient. Application requires pulling down the eyelid and applying a small amount (0.25 in) inside. Depending on the severity of the condition, it may be applied from every hour to just at bedtime. It should not be used with contact lenses. Specially designed glasses that form a moisture chamber around the eye may be used to create additional humidity.
s or with topical immunosuppressant
s such as Optimmune
(ciclosporin
). Elevated levels of tear NGF can be decreased with 0.1% prednisolone
.
s is associated with a decreased incidence of dry eyes syndrome in women. This finding is consistent with postulated biological mechanisms. Early experimental work on omega-3 has shown promising results when used in a topical application or given orally.
, marketed in the United States by Allergan
under the trade name Restasis. Approved as a prescription product by the U.S. Food and Drug Administration
in 2002, the drug decreases surface inflammation. It is thought to work through inhibition of transcription factors required for cytokine production and T-lymphocyte maturation. In a trial involving 1200 people, Restasis increased tear production in 15% of people, compared to 5% with placebo.
Usually, 1 gtt
(drop) of Restasis is instilled in each eye twice a day, 12 hours apart. It should not be used while wearing contact lenses, during eye infections or in people with a history of herpes virus infections. Side effects include burning sensation (common), redness, discharge, watery eyes, eye pain, foreign body sensation, itching, stinging, and blurred vision. Long term use of cyclosporin at high doses is associated with an increased risk of cancer.
Cheaper generic
alternatives to Restasis are available in some countries. In India, it is marketed as Cyclomune by Sun Pharma.
— little openings that drain tears into the tear ducts. There are methods to partially or completely close the tear ducts. This blocks the flow of tears into the nose, and thus more tears are available to the eyes.
Punctal plugs are inserted into the puncta to block tear drainage. For people who have not found dry eye relief with drugs, punctal plugs may help. They are reserved for people with moderate or severe dry eye when other medical treatment has not been adequate.
If punctal plugs are effective, thermal or electric cauterization
of puncti can be performed. In thermal cauterization, a local anesthetic is used, and then a hot wire is applied. This shrinks the drainage area tissues and causes scarring, which closes the tear duct.
, it creates a fluid filled layer over the cornea, thus preventing it from drying.
may be performed where the eyelids are partially sewn together. This reduces the palpebral fissure
(eyelid separation), ideally leading to a reduction in tear evaporation.
shows considerable variance, depending upon the severity of the condition. Most patients have mild-to-moderate cases, and can be treated symptomatically with lubricants. This provides an adequate relief of symptoms.
When dry eyes symptoms are severe, they can interfere with quality of life. People sometimes feel their vision blurs with use, or severe irritation to the point that they have trouble keeping their eyes open or they may not be able to work or drive.
While persons with autoimmune diseases have a high likelihood of having dry eyes, most persons with dry eyes do not have an autoimmune disease. Instances of Sjögren syndrome and keratoconjunctivitis sicca associated with it are present much more commonly in women, with a ratio of 9:1. In addition, milder forms of keratoconjunctivitis sicca also are more common in women. This is partly because hormonal changes, such as those that occur in pregnancy, menstruation, and menopause, can decrease tear production.
In areas of the world where malnutrition is common, vitamin A deficiency is a common cause. This is rare in the United States.
Racial predilections do not exist for this disease.
s. Most cases are caused by a genetic
predisposition, but chronic conjunctivitis
, canine distemper
, and drugs such as sulfasalazine and trimethoprim-sulfonamide
also cause the disease. Symptoms include eye redness, a yellow or greenish discharge, ulceration of the cornea
, pigment
ed cornea, and blood vessels on the cornea. Diagnosis is made by measuring tear production with a Schirmer tear test
. Less than 15 millimeters of tears produced in a minute is abnormal.
Tear replacers are a mainstay of treatment, preferably containing methylcellulose
or carboxymethyl cellulose
. Ciclosporin stimulates tear production and acts as a suppressant on the immune-mediated
processes that cause the disease. Topical antibiotic
s and corticosteroid
s are sometimes used to treat secondary infections and inflammation. A surgery known as parotid duct
transposition is used in some extreme cases where medical treatment has not helped. This redirects the duct from the parotid salivary gland
to the eye. Saliva
replaces the tears. Dogs suffering from cherry eye
should have the condition corrected to help prevent this disease.
Commonly affected breeds include:
s. Most cases seem to be caused by chronic conjunctivitis, especially secondary to feline herpesvirus. Diagnosis, symptoms, and treatment are similar to those for dogs.
Keratitis
Keratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:...
sicca, xerophthalmia
Xerophthalmia
Xerophthalmia is a medical condition in which the eye fails to produce tears. It may be caused by a deficiency in vitamin A and is sometimes used to describe that lack, although there may be other causes....
or dry eye syndrome (DES) is an eye disease caused by eye dryness
Dryness (medical)
Dryness is a medical condition in which there is local or more generalized decrease in normal lubrication of the skin or mucous membranes.Examples of local dryness include dry mouth, dry eyes, dry skin and vaginal dryness. These often have specific causes and treatments...
, which, in turn, is caused by either decreased tear
Tears
Tears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....
production or increased tear film evaporation. It is found in humans and some animals. The phrase "keratoconjunctivitis sicca" is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
, and its literal translation is "dry inflammation of the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
and conjunctiva
Conjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
".
Symptoms
Typical symptoms of keratoconjunctivitis sicca are dryness, burning and a sandy-gritty eye irritation that gets worse as the day goes on. Symptoms may also be described as itchy, scratchy, stingy or tired eyes. Other symptoms are pain, redness, a pulling sensation, and pressure behind the eye. There may be a feeling that something, such as a speck of dirt, is in the eye. The resultant damage to the eye surface increases discomfort and sensitivity to bright light. Both eyes usually are affected.There may also be a stringy discharge from the eyes. Although it may seem strange, dry eye can cause the eyes to water. This can happen because the eyes are irritated. One may experience excessive tearing in the same way as one would if something got into the eye. These reflex tears will not necessarily make the eyes feel better. This is because they are the watery type that are produced in response to injury, irritation, or emotion. They do not have the lubricating qualities necessary to prevent dry eye.
Because blinking coats the eye with tears, symptoms are worsened by activities in which the rate of blinking is reduced due to prolonged use of the eyes. These activities include prolonged reading, computer usage, driving, or watching television. Symptoms increase in windy, dusty or smoky (including cigarette smoke) areas, in dry environments, high altitudes including airplanes, on days with low humidity, and in areas where an air conditioner (especially in a car), fan, heater, or even a hair dryer is being used. Symptoms reduce during cool, rainy, or foggy weather and in humid places, such as in the shower.
Most people who have dry eyes experience mild irritation with no long-term effects. However, if the condition is left untreated or becomes severe, it can produce complications that can cause eye damage, resulting in impaired vision or (rarely) in the loss of vision.
Symptom assessment is a key component of dry eye diagnosis - to the extent that many believe dry eye syndrome to be a symptom-based disease. Several questionnaires have been developed to determine a score that would allow for dry eye diagnosis. The McMonnies & Ho dry eye questionnaire is often used in clinical studies of dry eyes. It has 14 questions, resulting in a score from 0 to 45. Scores above 14.5 are consistent with dry eyes.
Pathophysiology
Having dry eyes for a while can lead to tiny abrasions on the surface of the eyes. In advanced cases, the epitheliumEpithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
undergoes pathologic changes, namely squamous metaplasia
Squamous metaplasia
Squamous metaplasia refers to benign changes in the epithelial linings of certain organs within the body. These cells assume a more squamous morphology. Common sites for squamous metaplasia include the bladder and cervix. Smokers often exhibit squamous metaplasia in the linings of their airways...
and loss of goblet cell
Goblet cell
Goblet cells are glandular simple columnar epithelial cells whose sole function is to secrete mucin, which dissolves in water to form mucus. They use both apocrine and merocrine methods for secretion....
s. Some severe cases result in thickening of the corneal surface, corneal erosion, punctate keratopathy
Keratopathy
Keratopathy can refer to:* Florida keratopathy* Thygeson's superficial punctate keratopathy...
, epithelial
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
defects, corneal ulcer
Corneal ulcer
A corneal ulcer, or ulcerative keratitis, is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats...
ation (sterile and infected), corneal neovascularization
Neovascularization
Neovascularization is the formation of functional microvascular networks with red blood cell perfusion. Neovascularization differs from angiogenesis in that angiogenesis is mainly characterized by the protrusion and outgrowth of capillary buds and sprouts from pre-existing blood vessels.In...
, corneal scarring, corneal thinning, and even corneal perforation
Perforation
A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes are called a perforation...
.
Causes
Any abnormality of any one of the three layers of tearsTears
Tears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....
produces an unstable tear film, resulting in symptoms of keratitis sicca.
Deficient tear production
Keratoconjunctivitis sicca is usually due to inadequate tear production. The aqueous tear layer is affected, resulting in aqueous tear deficiency (ATD) or lacrimal hyposecretion. The lacrimal glandLacrimal gland
The lacrimal glands are paired almond-shaped glands, one for each eye, that secrete the aqueous layer of the tear film. They are situated in the upper, outer portion of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone. Inflammation of the lacrimal glands is called...
does not produce sufficient tears to keep the entire conjunctiva
Conjunctiva
The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:...
and cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
covered by a complete layer. This usually occurs in people who are otherwise healthy. Increased age is associated with decreased tearing. This is the most common type found in postmenopausal women.
Causes include idiopathic
Idiopathic
Idiopathic is an adjective used primarily in medicine meaning arising spontaneously or from an obscure or unknown cause. From Greek ἴδιος, idios + πάθος, pathos , it means approximately "a disease of its own kind". It is technically a term from nosology, the classification of disease...
, congenital alacrima, xerophthalmia, lacrimal gland ablation
Ablation
Ablation is removal of material from the surface of an object by vaporization, chipping, or other erosive processes. This occurs in spaceflight during ascent and atmospheric reentry, glaciology, medicine, and passive fire protection.-Spaceflight:...
, and sensory denervation. In rare cases, it may be a symptom of collagen vascular diseases, including rheumatoid arthritis
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
, Wegener's granulomatosis
Wegener's granulomatosis
Wegener's granulomatosis , more recently granulomatosis with polyangiitis , is an incurable form of vasculitis that affects the nose, lungs, kidneys and other organs. Due to its end-organ damage, it is life-threatening and requires long-term immunosuppression...
, and systemic lupus erythematosus
Lupus erythematosus
Lupus erythematosus is a category for a collection of diseases with similar underlying problems with immunity . Symptoms of these diseases can affect many different body systems, including joints, skin, kidneys, blood cells, heart, and lungs...
. Sjögren's syndrome
Sjögren's syndrome
Sjögren's syndrome , also known as "Mikulicz disease" and "Sicca syndrome", is a systemic autoimmune disease in which immune cells attack and destroy the exocrine glands that produce tears and saliva....
and autoimmune diseases
Autoimmunity
Autoimmunity is the failure of an organism to recognize its own constituent parts as self, which allows an immune response against its own cells and tissues. Any disease that results from such an aberrant immune response is termed an autoimmune disease...
associated with Sjögren's syndrome
Sjögren's syndrome
Sjögren's syndrome , also known as "Mikulicz disease" and "Sicca syndrome", is a systemic autoimmune disease in which immune cells attack and destroy the exocrine glands that produce tears and saliva....
are also conditions associated with aqueous tear deficiency. Drugs such as isotretinoin
Isotretinoin
Isotretinoin, INN, is a medication used mostly for cystic acne. It was first developed for brain, pancreatic and other cancers. It is used to treat harlequin-type ichthyosis, a usually lethal skin disease, and lamellar ichthyosis. Its effects are systemic and nonselective...
, sedatives, diuretics, tricyclic antidepressants, antihypertensive
Antihypertensive
The antihypertensives are a class of drugs that are used to treat hypertension . Evidence suggests that reduction of the blood pressure by 5 mmHg can decrease the risk of stroke by 34%, of ischaemic heart disease by 21%, and reduce the likelihood of dementia, heart failure, and mortality from...
s, oral contraceptive
Oral contraceptive
The combined oral contraceptive pill , often referred to as the birth-control pill or colloquially as "the Pill", is a birth control method that includes a combination of an estrogen and a progestin . When taken by mouth every day, these pills inhibit female fertility...
s, antihistamines, nasal decongestants, beta-blockers, phenothiazines, atropine, and pain relieving opiates such as morphine can cause or worsen this condition. Infiltration of the lacrimal glands by sarcoidosis
Sarcoidosis
Sarcoidosis , also called sarcoid, Besnier-Boeck disease or Besnier-Boeck-Schaumann disease, is a disease in which abnormal collections of chronic inflammatory cells form as nodules in multiple organs. The cause of sarcoidosis is unknown...
or tumors, or postradiation fibrosis of the lacrimal glands can also cause this condition.
Abnormal tear composition
Keratoconjunctivitis sicca can also be caused by abnormal tear composition resulting in rapid evaporation or premature destruction of the tears. When caused by rapid evaporation, it is termed evaporative dry eyes. In this, although the tear gland produces a sufficient amount of tears, the rate of evaporation of the tears is too rapid. There is a loss of water from the tears that results in tears that are too "salty" or hypertonic. As a result, the entire conjunctiva and cornea cannot be kept covered with a complete layer of tears during certain activities or in certain environments.Additional causes
Aging is one of the most common causes of dry eyes. This is because tear production decreases with age. It may be caused by thermal or chemical burns, or (in epidemic cases) by adenoviruses. A number of studies have found that diabetics are at increased risk for the disease.About half of all people who wear contact lenses complain of dry eyes. There are two potential connections between contact usage and dry eye. Traditionally, it was believed that soft contact lenses, which float on the tear film that covers the cornea, absorb the tears in the eyes. However, it is also now known that contact usage damages corneal nerve sensitivity, which subsequently may lead to decreased lacrimal gland tear production and dry eye. The effect of contact on corneal nerve sensitivity is well established for hard contacts as well as soft and rigid gas permeable. The connection between this loss in nerve sensitivity and tear production is the subject of current research .
Dry eyes also occurs or gets worse after LASIK
LASIK
LASIK or Lasik , commonly referred to simply as laser eye surgery, is a type of refractive surgery for correcting myopia, hyperopia, and astigmatism...
and other refractive surgeries
Refractive surgery
Refractive eye surgery is any eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. This can include various methods of surgical remodeling of the cornea or cataract surgery. The most common methods today use excimer lasers to...
, in which the corneal nerves are cut during the creation of a corneal flap
Flap
Flap may refer to:* Flap , a hinged surface on the trailing edge of an airplane wing* Roof flap, an aerodynamic feature of race cars* Flapping, one of the basic mechanics of flight in birds...
. The corneal nerves stimulate tear secretion. Dry eyes caused by these procedures usually resolves after several months, but it can be permanent. Persons who are thinking about refractive surgery should consider this.
An eye injury or other problem with the eyes or eyelid
Eyelid
An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...
s, such as bulging eyes or a drooping eyelid
Ptosis (eyelid)
Ptosis is a drooping of the upper or lower eyelid. The drooping may be worse after being awake longer, when the individual's muscles are tired. This condition is sometimes called "lazy eye", but that term normally refers to amblyopia...
can cause keratoconjunctivitis sicca. Disorders of the eyelid can impair the complex blinking motion required to spread tears.
Abnormalities of the lipid tear layer caused by blepharitis
Blepharitis
Blepharitis is an ocular condition characterized by chronic inflammation of the eyelid, the severity and time course of which can vary. Onset can be acute, resolving without treatment within 2–4 weeks , but more generally is a long standing inflammation varying in severity...
and rosacea
Rosacea
Rosacea is a chronic condition characterized by facial erythema . Pimples are sometimes included as part of the definition. Unless it affects the eyes, it is typically a harmless cosmetic condition...
, and abnormalities of the mucin tear layer caused by vitamin A
Vitamin A
Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...
deficiency, trachoma
Trachoma
Trachoma is an infectious disease causing a characteristic roughening of the inner surface of the eyelids. Also called granular conjunctivitis and Egyptian ophthalmia, it is the leading cause of infectious blindness in the world...
, diphtheric keratoconjunctivitis, mucocutaneous disorders and certain topical medications are causes of keratoconjunctivitis sicca.
Persons with keratoconjunctivitis sicca have elevated levels of tear nerve growth factor
Nerve growth factor
Nerve growth factor is a small secreted protein that is important for the growth, maintenance, and survival of certain target neurons . It also functions as a signaling molecule. It is perhaps the prototypical growth factor, in that it is one of the first to be described...
(NGF). It is possible that this ocular
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
surface NGF plays an important role in ocular surface inflammation associated with dry eyes.
Diagnosis
Dry eyes can usually be diagnosed by the symptoms alone. Tests can determine both the quantity and the quality of the tears. A slit lampSlit lamp
The slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye. It is used in conjunction with a biomicroscope...
examination can be performed to diagnose dry eyes and to document any damage to the eye.
A Schirmer's test
Schirmer's test
Schirmer's test determines whether the eye produces enough tears to keep it moist. This test is used when a person experiences very dry eyes or excessive watering of the eyes. It poses no risk to the subject. A negative test result is normal...
can measure the amount of moisture bathing the eye. This test is useful for determining the severity of the condition. A five-minute Schirmer's test with and without anesthesia using a Whatman #41 filter paper 5 mm wide by 35 mm long is performed. For this test, wetting under 5 mm with or without anesthesia is considered diagnostic for dry eyes.
If the results for the Schirmer's test are abnormal, a Schirmer II test can be performed to measure reflex secretion. In this test, the nasal mucosa is irritated with a cotton-tipped applicator, after which tear production is measured with a Whatman #41 filter paper. For this test, wetting under 15 mm after five minutes is considered abnormal.
A tear breakup time (TBUT) test measures the time it takes for tears to break up in the eye. The tear breakup time can be determined after placing a drop of fluorescein
Fluorescein
Fluorescein is a synthetic organic compound available as a dark orange/red powder soluble in water and alcohol. It is widely used as a fluorescent tracer for many applications....
in the cul-de-sac.
A tear protein analysis test measures the lysozyme
Lysozyme
Lysozyme, also known as muramidase or N-acetylmuramide glycanhydrolase, are glycoside hydrolases, enzymes that damage bacterial cell walls by catalyzing hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between...
contained within tears. In tears, lysozyme accounts for approximately 20 to 40 percent of total protein content.
A lactoferrin analysis test provides good correlation with other tests.
The presence of the recently described molecule Ap4A, naturally occurring in tears, is abnormally high in different states of ocular dryness. This molecule can be quantified biochemically simply by taking a tear sample with a plain Schirmer test. Utilizing this technique it is possible to determine the concentrations of Ap4A in the tears of patients and in such way diagnose objectively if the samples are indicative of dry eye.
Treatment
A variety of approaches can be taken to treatment. These can be summarised as: avoidance of exacerbating factors, tear stimulation and supplementation, increasing tear retention, and eyelid cleansing and treatment of eye inflammation.General measures
Dry eyes can be exacerbated by smokey environments, dust and air conditioning and by our natural tendency to reduce our blink rate when concentrating. Purposefully blinking, especially during computer use and resting tired eyes are basic steps that can be taken to minimise discomfort. Rubbing one's eyes can irritate them further, so should be avoided. Conditions such as blepharitisBlepharitis
Blepharitis is an ocular condition characterized by chronic inflammation of the eyelid, the severity and time course of which can vary. Onset can be acute, resolving without treatment within 2–4 weeks , but more generally is a long standing inflammation varying in severity...
can often co-exist and paying particular attention to cleaning the eyelids morning and night with mild shampoos and warm compresses can improve both conditions.
Environmental control
Dry, drafty environments and those with smoke and dust should be avoided. This includes avoiding hair dryers, heaters, air conditioners or fans, especially when these devices are directed toward the eyes. Wearing glasses or directing gaze downward, for example, by lowering computer screens can be helpful to protect the eyes when aggravating environmental factors cannot be avoided. Using a humidifierHumidifier
A humidifier is a household appliance that increases humidity in a single room or in the entire house. There are point-of-use humidifiers, which are commonly used to humidify a single room, and whole-house or furnace humidifiers, which connect to a home's HVAC system to provide humidity to the...
, especially in the winter, can help by adding moisture to the dry indoor air.
Rehydration
For mild and moderate cases, supplemental lubrication is the most important part of treatment.Artificial tears
Application of artificial tears every few hours can provide temporary relief.Autologous serum eye drops
None of the commercially available artificial tear preparations include essential tear components such as epidermal growth factorEpidermal growth factor
Epidermal growth factor or EGF is a growth factor that plays an important role in the regulation of cell growth, proliferation, and differentiation by binding to its receptor EGFR...
, hepatocyte growth factor
Hepatocyte growth factor
Hepatocyte growth factor/scatter factor is a paracrine cellular growth, motility and morphogenic factor. It is secreted by mesenchymal cells and targets and acts primarily upon epithelial cells and endothelial cells, but also acts on haemopoietic progenitor cells...
, fibronectin
Fibronectin
Fibronectin is a high-molecular weight glycoprotein of the extracellular matrix that binds to membrane-spanning receptor proteins called integrins. In addition to integrins, fibronectin also binds extracellular matrix components such as collagen, fibrin and heparan sulfate proteoglycans...
, neurotrophic growth factor
Nerve growth factor
Nerve growth factor is a small secreted protein that is important for the growth, maintenance, and survival of certain target neurons . It also functions as a signaling molecule. It is perhaps the prototypical growth factor, in that it is one of the first to be described...
, and vitamin A
Vitamin A
Vitamin A is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light and color vision...
—all of which have been shown to play important roles in the maintenance of a healthy ocular surface epithelial milieu. Autologous serum eye drops contain these essential factors. However, there is some controversy regarding the efficacy of this treatment. At least one study has demonstrated that this modality is more effective than artificial tears in a randomized control study.
Additional options
Lubricating tear ointments can be used during the day, but they generally are used at bedtime due to poor vision after application. They contain white petrolatumPetroleum jelly
Petroleum jelly, petrolatum, white petrolatum or soft paraffin, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons , originally promoted as a topical ointment for its healing properties...
, mineral oil
Mineral oil
A mineral oil is any of various colorless, odorless, light mixtures of alkanes in the C15 to C40 range from a non-vegetable source, particularly a distillate of petroleum....
, and similar lubricants. They serve as a lubricant and an emollient. Application requires pulling down the eyelid and applying a small amount (0.25 in) inside. Depending on the severity of the condition, it may be applied from every hour to just at bedtime. It should not be used with contact lenses. Specially designed glasses that form a moisture chamber around the eye may be used to create additional humidity.
Medication
Inflammation occurring in response to tears film hypertonicity can be suppressed by mild topical steroidSteroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
s or with topical immunosuppressant
Immunosuppressant
An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone...
s such as Optimmune
Optimmune
Optimmune is an ophthalmic ointment with cyclosporine as the active ingredient for the treatment of pannus and chronic idiopathic keratoconjunctivitis sicca in dogs. It is a veterinary product produced by Intervet, which is part of Merck. Optimmune was invented by Dr. Renee Kaswan, a DVM and...
(ciclosporin
Ciclosporin
Ciclosporin , cyclosporine , cyclosporin , or cyclosporin A is an immunosuppressant drug widely used in post-allogeneic organ transplant to reduce the activity of the immune system, and therefore the risk of organ rejection...
). Elevated levels of tear NGF can be decreased with 0.1% prednisolone
Prednisolone
Prednisolone is the active metabolite of prednisone, which is also used as a drug.-Uses:Prednisolone is a corticosteroid drug with predominant glucocorticoid and low mineralocorticoid activity, making it useful for the treatment of a wide range of inflammatory and auto-immune conditions such as...
.
Fish consumption and omega-3 fatty acids
Consumption of dark fleshed fish containing dietary omega-3 fatty acidOmega-3 fatty acid
N−3 fatty acids are essential unsaturated fatty acids with a double bond starting after the third carbon atom from the end of the carbon chain....
s is associated with a decreased incidence of dry eyes syndrome in women. This finding is consistent with postulated biological mechanisms. Early experimental work on omega-3 has shown promising results when used in a topical application or given orally.
Restasis
Topical cyclosporin (topical cyclosporin A, tCSA) 0.05% ophthalmic emulsion is an immunosuppressantImmunosuppressant
An immunosuppressant is any substance that performs immunosuppression of the immune system. They may be either exogenous, as immunosuppressive drugs, or endogenous, as ,e. g., testosterone...
, marketed in the United States by Allergan
Allergan
Allergan, Inc., is a global specialty pharmaceutical company. Their product ranges include ophthalmic pharmaceuticals, dermatology products, and neurological products.-Profile:...
under the trade name Restasis. Approved as a prescription product by the U.S. Food and Drug Administration
Food and Drug Administration
The Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
in 2002, the drug decreases surface inflammation. It is thought to work through inhibition of transcription factors required for cytokine production and T-lymphocyte maturation. In a trial involving 1200 people, Restasis increased tear production in 15% of people, compared to 5% with placebo.
Usually, 1 gtt
Guttae (medical)
In medicine, guttae, the plural of gutta, is Latin for drops. It is frequently abbreviated as gtts and often seen on prescriptions....
(drop) of Restasis is instilled in each eye twice a day, 12 hours apart. It should not be used while wearing contact lenses, during eye infections or in people with a history of herpes virus infections. Side effects include burning sensation (common), redness, discharge, watery eyes, eye pain, foreign body sensation, itching, stinging, and blurred vision. Long term use of cyclosporin at high doses is associated with an increased risk of cancer.
Generic alternatives
Cheaper generic
Generic drug
A generic drug is a drug defined as "a drug product that is comparable to brand/reference listed drug product in dosage form, strength, route of administration, quality and performance characteristics, and intended use." It has also been defined as a term referring to any drug marketed under its...
alternatives to Restasis are available in some countries. In India, it is marketed as Cyclomune by Sun Pharma.
Conserving tears
There are methods that allow both natural and artificial tears to stay longer.Blocking tear drainage
In each eye, there are two punctaLacrimal punctum
The lacrimal canaliculi, one in each eyelid, commence at minute orifices, termed puncta lacrimalia , on the summits of the papillae lacrimales, seen on the margins of the lids at the lateral extremity of the lacus lacrimalis...
— little openings that drain tears into the tear ducts. There are methods to partially or completely close the tear ducts. This blocks the flow of tears into the nose, and thus more tears are available to the eyes.
Punctal plugs
Punctal plugs are inserted into the puncta to block tear drainage. For people who have not found dry eye relief with drugs, punctal plugs may help. They are reserved for people with moderate or severe dry eye when other medical treatment has not been adequate.
Cauterization
If punctal plugs are effective, thermal or electric cauterization
Cauterization
The medical practice or technique of cauterization is the burning of part of a body to remove or close off a part of it in a process called cautery, which destroys some tissue, in an attempt to mitigate damage, remove an undesired growth, or minimize other potential medical harmful possibilities...
of puncti can be performed. In thermal cauterization, a local anesthetic is used, and then a hot wire is applied. This shrinks the drainage area tissues and causes scarring, which closes the tear duct.
Customized contact lenses
Persons with severe dry eyes may benefit from the Boston Scleral Lens which is a customized contact lens. Resting on the scleraSclera
The sclera , also known as the white or white of the eye, is the opaque , fibrous, protective, outer layer of the eye containing collagen and elastic fiber. In the development of the embryo, the sclera is derived from the neural crest...
, it creates a fluid filled layer over the cornea, thus preventing it from drying.
Surgery
In severe cases of keratoconjunctivitis sicca, tarsorrhaphyTarsorrhaphy
Tarsorrhaphy is a surgical procedure in which the eyelids are partially sewn together to narrow the opening .It may be done to protect the cornea in cases of corneal exposure or after corneal graft surgery.-External links:*...
may be performed where the eyelids are partially sewn together. This reduces the palpebral fissure
Palpebral fissure
Palpebral fissure is the anatomic name for the separation between the upper and lower eyelids. In adults, this measures about 10mm vertically and 30mm horizontally.It can be reduced in horizontal size by fetal alcohol syndrome and in Williams Syndrome...
(eyelid separation), ideally leading to a reduction in tear evaporation.
Prognosis
Keratoconjunctivitis sicca usually is a chronic problem. Its prognosisPrognosis
Prognosis is a medical term to describe the likely outcome of an illness.When applied to large statistical populations, prognostic estimates can be very accurate: for example the statement "45% of patients with severe septic shock will die within 28 days" can be made with some confidence, because...
shows considerable variance, depending upon the severity of the condition. Most patients have mild-to-moderate cases, and can be treated symptomatically with lubricants. This provides an adequate relief of symptoms.
When dry eyes symptoms are severe, they can interfere with quality of life. People sometimes feel their vision blurs with use, or severe irritation to the point that they have trouble keeping their eyes open or they may not be able to work or drive.
Prevention
There is no way to prevent keratoconjunctivitis sicca. Complications can be prevented by use of wetting and lubricating drops and ointments.Epidemiology
Keratoconjunctivitis sicca is relatively common within the United States, especially so in older patients. Specifically, the persons most likely to be affected by dry eyes are those aged 40 or older.While persons with autoimmune diseases have a high likelihood of having dry eyes, most persons with dry eyes do not have an autoimmune disease. Instances of Sjögren syndrome and keratoconjunctivitis sicca associated with it are present much more commonly in women, with a ratio of 9:1. In addition, milder forms of keratoconjunctivitis sicca also are more common in women. This is partly because hormonal changes, such as those that occur in pregnancy, menstruation, and menopause, can decrease tear production.
In areas of the world where malnutrition is common, vitamin A deficiency is a common cause. This is rare in the United States.
Racial predilections do not exist for this disease.
Occurrence in animals
Among animals, keratoconjunctivitis sicca occurs in dogs, cats, and horses.Dogs
Keratoconjunctivitis sicca is common in dogDog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s. Most cases are caused by a genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
predisposition, but chronic conjunctivitis
Conjunctivitis
Conjunctivitis refers to inflammation of the conjunctiva...
, canine distemper
Canine distemper
Canine distemper is a viral disease that affects animals in the families Canidae, Mustelidae, Mephitidae, Hyaenidae, Ailuridae, Procyonidae, Pinnipedia, some Viverridae and Felidae...
, and drugs such as sulfasalazine and trimethoprim-sulfonamide
Co-trimoxazole
Trimethoprim/sulfamethoxazole or co-trimoxazole is a sulfonamide antibiotic combination of trimethoprim and sulfamethoxazole, in the ratio of 1 to 5, used in the treatment of a variety of bacterial infections.The name co-trimoxazole is the British Approved Name, and has been marketed worldwide...
also cause the disease. Symptoms include eye redness, a yellow or greenish discharge, ulceration of the cornea
Corneal ulcer
A corneal ulcer, or ulcerative keratitis, is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats...
, pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
ed cornea, and blood vessels on the cornea. Diagnosis is made by measuring tear production with a Schirmer tear test
Schirmer's test
Schirmer's test determines whether the eye produces enough tears to keep it moist. This test is used when a person experiences very dry eyes or excessive watering of the eyes. It poses no risk to the subject. A negative test result is normal...
. Less than 15 millimeters of tears produced in a minute is abnormal.
Tear replacers are a mainstay of treatment, preferably containing methylcellulose
Methylcellulose
Methyl cellulose is a chemical compound derived from cellulose. It is a hydrophilic white powder in pure form and dissolves in cold water, forming a clear viscous solution or gel. It is sold under a variety of trade names and is used as a thickener and emulsifier in various food and cosmetic...
or carboxymethyl cellulose
Carboxymethyl cellulose
Carboxymethyl cellulose or cellulose gum is a cellulose derivative with carboxymethyl groups bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone...
. Ciclosporin stimulates tear production and acts as a suppressant on the immune-mediated
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
processes that cause the disease. Topical antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s and corticosteroid
Corticosteroid
Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s are sometimes used to treat secondary infections and inflammation. A surgery known as parotid duct
Parotid duct
The parotid duct, also known as Stensen's duct, is the route that saliva takes from the parotid gland into the mouth.It passes through the buccal fat, buccopharyngeal fascia, and buccinator muscle then opens into the vestibule of the mouth next to the maxillary second molar tooth. The buccinator...
transposition is used in some extreme cases where medical treatment has not helped. This redirects the duct from the parotid salivary gland
Parotid gland
The paired parotid glands are the largest of the salivary glands. They are each found wrapped around the mandibular ramus, and secrete saliva through Stensen's ducts into the oral cavity, to facilitate mastication and swallowing and to begin the digestion of starches.-Location:The parotid glands...
to the eye. Saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...
replaces the tears. Dogs suffering from cherry eye
Cherry eye
Cherry eye is the term used to refer to canine nictitans gland prolapse, a common congenital eye defect in various dog breeds where the gland of the third eyelid known as the nictitating membrane prolapses and becomes visible. Commonly affected breeds include the Bulldog, Chihuahua, Cocker...
should have the condition corrected to help prevent this disease.
Commonly affected breeds include:
- Cavalier King Charles SpanielCavalier King Charles SpanielThe Cavalier King Charles Spaniel is a small breed of Spaniel-type dog, and is classed as a toy dog by most kennel clubs. It is one of the most popular breeds in the United Kingdom. Since 2000, it has been growing in popularity in the United States. It is a smaller breed of spaniel, and Cavalier...
- BulldogBulldogBulldog is the name for a breed of dog commonly referred to as the English Bulldog. Other Bulldog breeds include the American Bulldog, Olde English Bulldogge and the French Bulldog. The Bulldog is a muscular heavy dog with a wrinkled face and a distinctive pushed-in nose...
- Chinese Shar-Pei
- Lhasa ApsoLhasa ApsoThe Lhasa Apso is a non-sporting dog breed originating in Tibet. It was bred as an interior sentinel in the Buddhist monasteries, who alerted the monks to any intruders who entered...
- Shih TzuShih TzuThe Shih Tzu is a breed of dog weighing with long silky hair. The breed originated in China and is among the earliest breeds. Shih Tzu were officially recognized by the American Kennel Club in 1969...
- West Highland White TerrierWest Highland White TerrierThe West Highland White Terrier, commonly known as the Westie, is a Scottish breed of dog with a distinctive white coat. The modern breed is descended from a number of breeding programes of white terriers in Scotland prior to the 20th century...
- PugPugThe pug is a "toy" breed of dog with a wrinkly, short-muzzled face, and curled tail. The breed has a fine, glossy coat that comes in a variety of colors, and a compact square body with well-developed muscle. They have been described as multum in parvo , referring to the pug's personality and...
- BloodhoundBloodhoundThe Bloodhound is a large breed of dog which, while originally bred to hunt deer and wild boar, was later bred specifically to track human beings. It is a scenthound, tracking by smell, as opposed to a sighthound, which tracks using vision. It is famed for its ability to discern human odors even...
- Cocker Spaniel
- PekingesePekingeseThe Pekingese, or "Peke" is an ancient breed of toy dog, originating in China. The breed was favored by the Chinese Imperial court, and its name refers to the city of Beijing where the Forbidden City resides...
- Boston TerrierBoston TerrierThe Boston Terrier is a breed of dog originating in the United States of America. This "American Gentleman" was accepted in 1893 by the American Kennel Club as a non-sporting breed. Color and markings are important when distinguishing this breed to the AKC standard. They should be either black,...
- Miniature SchnauzerMiniature SchnauzerThe Miniature Schnauzer is a breed of small dog of the Schnauzer type that originated in Germany in the mid-to-late 19th century. Miniature Schnauzers developed from crosses between the Standard Schnauzer and one or more smaller breeds such as the Poodle and Affenpinscher.The breed remains one of...
- SamoyedSamoyed (dog)The Samoyed dog takes its name from the Samoyedic peoples of Siberia. An alternate name for the breed, especially in Europe, is Bjelkier...
Cats
Keratoconjunctivitis sicca is uncommon in catCat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s. Most cases seem to be caused by chronic conjunctivitis, especially secondary to feline herpesvirus. Diagnosis, symptoms, and treatment are similar to those for dogs.
External links
- Facts About the Cornea and Corneal Disease The National Eye Institute (NEI).
- Dry Eye Syndrome on NHS Choices
- The Eye Digest: Dry eyes
- Dry eye pain
- Keratos - European association on ocular surface diseases and lachrymal dysfunctions
- Am.J.Managed Care - Dry Eye Disease: Pathophysiology, Classification, and Diagnosis
- Dry Eye Syndrome on eMedicineEMedicineeMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely, two medical doctors. The website is searchable by keyword and consists of approximately 6,800 articles, each of which is associated with one of 62 clinical subspecialty textbooks...