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{{SK}} KCS; Keratitis sicca; sicca syndrome; dry eye syndrome; DES; dry eyes; xerophthalmia;
{{SK}} KCS; Keratitis sicca; sicca syndrome; dry eye syndrome; DES; dry eyes; xerophthalmia;
==Overview==


'''Keratoconjunctivitis sicca (KCS)''', also called '''[[keratitis]] sicca''', '''sicca syndrome''', '''[[xerophthalmia]]''', '''dry eye syndrome''' ('''DES'''), or simply '''dry eyes''', is an [[eye]] [[disease]] caused by decreased [[Tears|tear]] production or increased tear film evaporation commonly found in humans and some animals<ref name=Merck-2>
{{cite web
| url = http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/30107.htm
| title = Keratoconjunctivitis, Sicca
| accessdate = 2006-11-18
| work = The Merck Veterinary Manua
| publisher = [[Merck & Co.|Merck & Co., Inc.]]
}}
</ref>. Keratoconjunctivitis sicca is [[Latin]] and its literal translation is "dryness of the [[cornea]] and [[conjunctiva]]".  It may be helpful to know that "sicca" is part of the English word "desiccate."


==Related Chapters==
'''When found in association with [[Xerostomia]] and [[polyarthritis]], it is called [[Sjogren's syndrome]].'''
 
==Symptoms==
Typical symptoms of keratoconjunctivitis are dryness, burning<ref name=Merck-1>
{{cite web
| url = http://www.merck.com/mmhe/sec20/ch230/ch230d.html
| title = Keratoconjunctivitis Sicca
| accessdate = 2006-11-12
| date = 2003-02-01
| work = [[Merck Manual of Diagnosis and Therapy|The Merck Manual, Home Edition]]
| publisher = [[Merck & Co.|Merck & Co., Inc.]]
}}
</ref> and a sandy-gritty eye irritation that gets worse as the day goes on. Symptoms may also be described as itchy,<ref name=Merck-1/> scratchy,<ref name=MedlinePlus-1>
{{cite web
| url = http://www.nlm.nih.gov/medlineplus/ency/article/003087.htm
| title = Dry eyes
| accessdate = 2006-11-16
| date = 2006-10-04
| work = [[MedlinePlus]] Medical Encyclopedia
| publisher = [[United States National Library of Medicine|U.S. National Library of Medicine]]
}}
</ref> stingy<ref name=Merck-1/> or tired<ref name=Merck-1/> eyes. Other symptoms are pain,<ref name=FDA-1>
{{cite web
| url = http://www.fda.gov/fdac/features/2005/305_eye.html
| title = Dealing with Dry Eye
| accessdate = 2006-11-16
| author = Michelle Meadows
| last = Meadows
| first = Michelle
| year = 2005
| month = May-June
| work = [http://www.fda.gov/fdac/ FDA Consumer Magazine]
| publisher = [[Food and Drug Administration|U.S. Food and Drug Administration]]
}}
</ref> redness,<ref name=FDA-1/> a pulling sensation,<ref name=Merck-1/> and pressure behind the eye<ref name=Merck-1/>. There may be a feeling that something,<ref name=Merck-1/> such as a speck of dirt,<ref name=FDA-1/> is in the eye. The resultant damage to the eye surface increases discomfort and sensitivity to bright light.<ref name=Merck-1/> Both eyes usually are affected.<ref name=MayoClinic-1>
{{cite web
| url = http://www.mayoclinic.com/health/dry-eyes/DS00463/DSECTION=1
| title = Dry eyes
| accessdate = 2006-11-17
| date = 2006-06-14
| work = [[Mayo Clinic]]
| publisher = Mayo Foundation for Medical Education and Research
}}
</ref>
 
There may also be a stringy discharge from the eyes.<ref name=FDA-1/> Although it may seem strange, dry eye can cause the eyes to water.<ref name=FDA-1/> This can happen because the eyes are irritated.<ref name=FDA-1/> One may experience excessive tearing in the same way as one would if something got into the eye.<ref name=FDA-1/> These reflex tears will not necessarily make the eyes feel better.<ref name=FDA-1/> This is because they are the watery type that are produced in response to injury, irritation, or emotion.<ref name=FDA-1/> They do not have the lubricating qualities necessary to prevent dry eye.<ref name=FDA-1/>
 
Because blinking coats the eye with tears,<ref name=FDA-1/> symptoms are worsened by activities in which the rate of blinking is reduced due to prolonged use of the eyes<ref name=Merck-1/>. These activities include prolonged reading, computer usage,<ref name=FDA-1/><ref name=Merck-1/> driving,<ref name=Merck-1/> or watching television<ref name=FDA-1/><ref name=Merck-1/>. Symptoms increase in windy,<ref name=FDA-1/> dusty<ref name=FDA-1/><ref name=Merck-1/> or smoky (including cigarette smoke<ref name=FDA-1/>) areas,<ref name=Merck-1/> in dry environments<ref name=Merck-1/>, high altitudes including airplanes, on days with low humidity,<ref name=Merck-1/> and in areas where an air conditioner<ref name=FDA-1/> (especially in a car<ref name=Merck-1/>), fan,<ref name=Merck-1/> heater,<ref name=Merck-1/> or even a hair dryer<ref name=FDA-1/> is being used. Symptoms reduce during cool, rainy, or foggy weather and in humid places, such as in the shower.<ref name=Merck-1/>
 
Most people who have dry eyes experience mild irritation with no long-term effects.<ref name=FDA-1/> However, if the condition is left untreated or becomes severe, it can produce complications that can cause eye damage,<ref name=FDA-1/> resulting in impaired vision or (rarely<ref name=Merck-1/>) in the loss of vision<ref name=FDA-1/>.
 
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. [http://www.agingeye.net/dryeyes/dryeyessymptoms.php McMonnies & Ho dry eye questionnaire] is the one that is often used in clinical studies of dry eyes. There are 14 questions that can give a score from 0 to 45. Scores above 14.5 are consistent with dry eye diagnosis.
 
==Pathophysiology==
Having dry eyes for a while can lead to tiny [[abrasion]]s on the surface of the eyes.<ref name=MedlinePlus-1/> In advanced cases, the [[epithelium]] undergoes pathologic changes, namely [[squamous metaplasia]] and loss of [[goblet cell]]s. Some severe cases result in thickening of the corneal surface,<ref name=Merck-1/> corneal erosion, punctate keratopathy, [[epithelium|epithelial]] defects, [[corneal ulcer]]ation (sterile and infected), corneal [[neovascularization]], corneal scarring,<ref name=Merck-1/> corneal thinning, and even corneal perforation.
 
==Causes==
Any abnormality of any one of the three layers 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.<ref name=Merck-1/> The aqueous tear layer is affected, resulting in '''aqueous tear deficiency''' ('''ATD''') or '''lacrimal hyposecretion'''. The [[lacrimal gland]] does not produce sufficient tears to keep the entire conjunctiva and cornea covered by a complete layer.<ref name=Merck-1/> 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.<ref name=Merck-1/><!--
  --><ref name=PE-1>{{cite journal | author=Sendecka M, Baryluk A, Polz-Dacewicz M | title=Prevalence and risk factors of dry eye syndrome | journal=Przegl Epidemiol | volume=58 | issue=1 | pages=227-33 | year=2004 | id=PMID 15218664}}</ref>
 
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]]<ref name=Merck-1/>, [[Wegener's granulomatosis]], and [[lupus erythematosus|systemic lupus erythematosus]]. [[Sjögren's syndrome]]<ref name=Merck-1/> and [[Autoimmunity|autoimmune diseases]] associated with [[Sjögren's syndrome]] are also conditions associated with aqueous tear deficiency. Drugs such as isotretinoin,<ref name=Merck-1/> sedatives,<ref name=Merck-1/> diuretics,<ref name=Merck-1/> tricyclic antidepressants, antihypertensives,<ref name=Merck-1/> oral contraceptives,<ref name=Merck-1/> antihistamines,<ref name=FDA-1/><ref name=Merck-1/> nasal decongestants,<ref name=FDA-1/> 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.
 
===Abnormal tear composition===
Keratoconjunctivitis sicca can also be caused by abnormal tear composition resulting in rapid evaporation<ref name=Merck-1/> or premature destruction of the tears. When caused by rapid evaporation, it is termed '''evaporative dry eyes'''.<ref name=Merck-1/> In this, although the tear gland produces a sufficient amount of tears, the rate of evaporation of the tears is too rapid.<ref name=Merck-1/> 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.<ref name=Merck-1/>
 
===Additional causes===
Aging is one of the most common causes of dry eyes.<ref name=FDA-1/> This is because tear production decreases with age.<ref name=FDA-1/> It may be caused by thermal or chemical burns, or (in epidemic cases) by [[adenovirus]]es. A number of studies have found that [[diabetes|diabetics]] are at increased risk for the disease.<!--
  --><ref name=Diabetic-1>{{cite journal | author=Kaiserman I, Kaiserman N, Nakar S, Vinker S | title=Dry eye in diabetic patients. | journal=Am J Ophthalmol | volume=139 | issue=3 | pages=498-503 | year=2005 | id=PMID 15767060}}</ref><!--
  --><ref name=Diabetic-2>{{cite journal | author=Li H, Pang G, Xu Z | title=Tear film function of patients with type 2 diabetes | journal=Zhongguo Yi Xue Ke Xue Yuan Xue Bao | volume=26 | issue=6 | pages=682-6 | year=2004 | id=PMID 15663232}}</ref>
 
An eye injury or other problem with the eyes or [[eyelid]]s, such as bulging eyes or a [[Ptosis (eyelid)|drooping eyelid]] can cause keratoconjunctivitis sicca.<ref name=MedlinePlus-1/> Disorders of the eyelid can impair the complex blinking motion required to spread tears.
 
About half of all people who wear contact lenses complain of dry eyes.<ref name=FDA-1/> This is because soft contact lenses, which float on the tear film that covers the cornea, absorb the tears in the eyes.<ref name=FDA-1/> Dry eyes also occurs or gets worse after [[LASIK]] and other [[refractive surgery|refractive surgeries]], in which the corneal nerves are cut during the creation of a corneal flap.<ref name=FDA-1/> The corneal nerves stimulate tear secretion.<ref name=FDA-1/> Dry eyes caused by these procedures usually resolves after several months. Persons who are thinking about refractive surgery should consider this.<ref name=FDA-1/>
 
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.
 
==Diagnosis==
Dry eyes can usually be diagnosed by the symptoms alone.<ref name=Merck-1/> Tests can determine both the quantity and the quality of the tears. A [[slit lamp]] examination can be performed to diagnose dry eyes and to document any damage to the eye.<ref name=Merck-1/>
 
A [[Schirmer's test]] can measure the amount of moisture bathing the eye.<ref name=Merck-1/> This test is useful for determining the severity of the condition.<ref name=FDA-1/> 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.<ref name=FDA-1/> 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.
 
Recently it was described a molecule - Ap4A- which is intrinsic component of the tears. The presence of this molecule  is abnormally high in different states of the ocular dryness. This molecule could  quantifyied biochemically simply taking one tear sample with a plain Schirmer test. Utilizing this technique is possible to determine the concentrations of Ap4A in the tear of the patients and such way to diagnose in an objective way if the samples are corresponding to dry eye<ref>A. Peral, G. Carracedo, M.C. Acosta, J. Gallar, J. Pintor."Increasing Levels of Diadenosine Polyphosphates in Dry Eye" (2006)Invest.Ophthalmol. Vis. Sci.47 (9):4053–4058 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed]</ref>.
 
==Treatment==
Purposefully blinking more often, and resting the eyes are basic steps one can take.<ref name=MedlinePlus-1/> Rubbing one's eyes can irritate them further, so it should be avoided. Persons with dry eyes caused by an eyelid disorder should undergo treatment for the underlying condition.
 
===Rehydration===
For mild and moderate cases, supplemental lubrication is the most important part of treatment.
 
====Artificial tears====
{{main|Artificial tears}}
 
<!-- Expanding this section much is not recommended. -->
Application of artificial tears every few hours<ref name=Merck-1/> can provide temporary relief.
 
====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 petrolatum, [[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.
 
===Environmental control===
Avoiding dry or drafty environments, or environments with smoke and dust, may help.<ref name=Merck-1/> This also includes avoiding environmental aggravation caused by hair dryers, heaters, air conditioners or fans, especially when directed toward the eyes. Wearing wraparound glasses when outside can help reduce the drying effects of the wind.
 
Using a humidifier,<ref name=Merck-1/><ref name=MedlinePlus-1/> especially in the winter,<ref name=MedlinePlus-1/> adds moisture to dry indoor air. Specially designed glasses that form a moisture chamber around the eye may be used to create additional humidity.
 
===Supplementation===
Consumption of dietary [[omega-3]] [[fatty acid]]s is associated with a decreased incidence of dry eyes syndrome in women.<!--
  --><ref name="AmJClinNutr2005-Miljanović">{{cite journal | author=Miljanović B, Trivedi K, Dana M, Gilbard J, Buring J, Schaumberg D | title=Relation between dietary n-3 and n-6 fatty acids and clinically diagnosed dry eye syndrome in women. | journal=Am J Clin Nutr | volume=82 | issue=4 | pages=887-93 | year=2005 | id=PMID 16210721}}</ref> This finding is consistent with postulated biological mechanisms.<ref name="AmJClinNutr2005-Miljanović"/>
 
===Medication===
Inflammation occurring in response to tears film hypertonicity can be suppressed by mild topical [[steroid]]s or with topical [[immunosuppressant]]s such as [[cyclosporine]].<!--
  --><ref>{{cite journal | author=Tatlipinar S, Akpek E | title=Topical cyclosporine in the treatment of ocular surface disorders. | journal=Br J Ophthalmol | volume=89 | issue=10 | pages=1363-7 | year=2005 | id=PMID 16170133}}</ref><!--
  --><ref>{{cite journal | author=Barber L, Pflugfelder S, Tauber J, Foulks G | title=Phase III safety evaluation of cyclosporine 0.1% ophthalmic emulsion administered twice daily to dry eye disease patients for up to 3 years. | journal=Ophthalmology | volume=112 | issue=10 | pages=1790-4 | year=2005 | id=PMID 16102833}}</ref> Elevated levels of tear NGF can be decreased with 0.1% [[prednisolone]].
 
====Restasis====
 
<!-- If this section expands sufficiently, perhaps most of the info here could be moved into its own "Restasis" article. -->
Topical cyclosporine A (tCSA) 0.05% ophthalmic emulsion, marketed in the United States by Allergan under the trade name Restasis, is the only prescription product approved for chronic dry eyes.<ref name=FDA-1/> Approved by the [[Food and Drug Administration|U.S. Food and Drug Administration]] in 2002 for this indication<ref name=FDA-1/>, the drug decreases inflammation on the eye surface.  Cyclosporine appears to work since the chronic inflammation of the ocular surface is mediated mainly by T-lymphocytes and cyclosporine’s proposed mechanism of action in immunosuppression is through T-lymphocyte inhibition<ref name=Micromedex>Micromedex® Healthcare Series, (electronic version). Thomson Micromedex, Greenwood Village, Colorado, USA. Available at: http://0-www.thomsonhc.com.library.uchsc.edu:80 (cited: 09/05/06).</ref> through “binding an intracellular protein that ultimately controls transcription factors required for cytokine production and T-lymphocyte maturation”.<ref name=RestasisPhaseIII>Barber LD, Pflugfelder SC, Tauber J, Foulks GN. Phase III safety evaluation of cyclosporine 0.1% ophthalmic emulsion administered twice daily to dry eye disease patients for up to 3 years. Ophthalmology. 2005 Oct;112(10):1790-4.</ref>
 
It increases healthy tear production, which may be reduced because of inflammation on the eye surface.<ref name=FDA-1/> In a clinical trial involving 1,200 individuals, Restasis increased tear production in 15 percent of patients, compared with 5 percent of patients in the placebo group.<ref name=FDA-1/>
 
Usually, 1 gutt (drop) of Restasis is instilled in each eye twice a day, 12 hours apart. It should not be used when wearing contact lenses, or by persons with eye infections<ref name=FDA-1/> or hypersensitivity<ref name=FDA-1/> to the ingredients. It has not been tested in people with herpes viral infections of the eye,<ref name=FDA-1/> and it should not be used by anyone with a history of such an infection. The most common side effect is a burning sensation.<ref name=FDA-1/> Other side effects may be eye redness, discharge, watery eyes, eye pain, foreign body sensation, itching, stinging, and blurred vision.<ref name=FDA-1/>
 
=====Generic alternatives=====
Cheaper [[Generic drug|generic]] alternatives to Restasis are available in some countries. In India, it is marketed as Cyclomune by [http://www.sunpharma.com Sun Pharma].<ref name=SunPharma-1>
{{cite web
| url = http://www.sunpharma.com/sunpharma-products/sunpharma-formulation/spopup11.php
| title = Sun Pharma Product List
| accessdate = 2006-11-27
| publisher = [http://www.sunpharma.com Sun Pharma]
}}
</ref>
 
===Conserving tears===
There are methods that allow both natural and artificial tears to stay longer.
 
====Blocking tear drainage====
In each eye, there are two puncta<ref name=NHS-1>
{{cite web
| url = http://www.nhsdirect.nhs.uk/articles/article.aspx?articleId=137&PrintPage=1
| title = Dry eye syndrome
| accessdate = 2007-02-26
| date = 2006-04-10
| work = [http://www.nhsdirect.nhs.uk/encyclopaedia/ Health encyclopaedia]
| publisher = [[NHS Direct]]
}}
</ref> — little openings that drain tears into the tear ducts<ref name=FDA-1/>. 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.<ref name=Merck-1/>
 
=====Punctal plugs=====
 
Punctal plugs are inserted into the puncta to block tear drainage.<ref name=FDA-1/> For people who have not found dry eye relief with drugs, punctal plugs may help.<ref name=FDA-1/> They are reserved for people with moderate or severe dry eye when other medical treatment has not been adequate.<ref name=FDA-1/>
 
=====Cauterization=====
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.
 
====Customized contact lenses====
Persons with severe dry eyes may benefit from the Boston Scleral Lens which is a customized contact lens. Resting on the [[sclera]], it creates a fluid filled layer over the cornea, thus preventing it from drying.
 
====Surgery====
In severe cases of keratoconjunctivitis sicca, the eyelids may be partially sewn together to reduce tear evaporation.<ref name=Merck-1/>
 
==Prognosis==
Keratoconjunctivitis sicca usually is a chronic problem. Its [[prognosis]] 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.<ref name=FDA-1/> People sometimes feel their vision blurs with use,<ref name=Merck-1/> or severe irritation<ref name=Merck-1/> to the point that they have trouble keeping their eyes open<ref name=FDA-1/> or they may not be able to work or drive<ref name=FDA-1/>.
 
==Prevention==
There is no way to prevent keratoconjunctivitis sicca.<ref name=MedlinePlus-2>
{{cite web
| url = http://www.nlm.nih.gov/medlineplus/ency/article/000426.htm
| title = Dry eyes syndrome
| accessdate = 2006-11-16
| date = 2006-10-04
| work = [[MedlinePlus]] Medical Encyclopedia
| publisher = [[United States National Library of Medicine|U.S. National Library of Medicine]]
}}
</ref> Complications can be prevented by use of wetting and lubricating drops and ointments.<ref name=MedlinePlus-2/>
 
==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 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.<ref name=FDA-1/>
 
In areas of the world where malnutrition is common, vitamin A deficiency is a common cause.<ref name=MedlinePlus-2/> This is rare in the United States.<ref name=MedlinePlus-2/>
 
Racial predilections do not exist for this disease.
 
==See also==
* [[Keratoconjunctivitis]]
* [[Keratoconjunctivitis]]
* [[List of eye diseases and disorders]]
* [[List of eye diseases and disorders]]
* [[Sjogren's syndrome]]
* [[Sjogren's syndrome]]
==References==
{{reflist|2}}


==Further reading==
==Further reading==
Line 40: Line 253:


{{Eye pathology}}
{{Eye pathology}}


[[Category:Overuse injuries]]
[[Category:Overuse injuries]]

Revision as of 13:20, 2 November 2012

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Synonyms and keywords: KCS; Keratitis sicca; sicca syndrome; dry eye syndrome; DES; dry eyes; xerophthalmia;

Overview

Keratoconjunctivitis sicca (KCS), also called keratitis sicca, sicca syndrome, xerophthalmia, dry eye syndrome (DES), or simply dry eyes, is an eye disease caused by decreased tear production or increased tear film evaporation commonly found in humans and some animals[1]. Keratoconjunctivitis sicca is Latin and its literal translation is "dryness of the cornea and conjunctiva". It may be helpful to know that "sicca" is part of the English word "desiccate."

When found in association with Xerostomia and polyarthritis, it is called Sjogren's syndrome.

Symptoms

Typical symptoms of keratoconjunctivitis are dryness, burning[2] and a sandy-gritty eye irritation that gets worse as the day goes on. Symptoms may also be described as itchy,[2] scratchy,[3] stingy[2] or tired[2] eyes. Other symptoms are pain,[4] redness,[4] a pulling sensation,[2] and pressure behind the eye[2]. There may be a feeling that something,[2] such as a speck of dirt,[4] is in the eye. The resultant damage to the eye surface increases discomfort and sensitivity to bright light.[2] Both eyes usually are affected.[5]

There may also be a stringy discharge from the eyes.[4] Although it may seem strange, dry eye can cause the eyes to water.[4] This can happen because the eyes are irritated.[4] One may experience excessive tearing in the same way as one would if something got into the eye.[4] These reflex tears will not necessarily make the eyes feel better.[4] This is because they are the watery type that are produced in response to injury, irritation, or emotion.[4] They do not have the lubricating qualities necessary to prevent dry eye.[4]

Because blinking coats the eye with tears,[4] symptoms are worsened by activities in which the rate of blinking is reduced due to prolonged use of the eyes[2]. These activities include prolonged reading, computer usage,[4][2] driving,[2] or watching television[4][2]. Symptoms increase in windy,[4] dusty[4][2] or smoky (including cigarette smoke[4]) areas,[2] in dry environments[2], high altitudes including airplanes, on days with low humidity,[2] and in areas where an air conditioner[4] (especially in a car[2]), fan,[2] heater,[2] or even a hair dryer[4] is being used. Symptoms reduce during cool, rainy, or foggy weather and in humid places, such as in the shower.[2]

Most people who have dry eyes experience mild irritation with no long-term effects.[4] However, if the condition is left untreated or becomes severe, it can produce complications that can cause eye damage,[4] resulting in impaired vision or (rarely[2]) in the loss of vision[4].

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. McMonnies & Ho dry eye questionnaire is the one that is often used in clinical studies of dry eyes. There are 14 questions that can give a score from 0 to 45. Scores above 14.5 are consistent with dry eye diagnosis.

Pathophysiology

Having dry eyes for a while can lead to tiny abrasions on the surface of the eyes.[3] In advanced cases, the epithelium undergoes pathologic changes, namely squamous metaplasia and loss of goblet cells. Some severe cases result in thickening of the corneal surface,[2] corneal erosion, punctate keratopathy, epithelial defects, corneal ulceration (sterile and infected), corneal neovascularization, corneal scarring,[2] corneal thinning, and even corneal perforation.

Causes

Any abnormality of any one of the three layers 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.[2] The aqueous tear layer is affected, resulting in aqueous tear deficiency (ATD) or lacrimal hyposecretion. The lacrimal gland does not produce sufficient tears to keep the entire conjunctiva and cornea covered by a complete layer.[2] 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.[2][6]

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[2], Wegener's granulomatosis, and systemic lupus erythematosus. Sjögren's syndrome[2] and autoimmune diseases associated with Sjögren's syndrome are also conditions associated with aqueous tear deficiency. Drugs such as isotretinoin,[2] sedatives,[2] diuretics,[2] tricyclic antidepressants, antihypertensives,[2] oral contraceptives,[2] antihistamines,[4][2] nasal decongestants,[4] 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.

Abnormal tear composition

Keratoconjunctivitis sicca can also be caused by abnormal tear composition resulting in rapid evaporation[2] or premature destruction of the tears. When caused by rapid evaporation, it is termed evaporative dry eyes.[2] In this, although the tear gland produces a sufficient amount of tears, the rate of evaporation of the tears is too rapid.[2] 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.[2]

Additional causes

Aging is one of the most common causes of dry eyes.[4] This is because tear production decreases with age.[4] 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.[7][8]

An eye injury or other problem with the eyes or eyelids, such as bulging eyes or a drooping eyelid can cause keratoconjunctivitis sicca.[3] Disorders of the eyelid can impair the complex blinking motion required to spread tears.

About half of all people who wear contact lenses complain of dry eyes.[4] This is because soft contact lenses, which float on the tear film that covers the cornea, absorb the tears in the eyes.[4] 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.[4] The corneal nerves stimulate tear secretion.[4] Dry eyes caused by these procedures usually resolves after several months. Persons who are thinking about refractive surgery should consider this.[4]

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.

Diagnosis

Dry eyes can usually be diagnosed by the symptoms alone.[2] Tests can determine both the quantity and the quality of the tears. A slit lamp examination can be performed to diagnose dry eyes and to document any damage to the eye.[2]

A Schirmer's test can measure the amount of moisture bathing the eye.[2] This test is useful for determining the severity of the condition.[4] 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.[4] 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.

Recently it was described a molecule - Ap4A- which is intrinsic component of the tears. The presence of this molecule is abnormally high in different states of the ocular dryness. This molecule could quantifyied biochemically simply taking one tear sample with a plain Schirmer test. Utilizing this technique is possible to determine the concentrations of Ap4A in the tear of the patients and such way to diagnose in an objective way if the samples are corresponding to dry eye[9].

Treatment

Purposefully blinking more often, and resting the eyes are basic steps one can take.[3] Rubbing one's eyes can irritate them further, so it should be avoided. Persons with dry eyes caused by an eyelid disorder should undergo treatment for the underlying condition.

Rehydration

For mild and moderate cases, supplemental lubrication is the most important part of treatment.

Artificial tears

Main article: Artificial tears

Application of artificial tears every few hours[2] can provide temporary relief.

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 petrolatum, 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.

Environmental control

Avoiding dry or drafty environments, or environments with smoke and dust, may help.[2] This also includes avoiding environmental aggravation caused by hair dryers, heaters, air conditioners or fans, especially when directed toward the eyes. Wearing wraparound glasses when outside can help reduce the drying effects of the wind.

Using a humidifier,[2][3] especially in the winter,[3] adds moisture to dry indoor air. Specially designed glasses that form a moisture chamber around the eye may be used to create additional humidity.

Supplementation

Consumption of dietary omega-3 fatty acids is associated with a decreased incidence of dry eyes syndrome in women.[10] This finding is consistent with postulated biological mechanisms.[10]

Medication

Inflammation occurring in response to tears film hypertonicity can be suppressed by mild topical steroids or with topical immunosuppressants such as cyclosporine.[11][12] Elevated levels of tear NGF can be decreased with 0.1% prednisolone.

Restasis

Topical cyclosporine A (tCSA) 0.05% ophthalmic emulsion, marketed in the United States by Allergan under the trade name Restasis, is the only prescription product approved for chronic dry eyes.[4] Approved by the U.S. Food and Drug Administration in 2002 for this indication[4], the drug decreases inflammation on the eye surface. Cyclosporine appears to work since the chronic inflammation of the ocular surface is mediated mainly by T-lymphocytes and cyclosporine’s proposed mechanism of action in immunosuppression is through T-lymphocyte inhibition[13] through “binding an intracellular protein that ultimately controls transcription factors required for cytokine production and T-lymphocyte maturation”.[14]

It increases healthy tear production, which may be reduced because of inflammation on the eye surface.[4] In a clinical trial involving 1,200 individuals, Restasis increased tear production in 15 percent of patients, compared with 5 percent of patients in the placebo group.[4]

Usually, 1 gutt (drop) of Restasis is instilled in each eye twice a day, 12 hours apart. It should not be used when wearing contact lenses, or by persons with eye infections[4] or hypersensitivity[4] to the ingredients. It has not been tested in people with herpes viral infections of the eye,[4] and it should not be used by anyone with a history of such an infection. The most common side effect is a burning sensation.[4] Other side effects may be eye redness, discharge, watery eyes, eye pain, foreign body sensation, itching, stinging, and blurred vision.[4]

Generic alternatives

Cheaper generic alternatives to Restasis are available in some countries. In India, it is marketed as Cyclomune by Sun Pharma.[15]

Conserving tears

There are methods that allow both natural and artificial tears to stay longer.

Blocking tear drainage

In each eye, there are two puncta[16] — little openings that drain tears into the tear ducts[4]. 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.[2]

Punctal plugs

Punctal plugs are inserted into the puncta to block tear drainage.[4] For people who have not found dry eye relief with drugs, punctal plugs may help.[4] They are reserved for people with moderate or severe dry eye when other medical treatment has not been adequate.[4]

Cauterization

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.

Customized contact lenses

Persons with severe dry eyes may benefit from the Boston Scleral Lens which is a customized contact lens. Resting on the sclera, it creates a fluid filled layer over the cornea, thus preventing it from drying.

Surgery

In severe cases of keratoconjunctivitis sicca, the eyelids may be partially sewn together to reduce tear evaporation.[2]

Prognosis

Keratoconjunctivitis sicca usually is a chronic problem. Its prognosis 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.[4] People sometimes feel their vision blurs with use,[2] or severe irritation[2] to the point that they have trouble keeping their eyes open[4] or they may not be able to work or drive[4].

Prevention

There is no way to prevent keratoconjunctivitis sicca.[17] Complications can be prevented by use of wetting and lubricating drops and ointments.[17]

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 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.[4]

In areas of the world where malnutrition is common, vitamin A deficiency is a common cause.[17] This is rare in the United States.[17]

Racial predilections do not exist for this disease.

See also

References

  1. ↑ "Keratoconjunctivitis, Sicca". The Merck Veterinary Manua. Merck & Co., Inc. Retrieved 2006-11-18.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 2.20 2.21 2.22 2.23 2.24 2.25 2.26 2.27 2.28 2.29 2.30 2.31 2.32 2.33 2.34 2.35 2.36 2.37 2.38 2.39 2.40 2.41 2.42 2.43 2.44 2.45 2.46 2.47 "Keratoconjunctivitis Sicca". The Merck Manual, Home Edition. Merck & Co., Inc. 2003-02-01. Retrieved 2006-11-12.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 "Dry eyes". MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. 2006-10-04. Retrieved 2006-11-16.
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28 4.29 4.30 4.31 4.32 4.33 4.34 4.35 4.36 4.37 4.38 4.39 4.40 4.41 4.42 4.43 4.44 4.45 4.46 4.47 4.48 Meadows, Michelle (2005). "Dealing with Dry Eye". FDA Consumer Magazine. U.S. Food and Drug Administration. Retrieved 2006-11-16. Unknown parameter |month= ignored (help); More than one of |author= and |last= specified (help); External link in |work= (help)
  5. ↑ "Dry eyes". Mayo Clinic. Mayo Foundation for Medical Education and Research. 2006-06-14. Retrieved 2006-11-17.
  6. ↑ Sendecka M, Baryluk A, Polz-Dacewicz M (2004). "Prevalence and risk factors of dry eye syndrome". Przegl Epidemiol. 58 (1): 227–33. PMID 15218664.
  7. ↑ Kaiserman I, Kaiserman N, Nakar S, Vinker S (2005). "Dry eye in diabetic patients". Am J Ophthalmol. 139 (3): 498–503. PMID 15767060.
  8. ↑ Li H, Pang G, Xu Z (2004). "Tear film function of patients with type 2 diabetes". Zhongguo Yi Xue Ke Xue Yuan Xue Bao. 26 (6): 682–6. PMID 15663232.
  9. ↑ A. Peral, G. Carracedo, M.C. Acosta, J. Gallar, J. Pintor."Increasing Levels of Diadenosine Polyphosphates in Dry Eye" (2006)Invest.Ophthalmol. Vis. Sci.47 (9):4053–4058 http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed]
  10. ↑ 10.0 10.1 Miljanović B, Trivedi K, Dana M, Gilbard J, Buring J, Schaumberg D (2005). "Relation between dietary n-3 and n-6 fatty acids and clinically diagnosed dry eye syndrome in women". Am J Clin Nutr. 82 (4): 887–93. PMID 16210721.
  11. ↑ Tatlipinar S, Akpek E (2005). "Topical cyclosporine in the treatment of ocular surface disorders". Br J Ophthalmol. 89 (10): 1363–7. PMID 16170133.
  12. ↑ Barber L, Pflugfelder S, Tauber J, Foulks G (2005). "Phase III safety evaluation of cyclosporine 0.1% ophthalmic emulsion administered twice daily to dry eye disease patients for up to 3 years". Ophthalmology. 112 (10): 1790–4. PMID 16102833.
  13. ↑ Micromedex® Healthcare Series, (electronic version). Thomson Micromedex, Greenwood Village, Colorado, USA. Available at: http://0-www.thomsonhc.com.library.uchsc.edu:80 (cited: 09/05/06).
  14. ↑ Barber LD, Pflugfelder SC, Tauber J, Foulks GN. Phase III safety evaluation of cyclosporine 0.1% ophthalmic emulsion administered twice daily to dry eye disease patients for up to 3 years. Ophthalmology. 2005 Oct;112(10):1790-4.
  15. ↑ "Sun Pharma Product List". Sun Pharma. Retrieved 2006-11-27. External link in |publisher= (help)
  16. ↑ "Dry eye syndrome". Health encyclopaedia. NHS Direct. 2006-04-10. Retrieved 2007-02-26. External link in |work= (help)
  17. ↑ 17.0 17.1 17.2 17.3 "Dry eyes syndrome". MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine. 2006-10-04. Retrieved 2006-11-16.

Further reading

  • The Dry Eye: A Practical Approach, by Sudi Patel, Kenny Blades, 2003, Butterworth-Heinemann, ISBN 0-7506-4978-X
  • Dry Eye Disease: The Clinician's Guide to Diagnosis And Treatment, by Penny A. Asbell, Michael A. Lemp, 2006, Thieme Medical Publishers, ISBN 1-58890-412-1
  • The Dry Eye Remedy: The Complete Guide to Restoring the Health and Beauty of Your Eyes, by Robert Latkany, 2007, Hatherleigh Press, ISBN 1-57826-242-9

External links


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