Keratoconjunctivitis sicca

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**Keratoconjunctivitis sicca**
*Classifications and external resources*
ICD-10	H 19.3, M 35.0
ICD-9	370.33, 710.2
DiseasesDB	12155
eMedicine	oph/695

Keratoconjunctivitis sicca (KCS), also called keratitis sicca,<ref name=eMedicine-1> Keratoconjunctivitis, Sicca. eMedicine. WebMD, Inc. (2006-04-21). Retrieved on 2006-11-12. </ref> sicca syndrome,<ref name=eMedicine-1/> xerophthalmia,<ref name=eMedicine-1/> dry eye syndrome (DES),<ref name=eMedicine-1/> or simply dry eyes,<ref name=eMedicine-1/> is an eye disease caused by decreased tear production or increased tear film evaporation commonly found in humans and some animals<ref name=Merck-2> Keratoconjunctivitis, Sicca. The Merck Veterinary Manual. Merck & Co., Inc.. Retrieved on 2006-11-18. </ref>. Keratoconjunctivitis sicca is Latin and its literal translation is "dryness of the cornea and conjunctiva".

[edit] Symptoms

Typical symptoms of keratoconjunctivitis are dryness, burning<ref name=Merck-1> Keratoconjunctivitis Sicca. The Merck Manual, Home Edition. Merck & Co., Inc. (2003-02-01). Retrieved on 2006-11-12. </ref> and a sandy-gritty eye irritation that gets worse as the day goes on.<ref name=eMedicine-1/> Symptoms may also be described as itchy,<ref name=Merck-1/> scratchy,<ref name=MedlinePlus-1> Dry eyes. MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine (2006-10-04). Retrieved on 2006-11-16. </ref> stingy<ref name=Merck-1/> or tired<ref name=Merck-1/> eyes. Other symptoms are pain,<ref name=FDA-1> Meadows, Michelle (May-June 2005). Dealing with Dry Eye. FDA Consumer Magazine. U.S. Food and Drug Administration. Retrieved on 2006-11-16. </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> Dry eyes. Mayo Clinic. Mayo Foundation for Medical Education and Research (2006-06-14). Retrieved on 2006-11-17. </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,<ref name=eMedicine-1/> computer usage,<ref name=eMedicine-1/><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=eMedicine-1/><ref name=Merck-1/> in dry environments<ref name=eMedicine-1/><ref name=Merck-1/>, high altitudes including airplanes,<ref name=MayoClinic-1/> 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/>.

[edit] Pathophysiology

Having dry eyes for a while can lead to tiny abrasions 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 cells.<ref name=eMedicine-1/> Some severe cases result in thickening of the corneal surface,<ref name=Merck-1/> corneal erosion,<ref name=eMedicine-1/> punctate keratopathy,<ref name=eMedicine-1/> epithelial defects,<ref name=eMedicine-1/> corneal ulceration (sterile and infected),<ref name=eMedicine-1/> corneal neovascularization,<ref name=eMedicine-1/> corneal scarring,<ref name=eMedicine-1/><ref name=Merck-1/> corneal thinning,<ref name=eMedicine-1/> and even corneal perforation<ref name=eMedicine-1/>.

[edit] Causes

Any abnormality of any one of the three layers of tears produces an unstable tear film, resulting in symptoms of keratitis sicca.<ref name=eMedicine-1/>

[edit] Deficient tear production

Keratoconjunctivitis sicca is usually due to inadequate tear production.<ref name=eMedicine-1/><ref name=Merck-1/> The aqueous tear layer is affected, resulting in aqueous tear deficiency (ATD) or lacrimal hyposecretion.<ref name=eMedicine-1/> 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.<ref name=eMedicine-1/> This is the most common type found in postmenopausal women.<ref name=Merck-1/><ref name=PE-1>Sendecka M, Baryluk A, Polz-Dacewicz M (2004). "Prevalence and risk factors of dry eye syndrome". Przegl Epidemiol 58 (1): 227-33. PMID 15218664.</ref>

Causes include idiopathic, congenital alacrima, xerophthalmia, lacrimal gland ablation, and sensory denervation.<ref name=eMedicine-1/> In rare cases, it may be a symptom of collagen vascular diseases, including rheumatoid arthritis<ref name=Merck-1/>, Wegener's granulomatosis, and systemic lupus erythematosus.<ref name=eMedicine-1/> Sjögren's syndrome<ref name=Merck-1/> and autoimmune diseases associated with Sjögren's syndrome are also conditions associated with aqueous tear deficiency.<ref name=eMedicine-1/> Drugs such as isotretinoin,<ref name=Merck-1/> sedatives,<ref name=Merck-1/><ref name=MayoClinic-1/> diuretics,<ref name=Merck-1/> tricyclic antidepressants,<ref name=MayoClinic-1/> antihypertensives,<ref name=Merck-1/> oral contraceptives,<ref name=eMedicine-1/><ref name=Merck-1/> antihistamines,<ref name=eMedicine-1/><ref name=FDA-1/><ref name=Merck-1/> nasal decongestants,<ref name=FDA-1/> beta-blockers,<ref name=eMedicine-1/> phenothiazines,<ref name=eMedicine-1/> atropine,<ref name=eMedicine-1/>, and pain relieving opiates such as morphine<ref name=MayoClinic-1/> 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.<ref name=eMedicine-1/>

[edit] 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.<ref name=eMedicine-1/> 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/>

[edit] 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 adenoviruses. A number of studies have found that diabetics are at increased risk for the disease.<ref name=Diabetic-1>Kaiserman I, Kaiserman N, Nakar S, Vinker S (2005). "Dry eye in diabetic patients.". Am J Ophthalmol 139 (3): 498-503. PMID 15767060.</ref><ref name=Diabetic-2>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.</ref>

An eye injury or other problem with the eyes or eyelids, such as bulging eyes or a drooping eyelid can cause keratoconjunctivitis sicca.<ref name=MedlinePlus-1/> Disorders of the eyelid can impair the complex blinking motion required to spread tears.<ref name=MayoClinic-1/>

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 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.<ref name=MayoClinic-1/> 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.<ref name=eMedicine-1/>

Persons with keratoconjunctivitis sicca have elevated levels of tear nerve growth factor (NGF).<ref name=eMedicine-1/> It is possible that this ocular surface NGF plays an important role in ocular surface inflammation associated with dry eyes.<ref name=eMedicine-1/>

[edit] 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.<ref name=MayoClinic-1/> A slit lamp examination can be performed to diagnose dry eyes and to document any damage to the eye.<ref name=eMedicine-1/><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.<ref name=eMedicine-1/> For this test, wetting under 5 mm with anesthesia and under 10 mm without anesthesia is considered abnormal.<ref name=eMedicine-1/>

If the results for the Schirmer's test are abnormal, a Schirmer II test can be performed to measure reflex secretion.<ref name=eMedicine-1/> 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.<ref name=eMedicine-1/> For this test, wetting under 15 mm after five minutes is considered abnormal.<ref name=eMedicine-1/>

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.<ref name=eMedicine-1/>

A tear protein analysis test measures the lysozyme contained within tears.<ref name=eMedicine-1/> In tears, lysozyme accounts for approximately 20 to 40 percent of total protein content.<ref name=eMedicine-1/>

A lactoferrin analysis test provides good correlation with other tests.<ref name=eMedicine-1/>

[edit] 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.<ref name=MayoClinic-1/> Persons with dry eyes caused by an eyelid disorder should undergo treatment for the underlying condition.<ref name=MayoClinic-1/>

[edit] Rehydration

For mild and moderate cases, supplemental lubrication is the most important part of treatment.<ref name=eMedicine-1/>

[edit] Artificial tears

Main article: Artificial tears

Application of artificial tears every few hours<ref name=Merck-1/> can provide temporary relief.

[edit] Additional options

Lubricating tear ointments can be used during the day, but they generally are used at bedtime due to poor vision after application.<ref name=eMedicine-1/> They contain white petrolatum, mineral oil, and similar lubricants.<ref name=eMedicine-1/> They serve as a lubricant and an emollient.<ref name=eMedicine-1/> Application requires pulling down the eyelid and applying a small amount (0.25 in) inside.<ref name=eMedicine-1/> Depending on the severity of the condition, it may be applied from every hour to just at bedtime.<ref name=eMedicine-1/> It should not be used with contact lenses.<ref name=eMedicine-1/>

[edit] 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.<ref name=MayoClinic-1/> Wearing wraparound glasses when outside can help reduce the drying effects of the wind.<ref name=MayoClinic-1/>

Using a humidifier,<ref name=Merck-1/><ref name=MedlinePlus-1/> especially in the winter,<ref name=MedlinePlus-1/> adds moisture<ref name=MayoClinic-1/> to dry indoor air. Specially designed glasses that form a moisture chamber around the eye may be used to create additional humidity.<ref name=MayoClinic-1/>

[edit] Supplementation

Consumption of dietary omega-3 fatty acids is associated with a decreased incidence of dry eyes syndrome in women.<ref name="AmJClinNutr2005-MiljanoviÄ‡">MiljanoviÄ‡ 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.</ref> This finding is consistent with postulated biological mechanisms.<ref name="AmJClinNutr2005-MiljanoviÄ‡"/>

[edit] Medication

Inflammation occurring in response to tears film hypertonicity can be suppressed by mild topical steroids or with topical immunosuppressants such as ciclosporin.<ref>Tatlipinar S, Akpek E (2005). "Topical ciclosporin in the treatment of ocular surface disorders.". Br J Ophthalmol 89 (10): 1363-7. PMID 16170133.</ref><ref>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.</ref> Elevated levels of tear NGF can be decreased with 0.1% prednisolone.<ref name=eMedicine-1/>

[edit] Restasis

Topical ciclosporin A (tCSA) 0.05% ophthalmic emulsion, marketed in the United States by Allergan under the trade name Restasis<ref name=eMedicine-1/>, is the only prescription product for chronic dry eyes.<ref name=FDA-1/> Approved by the U.S. Food and Drug Administration in 2002,<ref name=FDA-1/> the drug decreases inflammation<ref name=MayoClinic-1/> on the eye surface. It increases healthy tear production,<ref name=MayoClinic-1/> 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 gtt of Restasis is applied twice a day, 12 hours apart.<ref name=eMedicine-1/> It should not be used when wearing contact lenses,<ref name=eMedicine-1/> 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<ref name=MayoClinic-1/> 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=eMedicine-1/><ref name=FDA-1/>

[edit] Generic alternatives

Cheaper generic alternatives to Restasis are available in some countries. In India, it is marketed as Cyclomune by Sun Pharma.<ref name=SunPharma-1> Sun Pharma Product List. Sun Pharma. Retrieved on 2006-11-27. </ref>

[edit] Conserving tears

There are methods that allow both natural and artificial tears to stay longer.<ref name=MayoClinic-1/>

[edit] Blocking tear drainage

In each eye, there are four puncta — little openings that drain tears into the tear ducts.<ref name=FDA-1/> There are methods to partially or completely close the tear ducts.<ref name=MayoClinic-1/> This blocks the flow of tears into the nose, and thus more tears are available to the eyes.<ref name=Merck-1/>

[edit] 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/>

A temporary punctal occlusion can be inserted and tried first.<ref name=eMedicine-1/><ref name=FDA-1/> These are made of collagen and are dissolvable.<ref name=eMedicine-1/><ref name=FDA-1/> This is to ascertain that permanent ones will not cause excessive tearing.<ref name=FDA-1/>

Permanent punctal plugs are usually made of silicone.<ref name=FDA-1/> Some plugs are made of thermally reactive material.<ref name=FDA-1/> Some of these are inserted into the punctum as a liquid and then they harden and conform to the individual's drainage system.<ref name=FDA-1/> Others start out rigid and become soft and flexible, adapting to the individual's punctal size after they are inserted.<ref name=FDA-1/>

Artificial tears are usually still required after punctal plug insertion.<ref name=FDA-1/>

The risks of punctal plugs are fairly minimal.<ref name=FDA-1/> There is a risk of eye irritation, excessive tearing, and, in rare cases, infection.<ref name=FDA-1/>

[edit] Cauterization

If punctal plugs are effective, thermal<ref name=MayoClinic-1/> or electric<ref name=eMedicine-1/> cauterization of puncti can be performed.

In thermal cauterization, a local anesthetic is used, and then a hot wire is applied.<ref name=MayoClinic-1/> This shrinks the drainage area tissues and causes scarring, which closes the tear duct.<ref name=MayoClinic-1/>

[edit] Customized contact lenses

Persons with severe dry eyes may benefit from the Boston Scleral Lens which is a customized contact lense.<ref name=MayoClinic-1/> Resting on the sclera, it creates a fluid filled layer over the cornea, thus preventing it from drying.<ref name=MayoClinic-1/>

[edit] Surgery

In severe cases of keratoconjunctivitis sicca, the eyelids may be partially sewn together to reduce tear evaporation.<ref name=Merck-1/>

[edit] Prognosis

Keratoconjunctivitis sicca usually is a chronic problem.<ref name=MayoClinic-1/> Its prognosis shows considerable variance, depending upon the severity of the condition.<ref name=eMedicine-1/> Most patients have mild-to-moderate cases, and can be treated symptomatically with lubricants.<ref name=eMedicine-1/> This provides an adequate relief of symptoms.<ref name=eMedicine-1/>

When dry eyes symptoms are severe, they can interfere with quality of life.<ref name=FDA-1/> People sometimes feel their vision blurs with 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/>.

[edit] Prevention

There is no way to prevent keratoconjunctivitis sicca.<ref name=MedlinePlus-2> Dry eyes syndrome. MedlinePlus Medical Encyclopedia. U.S. National Library of Medicine (2006-10-04). Retrieved on 2006-11-16. </ref> Complications can be prevented by use of wetting and lubricating drops and ointments.<ref name=MedlinePlus-2/>

[edit] Epidemiology

Keratoconjunctivitis sicca is relatively common within the United States, especially so in older patients.<ref name=eMedicine-1/> Specifically, the persons most likely to be affected by dry eyes are those aged 40 or older.<ref name=MayoClinic-1/>

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.<ref name=MayoClinic-1/> Instances of Sjögren syndrome and keratoconjunctivitis sicca associated with it are present much more commonly in women, with a ratio of 9:1.<ref name=eMedicine-1/> In addition, milder forms of keratoconjunctivitis sicca also are more common in women.<ref name=eMedicine-1/> This is partly because hormonal changes,<ref name=MayoClinic-1/> such as those that occur in pregnancy, menstruation, and menopause,<ref name=MayoClinic-1/> 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.<ref name=eMedicine-1/>

[edit] Occurrence in animals

Among animals, keratoconjunctivitis sicca occurs in dogs, cats, and horses.<ref name=Merck-2/>

[edit] Dogs

Keratoconjunctivitis sicca is common in dogs. 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.<ref name=Gelatt_1999>Gelatt, Kirk N. (ed.) (1999). Veterinary Ophthalmology, 3rd ed., Lippincott, Williams & Wilkins. ISBN 0-683-30076-8.</ref> Symptoms include eye redness, a yellow or greenish discharge, ulceration of the cornea, pigmented 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.<ref name=Gelatt_1999/>

Tear replacers are a mainstay of treatment, preferably containing methylcellulose or carboxymethyl cellulose.<ref name=Gelatt_1999/> Ciclosporin stimulates tear production and acts as a suppressant on the immune-mediated processes that cause the disease. Topical antibiotics and corticosteroids 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:

[edit] Cats

Keratoconjunctivitis sicca is uncommon in cats. Most cases seem to be caused by chronic conjunctivitis, especially secondary to feline herpesvirus.<ref name=Gelatt_1999/> Diagnosis, symptoms, and treatment are similar to those for dogs.

[edit] See also

[edit] References

[edit] 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

[edit] External links

[edit] Animals

id:Xerophtalmia nl:Keratoconjunctivitis sicca pl:Zespół suchego oka ja:ドライアイ zh:乾眼症

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