Artificial tears
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[[Image:Artificial tears brands.jpg|thumb|A subset of various brands of artificial tears displayed in a store]]
'''Artificial tears''' are lubricant [[eye drops]] used to treat the dryness and irritation associated with deficient tear production in [[keratoconjunctivitis sicca]] (dry eyes).<ref name=eMedicine-1>
{{cite web
| url = http://www.emedicine.com/oph/topic695.htm
| title = Keratoconjunctivitis, Sicca
| accessdate = 2006-11-12
| date = 2006-04-21
| work = [[eMedicine]]
| publisher = [[WebMD|WebMD, Inc.]]
}}
</ref> They are also used to moisten [[contact lens]]es and in eye examinations.
Artificial tears are available [[Over-the-counter drug|over-the-counter]]. Artificial tears are supplemented with other treatments in moderate to severe forms of dry eyes.
==Chemistry==
Preparations contain [[carboxymethyl cellulose]],<ref name=eMedicine-1/><ref name=FDA-1/> [[Hypromellose|hydroxypropyl methylcellulose]]<ref name=FDA-1/> (a.k.a. HPMC or hypromellose), and [[hydroxypropyl cellulose]]<ref name=eMedicine-1/>. They contain water, salts and polymers but lack the proteins found in natural tears. Patients who use them more frequently than once every three hours<ref name=eMedicine-1/> should choose a brand without preservatives<ref name=eMedicine-1/> or one with special non-irritating preservatives.
==Effects==
Application of artificial tears every few hours<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> can provide temporary relief from the symptoms of dry eyes.
Hydroxypropyl cellulose stabilizes and thickens the precorneal tear film, and prolongs the tear film breakup time.<ref name=eMedicine-1/>
==Usage==
Artificial tears usually are the first line of treatment for dry eyes.<ref name=FDA-1/> While mild cases require application of lubricant drops four times a day, severe cases require more aggressive treatment, such as ten to twelve times a day.<ref name=eMedicine-1/> Thicker artificial tears can be used in severe cases, although these may temporarily blur vision.<ref name=eMedicine-1/>
An artificial tear insert such as [[Lacrisert]] which contains hydroxypropyl cellulose can also be used every morning.<ref name=eMedicine-1/>
===Precautions===
Drops for red eyes can make the eyes even drier.<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> If wearing contact lenses, rewetting or lubricating drops specifically for contact lenses should be used.<ref name=FDA-1/> Other types of drops may contain ingredients that damage the lens.<ref name=FDA-1/>
==Adverse effects, interactions and contraindications==
Possible [[Adverse effect (medicine)|adverse effects]] of carboxymethyl cellulose and other similar lubricants include eye pain, irritation, continued redness, or vision changes.<ref name=eMedicine-1/> Use should be discontinued if any of them occur.<ref name=eMedicine-1/> Those of hydroxypropyl cellulose include [[hyperaemia]], [[photophobia]], stickiness of eyelashes, discomfort, and irritation.<ref name=eMedicine-1/> Long term use of preservatives present in some artificial tears may harm the eye.{{Fact|date=June 2007}}
Artificial tears have no reported [[interaction]]s.<ref name=eMedicine-1/> A documented [[contraindication]] of artificial tears is [[hypersensitivity]].<ref name=eMedicine-1/>
==Veterinary uses==
Artificial tears are a part of the topical therapy for keratoconjunctivitis sicca for animals such as dogs, cats and horses.<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 = [[Merck Veterinary Manual|The Merck Veterinary Manual]]
| publisher = [[Merck & Co.|Merck & Co., Inc.]]
}}
</ref>
==External links==
*[http://preservative.free.fr/English/indexen.htm Use of preservatives in artificial tears]
==References==
<references/>
[[Category:Drugs]]
[[Category:Ophthalmology]]
[[Category:Electrolyte disturbances]]
[[Category:Dog health]]
[[Category:Cat health]]
[[Category:Equine medications]]
[[pt:Lágrimas artificiais]]