Artificial tears
From Wikipedia, the free encyclopedia
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> Keratoconjunctivitis, Sicca. eMedicine. WebMD, Inc. (2006-04-21). Retrieved on 2006-11-12. </ref> They are also used to moisten contact lenses and in eye examinations.
Artificial tears are available over-the-counter. Artificial tears are supplemented with other treatments in moderate to severe forms of dry eyes.
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[edit] Chemistry
Preparations contain carboxymethyl cellulose,<ref name=eMedicine-1/><ref name=FDA-1/> hydroxypropyl methylcellulose<ref name=FDA-1/> (HPMC) (a.k.a. hypermellose), 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.
[edit] Effects
Application of artificial tears every few hours<ref name=Merck-1> Keratoconjunctivitis Sicca. The Merck Manual, Home Edition. Merck & Co., Inc. (2003-02-01). Retrieved on 2006-11-12. </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/>
[edit] 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/>
[edit] Precautions
Drops for red eyes can make the eyes even more dry.<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> 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/>
[edit] Adverse effects, interactions and contraindications
Possible 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/>
Artificial tears have no reported interactions.<ref name=eMedicine-1/> A documented contraindication of artificial tears is hypersensitivity.<ref name=eMedicine-1/>
[edit] 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> Keratoconjunctivitis, Sicca. The Merck Veterinary Manual. Merck & Co., Inc.. Retrieved on 2006-11-18. </ref>
[edit] References
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