Artificial tears

Artificial tears are lubricant eye drops used to treat the dryness and irritation associated with deficient tear production in keratoconjunctivitis sicca (dry eyes).^[1] 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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Chemistry

Preparations contain carboxymethyl cellulose,^[1][2] hydroxypropyl methylcellulose^[2] (a.k.a. HPMC or hypromellose), and hydroxypropyl cellulose^[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^[1] should choose a brand without preservatives^[1] or one with special non-irritating preservatives.

Effects

Application of artificial tears every few hours^[3] 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.^[1]

Usage

Artificial tears usually are the first line of treatment for dry eyes.^[2] 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.^[1] Thicker artificial tears can be used in severe cases, although these may temporarily blur vision.^[1]

An artificial tear insert such as Lacrisert which contains hydroxypropyl cellulose can also be used every morning.^[1]

Precautions

Drops for red eyes can make the eyes even drier.^[2] If wearing contact lenses, rewetting or lubricating drops specifically for contact lenses should be used.^[2] Other types of drops may contain ingredients that damage the lens.^[2]

Adverse effects, interactions and contraindications

Possible adverse effects of carboxymethyl cellulose and other similar lubricants include eye pain, irritation, continued redness, or vision changes.^[1] Use should be discontinued if any of them occur.^[1] Those of hydroxypropyl cellulose include hyperaemia, photophobia, stickiness of eyelashes, discomfort, and irritation.^[1] Long term use of preservatives present in some artificial tears may harm the eye.^{[citation needed]}

Artificial tears have no reported interactions.^[1] A documented contraindication of artificial tears is hypersensitivity.^[1]

Veterinary uses

Artificial tears are a part of the topical therapy for keratoconjunctivitis sicca for animals such as dogs, cats and horses.^[4]

References

1. ^ ^{a b c d e f g h i j k l m n} Keratoconjunctivitis, Sicca. eMedicine. WebMD, Inc. (2006-04-21). Retrieved on 2006-11-12.
2. ^ ^{a b c d e f} Meadows, Michelle (May-June 2005). Dealing with Dry Eye. FDA Consumer Magazine. U.S. Food and Drug Administration. Retrieved on 2006-11-16.
3. ^ Keratoconjunctivitis Sicca. The Merck Manual, Home Edition. Merck & Co., Inc. (2003-02-01). Retrieved on 2006-11-12.
4. ^ Keratoconjunctivitis, Sicca. The Merck Veterinary Manual. Merck & Co., Inc.. Retrieved on 2006-11-18.