Relief Is in Sight for Symptoms of Dry Eye
This article is brought to you by Allergan Dry Eye
Dry eye syndrome is the mostcommon ocular complaint inthe United States affectingmillions of Americans each year.1
The reported prevalence of dry eyegarnered from different studies variessubstantially from 7.8%1 to as high as20%. Risk factors for dry eye include:
- Advanced age
- Female sex
- Menopausal hormone therapy
- Low omega-3 fatty acid intake
Other possible risk factors includelow androgen levels, autoimmune diseasesand other disorders, medicationuse, genetic predisposition, andalcohol use. It has been well-documentedthat women are twice as likelyto develop dry eye and that theprevalence increases significantlywith age, most especially in postmenopausalwomen.1-3
The major symptoms associatedwith dry eye include blurred vision, oculardischarge, eye discomfort, a burningsensation, increased awareness of theeye, redness, sensitivity to light, and thefeeling of grit or sand in the eye.4
An accurate diagnosis may beobtained from patient history.5Patients with dry eye will state thatthe eye discomfort, such as burningor a feeling of grit, gets worse as theday progresses. Symptoms may startslowly and occur episodically overweeks to months, with the eyesbecoming acutely sensitive to environmentalinsults (eg, low humidity).
A classification system for dry eyeproposed by the National Eye Institutedivides dry eye into 2 categories, ofwhich the first is the more common:
1. Deficiency of aqueous tear production(eg, from Sj?gren's syndrome,lacrimal gland disease, lacrimal glandduct obstruction, loss of reflex tearing,LASIK surgery)
2. Increased tear evaporation (eg,from meibomian gland disorder,exposure, contact lenses, blink abnormality)6
Both categories lead to anincrease in tear film osmolarity. Thisincreased osmolarity leads to anosmotic dehydration of the surfaceof the eye and to the symptomsassociated with dry eye.5
Generally, nonprescription artificialtear products provide sufficient reliefof the symptoms of dry eye.7 Artificialtear products contain demulcentsthat mimic the action of mucin, protectivelycovering and wetting thecornea.8,9 Substituted cellulose ethers(eg, carboxymethylcellulose) arewater-soluble ingredients that areassociated with little if any adverseeffects and show a longer duration ofaction than other demulcents.8
Other demulcents found in artificialtear formulations include polyvinylalcohol and water-soluble polyols,such as glycerin and propylene andpolyethylene glycol. Dextran 70 hasbeen shown to be an effective demulcent,but it can cause stinging andblurring. Although transient, theseadverse effects may influence patientadherence.7
Alternative available products areocular emollients that produce a protectivefilm that covers the ocular surface.10 They may contain such compoundsas lanolin, mineral oil, paraffin,or petrolatum. They have beenshown to cause blurred vision and aretherefore recommended to beapplied at bedtime.11
Many ophthalmic products containpreservatives (Table 1), such as surfactants(eg, benzalkonium chloride, benzethoniumchloride), metals (iodine,mercury), chlorobutanol, ethylenediaminetetraaceticacid, methylparaben,polyquaternium-1 (Polyquad), andpropylparaben.12 Newer preservativesused are sodium perborate and Purite(oxychloro complex), which have beendesigned so that they dissociate oncontact with the eye (called disappearingpreservatives). These agents havedemonstrated a decreased risk of theadverse effects that are associatedwith other preservatives.12
The presence of a preservativeincreases the risk of both adverseeffects on the corneal surface andthe possibility of hypersensitivityreactions. These risks increase withboth the duration of use and thenumber of drops administered perday.13 The use of preservative-freeproducts or disappearing preservativesdecreases the risk of these effectsand should be considered,especially for long-term therapy orhigh-frequency use per day.12
Artificial Tear Products
Several pharmaceutical companiesmanufacture numerous tear productsfor the treatment of dry eye. Table 1summarizes these products and theircomponents by brand names. TheseOTC products varymainly in their ingredients,availability ofpreservatives, indications,and dosageforms.
The administrationof products that contain substancesknown as compatible solutes mightprovide a novel approach to thetreatment of dry eyes. These compatiblesolutes theoretically may haveosmoprotective properties, whichmay protect the surface cells of theeye from osmotic stress. This optionwould seem to be a rational therapybecause dry eye is known to be associatedwith increased osmolarity.5
Optive, a new product fromAllergan, may provide a novel, effective,and safe approach to the treatmentof dry eyes. Optive, designatedas a next-generation tears (NGT) product,contains 2 such solutes: LCarnitineand erythritol. NGT productsare purported not to change theosmolarity of the fluid of the eye but tocompensate for it.
Helping Patients Choose anArtificial Tear Product
When recommending an appropriateand optimal artificial tear productfor patients consider certain factors(Table 2). As a general rule, althoughmore costly, products that are preservative-free or contain disappearingpreservatives may be more appropriatefor patients with more sensitiveeyes. Patients who fail with a particularproduct may be instructed to tryanother product with a differentingredient, add bedtime ointmenttherapy, or consult a health careprovider for further evaluation.
Dr. Tafreshi is an associate professor at Midwestern University College of Pharmacy-Glendale (MWU-CPG). Dr. Fisher is a professor at MWU-CPG.
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