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EW Supplement: Cornea Society News



     

Latest Trends in Dry Eye Treatments


by Marguerite McDonald, MD
 
 

This issue of Cornea Society News is supported by an unrestricted educational grant from

 

More than 20 million Americans suffer from dry eye, a condition resulting from insufficient tear production, excessive tear evaporation or abnormal tear composition. Symptoms of dry eye include itching, irritation, sensitivity to light, blurred vision and contact lens intolerance and even too much tear production. Dry eye can be associated with older age, ocular surface diseases, certain medications as well as autoimmune diseases such as lupus or arthritis. Mild or episodic dry eye can progress to a chronic condition and if left untreated, can eventually lead to infection or loss of vision, underscoring the importance of proper diagnosis and early treatment.

New Understanding of Dry Eye and Treatment Strategies

Until recently, the disease was broadly defined as a disorder of the tear film, caused by tear deficiency or excessive evaporation. However, in 2004, as a result of an evolved understanding of the condition and a recognized need for new, applicable treatment guidelines, an International Task Force (ITF) of dry-eye specialists created guidelines for diagnosis and treatment of the condition.
The ITF guidelines were based on the symptoms and signs of dry eye. The ITF guidelines underscore how a constantly evolving understanding of dry eye is helping improve treatment strategies that not only include new, innovative products, but also better diagnosis through conversations with patients and diagnostic tests such as ocular surface staining (e.g., with fluorescein, lissamine green).

The Role of Hypertonicity and Osmotic Stress in Dry Eye

Leveraging a new technology platform, Allergan recently introduced Optive, an artificial tear with an advanced formulation that provides lubrication of the surface of the eye while offering osmoprotection to the corneal epithelial cells. On a healthy eye surface, the tear film is isotonic and uncompromised and the epithelial cells are hydrated and in osmotic balance, providing maximum comfort to the eye. With dry eye, the quantity of water in the tear film is decreased as a result of high evaporation or because sufficient water is not produced in the first place. As a result, the tear film is not offering adequate support of the ocular epithelium, the outside layer of cells on the eye surface, causing surface inflammation and eye pain. The normal tear film composition is changed and tears become hypertonic, causing what's commonly referred to as osmotic stress.
Osmotic stress occurs when the concentration of molecules in solution outside of the cell is different than that inside the cell. When this happens, water flows either into or out of the cell by osmosis, thereby altering the intracellular environment. When tears are hypertonic and under osmotic stress, cells on the cornea lose cell water and as a result begin to absorb solutes such as sodium and potassium from the environment. This upsets the delicate chemical balance of the tear, which can lead to damage to, and malnourishment of, the ocular surface unless the cells are replenished with compounds referred to as compatible solutes.
Compatible solutes are small, nonionic organic compounds that build osmotic strength within the cells. All cells must absorb these compounds to remain healthy and functioning, a state referred to as "osmoprotection."

Dry Eye Treatment Options


Several treatment options are available for dry eye depending on the frequency and severity of the condition, however treatment with artificial tears currently accounts for approximately 79 percent of all dry eye therapies. Commonly sold over-the-counter as drops or gels, artificial tears use different approaches for moisturizing the eyes:
• hypotonic solutions temporarily increase water content
oil-containing tears improve lipid layer of tear film to prevent evaporation tears with bioadhesive properties increase retention of water
advanced artificial tears that contain compatible solutes to build osmotic strength.

The most recent addition to Allergan's dry eye portfolio is Optive Lubricant Eye Drops. The over-thecounter product contains a dual-action formula that provides long-lasting hydration of the eye while penetrating the corneal surface to protect the cells from hypertonic stress. Unlike traditional artificial tears, the advanced formula works in two ways and contains compatible solutes, that help restore osmoprotection in the corneal epithelial cell, while moisturizing the entire ocular surface with the lubricants, carboxymethylcellulose (CMC) and glycerin. CMC coats the ocular surface with a hydrating protective shield, while glycerin enters the corneal cells to protect against hypertonic stress. CMC is commonly considered one of the most effective lubricants, providing long-lasting comfort and relief to the ocular surface and glycerin is a nonblurring compatible solute that binds water to the cells. , Optive is preserved with Purite. Studies have demonstrated that Puritehas no cytotoxic, allergenic or irritating effects, and in the bottle, Purite preservative meets FDA standards for killing harmful bacteria and fungi.
In a 90-day clinical trial, Optive demonstrated statistically significant improvement versus baseline in six common signs and symptoms of dry eye with dry eye sufferers using Optive experiencing very little blur. When compared to other commercial tear products, data from the clinical trial also showed Optive provided longerlasting relief and patients were five times less likely to have administered Optive within the hour preceding the exam to relieve dry eye symptoms than those patients using a competitive product.
Artificial tears provide symptom relief and are a foundation to manage dry eye. Anyone using artificial tears three or more times a day may need to add prescription therapy. Restasis is currently the only prescription eye drop approved by the FDA to help increase the ability to produce tears which may be reduced by inflammation due to chronic dry eye. Advanced artificial tears may offer optimal relief to patients in combination with prescription therapy.
In more severe dry eye cases punctal occlusion may be needed to seal off the tear ducts in order to conserve tear volume. However, since occlusion may lead to increased risk of infection on the ocular surface, the ITF guidelines recommend initiating treatment prior to punctual occlusion to prevent or treat inflammation.
Our continued research and understanding of dry eye have led to several advances in new, advanced products and we can today offer a full continuum of care to our patients.

References


1 Pflugfelder SP, Beuerman RW, Stern ME. 2004. Dry eye and ocular surface disorders. New York, New York. Marcel Dekker
2 The 2002 Gallup Study of Dry Eye Sufferers. Multi-Sponsor Surveys, Inc. Princeton, NJ. October 2002.
3 Schaumberg D, Sullivan D, Buring J, Dana R. Prevalence of dry eye syndrome among U.S. women. Am J Ophthalmol. 2003;136:318-326.
4 American Academy of Ophthalmology Cornea/External Disease Panel. Dry Eye Syndrome Preferred Practice Pattern. American Academy of Ophthalmology, San Francisco, California, 2003.
5 Behrens A, Doyle JJ, Stern L, Chuck RS, McDonnell PJ, and the Dysfunctional Tear Syndrome Study Group. Dysfunctional Tear Syndrome: A Delphi Approach to Treatment Recommendations. Cornea 2006 (In Press).
6 Foulks GN. The evolving treatment of dry eye. Ophthalmol Clin N Am. 2003; 16-29-35.
7 Foulks GN. The evolving treatment of dry eye. Ophthalmol Clin N Am. 2003; 16-29-35.
8 Gallup Organization. The 2004 Gallup Study of Dry Eye Sufferers. Princeton, NJ; Gallup Organization, 2004.
9 Hunt et al. In: Drug Delivery Systems: Fundamentals and Techniques. 1987; 2. Simmons et al. ARVO. 2006.
10 Simmons et al. ARVO. 2006.
11 Noecker R. Effects of common ophthalmic preservatives on ocular health. Adv Ther. 2001;18:205-215.
12 Noecker R. Ophthalmic preservatives: considerations for long-term use in patients with dry eye or glaucoma. Rev Ophthalmol.
13 Clinical Trial #AG9689-001. Data on File, Allergan, Inc.





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