Ocular Health and Next Generation Solutions
Understanding taurine and its possible role in ocular health.
BY J. JAMES THIMONS, O.D., F.A.A.O.

The new generation of multipurpose solutions for contact lenses is helping us achieve a number of our treatment goals, including improved patient comfort and ocular health. One lens care product, Complete MoisturePlus, has the moisturizing properties of the dual ophthalmic demulcents hydroxypropyl methylcellulose (HPMC) and propylene glycol (PG) as well as cleaning and disinfecting agents. This combination has been a recipe for success in my practice, as we inevitably switch patients to Complete MoisturePlus.

Another feature that sets Complete MoisturePlus apart is that it's the only solution available in the United States that contains taurine. This naturally occurring amino acid may help address the conditions that cause contact lens discomfort. In this article, I'll describe some key study results surrounding taurine and how these factors may affect contact lens wear.

Why is taurine important?

Taurine is the most common amino acid in ocular tissue and tears. It's an essential nutrient that helps maintain the cell membranes of muscles, brain and ocular tissues. We don't know taurine's exact role in ocular health, but we can see some interesting possibilities from current research.

Taurine may help prevent cell damage by acting as an antioxidant or osmoregulator. For example, studies have shown that taurine protects corneal cells exposed to conditions of hypertonic stress. In a separate study, taurine acted as an antioxidant to protect corneal cells from a strong oxidizing agent (HOCl).

It has also been demonstrated that taurine inhibits protein denaturation, which may decrease protein binding to contact lenses. This protein binding causes discomfort for lens wearers.

Histamine release is inhibited by taurine in the gastrointestinal tract. In the eye, histamine release is associated with tearing and itching. In side-by-side clinical studies of multipurpose solutions with and without taurine, participants experienced fewer symptoms of tearing and itching with the solution that contains taurine. More research is needed to determine whether taurine affects histamine release at the ocular surface.

Emerging potential

As we continue to use and study Complete MoisturePlus, the role of taurine in ocular health will emerge. The combination of HPMC and PG, FDA-recognized demulcents, in Complete MoisturePlus offers a more comfortable solution.

In the meantime, dual ophthalmic demulcents, taurine and essential electrolytes make Complete MoisturePlus my solution for patient success.

References
1. Heinemaki A, Muhonen A, Piha R. Taurine and other free amino acids in the retina, vitreous, lens, iris ciliary body, and cornea of the rat eye. Neurochem Res. 1986;11:535-42.
2. Puck A, Liappis N, Hildenbrand G. Ion exchange column chromatographic investigation of free amino acids in tears of healthy adults. Ophthal Res. 1984;16:284-88.
3. Shioda R et al. Osmosensitive taurine transporter expression and activity in human corneal epilethial cells. Invest Ophthalmol Vis Sci. 2002;43:2916-2921.
4. Arakawa T, Timasheff SN. The stabilization of proteins by osmolytes. Biophys J. 1985;47:411-14.
5. Endo Y et al. Mechanisms of cytoprotective effect of amino acids on local toxicity caused by sodium laurate, a drug absorption enhancer, in intestinal epithelium. J Pharm Sci. 2002;9:730-43.
6. Koyama I, Nadamori K, Nagahama T et al. The reactivity of taurine with hypochlorous acid and its application for eye drops. Adv Exp Med Biol. 1996;403:9-18. 

Simplicity, Cleaning and Comfort

Of all the contact lens solutions I've ever tested as a clinical investigator, Complete MoisturePlus is the product that patients unanimously want. They like its simplicity, cleaning and comfort. I see many patients with allergies at my practice in Des Moines, Iowa, and no other soft lens care product provides our patients with fewer allergies, thus giving them the satisfaction and lack of ocular irritation. This translates to less chair time than other products. When our patients have tried other products, they always go back to Complete Moisture Plus. I find a high percentage remain loyal to the product. David Hansen, O.D., F.A.A.O., Des Moines, Iowa

Raising the Bar for Multipurpose Solutions

Most of my contact lens patients spend their days working on computers in office buildings with dry, recycled air. By the end of the day, many of them have varying degrees of ocular discomfort symptoms, particularly dry eye. In the past, I recommended switching to low-water contact lenses and/or instilling ocular lubricants during the day. With Complete MoisturePlus and its comfort-enhancing agents -- HPMC, propylene glycol and taurine -- I've been able to help patients reduce the likelihood of lens dryness. By addressing the comfort problem in contact lens wear, AMO has raised the bar for multipurpose solutions. It gives us a weapon in the battle for continuous contact lens comfort and enhances the role of lens care in overall contact lens success. Complete MoisturePlus has allowed me to increase my value proposition to my patients and increase my standard of care. Jerry Nolfi, O.D., M.B.A., Toronto, Ontario, Canada