Dry Eye Dx and Tx

Treating Dry Eye: Is There Hope on the Horizon?

BY WILLIAM TOWNSEND, OD, FAAO

The literature is replete with studies demonstrating how common and, in some cases, debilitating dry eye syndrome can be (Bron et al, 2014; Paulsen et al, 2014). It is interesting to note that despite this, there are currently only two U.S. Food and Drug Administration (FDA)-approved prescription therapies for dry eye. In 2014, the FDA approved 44 new drugs, none of which were targeted at dry eye (www.forbes.com/sites/bernardmunos/2015/01/02/the-fda-approvals-of-2014). The obvious questions are, “Why have we had no new approvals for prescriptive medications for dry eye?” and “Is there any hope on the horizon?”

Dry eye is, by its very nature, a complex and multifactorial disease with a variety of signs and symptoms that often correlate poorly or not at all. Because it is caused by a variety of disparate underlying pathological processes, developing a therapeutic agent to treat “dry eye” can be frustrating. A therapeutic agent may be very beneficial in specific forms of the disease, but ineffective in others (Bron et al, 2014). These factors explain the wide variety of agents recently or currently in clinical trials for FDA approval.

Trehalose

Thealoz (trehalose 3%, Spectrum Thea Pharmaceuticals) contains trehalose, a disaccharide (sugar) commonly found in nature that is characterized by high water retention capabilities and is thought to prevent disruption of internal cell organelles by forming a gel phase (www.inchem.org/documents/jecfa/jecmono/v46je0.htm). Thealoz is currently used in Europe to treat dry eye. It underwent FDA clinical trials from 2012 to 2014, all of which are completed.

Human Growth Hormone

Human growth hormone (HGH, somatotropin, somatropin) is a naturally occurring peptide hormone secreted by the anterior pituitary; it stimulates growth, cell reproduction, and regeneration (www.news-medical.net/health/What-are-Growth-Hormones.aspx). An ongoing study, “Safety and Efficacy of rhNGF Eye Drops at Different Doses in Patients With Dry Eye,” is currently recruiting subjects to evaluate the effects of HGH on dry eye (https://clinicaltrials.gov/ct2/show/NCT02101281).

HGH has been successfully used to treat individuals who have severe dry skin secondary to anterior pituitary insufficiency (Sheehan’s syndrome) (Tanriverdi et al, 2006). If HGH can produce similar effects in ocular tissue, it may benefit individuals who have dry eye. This study is projected to conclude sometime in 2015.

Cyclosporine A 2%

Prior to the approval of Restasis (cyclosporine A 0.5%, Allergan) for humans, cyclosporine was used at higher concentrations to treat dry eye and other ocular conditions, first in canines (Kern, 1989) and then in humans (Laibovitz et al, 1993). A current FDA trial, “Phase 2 Study of a New Ophthalmic Formulation of Cyclosporine (Restasis® X) in Patients With Dry Eye Disease,” evaluates cyclosporine A 2% for the treatment of dry eye.

Prior to the approval of Restasis, many practitioners, including myself, prescribed compounded 1% and 2% cyclosporine to successfully manage severe dry eye. If approved, the cyclosporine at higher concentration may prove superior in managing dry eye cases that are unresponsive to the currently available form. CLS

For references, please visit www.clspectrum.com/references and click on document #236.

Dr. Townsend practices in Canyon, Texas, and is an adjunct professor at the University of Houston College of Optometry. He is president of the Ocular Surface Society of Optometry and conducts research in ocular surface disease, lens care solutions, and medications. He is also a consultant or advisor to Alcon, Allergan, NovaBay, TearScience, TearLab, and Science Based Health. Contact him at drbilltownsend@gmail.com.