Dry Eye Dx and Tx

What’s on the Horizon in Dry Eye Diagnosis and Treatment

BY WILLIAM TOWNSEND, OD, FAAO

When considering the “dry eye pipeline,” we often focus entirely on therapeutic agents. But, in many instances, establishing a definitive diagnosis continues to be problematic. This article discusses a dry eye diagnostic tool as well as treatments on the horizon.

An App for Meniscometry

Meniscometry is an effective, objective means of evaluating tear volume. It can be performed with a free-standing meniscometer or with some optical coherence tomographers (Uchida, 2007; Salomon-Ben Zeev, 2014).

Bandlitz et al (2014) reported the use of a new tear meniscometer application in diagnosing dry eye disease (DED). This digital meniscometer app couples an iPod or iPad with a slit lamp to analyze the lower tear meniscus. It may emerge as another objective means of accurately identifying the condition.

Potential Immunomodulator

Janus kinases (JAKs) are gatekeeper molecules named after Janus, the Roman god of doors and gates. JAKs are involved in acquired and innate immunity, and they play a critical role in immune-mediated tissue damage and destruction in rheumatoid arthritis (RA). Because JAK enzymes are crucial to immune cell development and function, they are attractive targets for modulating immune function (Lomonte, 2012).

Tofacitinib is a JAK inhibitor that has been evaluated as a treatment for RA (Lomonte, 2012) and for DED (Liew et al, 2012). It works though an entirely different mechanism compared to Restasis (cyclosporine A, Allergan). Liew et al (2012) reported that tofacitinib exhibited better patient-reported ocular tolerability compared to cyclosporine, and it was superior to cyclosporine in both objective and subjective testing. The FDA trial for this medication has been suspended, but may be reinstituted in the future (http://clinicaltrials.gov/).

Increasing Mucin Production

Mucin deficiency is a well-recognized issue in DED. Rebamipide is a mucin secretagogue that exhibits mucosal protective activity and is marketed in Japan as a systemic treatment of gastric mucosal disorders and gastritis (Kashima, 2014).

Kenoshita et al (2013) demonstrated the superiority of rebamipide 2% over sodium hyaluronate 1% solution for both objective signs and subjective symptoms of DED; they also found that 2% rebamipide is well-tolerated by the ocular surface.

Nanoparticle Drug Delivery

Nanotechnology has assumed an increasingly important role in drug delivery. Contreras-Ruiz et al (2013) instilled plasmin-loaded gelatin-based nanoparticles of modified MUC5AC into the eyes of normal and dry eye mice. They found no significant changes in the ocular surface of the controls. The eyes of the dry eye mice showed increased tear production, reduced fluorescein staining, and decreased CD4+ T-cells, suggesting a reduction in overall inflammation.

Diabetes and Dry Eye

While the precise mechanism is unclear, diabetes-associated dry eye has been linked to insulin deprivation and/or insulin resistance leading to nerve-conduction abnormalities (Rocha, 2013).

Topical insulin normalizes wound healing in diabetics, and in the future could potentially be a useful therapy for diabetes-associated dry eye (Módulo, 2009). CLS

For references, please visit www.clspectrum.com/references and click on document #224.

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 an advisor to Alcon, B+L, CooperVision, Tearlab Corporation, and Vistakon. Contact him at drbilltownsend@gmail.com.