My internist recently treated me for musculoskeletal pain and inflammation, and as part of the overall therapy, he prescribed turmeric. I was pleasantly surprised by how well it relieved most of my symptoms. Anti-inflammatory agents such as corticosteroids (Hessen and Akpek, 2014), cyclosporine A (Abidi et al, 2016), and lifitegrast (Radomska-Leśniewska et al, 2019) have been used to successfully reduce signs and symptoms of dry eye disease (DED). Given the well-established association between DED and inflammation (Tear Film & Ocular Surface Society [TFOS], 2007), it occurred to me that turmeric might also be beneficial in managing this condition.

Curcumin is a natural polyphenol (TFOS, 2007) derived from the rhizomes of Curcuma longa, the active ingredient found in turmeric, a dietary spice (Hewlings and Kalman, 2017). This perennial herb is widely cultivated in tropical regions of Asia and has been used for thousands of years, not only to color and flavor food (Hewlings and Kalman, 2017) but also for medicinal purposes (Radomska-Leśniewska et al, 2019).

Traditional Chinese medicine has successfully utilized curcumin in treating conditions such as allergy, asthma, bronchial hyperactivity, sinusitis, cough, and hepatic diseases (Liu et al, 2017). Regrettably, curcumin in its natural state has poor solubility and bioavailability due to poor absorption in the gastrointestinal tract (Radomska-Leśniewska et al, 2019). Fortunately, by supplementing curcumin preparations with piperine—a component of black pepper—it is possible to increase bioavailability by as much as 2,000% (Hewlings and Kalman, 2017). In a murine-based study, curcumin formulated with phosphatidylcholine produced a fivefold higher tissue concentration compared to the equivalent values with unformulated curcumin (Marczylo et al, 2007).

What the Literature Says

A search of PubMed on the efficacy of curcumin produces abundant information relating to potential systemic benefits, but research directed at its impact on the ocular surface is limited. Kimura (2010) conducted a study evaluating the impact of curcumin on the ocular surface; it was determined that tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine that negatively impacts tight junctions and barrier functions in human corneal epithelial cells (Kimura, 2010). This is strongly associated with dry eye (Kimura, 2010). Kimura reported that dietary curcumin blocks the negative effects of TNF-alpha on both barrier functions.

Specific tissue markers are often associated with DED. Na et al (2012) noted increased levels of cytokine interleukins IL-1beta, IL-6, IL-16, IL-33, G-CSF, and transforming growth factor (TGF)-alpha in patients who have DED. Therapies that reduce these inflammatory molecules could potentially impact dry eye.

Pescolido et al (2014) conducted a literature search evaluating the potential benefits of utilizing systemic curcumin in eye care. They determined that it downregulated the expression of the cyclooxygenase-2 gene, the prostaglandin E-2 gene, IL-1, IL-6, IL-8, and TNF-alpha, several of which contribute to ocular inflammation. These findings suggest that systemic curcumin has potential as a therapeutic agent for dry eye.

Hyperosmolarity is well recognized as an integral feature in DED. Chen et al (2010) used an in vitro model to evaluate the influence of hyperosmolarity on human corneal epithelial cells and the subsequent impact of curcumin on cell viability and health. Elevated osmolarity led to increased levels of IL-1beta, IL-6, and TNF-alpha. Treating the cells with curcumin afterward did not impact the damage; however, pretreatment of the cells with curcumin abolished the effects of the inflammatory mediators (Chen et al, 2010).

The potential use of curcumin in eye care is early in its development. At this time, there is no commercially available topical agent, but there is always the option of systemic therapy. Keep in mind that preparations containing piperine are much more efficacious. CLS

For references, please visit www.clspectrum.com/references and click on document #296.