One of my favorite patients recently told me about a new supplement she said helped her dry eyes. She is on 500mg twice per day and feels an improvement.It turns out there is some proof in good medical journals that show the benefit of NAC for Dry Eyes noted below.
Sandra Lora Cremers, MD, FACS
The pathogenesis of DES is complex with multiple etiologies. Inflammation of the tear-secreting apparatus that results in compositional changes of the tear film and loss of its integrity is thought to be 1 of the important mechanisms that leads to ocular surface injury in DES.26 Cell damage in the cornea and conjunctiva, by means of apoptosis and direct mechanical and/or osmotic stress, will stimulate the reflex neurosensory arc, in turn stimulating lacrimal gland and neurogenic inflammation and inflammatory involvement of the conjunctival epithelium.27 Lacrimal gland dysfunction that causes tear hyperosmolarity can lead to the release of IL-1, IL-6, IL-8, TNF-α, and matrix metalloproteinase 9, 1, 13, and 3 from the ocular surface epithelium.28– 30 In our previous study using gene microarray analysis in the BTX-B–induced dry eye murine model, we found that MIF, Toll-interacting protein, IL-1β, IL-10, IL-12α, and TNF-α were highly expressed.21 Various anti-inflammatory treatments have been demonstrated to be useful for DES treatment.31– 34 At present, topical cyclosporine has become 1 of the standard treatments for patients with moderate to severe DES.35– 38 However, no single treatment successfully cures DES. Other medications have been evaluated for improving quality of life in patients with DES. Absolon and Brown13 conducted a double-masked crossover trial in patients with dry eye, comparing NAC alone with artificial tears; the objective findings in the NAC-treated group were significantly better than those in the artificial tear group, though there were no significant differences in subjective findings.Although corneal fluorescein staining scores were lower in the C-NAC, 0.5%, and fluorometholone groups compared with the control group, the effect was not statistically significant. In our study, we demonstrated that C-NAC, 0.3%, can decrease ocular surface messenger RNA expression of IL-1β, IL-10, IL-12α, and TNF-α. A higher concentration of C-NAC (0.5%) was shown to suppress MIF expression significantly better than a vehicle, artificial tears, and (surprisingly) fluorometholone in addition to significantly decreasing the expression of IL-1β and IL-12α. These inflammatory cytokines are thought to be important in the pathogenesis of disease in the BTX-B–induced dry eye murine model.21 We postulate that the mucoadhesive properties of thiolated chitosan in conjunction with the antioxidative and mucolytic property of N-acetylcysteine played a role in protecting the ocular surface and suppressing the inflammatory response in the mice. Furthermore, our data support an anti-inflammatory role for C-NAC, which is a novel concept and begs further investigation.
1. Reactive oxygen species activated NLRP3 inflammasomes initiate inflammation in hyperosmolarity stressed human corneal epithelial cells and environment-induced dry eye patients.Zheng Q, Ren Y, Reinach PS, Xiao B, Lu H, Zhu Y, Qu J, Chen W.Exp Eye Res. 2015 May;134:133-40. doi: 10.1016/j.exer.2015.02.013. Epub 2015 Feb 18.PMID: