N-Acetyl-cysteine (NAC) For Dry Eyes

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
N-Acetyl-cysteine (NAC)N-acetylcysteine (NAC) is a derivative of amino acid L-cysteine and is a reducing agent with antioxidative activity. It is well known for its mucolytic and anticollagenolytic properties and is still widely used to reduce viscosity in many bronchopulmonary disorders.⁸N-acetylcysteine has been used in ophthalmology in topical form to treat many corneal and external eye diseases, such as corneal ulcers,⁹ alkaline-burned corneas,¹⁰ chronic blepharitis,¹¹ filamentous keratitis,¹² and keratoconjunctivitis sicca.^12,13 It has also been shown to promote corneal wound healing in dogs.¹⁴The 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.Because it leads to the increased production of glutathione, NAC helps to protect your eye against oxidation and the toxic waste materials that come with it. Your eye uses glutathione as its principal antioxidant, and whilst, its highest concentration (aside from the liver, where it is produced) is in the eyes. Researchers have found that nearly all eye diseases are associated with low glutathione levels, so adequate levels of glutathione are essential to eye health.NAC is deployed as a drug to unclog mucous blockages in the body, such as in the lungs of patients with chronic emphysema, chronic bronchitis, cystic fibrosis, and pneumonia. As an antioxidant, NAC prevents lipids from being oxidised, which enables NAC to break up thick accumulations of mucous. Its mucous-dissolving properties, makes NAC a powerful agent for treating problems associated with lipid oxidation in the eyes. Several studies have shown that use of NAC is more effective than artificial tears in producing significant improvement in the discomforts experienced by people with blepharitis. Trial doses involving 100mg of NAC taken three times daily improved the constitution of the tear film, reducing the symptoms of blepharitis.Several research reports have documented the beneficial effects of NAC on the autoimmune disease Sjögren’s syndrome which also affects the eyes. NAC’s fast-acting ability to thin out mucosal secretions unblocks the cellular channels, enabling free-flow of moisture. research studies on people with the Sjögren’s syndrome, it was found that 200mg of NAC taken three times a day helped improve the dry eye symptoms associated with the disease.



References:1. http://jamanetwork.com.ezp.welch.jhmi.edu/journals/jamaophthalmology/fullarticle/4229412. http://www.raumclone.com/archives/20403. Below are all the sites related to NAC & Dry eye today.
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:
25701684
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 2.PMID:Select item 19365035