How plant oils may help dry eye

Nary a day goes by that I don’t learn something interesting from a patient. This week, examining a patient with dry eye/dysfunctional tear syndrome/ocular surface complaints, I learned about using coconut oil for chemotherapy-instigated dry skin.

Learning from a patient

My patient seated herself in the exam chair. She sported a lovingly hand-crocheted rainbow-colored beanie hat. It was obvious that beneath the cap, sparse or no scalp hair remained. Her eyebrows were thin, her eyelashes barely visible.

My patient recounted to me her past year’s breast cancer history. Receiving postmastectomy chemotherapy, she told me that of late, her sometimes dry eye had escalated to more significant ocular symptomatology. She also reported that her skin was very, very dry.

During chemotherapy, skin can become dry, rough, itchy, and red. Skin can peel and crack and develop sores or rashes. Chemotherapy may make skin photosensitive, increasing the risk of sunburn.

As an example, tamoxifen, a selective estrogen receptor modulator, acts against breast cancer by occupying estrogen receptors. Photosensitivity reaction is seen in patients who take tamoxifen citrate, especially those who are female, aged 40 to 49 years, and have been taking the drug for 1 to 6 months.¹ Because estrogen affects a wide variety of physiological functions and estrogen receptors are present in the eye, the changes in estrogenic activity brought about by tamoxifen have the potential to affect the retina as well as the lacrimal and meibomian glands.²

My patient told me that her doctor recommended she apply coconut oil to her skin “all over her body” to relieve chemotherapy-induced dryness and discomfort. This was very interesting to me.

Using plant oils

Plant oils have been used for a variety of purposes throughout history, with integration into foods, cosmetics, and pharmaceutical products. Plant oils (olive, olive pomace, sunflower seed, coconut, safflower seed, argan, soybean, peanut, sesame, avocado, borage, jojoba, oat, pomegranate seed, almond, bitter apricot, rose hip, German chamomile, and shea butter) are increasingly recognized for their effects on both skin diseases and the restoration of cutaneous homeostasis.³ Ah, that important concept of homeostasis. Many natural oils possess specific compounds with antimicrobial, antioxidant, anti-inflammatory, and antipruritic properties, making them attractive alternative and complementary treatments for xerotic and inflammatory dermatoses associated with skin-barrier disruption.⁴

Traditionally used as a moisturizer for centuries, coconut oil improves the symptoms of skin disorders by moisturizing and soothing the skin, according to study results. Findings from an in vitro study demonstrated coconut that oil suppressed inflammatory markers and protected the skin by enhancing skin barrier function.⁵ Interestingly, the authors concluded that topical application of coconut oil reduced the risk of infection and improved weight gain and skin condition in preterm infants.⁶ Could we translate this type of natural oil therapy for the management and symptomatic relief of “dry eye”?

Plant oils and dry eye

At the air-water interface, the tear film lipid layer, a mixture of lipids and proteins, plays a key role in tear surface tension and is important for the physiological hydration of the ocular surface and for ocular homeostasis. Over the last 2 decades, our understanding of the nature and importance of lipids in the tear film in health and disease has substantially increased. Lipid-based therapies not only

relieve patient symptoms immediately after topical administration, they also improve the lipid tear film structure and thickness component in ocular surface disease, resulting in enhanced tear film stability.⁷

Study results in rabbit models suggest that virgin coconut oil is safe to use as an ocular rewetting agent in humans.⁸

Derived from another seed, castor oil, a natural derivative of the Ricinus communis plant bean, is a vegetable oil pressed from castor beans. Castor oil and its derivatives are used in the manufacturing of soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, cold resistant plastics, waxes and polishes, nylon, pharmaceuticals, perfumes, wound dressings and drug delivery systems.⁹ Castor oil is deemed safe, with strong antimicrobial, anti-inflammatory, antinociceptive, analgesic, antioxidant, wound healing, and vasoconstrictive properties. Its main constituent, ricinoleic acid, has a bipolar molecular structure that promotes the formation of esters, amides, and polymers. These can supplement deficient physiological tear film lipids, enabling enhanced lipid spreading characteristics and reducing aqueous tear evaporation.

Research reveals that castor oil applied topically to the ocular surface has a prolonged residence time, facilitating increased lipid layer thickness stability and improved ocular surface staining and symptoms.

The biochemical and medicinal actions of castor oil not only temper microbial and demodectic processes over colonization and inflammatory and oxidative processes, they can improve the clinical signs and symptoms of dryness and discomfort in lid disease.¹⁰ In one study, castor oil eye drops achieved a residence time of at least 4 hours post instillation, producing a stable tear film and an associated significant decrease in ocular symptoms over the follow-up period.¹¹

Many testimonials and videos are posted on internet sites and YouTube by individuals of all ages touting success with the use of natural oils in and around the eye for relief of mild to debilitating dry eye-related discomfort and pain. Many of the recommendations provided by the video author are based on generally accepted knowledge.^12,13

Conclusion

The shared information provided by online posters may be accurate, albeit not supported by evidence- based medicine. Many preparations suggested are not formulated for ophthalmic use. However, this begs the question: Do they have to be?

I personally plan to investigate some coconut oil and castor oil treatments. I will keep an open mind when investigating nonscientific, anecdotal data. After all, some of our greatest scientific therapeutics are based ased in botanicals. Hail Mother Nature.

References

1. Tamoxifen citrate and Photosensitivity reaction - a phase IV clinical study of FDA data. eHealthMe. April 8, 2021. Accessed June 22, 2021. https://www.ehealthme.com/ds/tamoxifen-citrate/photosensitivityreaction/#:~: text=Summary%3A%20Photosensitivity%20 reaction%20is%20found%20among%20people%20who,people%20 take%20Tamoxifen%20citrate%20and%20have%20 Photosensitivity%20reaction.

2. Boughton B. Watch for ocular effects of breast cancer drugs. EyeNet Magazine. March 2013. Accessed June 13, 2021. https://www.aao.org/ eyenet/article/watch-ocular-effects-of-breast-cancer-drugs

3. Lin TK, Zhong L, Santiago JL. Anti-inflammatory and skin barrier repair effects of topical application of some plant oils. Int J Mol Sci. 2017;19(1):70. doi:10.3390/ijms19010070

4. Vaughn AR, Clark AK, Sivamani RK, Shi VY. Natural oils for skinbarrier repair: ancient compounds now backed by modern science. Am J Clin Dermatol. 2018;19(1):103-117. doi:10.1007/s40257-017-0301-1

5. Varma SR, Sivaprakasam TO, Arumugam I, et al. In vitro antiinflammatory and skin protective properties of virgin coconut oil. J Tradit Complement Med. 2018;9(1):5-14. doi:10.1016/j.jtcme.2017.06.012

6. Pupala SS, Rao S, Strunk T, Patole S. Topical application of coconut oil to the skin of preterm infants: a systematic review. Eur J Pediatr. 2019;178(9):1317-1324. doi:10.1007/s00431-019-03407-7

7. Garrigue JS, Amrane M, Faure MO, Holopainen JM, Tong T. Relevance of lipid-based products in the management of dry eye disease. J Ocul Pharmacol Ther. 2017;33(9):647-661. doi:10.1089/jop.2017.0052

8. Mutalib HA, Kaur S, Ghazali AR, Chinn Hooi N, Safie NH. A pilot study: the efficacy of virgin coconut oil as ocular rewetting agent on rabbit eyes. Evid Based Complement Alternat Med. 2015;2015:135987. doi:10.1155/2015/135987

9. Castor oil. Wikipedia. Accessed June 13, 2021. https://en.wikipedia. org/wiki/Castor_oil

10. Sandford EC, Muntz A, Craig JP. Therapeutic potential of castor oil in managing blepharitis, meibomian gland dysfunction and dry eye. Clin Exp Optom. 2021;104(3):315-322. doi:10.1111/cxo.13148

11. Maïssa C, Guillon M, Simmons P, Vehige J. Effect of castor oil emulsion eyedrops on tear film composition and stability. Cont Lens Anterior Eye. 2010;33(2):76-82. doi:10.1016/j.clae.2009.10.005

12. Higuera V. Is it safe to use coconut oil to treat dry eyes? Healthline. March 9, 2020. Accessed June 13, 2021. https://www.healthline.com/ health/coconut-oil-for-dry-eyes

13. Reved D. How to use coconut oil & castor oil to manage my dry eyes. April 17, 2019. Accessed June 13, 2021. https://www.youtube.com/ watch?v=R6I04z0oZSM