Eye Health The Composition of Tears and Their Role in Eye Health By Troy Bedinghaus, OD Troy Bedinghaus, OD LinkedIn Troy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association. Learn about our editorial process Updated on May 06, 2020 Medically reviewed Verywell Health articles are reviewed by board-certified physicians and healthcare professionals. These medical reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Johnstone M. Kim, MD Medically reviewed by Johnstone M. Kim, MD Johnstone M. Kim, MD, is board-certified in ophthalmology. He's a practicing physician at Midwest Retina in Dublin, Ohio and previously served as a full-time faculty member at the Wayne State University School of Medicine and the Kresge Eye Institute in Detroit, Michigan. Learn about our Medical Expert Board Print Pierre Bourrier / Getty Images Your tears obviously are made of water with some salt, as you've tasted when you've had a good cry. But are there other ingredients in tears? Are some tears different from others? Tears are produced in the lacrimal glands (tear ducts) that are in the outer corners of your eyelids. These glands produce tears from your blood plasma, selecting some components but not others. Basic Components of Tears Tears are composed of:WaterElectrolytes (sodium, potassium, chloride, bicarbonate, magnesium, and calcium). These are what give tears their salty taste.Proteins (lysozyme, lactoferrin, lipocalin, and IgA). The tears have only about one-tenth of the protein of the blood plasma.LipidsMucins The Composition of Basal Tears and Role in Eye Health Tears play an important role in keeping us healthy. Tears keep the surface of our eyeballs clean and moist and help protect our eyes from damage. Although they may appear to be nothing more than water, our tears are actually quite complex. Tears are made of mucus, water, and oil, and each component plays a role in the eye. Mucus coats the surface of the eye and helps bind the tear layer to the eye. Without a healthy mucus layer, dry spots may form on the cornea, the clear, dome-like structure on the front of the eye. The water is really more of a saline (salt) solution that contains various vitamins and minerals vital to normal cell function. These nutrients are important for keeping the top layer of cells on the surface of the eye, the epithelium, healthy and functioning normally. The oil of the tear film prevents evaporation of the tears. Some people don't make enough oil (or sometimes too much oil), resulting in dry eyes. If the oil component is not normal, the tears evaporate too quickly. Our tears also contain natural antibiotics called lysozymes. Lysozymes help to keep the surface of the eye healthy by fighting off bacteria and viruses. Because the cornea has no blood vessels, the tears also provide a means of bringing nutrients to its cells. Reflex Tears From Irritants When your eye is irritated, it produces reflex tears to wash out the irritants. You've probably shed a few tears when chopping onions or when you get dust in your eyes. Emotional Tears The tears you shed when overcome with emotions have a higher protein content than the tears shed from irritants. Emotional tears have been found to have more hormones, including prolactin, adrenocorticotropic hormone, and leucine enkephalin. Tears When You Sleep When you sleep, your tear ducts add less water and protein to your tears, but they increase the number of antibodies present, while infection-fighting cells also migrate to the conjunctival sac. Tears as You Age As you age, you usually produce fewer tears by volume, and this can lead to developing dry eyes. The proteins your lacrimal ducts normally add to tears decreases. Was this page helpful? Thanks for your feedback! Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit 4 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Mukamal R. American Academy of Ophthalmology. Facts about tears. Mukamal R. American Academy of Ophthalmology. All about emotional tears. Dartt DA, Willcox MD. Complexity of the tear film: importance in homeostasis and dysfunction during disease. Exp Eye Res. 2013;117:1–3. doi:10.1016/j.exer.2013.10.008 American Optometric Association. Dry eye. Additional Reading Bartlett JD, Jaanus SD. Clinical Ocular Pharmacology, 5th Edition. St. Louis, MO: Butterworth Heinemann; 2008.