Tear Chemistry And Eye Health

cryingThe next time you feel tears coming and struggle to hold them back, think of Mr. Bumbles’ lines from Charles Dickens’ Oliver Twist, Crying opens the lungs, washes the countenance, exercises the eyes, and softens down the temper. So cry away!

Major Kudos to The Ocular Surface journal for ranking #3 out of 48 for impact factor in Ophthalmology / Vision journals.  Every issue of The Ocular Surface delivers elegant science prose that will dramatically enhance your medical journal reading experience. Dr. Juan Murube’s beautifully written piece on the three types of tears in the current Sources in Time section is not to be missed. LaVon and David Kellner are rock stars who have set a new bar in ophthalmic journal publishing.

Basal, Reflex and Emotional Tears

Dr. Murube’s extensively researched article explains that basal tears seem to develop in humans months before birth.  Reflex tears appear in humans days or weeks after birth. Psycho-emotional tears, as an ’appeal for help,’ take longer to appear.  He also suggests that psycho-emotional ‘offer-to-help’ tears take years after birth to appear.

Emotional tears are associated with rage, grief and joy. They can be biochemically distinguished from reflex tears that spring to our eyes in response to smoke, onion vapors, allergens or foreign bodies, and continuous basal tears, which keep our eyes from drying up.

Basal tears have numerous components. A small amount of nutrient-rich mucus allows them to adhere to the ocular surface, while water and salts, like sodium and potassium chloride, as well as specific vitamins, minerals, antioxidants and proteins, make up the liquid portion of the tear film, which is held on the ocular surface by a thin layer of antioxidant vitamin, mineral and essential-fatty-acid-rich oil.

Reflex tears are similar to basal tears and are produced to protect the ocular surface. However, they are designed to eliminate intruders like airborne dust, allergens and pathogens. These tears contain a greater concentration of protein antibodies, immunoglobulins and lysozymes that target micro-organisms. So, reflex tears are not just basal tears in greater quantity; they are different biologically.

The voluminous tears that are secreted in moments of intense feelings tend to be chemically different again from basal and reflex tears, and they are different in males and females. These tears are not produced to cleanse the eyes of irritating microbes or debris. However, a large body of tear research from biochemist William H. Frey, PhD, of Minnesota suggests that they serve a very important purpose.

Dr. Frey suggests that proteins found in emotional tears are hormones that build up to very high levels when the body withstands emotional stress. When these protein chemicals associated with stress do not discharge, they build up to toxic levels that weaken the body’s immune system and other biological processes. Emotional tears are a safety valve for the heart.

We secrete stress chemicals when we sweat and when we cry. The reason people (think females) frequently report feeling better after a good cry is most likely connected to the discharge of stress-related proteins that are excreted in our tears.

One major stress hormone that triggers tears is prolactin, which is about four times as high in females as males. This is the hormone that is also associated with the synthesis of breast milk. Thus, women’s tendency to tear up during periods of stress may be our bodies’ natural way of maintaining homeostasis.

Another hormone that triggers emotional tears and emotional sweat (think males sweating bullets) is adrenocorticotropic hormone (ACTH), which is one of the best-known indicators of stress. Research indicates that suppressing tears or sweat increases stress levels and can contribute to those diseases that are aggravated by stress, such as high blood pressure and cardiac disease. Although the exact role of these chemicals in lowering stress in not yet fully clear, a good cry or sweat producing exercise can be a healthy response to emotional stress.

New research also suggests that patients with rheumatoid arthritis are easily moved to tears. Tears as an emotional expression, are thought to suppress the negative influence of stress on the neuroendocrine responses.

Interestingly, boys and girls tend to shed equal amount of tears. This tendency changes at puberty. Researchers continually debate whether this phenomenon is physiological or psychological.

Ellen Troyer, MT MA

Biosyntrx Chief Research Officer

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