What Are Tears For?

• Tears contain electrolytes (e.g. sodium chloride), antibodies, enzymes and white blood cells that shield the eyes against infection. Tears clear away small particles that enter the eye. This fluid also cleanse and moisten the surface between the eyeball and eyelid.
• Tears are usually released onto the eye’s surface in tiny amounts but extra tears are produced when eyes are irritated so as to wash away the foreign particles.
• Tears, or what scientists call tear film, is made up of three microscopic layers. The outer, oily (lipid) layer keeps tears from evaporating too quickly and helps retain tears on the eye; the middle is the watery (aqueous) layer which nourishes the cornea and conjunctiva; and a inner (mucin) layer helps to spread the watery layer all over the eye to ensure that the eye remains moist.
• There are three types of tears :
  1. Basal (or continuous) tears coat the eyes to keep them lubricated constantly.
  2. Reflex (or irritant) tears are produced to flood our eyes in response to an irritant or when a foreign particle gets into the eye. They do not have the same consistency as basal tears which means having lots of reflex tears will not lubricate dry eyes.
  3. Psychogenic (or emotional) tears are most definitely governed by emotions.
• Each type of tear has a different consistency. Each contains different amounts of chemicals and hormones. It is still uncertain why this is so.
• Tears are produced by the almond-shaped lacrimal gland found under the upper corner of the eyelid next to the nose. Tears go into the lacrimal sac (or bag) and are then drained into 2 small canals or tear ducts (also known as the nasolacrimal duct), one on the upper lid and one on the lower lid where they are released into the lining of the eye lids to keep the eye moist. These two tear ducts merge into a bigger duct that drains tears into the back of the nose and flows down the throat.
• Blinking helps to distribute tears over the eye.
• Tear ducts can be blocked due to the underdevelopment of the tear ducts in babies, injury to the nose and eyes, enlargement of facial bones in the nose region or nasal polyps. Consult a physician when blockages are persistent. Blockages may be cleared by inserting a fine probe.
• Infection in the tear ducts results when bacteria gathers in the blocked tear ducts or in the lacrimal sac. This condition is called dacryocystitis.
• Excessive tearing may be caused by :
  1. Allergies (e.g. dust, mold)
  2. Conjunctivitis (redness/itch)
  3. Emotions
  4. Environmental irritants, including smog or chemicals in the air, exposure to hot wind, strong light, blowing dust or airborne allergens
  5. Ectropion (eyelid turns outward)
  6. Entropion (occurs in older people where eyelashes rub against the eye)
  7. Foreign bodies
  8. Physical stress
  9. Styes
• Tearing also occurs when we are yawn, strain the eye, vomit or laugh heartily. This could be due to pressure exerted on the lacrimal sac which causes tears to flow out.
• When we are stirred by emotions such as joy, pain or suffering, our nervous system stimulates the seventh cranial nerve located in the brain to send signals to the neurotransmitters to the lacrimal glands to release tears.
• Scientists have come up with different explanations as to why humans cry. One of which comes from William Frey II, a biochemist who found that emotional tears contain higher levels of manganese and the pituitary hormone prolactin, a hormone that regulates milk production compared to the other tear types. These two chemicals have mood effects.

  He wrote in “Crying: The Mystery of Tears” (Winston Pr, 1985) :

  “Emotional tearing may be similar to the other excretory processes, which remove waste products or toxic materials from the body. My formal study of crying began with the theory that emotional tears play a precise and central role in helping restore the chemical balance of the body by excreting substances produced by the body in response to stress.”
  

• As we age, tears may become lesser. That’s like saying aging makes our senses less sharp.

Tear talk

• Bored to tears — very bored
• Cocodile tears — fake or insincere tears
• Tear gas — gas that stinks the eyes and cause tears
• Tears — an acronym for Telecommunications Emitter Automated Retrieval System (Army)

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