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Tears, the precious Gem of our Eyes

Updated on October 3, 2010

Tears, the precious Gem of our Eyes

Tears are the salty liquid drops that comes out of our eyes as a result of crying. Infact it is the liquid that helps to lubricate our eyes and protects it from foreign substances like dust. Tears flow from tear glands which is also called 'lacrimal glands', through tiny tear ducts. The tear glands are located under the upper lids of our eyes, and when stimulated, produce tears to form a thin film over the eyeballs. With every blink of our eyes, the film spreads over the eyes to keep them moist and free of dust and other irritants. The lacrimal glands secrete lacrimal fluid which flows through the main excretory ducts into the space between the eyeball and eyelids. When the eyes blink, the lacrimal fluid spreads across the surface of the eye. Lacrimal fluid then gathers in the lacrimal lake, and draws into the puncta by capillary action.It then flows through the lacrimal canaliculi at the inner corner of the eyelids and enters the lacrimal sac,which then goes to the nasolacrimal duct, and finally into the nasal cavity. Thus an excess of tears, as with strong emotion, can cause the nose to run.

Lacrimal lake -The lacrimal lake is the pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system (the puncta). The volume of the lacrimal lake has been estimated to be between 7 and 10 µL(microlitre). The lacrimal lake usually contains 7-10 µL of tears, but the maximum fluid it can usually hold is 25-30 µL before tearing occurs.

Conjunctiva- The conjunctiva is a clear mucous membrane that lines the eyelids and covers the exposed surface of the eyeball

Conjunctivitis- It is the inflammation of the conjunctiva.

Conjunctivitis can be caused by allergies, bacteria, viruses, chemicals,or underlying health conditions.

The eyes are susceptible to infection because they are not sterile. They rely on lysozyme (an enzyme found in the tears) to destroy bacteria. Bacteria line the surface of the eyelids (all the way down into the shaft of the eyelashes), which makes the conjunctiva predisposed to germs and conjunctivitis.

With the advent of the monsoon, the number of conjunctivitis cases also increases. Conjunctivitis is highly contagious. Although conjunctivitis is not life-threatening, patients should not be allowed to attend school or office, as they may spread the infection. Self-medication should never be attempted. People should consult an eye specialist instead of buying off-the-counter medicine. The treatment includes use of antibiotics and eye drops prescribed by the doctor.

Crocodile's Tear- To shed crocodile tears is to put on an insincere show of sorrow. The allusion is to the ancient notion that crocodiles weep while devouring their prey. Crocodiles do indeed have lacrimal glands and produce tears to lubricate the eyes as humans do. But they don't cry with emotion.

Types of Tears

There are three basic types of tears-

  1. Basal Tears - They lubricate the eye, and help to keep it clear of dust. The cornea is continually kept wet and nourished by basal tears.

  2. Reflex Tears- The Reflex tears results from irritation of the eye by foreign particles, or irritant substances such as onion,tear gas including the cornea, conjunctiva, or nasal mucosa. It can also occur with bright light and hot or peppery stimuli to the tongue and mouth. Reflex Tears wash out irritants that may have come into contact with the eye.

  3. Psychic Tears- This type of tears results from crying or weeping due to strong emotional stress, suffering, mourning, or physical pain.

Disorders related to tears:

Sjogren's Syndrome or Dry Eye Syndrome

Dry Eye Syndrome is caused when the tear glands are damaged and produce an inadequate amount of tears. It is a chronic (lifelong) disorders that causes dry eyes and a dry mouth. In Sjogren's syndrome, changes occur in the immune system - the body's defense against disease. The immune system lacks the usual controls. This causes white blood cells to invade glands in the body that produce moisture, such as the tear and salivary glands. They can destroy the glands and cause them to stop producing moisture.

Crocodile tears syndrome

Spontaneous tearing in parallel with the normal salivation of eating. The crocodile tears syndrome occurs most often following facial paralysis when nerve fibers destined for a salivary gland are damaged and by mistake regrow into a tear gland. Also called Bogorad's syndrome, gustatolacrimal reflex, paroxysmal lacrimation.


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