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In each eye, there are two puncta [59] – little openings that drain tears into the tear ducts. [4] There are methods to partially or completely close the tear ducts. [16] This blocks the flow of tears into the nose, and thus more tears are available to the eyes. [13] Drainage into either one or both puncta in each eye can be blocked.
Nasolacrimal duct obstruction is the obstruction of the nasolacrimal ducts (better known as the tear ducts) and may be either congenital or acquired. Obstruction of the nasolacrimal ducts leads to the excess overflow of tears called epiphora .
Xerophthalmia (from Ancient Greek xērós (ξηρός) meaning "dry" and ophthalmos (οφθαλμός) meaning "eye") is a medical condition in which the eye fails to produce tears. It may be caused by vitamin A deficiency, [1] which is sometimes used to describe that condition, although there may be other causes.
Causes of epiphora are any that cause either overproduction of tears or decreased drainage of tears, resulting in tearing onto the cheek. [2] This can be due to ocular irritation and inflammation (including trichiasis and entropion) or an obstructed tear outflow tract, which is divided according to its anatomical location (i.e., ectropion, punctal, canalicular or nasolacrimal duct obstruction).
Persons with dry eye conditions can be fitted with punctal plugs that seal the ducts to limit the amount of fluid drainage and retain moisture. During an ear infection, excess mucus may drain through the nasolacrimal duct in the opposite way tears drain. [citation needed] In humans, the tear ducts in males tend to be larger than the ones in ...
The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage. [1]It consists of: The lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the eye; it is a j-shaped serous gland located in lacrimal fossa.
They produce meibum, an oily substance that prevents evaporation of the eye's tear film. Meibum prevents tears from spilling onto the cheek, traps them between the oiled edge and the eyeball, and makes the closed lids airtight. [1] There are about 25 such glands on the upper eyelid, and 20 on the lower eyelid.
Dacryocystitis is an infection of the lacrimal sac, secondary to obstruction of the nasolacrimal duct at the junction of the lacrimal sac. [1] The term derives from Greek dákryon 'tear' cysta 'sac' and -itis 'inflammation'. [2] It causes pain, redness, and swelling over the inner aspect of the lower eyelid and epiphora.