Tears are necessary to keep our eyes moist and healthy. The lacrimal gland and other small glands inside the eyelid and on the white part of the eye constantly produce tears to keep the eye healthy.
Tears drain from the eye through two small openings called upper and lower puncta located at the inside corner of the eyelids near the nose. Tears move through a passage called the canaliculus and into the lacrimal sac. They then drop into a tear drop called the nasal-lacrimal duct and drain into the back of your nose and throat. That’s why your nose runs when you cry!
Tears lubricate eyes and make it possible to see the world clearly. When you blink, a tear film spreads over the eye, making the surface smooth and clear. This film is made up of three distinct layers. The outer most layer is oily. Next, the watery layer makes up most of what we think of as tears. Finally, a layer of mucus helps the watery layer spread evenly over the surface of the eye. Each of these three distinct layers is necessary in order for the tear film to adequately lubricate our eyes.
Tears drain out of the eye through a tiny opening of the tear ducts on the eyelid margin, called puncta, then through a small channel into the nose. This is why your nose runs when you cry. Your ophthalmologist may recommend closing off the puncta, either temporarily or permanently, using tiny punctual plugs. Punctal plugs can be inserted in the lower eyelid, the upper eyelid, or in both eyelids. Using punctual plugs saves your own tears from draining away, and helps artificial tears last longer.