Why Do We Tear?
Tiny glands, located in the surface tissue on the white of the eye and lining the eyelids, constantly produce a baseline level of tears to keep our eyes comfortable and lubricated. The lacrimal gland, a large gland located beneath the outside brow responds to emotion or eye irritation by producing larger quantities of tears.
In some people, tearing becomes a problem. Excess tears well up in the eye because too many tears are produced or, because the tears are not draining properly. Excess tears give the eye a moist appearance, and can collect along the border of the lower lid and overflow onto the cheek.
The tears of each eye drain into a tiny opening in each lid called a punctum. They then flow through a small canal into the lacrimal sac and down the nasolacrimal duct into the nose. This is why our noses run when we cry, since excess tears reach the nose through the normal tear drainage system.
Excessive tearing can result from injuries, birth defects and infections, especially those of the lacrimal sac These processes can block tear drainage at the punctum, lacrimal sac or nasolacrimal duct and cause overflow tearing. Abnormal lid positions, an inturned eyelash, wind exposure, yawning, glaucoma, certain drugs, or eyestrain can also cause excessive tearing.
However, excessive tearing does not always mean an excess of tears or blockage of the drainage system. Patients with a dry eye often complain of tearing. When the amount of lubricating tears secreted is too low to maintain necessary moisture for the eye, the large lacrimal gland often reacts by flooding the eye with additional tears, causing episodes of overflow tearing even though the underlying problem is dry eyes.
A thorough examination by an ophthalmologist is necessary to determine the cause of excessive tearing. He or she may attempt to irrigate fluid through the tear drainage system to locate a blockage. Other tests such as measuring tear production or recovering tears from the nose may also be performed.
