If your eyes water, it could from one of several problems. The most common reason for the eyes to water is actually dry eyes, which seems counter intuitive. The reason that dry eyes can cause watering is from reflex tearing. There are two types of tear glands: smaller ones, known as accessory lacrimal glands, that provide basal tear production and a larger, or main lacrimal gland, that provides reflex tears. Reflex tearing can occur when a foreign body gets into the eye and the main lacrimal gland expresses a large amount of fluid in order to flush the foreign object from the eye. In a similar manner, if the eye becomes dry from not enough tear production from the accessory lacrimal glands, the main lacrimal gland reacts as if a foreign body is in the eye and it releases a large amount of fluid in order to provide relief to the dry eye. Thus, the eyes water when they are dry.
Another cause of watering includes allergies. Allergies can cause a condition called allergic conjunctivitis which creates inflammation on the outer coating of the eye called the conjunctiva. The conjunctiva has many blood vessels that can become dilated and leaky when they are exposed to an allergen if you are allergic to the substance. Examples include dog or cat dander, pollens and ragweed. When the allergen comes in contact with the conjunctiva, chemical substances such as histamine are released which can lead to redness, itching and watering of the eye.
Blocked Tear Duct
Finally, a blocked tear duct can cause tearing. A blocked tear duct, known as nasolacrimal duct obstruction, can occur from several causes, including trauma, congenital, aging, infections and even tumors, although this is rare. Nasolacrimal duct obstruction typically causes continuous tearing and can become quite bothersome to the patient. This condition can only be definitively diagnosed through a minor procedure typically done in the office called lacrimal system irrigation. During this procedure, a very small cannula is passed through the upper portion of the lacrimal drainage system known as the canaliculus. A solution, called balanced salt solution, is then injected through the lacrimal system in order to evaluate the patency of the system. If the system is open, the solution will pass into the nose and then into the mouth and the patient will taste a salty solution in the mouth. If the system is totally obstructed, the fluid will not be able to be passed into the nose and the patient will not taste any salty solution. If the lacrimal system is completely obstructed, correction usually requires a surgical procedure which is called a dacryocystorhinostomy, or DCR.