Tears are essential for nourishment and lubrication of the human eye. Every time you blink, you're washing your eyes with tears produced by the lacrimal glands in your upper eyelids. But people with watery eyes are usually experiencing an overproduction of tears, which are made up of water, oil, and mucous. These excess tears can be caused by:
Dry eye syndrome: It may not make sense, but dry eyes often lead to watery eyes. When eyes dry out, they become irritated and uncomfortable. That prompts the lacrimal glands to produce so many tears that they overwhelm the eye's natural drainage system. Tear production tends to lessen with age, so dry eyes are more common in older adults.
Some medical conditions and medications can also lead to dryness as can a dry and windy environment, but the most common cause of dry eye syndrome is a chronic condition called keratoconjunctivitis sicca (KCS). People with this condition make tears, but the tears do not contain enough water. In addition to excessive tearing, symptoms of dry eye syndrome may include blurred vision, itchy eyes, or burning eyes. One remedy for milder cases of dry eye is using over-the-counter artificial tears.
Allergies: Substances that cause an allergic reaction are called allergens. Reaction to allergens can cause your eyes to become red and irritated, prompting tear production. Along with excess tear production, allergies of the eyes can cause itching and burning. The most common outdoor causes are grass, tree, and weed pollens.
The most common indoor causes are pet dander, dust mites, and molds. Other causes of itchy, watery eyes that are not true allergens include exhaust fumes, aerosol sprays, perfumes, and cigarette smoke.
Infections: Part of your body's response to an eye infection can be to produce excess tears, an effort to keep the eye lubricated and wash away germs and discharge. Conjunctivitis (infection of the thin, clear membrane covering most of the eye) and blepharitis (infection of the eyelid margins) are two infectious diseases known to cause watery eyes. "Pink eye" is a common term used for conjunctivitis. Causes include bacteria, fungi, and most commonly viruses. Wearing contact lenses may increase the risk of conjunctivitis. Conjunctivitis can occur in one or both eyes. Symptoms may include eye pain, blurred vision, redness, gritty feeling in the eyes, discharge, and crusts that form at night along with increased tearing.
Irritants: Your eyes produce excess tears in response to other types of irritation, too, be it dry air, bright light, wind, smoke, dust, an eyelash, or exposure to chemicals. Eyestrain also can cause watery eyes.
Ectropion: Another watery eye type is related to poor eyelid function. In order for tears to be spread evenly over the eyes and to be pushed to the corners of the eye for proper drainage, the eyelids need to close correctly. One of the most common causes of this type of watery eye problem is called "ectropion."
This condition is a drooping and pulling away of the lower eyelid. It is usually seen in older people who gradually develop a weakness of the lower lid. Ectropion may cause the eyes to be dry, sore, red, and burning. It may also increase the risk of eye infection.