Blocked tear ducts
Tear ducts are the tubes that excess tears drain away through. If they become blocked, it can cause your eyes to water.
Blocked tear ducts in babies
Babies are sometimes born with under-developed tear ducts. The tear ducts can be completely or partially closed (congenital nasolacrimal duct obstruction) and can cause the baby’s eyes to water. Most blocked tear ducts in babies get better on their own before the baby is one year old.
In some cases, babies with a blocked tear duct can develop eye infections (conjunctivitis). Their eye may be red and have a sticky discharge coming from it. Take your baby to see your GP if you think that they might have an eye infection.
If your baby's eyes are still watering after the age of one, they may need to have a small procedure done called "probing" to unblock the tear duct. Only a very small number of babies with watering eyes require this type of treatment. See treating watering eyes for more information about probing.
Blocked tear ducts in adults
In adults, a blocked or narrowed tear duct is the most common cause of a watering eye. Over time, the tear ducts can become narrowed, often as a result of inflammation (swelling). This can occur more often with sinus disease and allergy, as well as with old age.
If your tear ducts are blocked or narrowed, your tears will be unable to drain away and will remain in the tear sac. If this happens, the tear sac may become infected and your eye will produce a sticky liquid (mucus).
You may also develop a swelling on the side of your nose, next to your eye, which is called a mucocoele. If this becomes infected, it can cause a painful abscess to develop just below your eye which may need to be treated with antibiotics and possibly surgery.
Occasionally, the canaliculi (the narrow drainage channels on the inside of your eyes) can become blocked. This can be caused by inflammation or scarring due to a viral infection, trauma or another form of damage.
Excess tears
If your eyes become irritated, they will automatically produce extra tears to wash away the irritant. This is called over-watering or hypersecretion. Irritants that can cause extra tears to be produced include:
- chemical irritants, such as onions or fumes
- an eye infection, such as conjunctivitis
- an allergy
- an eye injury, such as a piece of grit that becomes lodged in the eye
- an inward-growing eyelash (entropion)
Related eye conditions
There are several eye conditions that may cause excess tears to develop or your tear ducts to become blocked. Some of these are briefly outlined below.
Uveitis
Inflammation of the middle part of your eye (uveitis) can also cause your eye to water. This may be the result of an injury, infection or an underlying health condition. Uveitis may also cause other symptoms, such as redness or pain.
Ectropion
A watering eye can also be caused when the lower eyelid turns outwards away from the eye. This is known as ectropion. If this happens, your tears may not drain away properly.
Abnormal tears
Tears are made up of different substances including water, proteins and fats. If your tears have an abnormal fat content, they may not be able to spread evenly across your eye. This can result in dry patches developing on your eyes which become sore and cause extra tears to be produced.
If you have abnormal tears and dry patches, you may have dry eye syndrome. Your eyes may be red and feel gritty or sore. Sometimes, they can also water.
Blepharitis
Blepharitis is a condition where the rims of your eyelids become inflamed, resulting in your eyes stinging or itching. It can also affect how your tears are spread across the surface of your eyes. If your tears are not spread out properly, this can also cause you to have watering eyes.
