There is insufficient tear film drainage from the eye(s) - instead of all the tears draining through the nasolacrimal system, they overflow onto the face.

Epiphora can develop at any age. It is, however, more common among babies aged under 12 months, and adults over the age of 60 years. The condition may present symptoms in just one or both eyes.

In most cases watering eye can be treated effectively. Depending on the severity of symptoms, watering eye can sometimes make driving difficult and dangerous.

There are two main causes of epiphora - blocked tear ducts or excessive production of tears.

Blocked tear ducts: The most common cause of watering eyes among adults and older children is blocked ducts, or ducts that are too narrow. Narrowed tear ducts usually become so as a result of swelling (inflammation).

If a patient's tear ducts are narrow or blocked, their tears will not be able to drain away and will build up in the tear sac. Stagnant tears in the tear sac increase the risk of infection in that area and the eye will produce a sticky liquid, further exacerbating the problem. Infection can also lead to inflammation on the side of the nose, next to the eye.

Narrow drainage channels on the insides of the eyes (canaliculi) can become blocked. This is caused by swelling or scarring.

Over-production of tears: Irritated eyes may produce more tears than normal as the body tries to rinse the irritant away. The following irritants can cause the over-production of tears:

- Some chemicals, such as fumes, and even onions
- Infective conjunctivitis
- Allergic conjunctivitis
- An injury to the eye, such as a scratch or a bit of grit (tiny pebble or piece of dirt)
- Entropion (inward-growing eyelash)
- Ectropion - this is when the lower eyelid turns outwards
- The tears of some patients have a high fat (lipid) content. This may interfere with the even spread of liquid across the eye, leaving dry patches which become sore, irritated and cause the eye to produce more tears.

Epiphora is a fairly easy condition for a medical expert to diagnose. The doctor will try to find out whether it has been caused by a lesion, infection, entropion (inward-growing eyelash) or ectropion (outward-turning eyelid).

If the doctor is unclear, patient may be referred to an eye-care specialist doctor (ophthalmologist). The specialist will examine the patient's eye(s) carefully - usually, the patient will be anesthetized.

A probe might be inserted into the narrow drainage channels on the inside of the eye (canaliculi) to see whether they are blocked.

Liquid may be inserted into a tear duct to find out whether it comes out of the patient's nose. If it is found to be blocked, a dye may be injected to find the exact location of the blockage - this will be done by using an X-ray image of the area. The dye shows up on the X-ray.

Treatment options depend on the severity of the epiphora and its causes. In mild cases doctors may recommend just watchful waiting - doing nothing and monitoring the patient's progress.

If the watering eye is caused by infective conjunctivitis, the doctor may prefer to wait for a week or so to see if the problem resolves itself without antibiotics.

When allergic conjunctivitis is the cause the patient may be prescribed an antihistamine, which is effective in bringing down the inflammation.

If an inward-growing eyelash, or some foreign object is lodged in the eye, the doctor will remove it.

If the patientís eyelid has turned outwards, the patient may need to undergo surgery in which the tendon that holds the outer eyelid in place is tightened.

If a tear duct is blocked, then surgery which creates a new channel from the tear sac to the inside of the nose may be necessary. This allows the tears to bypass the blocked part of the tear duct.