Watering eyes result from either increased tear production (typically allergic conjunctivitis) or decreased tear drainage.  Tears drain through small holes on the eyelid margin near the nose (lacrimal puncti), through small canals (canaliculi) into a sac (lacrimal sac) in the corner of the eye and from their through the nasolacrimal duct into the nose.

A watering eye can therefore result from a droopy eyelid, canalicular obstruction or nasolacrimal duct obstruction.  Canalicular obstruction will just cause watering of the eye whereas nasolacrimal duct obstruction is frequently associated with stickiness in the eye on wakening, recurrent conjunctivitis, infection and swelling of the lacrimal sac (mucocele).

Examination of the eye under the slit lamp will reveal whether or not you have one of the many causes of tear overproduction.  To investigate decreased tear drainage, you will need to a syringing of the tear duct.  This is usually done after local anaesthetic drops have been put in your eye and is rarely painful, although it is occasionally a little uncomfortable.  Usually the tear draingage system isn’t completely blocked and fluid (water or saline) will pass to your nose or the back of your throat, which may make you splutter.  In these situations, the process of syringing the tear duct will often ease your symptoms, by flushing through the debris which had caused partial obstruction.  Otherwise, fluid will reflux onto your cheek.  A total obstruction would need surgery to correct in the form of a Dacrocystorhinostomy (DCR).