What are Watering Eyes?
"Tears are just water, and watering eyes are just due to the drain being blocked." Sadly, this is just too simplistic. Firstly, tears are not just water; they are a complex multilayered structure consisting of mucus, an aqueous layer (with salts and proteins) and a lipid layer to prevent evaporation.
In normal eyes, the tears secreted drain through tiny holes in the nasal ends of the eye-lids down to the back of the nose. This is not entirely a passive (gravity-powered) phenomenon. Blinking causes a degree of suction: the "lacrimal pump". Blockages anywhere along the drainage system (punctum, canaliculus and nasolacrimal duct) or pump failure can cause watering or "epiphora".
"Paradoxical epiphora" is very common. Almost unbelievably, it occurs in "dry eyes". How can this be? The term "dry eye" is rather poor, but is so entrenched that it cannot be changed. Although some people with dry eye secrete very little in the way of tears, it is quite common for the problem to be that the tears secreted are not "good" tears able to wet the surface effectively. Since these tears are not efficient, the feed-back mechanism says "make more tears" and the result is a watering eye. So the paradox is that a dry eye (with "bad" tears) can also be a watering eye! A further paradox is that the treatment is to add more tears – artificial tears from a bottle! Surprisingly, this is usually very effective......
Of course there are many other causes of watering eyes, and a full examination with special testing when indicated is required to make the correct diagnosis without which no treatment can have a logical basis.
In some patients, there is "proximal blockage", i.e. a blockage at the level of the punctum of the eyelid: the entry into then canaliculus leading to the nasolacrimal duct. If this is the case, it may be possible to dilate ("stretch") the hole and cure the watering. In some cases a small operation "punctoplasty" may be reyuired. This is done under a few drops of local anaesthetic as an out-patient procedure.
Until recently, more significant blockages of the drainage system required major surgery, but recently a new treatment involving injection of botulinum toxin into the lacrimal gland has been discovered and appears to be equally effective. This is of course a much less invasive procedure and is likely to be much more acceptable to patients.