Watery eye could be secondary to a variety of reason, and does not always indicate a blockage of the tear duct.
Dry eye and eye exposure could cause reflex tearing, which is an excess of the tear production to counteract the dry eye.
Watery eyes could be related to lid malposition, mostly ectropion (the outward turning of the eyelid), as it causes the punctum (the opening of the tear duct in the eyelid) to face outward, instead of the inward, which is the normal position, hence the drainage of the tear would be suboptimal, causing watery eyes.
Lid laxity, which is associated with the aging process or as a result of facial palsy, could cause watery eyes as a result of the suboptimal function of the pumping machine of the tear sac (Horner’s muscle).
When a patient suffers from watery eyes, one should not presumed that it is due to blockage of the tear duct. Thorough examination of the ocular surface and eyelids should be taking place before considering ordering expensive diagnostic tools or having to put the patient under unnecessary invasive procedures.