[Watery eyes: diagnostic and therapeutic considerations].

Tear complaints can arise from either an increased tear production or from a disturbed tear drainage. Increased tear production from the lacrimal gland is a neuroregulated response to a dried out or irritated ocular surface. Dryness often results from a reduced quality of the tear film, but can also be caused by eyelid malposition with increased globe exposure. Impaired tear drainage usually occurs when the lacrimal drainage system is blocked at the level of the ductus nasolacrimalis, the canaliculi or the lacrimal punctae. Anatomical knowledge of the lacrimal system is necessary to distinguish between the different causes. Using cases and illustrations, we provide insight into the diagnostic considerations for a patient with a watery eye.