What causes it?
Many people shed tears on cold, windy days. But otherwise tearing reflects overproduction or poor drainage.
Overproduction is usually caused by inflammation or surface erosion of the cornea. The cornea may be poked by eyelashes arising from an inturned eyelid (""). To see if the corneal surface has been eroded, instill fluorescein dye.
Inadequate drainage comes from having poor apposition of the or (congenital nasolacrimal stenosis, inflammation, trauma, tumor).
Surprisingly, patients who have inadequate basic tear production from eyelid pathology will complain of tearing! This is because their corneas dry out and stimulate reflex tearing from the lacrimal gland. The commonest cause is , often a component of rheumatoid arthritis or Sjogren's syndrome.
What to do?
Refer any patient who complains of excessive tearing to an ophthalmologist. The urgency is greater if the patient also complains of foreign body sensation, reduced vision or periocular pain.