dacryology

Dacryology is the medical discipline that studies the lacrimal apparatus and the tear film. It covers tear production by the lacrimal glands, distribution of tears across the ocular surface, and drainage through the puncta, canaliculi, lacrimal sac, and nasolacrimal duct. The field encompasses normal tear physiology as well as disorders of tear production, tear film stability, and tear drainage.

The tear film consists of lipid, aqueous, and mucin layers that protect and lubricate the cornea, maintain a smooth optical surface, and support ocular surface health. The lacrimal glands provide the aqueous component, while blinking spreads tears and facilitates drainage into the lacrimal drainage system. Neural control of tearing involves autonomic innervation, notably parasympathetic input from the facial nerve.

Common dacryologic disorders include dry eye disease, which reduces tear film quality and quantity; epiphora from overproduction or obstruction of drainage; canaliculitis and dacryocystitis; and nasolacrimal duct obstruction. Diagnostic methods include the Schirmer test for tear production, tear breakup time, ocular surface staining, and imaging or probing of the lacrimal drainage pathways.

Management depends on the specific disorder and may include artificial tears, anti-inflammatory therapy, punctal plugs to conserve tears, lacrimal duct intubation, or surgical procedures such as dacryocystorhinostomy for chronic nasolacrimal duct obstruction.