Anatomy and physiology of the lacrimal apparatus The lacrimal apparatus consists of the lacrimal gland and the lacrimal duct. The lacrimal gland in newborns is very small and does not become fully functional until about 1-1.5 months of age, therefore, newborns cry without tears, but reflex tear secretion (e.g., stimulation of the conjunctiva or nasal mucosa) can occur earlier. In newborns, the lower opening of the nasolacrimal duct is covered by a membranous tissue called HARB’s membrane, which gradually atrophies during the development of the nasolacrimal duct and eventually disappears. This process usually occurs before birth or during the first month of life. HARB’s membrane can also rupture spontaneously at birth, due to the pressure of the birth canal. Clinical manifestations of lacrimal duct obstruction Up to 30% of infants will have lacrimal overflow during this time, some of which will require lacrimal sac massage and topical antibiotic eye drops to assist in the treatment of episodes of dacryocystitis and conjunctivitis, which manifest as increased ocular discharge. About 6% have symptoms for a longer period of time, and if this membrane does not atrophy by 4-6 months, lacrimal flushing or probing will be required. In acute dacryocystitis, early probing is often required. Diagnosis Diagnosis: clinical presentation and diagnostic treatment – lacrimal duct flushing. A minority of children with more extensive congenital nasolacrimal duct developmental anomalies and craniofacial bony malformations present with ineffective flushing and probing, requiring lacrimal intubation, dilation of the lacrimal sac, or nasal anastomosis of the lacrimal sac in adulthood. Differential diagnosis: tear overflow, which may also be due to inflammatory disease of the anterior segment of the eye, congenital glaucoma, etc., requires exclusion of the appropriate eye disease.