The tear drainage system, commonly called the tear ducts, is a network of passages that manages moisture on the eye’s surface. Tears are necessary to keep the eyes lubricated, nourished, and protected from foreign particles. Development begins long before birth, but the full function, particularly the ability to shed visible tears, only becomes apparent in the weeks following delivery. This timeline clarifies why newborns often cry without tears and when to expect the full tear response to emerge.
Prenatal Development and Early Function
The structural formation of the tear ducts, including the lacrimal glands and the draining nasolacrimal duct, begins early in fetal development, around the eighth week of gestation. The nasolacrimal duct, which drains tears into the nose, starts as a solid cord of tissue that must hollow out (canalize) to become a functioning tube. This canalization process is often incomplete at birth, frequently leaving a thin membrane at the duct’s opening into the nose.
Because the drainage system is still developing and the lacrimal glands are immature, newborns do not produce large amounts of tears. They produce only basal tears, which are just enough to keep the eye moist and healthy. This results in a newborn’s crying often being “dry,” without the visible stream of tears seen in older children or adults. Visible, emotional tearing typically begins when the lacrimal glands mature and the drainage system fully opens, usually between two weeks and three months after birth.
The Mechanism of Tear Production and Drainage
The fully functional tear system, known as the lacrimal apparatus, works as a coordinated production and drainage unit. Tears are created primarily by the lacrimal glands, located above the outer corner of each eye. These glands produce the watery layer of tears, containing salts and protective substances like lysozyme, an antibacterial enzyme.
After production, tears wash across the eye’s surface to lubricate and clean it, mixing with oil from meibomian glands to slow evaporation. The tears then collect at the inner corner of the eye and drain through two tiny openings called the puncta, located on the upper and lower eyelids. From the puncta, the tears travel through small tubes called canaliculi into the lacrimal sac, and finally down the nasolacrimal duct, exiting into the nasal cavity.
Tears are classified into three types based on their function. Basal tears are produced constantly to maintain eye health and lubrication. Reflex tears are generated to flush out irritants, such as dust or onion fumes. Emotional tears, which appear during strong feelings like sadness or joy, become visible on the cheeks after the first few months of life.
Addressing Common Developmental Delays and Blockages
A common issue related to the incomplete development of the tear drainage system is dacryostenosis, or congenital blocked tear duct, affecting up to 6% of newborns. This condition occurs when the membrane at the end of the nasolacrimal duct, which should dissolve before or shortly after birth, remains intact. The primary symptoms of a blockage are excessive watering of the eye (epiphora), often accompanied by crusting or a mild, yellowish discharge.
Most blocked tear ducts resolve spontaneously, usually by the time the child reaches six to twelve months of age, as pressure from tears or a change in facial structure naturally opens the duct. Parents can often help resolve the blockage with gentle nasolacrimal sac massage. A physician demonstrates how to apply light pressure near the inner corner of the eye, which can help force fluid through the membrane to open the duct.
If the blockage persists past one year of age, or if there are signs of infection like redness, swelling, or thick pus, a medical consultation is necessary. While most cases require only observation and massage, persistent blockages may require a simple outpatient procedure called probing to open the duct manually. This intervention is highly effective when non-invasive methods have not resulted in a resolution.