The nasolacrimal sac is a small, membranous reservoir that forms a portion of the tear drainage system, located near the inner corner of the eye next to the nose. It is the dilated, superior end of the nasolacrimal duct, which is the final tube connecting the eye area to the nasal cavity. The primary function of this sac is to collect tears after they have performed their job of lubricating and protecting the eye’s surface. Without this structure, tears would constantly spill over the eyelids, a condition known as epiphora.
Understanding Tear Drainage
Tears are initially produced by the lacrimal gland, which is situated above and to the outside of the eyeball, providing a constant flow of fluid across the eye’s surface. After coating the eye, the fluid gathers toward the inner corner of the eye, where the drainage system begins. The tears enter the system through two tiny openings on the upper and lower eyelids, known as the puncta.
From the puncta, tears travel through small channels called the canaliculi, which converge before emptying directly into the nasolacrimal sac. The movement of tears through this system is assisted by a lacrimal pump mechanism, where the action of blinking helps to squeeze the sac and propel fluid forward. The sac then directs the tears downward into the nasolacrimal duct, which is a bony channel.
The duct terminates in the nasal cavity, specifically opening into the inferior meatus, which is the space beneath the inferior turbinate bone. A small mucosal fold, known as the Valve of Hasner, partially covers this opening, acting as a final gateway before the tears are absorbed or exit through the nose.
Common Causes of Nasolacrimal Sac Issues
Problems with the nasolacrimal sac and the entire drainage system typically stem from an obstruction in the pathway, which prevents tears from draining correctly. In infants, the most frequent cause is a congenital blockage, where the Valve of Hasner membrane at the bottom of the nasolacrimal duct fails to open completely at or shortly after birth. This condition leads to persistent tearing and discharge.
For adults, obstructions are generally acquired and can be caused by various factors that lead to narrowing or scarring of the duct. Age-related changes can cause the tiny puncta openings to narrow, while chronic inflammation from conditions like sinusitis or eye infections can also constrict the duct. Trauma to the face, such as a nasal or orbital bone fracture, can similarly disrupt the delicate bony canal surrounding the duct.
When the drainage system is blocked, tears stagnate within the nasolacrimal sac, creating a warm, moist environment that encourages bacterial growth. This stagnation often leads to an infection and inflammation of the sac itself, a condition termed dacryocystitis. Symptoms of a blockage or infection include a constant overflow of tears onto the cheek, along with crusting or discharge on the eyelids. Acute dacryocystitis presents with more pronounced symptoms, including sudden pain, redness, and swelling in the area of the inner corner of the eye. In rare instances, tumors or systemic inflammatory disorders like sarcoidosis can also cause acquired obstructions by compressing or inflaming the drainage structures.
Fixing Tear Duct Blockages and Infections
The approach to relieving a blocked tear duct depends heavily on the patient’s age and the severity of the obstruction. For infants with congenital blockage, conservative management is typically the first step, as about 90 percent of cases resolve spontaneously within the first year of life as the drainage system matures. Parents are often taught a specific massage technique, sometimes called the Crigler massage, to apply pressure over the nasolacrimal sac several times a day to help rupture the persistent membrane.
If the blockage persists beyond six to twelve months despite conservative efforts, a minor procedure called probing and irrigation may be performed, often under general anesthesia. This involves gently inserting a thin probe through the punctum and down the duct to break open the obstructing membrane at the Valve of Hasner. A balloon catheter dilation, where a deflated balloon is inserted and repeatedly inflated to widen the duct, is another option used when probing is unsuccessful or for partial blockages.
In cases of acute dacryocystitis, whether in infants or adults, the infection must first be addressed with antibiotics, usually in the form of eye drops or oral medication. However, antibiotics treat the infection but not the underlying mechanical obstruction, meaning recurrence is likely unless the blockage is cleared. For adults with acquired or chronic blockages, surgical intervention is frequently required.
The most common surgical solution for adults is Dacryocystorhinostomy, or DCR, which creates a new, direct drainage pathway from the nasolacrimal sac into the nasal cavity, bypassing the blocked duct. This procedure can be performed externally through a small skin incision near the nose, or endoscopically through the nasal passages, which avoids an external scar. A small silicone tube, or stent, is often temporarily placed in the new passage to keep it open during the healing process, typically for several months.