The nasolacrimal sac is a small, yet significant, component of the eye’s intricate drainage system. Its primary function involves managing tears, ensuring they are effectively cleared from the eye’s surface. It helps maintain both comfort and overall eye health by preventing tear overflow.
Understanding the Nasolacrimal Sac
The nasolacrimal sac is part of the lacrimal drainage system, located in the inner corner of the eye, close to the nose. This drainage is a continuous process that helps keep the eye surface clean and clear.
Tears begin their journey from small openings called puncta, found on the inner edges of both the upper and lower eyelids. From the puncta, tears travel through tiny tubes known as canaliculi, which are approximately 2 millimeters vertically and 8 millimeters horizontally. These canaliculi converge and lead directly into the nasolacrimal sac.
Once collected in the sac, tears then flow downwards through the nasolacrimal duct, which empties into the nasal cavity. The presence of antimicrobial substances like lysozyme in tears also helps protect against bacterial growth on the eye’s surface.
Common Problems Affecting the Nasolacrimal Sac
Nasolacrimal duct obstruction (NLDO) is a common issue where the tear drainage pathway becomes blocked. This blockage can occur at any point from the puncta to the nasal opening of the duct. NLDO can be either congenital, meaning present at birth, or acquired later in life.
Congenital NLDO often results from a thin tissue membrane, called the valve of Hasner, remaining over the duct’s opening into the nose. This condition is observed in approximately 5% of infants and frequently resolves on its own within the first year of life. Acquired NLDO can develop due to various factors, including chronic inflammation or infection of the eyes or nose, injury to the face causing bone damage or scarring, or age-related narrowing of the puncta.
An infection of the nasolacrimal sac is known as dacryocystitis. Symptoms include pain, redness, and swelling in the inner corner of the eye. Patients may also experience discharge from the eye and, in some cases, a fever. Dacryocystitis often occurs when an underlying obstruction in the tear drainage system allows bacteria to accumulate in the sac.
Excessive tearing, or epiphora, is a common symptom that indicates a problem with the nasolacrimal sac or its associated drainage system. Epiphora can be a sign of either an obstruction or an infection within the lacrimal drainage pathway.
How Nasolacrimal Sac Issues are Addressed
Diagnosing nasolacrimal sac issues often begins with a physical examination. A dye disappearance test may be performed, where a dye is placed in the eye to observe how quickly it drains, indicating potential blockages. In some cases, probing the tear drainage system can help identify the exact location of an obstruction.
For congenital nasolacrimal duct obstruction (NLDO), management often includes conservative approaches like regular massage of the lacrimal sac area. Many cases of congenital NLDO resolve without further intervention within the first year of life. If the obstruction persists, a procedure called lacrimal duct probing may be performed, where a thin probe is gently inserted into the tear duct to open the blockage.
Acquired NLDO, which is less likely to resolve spontaneously, often requires surgical intervention. The most common surgical procedure for acquired NLDO is dacryocystorhinostomy (DCR). DCR involves creating a new drainage pathway between the lacrimal sac and the nasal cavity, bypassing the obstructed nasolacrimal duct. This new connection allows tears to drain directly into the nose, alleviating symptoms of tearing and reducing the risk of infection.
Dacryocystitis, an infection of the nasolacrimal sac, is treated with antibiotics, which can be administered orally or as topical eye drops. Warm compresses applied to the affected area can also help reduce swelling and discomfort. Once the acute infection subsides, the underlying obstruction that led to the dacryocystitis usually needs to be addressed, often through surgical procedures like DCR, to prevent recurrent infections.