Lacrimal canaliculi are small tubes located within the eyelids that manage tears. They act as a pathway for tears to exit the eye’s surface, contributing to eye comfort and clear vision. Problems with these canals can lead to noticeable symptoms, making daily life uncomfortable.
Anatomy and Role in Tear Drainage
The lacrimal canaliculi are narrow channels in the inner corner of both the upper and lower eyelids. Each canaliculus begins at a tiny opening on the eyelid margin called a punctum, which acts like a drain on the eye’s surface. The upper punctum is about 5 mm from the inner corner of the eye, while the lower one is approximately 6 mm away.
From each punctum, a short vertical segment, about 2 mm long, extends before widening into an ampulla. After the ampulla, the canaliculus turns sharply and continues horizontally for about 8 to 10 mm, following the curve of the eyelid. Often, the upper and lower canaliculi merge to form a single common canaliculus, typically 3 to 5 mm long, before connecting to the lacrimal sac.
The lacrimal sac is a small pouch near the bridge of the nose, serving as a collection point for tears. From the lacrimal sac, tears flow into the nasolacrimal duct, a passageway that empties into the nasal cavity. This system ensures tears are collected and drained, preventing overflow and maintaining a balanced tear film on the eye’s surface. Blinking also helps pump tears through this system.
Common Problems Affecting the Canals
Issues affecting the lacrimal canaliculi often involve blockages or infections. When the tear drainage system becomes obstructed, tears cannot drain properly, leading to an overflow of tears, a condition known as epiphora. This excessive tearing can be constant or intermittent and may affect one or both eyes.
Blockages can arise from several factors, including inflammation, injury, or congenital abnormalities. Trauma to the face or nose can also damage the tear drainage system, causing obstructions. Infections within the lacrimal canaliculi, the lacrimal sac, or surrounding tissues can lead to inflammation and narrowing or blockage of the canals.
A specific type of infection is canaliculitis, which involves inflammation of the canaliculi. This condition often affects individuals over 50 and is caused by bacteria, fungi, or viruses. Symptoms often include a red and inflamed inner eye, accompanied by a thick, discolored discharge. The punctum may appear swollen and tender. Other common symptoms associated with blockages or infections include recurrent eye infections, crusting of the eyelids, a feeling of something being in the eye, and occasionally blurred vision.
Identifying and Treating Issues
Diagnosing problems with the lacrimal canaliculi involves examination by an eye care specialist. A physical examination may reveal swelling or redness around the inner corner of the eye, particularly at the punctum. The doctor might apply gentle pressure near the lacrimal sac to see if any discharge, such as pus or mucus, is expressed through the punctum. Discharge can be cultured to identify microorganisms.
Another diagnostic method is the dye disappearance test, where dye is placed in the eye to observe drainage speed. If drainage is slow, it suggests a blockage. Probing and syringing of the lacrimal system, involving a thin probe or saline flush, can help pinpoint the location and nature of an obstruction. If a gritty sensation is felt during probing, it may indicate “sulfur granules” or concretions, which are small, stone-like formations associated with canaliculitis.
Treatment approaches vary depending on the issue. For infections like canaliculitis, initial steps include warm compresses and topical antibiotics. Antibiotic solutions may also be irrigated directly into the canaliculus. If non-surgical methods are insufficient or blockages persist, surgery may be considered. Procedures range from simple punctum dilation to remove infected material or concretions, to canaliculotomy, which incises to open the blocked duct. For complex or chronic blockages, a dacryocystorhinostomy (DCR) may create a new tear drainage pathway into the nasal cavity.