What Are the Lacrimal Canaliculi?

Lacrimal canaliculi, also known as lacrimal ducts, are small tubes between the punctum and the lacrimal sac, one on each side. Each root is divided into a vertical portion and a horizontal portion. The vertical part is about 1 to 2 mm, and continues to the horizontal part inwardly at a right angle, about 6 to 8 mm reaches the lacrimal sac, and the tube diameter is about 0.5 to 0.8 mm. The junction of the two is the enlarged ampulla of the lacrimal canaliculus. The horizontal part of the upper and lower lacrimal canaliculi is tilted inward along the eyelid margin, the upper inward and downward, the lower inward and slightly upward, respectively, through the lacrimal fascia, and may form the common lacrimal duct alone, or later on the lateral center of the lateral lacrimal sac , Enter the lacrimal sac about 2.5 mm from the top of the lacrimal sac (the opening is generally the same height as the medial ligament of the eyelid).

Lacrimal canaliculi, also known as lacrimal ducts, are small tubes between the punctum and the lacrimal sac, one on each side. Each root is divided into a vertical portion and a horizontal portion. The vertical part is about 1 to 2 mm, and continues to the horizontal part inwardly at a right angle, about 6 to 8 mm reaches the lacrimal sac, and the tube diameter is about 0.5 to 0.8 mm. The junction of the two is the enlarged ampulla of the lacrimal canaliculus. The horizontal part of the upper and lower lacrimal canaliculi is tilted inward along the eyelid margin, the upper inward and downward, the lower inward and slightly upward, respectively, through the lacrimal fascia, and may form the common lacrimal duct alone, or later on the lateral center of the lateral lacrimal sac , Enter the lacrimal sac about 2.5 mm from the top of the lacrimal sac (the opening is generally the same height as the medial ligament of the eyelid).

Chinese name

Lacrimal duct

Foreign name

ductus lacrimalis

Lacrimal tubule overview

The lacrimal canaliculi are composed of stratified squamous epithelium and elastic dermis. The tube wall is thin and flexible, so when it is probed, it can be enlarged to three times normal, and the ampulla can be straightened. The lacrimal canaliculi are surrounded by the orbicularis muscle fibers, both vertical and horizontal. The relaxation and contraction of these fibers helps to inhale tear fluid from the upper part and discharge it to the lower part. If this part is narrow or blocked, it can cause tears.

Preliminary application of diagnosis of lacrimal ductal disease

Preliminary application of ultrasound biomicroscopy in the diagnosis of lacrimal canaliculi:

Due to the superficial position and fine structure of the lacrimal canaliculi, it is difficult to clearly show the structure of lacrimal ducts by common imaging examinations of lacrimal ducts (including lacrimal duct radiography, ophthalmic B-ultrasound, CT, MRI, and nuclide scanning); in recent years, the emerging lacrimal ductal endoscope is a lacrimal duct Examination of the disease provides greater convenience, but it is difficult to display congenital tear spots, such as the situation of the lacrimal canaliculi after the lacrimal canaliculus obstruction and its relationship with surrounding tissues. Certain trauma, lacrimal endoscope instruments are expensive, not easy to popularize and other shortcomings. Ultrasound biomicroscope (UBM) is a newer non-invasive examination instrument for ophthalmology, and its high resolution makes it an ideal method for lacrimal duct examination.

Lacrimal canaliculi related diseases-lacrimal ductitis

Lacrimal canaliculi ^[1] is chronic inflammation of lacrimal canaliculi, and the following is more common. Inflammation can spread from the conjunctiva, or it can be caused by ascending dacryocystitis. Lacrimal ductitis caused by Chlamydia trachomatis is a common complication of trachoma. Actinomycosis and mold can also invade lacrimal tubules ^[2] . Cases in which the pus secretions can still be squeezed out from the lacrimal sac after the lacrimal sac is removed are evidence of lacrimal ductitis, which is a possible source of infection after intraocular surgery and should be taken seriously. The treatment can be rinsed with antibiotic solution. In severe cases, the lacrimal canaliculus can be cut open and scraped, and iodine tincture can be applied to make the walls adhere and clear the residual cavity.

Clinical characteristics:

1. Diagnosis basis ^[3] :

(1) The conjunctival sac has filamentous or strip-shaped secretions;

(2) The tear ducts around the lesion are red and swollen, and there is no tenderness or fluctuation. The tear points are turned out and show papillary protrusions;

(3) Pus or yellow bean dreg-like substance is squeezed out from the compressed lacrimal duct;

(4) The lacrimal duct flushing liquid flows back from the lacrimal punctum with a small amount of secretion, while the lacrimal duct flushes from the other end, the lacrimal duct is unobstructed;

2. Main manifestations: redness and bulging of tear spots, redness and swelling around the skin. When the skin of the lacrimal sac is compressed, mucus purulent discharge or stones overflow from the tear spots.

3. Secondary performance: The accumulation of inflammatory substances in the lacrimal canaliculus can expand the lacrimal canaliculus into a mucous cyst or abscess with fluctuations.

4. Misdiagnosis analysis: The clinical features of diseases that are easily misdiagnosed as lacrimal ductitis are as follows.

(1) Acute dacryocystitis: The nasal dacryocystitis area is swollen, painful, tears overflow, accompanied by secretions, fever, and can be recurrent.

(2) Conjunctivitis: conjunctival congestion, follicles and / or nipples, and conjunctival sac with secretions. No punctum bulges, no secretions from the skin of the lacrimal sac area overflowing from the punctum.