The lacrimal excretory system is prone to infection and inflammation for various reasons. This mucous membrane-lined tract is contiguous with 2 surfaces (conjunctival and nasal mucosal) that are normally colonized with bacteria. The functional purpose of the lacrimal excretory system is to drain tears from the eye into the nasal cavity. Stagnation of tears in a pathologically closed lacrimal drainage system can result in dacryocystitis.
Acquired dacryocystitis can be acute or chronic.  Acute dacryocystitis is heralded by the sudden onset of pain and redness in the medial canthal region. An insidious onset of epiphora is characteristic of chronic inflammation or infection of the lacrimal sac.
See the image below.
A special form of inflammation of the lacrimal sac is that of congenital dacryocystitis, the pathophysiology of which is intimately related to the lacrimal excretory system embryogenesis.
Dacryocystitis has long been noted to occur more frequently on the left side than on the right side. In many instances, the nasolacrimal duct and lacrimal fossa formed a greater angle on the right side than on the left side.
Individuals with brachycephalic heads have a higher incidence of dacryocystitis than dolichocephalic or mesocephalic skulls. This is because brachycephalic skulls demonstrate a narrower diameter of inlet into the nasolacrimal duct, the nasolacrimal duct is longer, and the lacrimal fossa is narrower. Furthermore, patients with a flat nose and narrow face are at a higher risk for developing dacryocystitis, presumably because of the narrow osseous nasolacrimal canal.
In 1883, Nieden noted a 9% incidence of hereditary lacrimal excretory system inflammation. This is significantly higher than what has been found by the author in studies.
Dacryocystitis occurs in the following 3 forms: acute, chronic, and congenital.
In acute dacryocystitis, patients can experience severe morbidity and rarely mortality. Morbidity is related primarily to the lacrimal sac abscess and spread of the infection.
Chronic dacryocystitis is rarely associated with severe morbidity unless caused by a systemic disease. The primary morbidity is associated with chronic tearing, mattering, and conjunctival inflammation and infection.
Congenital dacryocystitis is a very serious disease associated with significant morbidity and mortality. If not treated promptly and aggressively, newborn infants can experience orbital cellulitis (because the orbital septum is formed poorly in infants), brain abscess, meningitis, sepsis, and death. Congenital dacryocystitis can be associated with an amniotocele, which, in severe cases, can lead to airway obstruction. More indolent forms of congenital dacryocystitis can be difficult to diagnose and can be associated with chronic tearing, mattering, amblyopia, and failure to thrive.
Blacks rarely develop dacryocystitis because the nasolacrimal ostium into the nose is large. In addition, the lacrimal canal is shorter and straighter in blacks than in whites.
In adults, females are afflicted more commonly by dacryocystitis. Most studies demonstrate that 70-83% of cases of dacryocystitis occur in females. Congenital dacryocystitis occurs with equal frequency in both sexes.
Lacrimal sac infections and inflammations commonly occur in 2 discrete age categories, infants and adults older than 40 years. Acute dacryocystitis in newborns is rare, occurring in fewer than 1% of all newborns. Acquired dacryocystitis is primarily a disease of females and is most common in patients older than 40 years, with a peak in patients aged 60-70 years.
Embryology and Anatomy
The naso-optic fissure is the source of origin of the lacrimal drainage system. The ectoderm in this region thickens and becomes embedded in the mesenchyme between the lateral nasal and maxillary processes. This cord of ectoderm subsequently canalizes and opens into the conjunctival fornix prior to opening into the nasal vestibule. Frequently, this opening into the nasal cavity is incomplete at birth. Canalization of the lacrimal excretory system begins in the superior portion first and is segmental, only later coalescing to form a continuous lumen. The canaliculi, which develop as outpouchings from the solid cord of ectodermal tissue prior to canalization, also canalize prior to the vertical portions of the nasolacrimal duct.
Many variations in the anatomy of the lacrimal drainage system have been noted. Normally, tears drain into the lacrimal system through two puncta, one present in the upper lid and the other in the lower lid. More commonly, the lower punctum lies slightly temporal to the upper punctum.
The connections from the puncta to the lacrimal sac are called canaliculi. These canaliculi have a short vertical segment, averaging 2 mm in length, and a longer horizontal segment, averaging 10-12 mm in length.
An ampulla connects the vertical and horizontal segments. The individual canalicular horizontal segments join to form a common canaliculus in 90% of patients. This common canaliculus dilates, forming the sinus of Maier just lateral to the lacrimal sac.
A fold of mucosa known as the valve of Rosenmüller marks the junction of the lacrimal sac and the common canaliculus. The lacrimal sac lies in the bony lacrimal fossa derived from the lacrimal and maxillary bones. The average width of the sac is approximately 6-7 mm and the length varies from 12-15 mm. The mucosa of the sac is lined by pseudostratified columnar epithelium with substantial amounts of lymphoid and elastic tissue interposed within the connective tissue layer. The sac is normally irregular and flat in shape with a collapsed lumen.
The lacrimal sac is covered on its outer surface by the lacrimal fascia of the periorbita. This fascia splits to envelop the lacrimal sac between the attachments of the lacrimal fascia to the anterior and posterior lacrimal crests. The lacrimal sac mucosa only loosely adheres to the lacrimal fascia. However, posterior to the sac are the deep heads of the pretarsal and preseptal orbicularis muscles. Anteriorly, the medial canthal tendon covers the upper two fifths of the lacrimal sac.
The nasolacrimal duct averages 18 mm in length and 4.5-5 mm in diameter. Multiple valves are present in the nasolacrimal duct, representing analog from the segmental canalization of the ectodermal cord that develops into the nasolacrimal duct. Of these, the most prominent valves are the valve of Taillefer, the valve of Krause, and the valve of Hasner (located at the junction of the duct with the nasal mucosa). Like the lacrimal sac, the nasolacrimal duct is lined by pseudostratified columnar epithelium.
The lacrimal, maxillary, and ethmoid bones form the bony nasolacrimal canal. The bulk of the duct is contributed by the maxilla, anteriorly, laterally, and posteriorly. The lacrimal bone forms the medial wall superiorly, and the inferior concha of the ethmoid bone forms the medial wall of the canal inferiorly. The mucosal opening of the nasolacrimal duct under the inferior turbinate lies 5-8 mm from the anterior tip of the inferior turbinate. The lacrimal bone and the nasal process of the maxilla make up the lacrimal fossa equally. The anterior and posterior lacrimal crests form the anterior and posterior borders of the lacrimal fossa, respectively.
The dimensions of the lacrimal fossa are 4-8 mm in width, 15 mm in height, and 2 mm in depth. Ethmoid air cells in approximately 40-60% of patients separate the lacrimal fossa from the nasal cavity, although considerable variability exists in the number and location of these air cells. The lacrimal sac fossa lies at the level of the anterior tip of the middle turbinate.
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