Punctum and/or Canaliculi. Acquired stenosis or occlusion of the punctum, ampullae, and canaliculi may be caused by a variety of conditions, including inflammatory conditions, infections, trachoma, cicatrizing diseases of the conjunctiva, secondary to the toxic effect of topical or systemic medications, especially systemic chemotherapeutic medications, masses in the area of the punctum, retained punctal plugs, surgery, burns, trauma, longstanding ectropion or lid malposition, aging changes, chronic infections, viruses (herpes simples or human papilloma viruses), blepharitis, lichen planus, trauma, tumors, graft-vs.-host disease or iatrogenic. Most traumatic injuries are due to lacerations, such a stab wound or animal bites, or secondary traction that results from a sudden lateral displacement of the eyelid, avulsing the medial canthal tendon and canaliculus. The canaliculus is without tarsal support, and therefore the weakest part of the eyelid. Abnormally large puncta can also cause epiphora due to the disruption of the lacrimal pump. This prevents the development of an adequate seal when the eyelids are closed, and prevents the creation of negative pressure, and suctioning of tears. Enlargement of the puncta is frequently secondary to iatrogenic injury, “cheese-wiring” due to canalicular stents, punctoplasty, excision of adjacent lesions. Extreme care should always be taken when dealing with the puncta because there is no effective treatment available, leaving a Conjunctivodacryocystorhinostomy (CDCR) as the only treatment option.

Punctal agenesis is frequently associated with the absence of the associated canaliculi, especially when both the superior and inferior puncta are absent. In patients that are symptomatic, surgical exploration is required to determine if there is also agenesis of the canaliculi that can be salvaged (if more than 8 mm of canaliculi exist, surgical intervention may be curative), or the patient will require a CDCR [10].

Punctal stenosis is more common in postmenopausal female, probably secondary to hormonal changes. Chronic blepharitis causes inflammatory and cicatricial changes resulting in inflammatory membrane formation, conjunctival epithelial overgrowth, and keratinization of the walls of the punctum. Membranous stenosis at the internal punctum is the most common location for canalicular stenosis. Involutional changes of these tissues, atrophy, dense fibrous stricture of the punctum cause it to be less resilient and the orbicularis muscle fibers to become atonic and stenotic.

Conjunctivochalasis, excess conjunctiva that occludes the inferior punctum is often overlooked. The etiology is not completely known, and may be secondary to natural aging, eye rubbing, abnormalities of the eyelid position and ocular movement, changes in Tenon’s capsule leading to a loss of the adhesion between the conjunctiva and underlying sclera, an over-expression of matrix metalloproteinases which modifies or degrades the extracellular matrix, a nongranulomatous inflammation along with elastosis, increased collagenolytic activity, all of which may contribute to conjunctival laxity and conjunctivochalasis. Conjunctivochalasis is generally bilateral, seen in older patients, and characterized by loose redundant conjunctival folds interspersed between the eyelid and the globe, more frequently along the lower eyelid temporally. This can misdirect the tear flow toward the outer corner of the eye. In mild cases it may cause tearing due to tear film instability, in moderate cases it may cause obstruction of the punctum, interrupting the tear meniscus, and in severe cases due to foreign body sensation and irritation that results from ocular surface exposure. If the patient is experiencing pain, then apply slight pressure in the area of the pain before a topical anesthetic is applied, and have the patient look up and down; this will reproduce the pain assisting in making the diagnosis of conjunctivochalasis. If the symptoms are not resolved with topical treatment, then surgical treatment may be indicted.

Chronic recurrent mucopurulent conjunctivitis may be secondary to Giant Fornix Syndrome. The superior fornix is usually large and can harbor a coagulum of proteinaceous debris colonized with bacteria that can cause relapses of purulent conjunctivitis and toxic keratitis [11].

Obstruction may occur within either the upper or lower canaliculus or in the common canaliculus. Canalicular obstructions may involve the proximal segment, the first 2–3 mm, the midcanalicular segment, 3–8 mm from the puncta, and or the distal segment, at the opening of the common canaliculus into the lacrimal sac. Membranous stenosis at the internal common punctum is one of the most common locations for canalicular stenosis. Causes of acquired canalicular obstruction include trauma and toxicity due to medications (5-fluorouracil, idoxuridine, phospholine iodide, eserine, preservatives in ophthalmic medications, etc.). Canalicular obstructions may be caused by chlamydial infections (trachoma), viruses (herpes zoster, herpes simplex, chicken pox and small pox), bacteria, cicatrizing diseases (Stevens–Johnson syndrome or Pemphigoid), or atopic conjunctivitis can cause a cicatrizing conjunctivitis and punctal stenosis.

Punctal plugs may be associated with punctal and canalicular complications: punctal sphincter rupture during insertion, pyogenic granuloma, migration, local inflammatory reaction, canaliculitis, which can lead to stenosis or occlusion [12, 13]. Repeated probing, especially when not performed correctly, may lead to canalicular stenosis.

Canalicular cyst presents as a bluish mass or a cyst-like swelling. These cysts may arise after an episode of canaliculitis with an ecstatic canalicular diverticulum, an encysted abscess or chronic canaliculitis, in which both the medial and lateral ends of the canaliculus are obstructer, creating a one-way valve effect, allowing ingress of fluid but preventing egress. The canalicular enlargement has been termed a canaliculocele or canaliculops. Intrinsic canaliculi tumors such as papillomas and pyogenic granulomas may occlude the canaliculi and produce a secondary inflammation and stenosis. Skin cancer may invade the puncta and canaliculi. Irradiation of tumors in the area may cause an occlusion of the canaliculi, but the placement of canaliculi tubes may prevent this complication. Other lesions arising from the adjacent areas include those arising from the lacrimal sac (dacryocystocele, lacrimal sac diverticulum, lacrimal sac tumor); eyelid (ocular adnexal cyst or tumors); paranasal sinuses (sinus mucoceles); orbit (dermoid cyst, epidermoid cyst); or intracranial space (meningoencephalocele associated with hypertelorism) [14].

Lacrimal Pump. The lacrimal pump is the mechanism that assists the tears in their travels from the tear pool through the nasolacrimal duct system into the interior meatus of the nose. The action of the pretarsal and preseptal orbicularis oculi, Horner muscle, produces the forces that drive the lacrimal pump. Additional functions such as gravity, pressure gradients in the lacrimal tract, and tear reabsorption by the cavernous structure support the lacrimal drainage.

Patients with tearing whose nasolacrimal duct systems are patent to syringing may have an incomplete anatomic obstruction or nonfunctional segments of the lacrimal passage from prior episodes of dacryocystitis, or an anatomically normal nasolacrimal duct system, but a physiologic dysfunction of the eyelids, punctum, lacrimal pump, or a lacrimal sac that drains poorly.

Lacrimal Sac and Duct. The mucosal lining of the nasolacrimal sac and duct are inherently resistant to microbial invasion. The mucous membrane of the lacrimal sac and duct is a pseudostratified columnar epithelium, with the underlying lamina propria that consists of two strata: a loose connective tissue with scattered lymphocytes or groups of lymphocytes and a rich venous plexus situated under the loose connective tissue, a cavernous body that may facilitate opening and closure of the lumen of the lacrimal passage by shrinkage and swelling that regulates tear outflow. It produces a broad spectrum of antimicrobial peptides that have a therapeutic potential in infections and also accelerate epithelial healing. The antimicrobial peptides IgA and immunocompetent cells, lymphocytes and macrophages, provide a defense mechanism. These peptides also promote fibrin formation and cell proliferation which may also cause scarring and the resultant dacryostenosis. This may be an integral part of the specific mucosal immune system and belongs to the mucosa-associated lymphoid tissue (MALT) [15]. They excrete a range of mucin materials, carbohydrates, TFF-peptides, and antimicrobial peptides, which may aid in the flow of tears and provide a defense against microbes. Researchers have identified mRNA for a variety of mucins in human lacrimal sacs and ducts. Reduced level of mucin mRNA in patients with epiphora secondary to a nonfunctioning segment of the nasolacrimal drainage system, but still patent to irrigation, suggests that mucins may reduce drag and enhance tear flow through the nasolacrimal drainage system [16]. When an obstruction occurs, the tears that are laden with inflammatory material that accumulates and the increase in inflammatory cytokines induce changes in the mucosal cellular structures. These changes in the lacrimal sac and duct epithelium and lamina propria allow the microbial buildup, creating an environment unopposed to the spread of infection. In patients with functional dacryostenosis, it has been noted that the epithelia of the nasolacrimal drainage system is characterized by squamous metaplasia with loss of goblet-cell-associated mucins MUC2, -5AC, and -5B. There were no changes in MUC7 which is antibimicrobial and may explain the low incidence of dacryocystitis in patients with functional dacryostenosis. The malfunction of the pathophysiology of the cavernous body of the lacrimal sac and nasolacrimal duct may reduce absorption of tears as they pass through the nasolacrimal system or cause swelling and obstruction and lacrimal pump dysfunction.

Inflammation, trauma, canal tortuosity, soft tissue physiology, irritations, hormone-induced epithelial changes, osteoporosis, or congenital defect in the drainage system may cause epiphora, dacryostenosis, and dacryocystitis. An anatomical etiology can explain some of the causes of obstruction, but does not fully explain all the epidemiologic variabilities. Inflammation originating at the eye, conjunctival sac, diverticula of the lacrimal system, or from the nose, infections or diseases of the nasal mucous membrane or sinuses can induce swelling of the lacrimal system’s mucous membranes, resulting in narrowing or occlusion of the nasolacrimal system from the epithelial changes and fibrosis of the lamina propria [7]. The various mechanisms that cause inflammation result in a secondary fibrosis that causes a narrowing of the nasolacrimal duct system, and eventually occlusion by scar tissue. The lacrimal sac and duct undergo similar changes, as the pseudostratified, ciliated, columnar epithelium undergoes squamous metaplasia and hyperplasia with loss of goblet cells, and ulceration. The underlying submucosa develops a secondary fibrosis. Basement membrane thickening may develop in the nasal mucosa but not in the lacrimal sac. The inflammation may cause a fibrosis of the lacrimal sac and the internal common punctum, which may result in obstruction, and in post-op cases, to failure of dacryocystorhinostomies [17].

Several valves are present in the nasolacrimal duct system to prevent the retrograde flow of tears. The most important valve clinically is the valve of Hasner, located at the entrance of the nasolacrimal duct into the inferior meatus, and frequently responsible for congenital nasolacrimal duct obstruction. The valve of Rosenmuller is found at the junction of the common canaliculus into the lacrimal sac. The superior and inferior canaliculi join together to form a common canaliculus that drains into the lacrimal sac in 90 % of patients, while in 10 % of patients, each canaliculus enters separately into the lacrimal sac [18]. This valve prevents retrograde flow of fluid from the sac into the canaliculi and fornix. In episodes of dacryocystitis, this valve may swell closed even more tightly. Tears and the infection cannot drain out of the sac into the nose, or to the fornix. The valve of Rosenmuller is not a true valve, but an angulated entrance of the common canaliculus into the sac, functioning as a valve.

Descending inflammation from the eye or ascending inflammation from the nasal cavity may initiate swelling of the mucous membranes of the nasolacrimal duct system, remodeling of the helical arrangement of connective tissue fibers, malfunctions in the subepithelial cavernous body with reactive hyperemia, and temporary occlusion of the nasolacrimal duct system. The submucosa is a very vascular, cavernous structure and rich in lymphatics so that a slight infection once established will settle. The constriction of the tissue within the fixed space of the bony canal makes it understandable that any significant swelling will lead to blockage. The submucosa of the nasolacrimal duct system surrounded by bone contains arterioles with sphincters and cavernous vessel complexes, which can cause swelling and approximation of the lumen according to the blood flow. A cascade of multifactorial events leads to the development of inflammation, obstruction, and stasis. This result in vascular congestion and edema from the inflammation causing obstruction while the cellular debris and mucus trapped in the nasolacrimal sac and duct causes an infection-induced fibrosis and atrophy of the walls. Repeated episodes of dacryocystitis will result in permanent changes of the epithelial and subepithelial tissues, loss of goblet and epithelial cells which are important in the tear outflow mechanism, fibrosis of the helical system of connective tissue fibers, and reduction and destruction of the vascular plexus, leading to a malfunction of the tear flow mechanism, all of which results in a vicious cycle [7]. These structural epithelial and subepithelial changes, may lead to either a total fibrous closure of the lumen of the nasolacrimal duct system or to a nonfunctional segment that may cause chronic epiphora and discharge, but may patent to syringing.