Dacryostenosis

Etiology

Depending on the etiological factors, dacryostenosis can be classified into the following two broad categories:

Congenital Dacryostenosis

The most common cause of congenital dacryostenosis is a mechanical obstruction located in the distal part of the nasolacrimal duct (NLD) at the level of the valve of Hasner, where this structure enters the nose.[2][3] Persistence of an embryonal membrane or bone development abnormalities can cause difficulties in tear flow and eventually, mucopurulent discharge.  For this reason, epiphora seems to be more common in premature infants compared to full-term babies.[4] More rarely, the obstruction can be located near the nasolacrimal sac at the level of the valve of Rosenmueller: this more commonly causes a watery discharge.[5]

When both the proximal and distal portions of the nasolacrimal system are obstructed, a dacryocystocele can occur. In this case, a bluish bulge below the medial canthus is seen. Congenital dacryocystoceles are less common but may be associated with potentially serious complications.

Acquired Dacryostenosis

The etiology of acquired dacryostenosis is multifactorial and is not fully understood. Some cases may be related to trauma, neoplasm, systemic disease, radiotherapy, or chemotherapy.[6] However, in most cases, the cause is "involutional" and classified as "idiopathic." Some authors have reported that the cause is secondary to anatomic changes in the diameter of the bony lacrimal canal, which occurs with aging. Women, in particular, have a smaller diameter of the lacrimal duct that tends to narrow with time.[7] A congenital narrowness within the lacrimal drainage system is generally regarded as a disposition for lacrimal stenosis.

Some authors suggest that the cause may be from ascending inflammation from the region of the nose and sinus cavities.[8] A descending infection from the conjunctiva has also been suggested as a cause of acquired dacryostenosis. Clinical studies indicate that nasal disease is sporadic in patients undergoing DCR.[9]

Familial predisposition and osteoporotic changes have also been suggested as being predisposing factors.[9]

Epidemiology

Congenital dacryostenosis is quite common among newborns, with an incidence of between 1.2% and 20%.[10] Congenital dacryostenosis is the most common cause of persistent tearing and ocular discharge in infants and young children. In one study, 20 percent of healthy infants were found to have problems in the lacrimal drainage at some point during the first year of life.[11]

Acquired obstruction of the lacrimal drainage system causing epiphora, punctal discharge, and medial canthal swelling is a common ophthalmic complaint comprising approximately 3% of clinic visits in some series, with an annual incidence calculated as 37 cases per 100,000.[12][13] The obstruction is more frequently situated at the level of the nasolacrimal duct or puncta, and less frequently at the level of the canaliculi. The incidence is higher among older people and in women.[13][14]

Pathophysiology

Several factors may contribute to the chronic inflammation that arises in the epithelial layer of the nasolacrimal duct. Repeated episodes of dacryocystitis may lead to changes in the structural epithelial and subepithelial cells. In particular, loss of typical goblet and epithelial cells, which play a crucial role in tear outflow mechanism, has been described in pathological studies. Chronic inflammation may also cause fibrosis of the connective tissue fibers in the area of the lacrimal sac and nasolacrimal duct, with loss of blood vessels of the cavernous body that contribute to malfunctioning of the tear outflow mechanism and initiate a vicious circle.[9]

History and Physical

In most instances of dacryostenosis, epiphora is the most common presenting symptom. However, other causes of epiphora should also be excluded.

Children with congenital dacryostenosis have a history of chronic or intermittent tearing and debris on the eyelashes. Usually, there is no conjunctival erythema, although some degree of irritation can result from overflow tearing and chronic rubbing of the eyes. Palpation of the lateral wall of the nose may cause watery reflux or mucopurulent discharge onto the eye. In adults, the most common complaint is epiphora (excessive tearing). Patients may also experience vision abnormalities. It has been demonstrated that these symptoms ultimately affect the quality of life.[15][16]

In the case of bacterial infection of the content of the lacrimal sac, acute dacryocystitis can occur. Redness, pain, pulsation, epiphora, and tightness in the medial lid angle, along with a severe headache, will cause the patient to seek medical advice.[17] If the obstruction does not resolve, mucous membrane inflammation may become chronic and acute episodes will recur.

The lumen of the duct may decrease continuously, sometimes even up to a complete closure that results in dilation of the lacrimal sac. Clinically, a bulge of the medial canthus due to the enlarged lacrimal sac is the typical sign of a chronic dacryostenosis. Mucous secretions are frequently visible coming out from the lacrimal puncta after slight pressure of the medial canthal swelling.

Evaluation

Diagnosis is typically made by history and physical examination.

Physical examination begins with an inspection of the eyelids, the lacrimal puncta, and the conjunctiva to rule out gross abnormalities. The lower eyelid may present with mild redness and an increase in the size of the tear film (tear meniscus). Massage of the lacrimal sac may provoke reflux of tears and/or mucous onto the eye through the puncta.

Additional Tests to Consider

• Lacrimal irrigation consists of inserting a tube (known as a cannula) into the puncta and canaliculi with saline irrigation. Complete reflux from the opposite punctum of the same eye is diagnostic of dacryostenosis or a common canalicular obstruction.
• The fluorescein test consists of the application of fluorescein dye into the eye and to observe after 5 minutes: normally, the dye should drain into the nose within five minutes if the lacrimal drainage system has no obstruction. In case of obstruction, a large amount of the dye persists or escapes over the lower eyelid and down the cheek.
• Dacryocystography: standard conventional radiography obtained after injecting a contrast agent in the lacrimal system, is considered the standard diagnostic tool.
• In order to exclude tumors in the lacrimal passage or a pathological change in the nose or sinuses, a CT scan can be done. Moreover, a CT scan is useful to rule out nasal pathologies (septal deviation, hypertrophy of the turbinates, sinusitis, concha bullosa) that can aggravate the symptoms of lacrimal stenosis and to plan a surgical procedure.[18] However, routine screening with computed tomography is not recommended due to the radiation exposure risks.[19] If a tumor of the lacrimal system or the sinuses is suspected, an MRI with Gadolinium gives more useful information. Since there is no single reliable method for testing patency of the lacrimal drainage system, physicians should refer to different complementary tests in a clinic setting.[20][21]

Treatment / Management

The majority of congenital dacryostenosis cases resolve without the need for surgery. Treatment consists of performing lacrimal sac massages performed by the parents. Moderate pressure over the lacrimal sac should be applied in a downward direction two or three times per day.[22] Antibacterial ointment application may be prescribed to avoid bacterial infection.[23](A1)

If the obstruction persists beyond the age of six months, lacrimal duct probing is advocated. This procedure is performed by an ophthalmologist, usually under general anesthesia. The procedure is performed by inserting a small blunt probe or irrigation cannula into the punctum and advancing it until it abuts the obstruction and reaches the nasal cavity. Irrigation with saline is often performed to ensure patency.[24]

The combination of probing and irrigation is an easy, quick procedure with a high rate of success.[10] Nasolacrimal intubation may be performed if there is significant stenosis of the bottom end of the nasolacrimal duct. The stent, which is made of silicone, is placed in the nasolacrimal system and removed in the office after two to six months.[25] Success rates with this procedure are 90 to 96 percent in the case of primary treatment and 84 percent when performed after failed probing.[25](B2)

Additional procedures include balloon dacryocystoplasty, dacryocystorhinostomy, and conjunctivodacryocystorhinostomy. These interventions can be performed both in pediatric and adult patients. The balloon dacryocystoplasty is a simple and minimally invasive technique. It is usually advisable for the treatment of incomplete obstruction of the lacrimal drainage system and for cases who have failed a simple probing and irrigation procedure. Usually, a stent is left in place after the procedure.[26]

Dacryocystorhinostomy (DCR) is a more complex procedure that requires the removal of a part of the lacrimal bone to create a window between the lacrimal sac and the nasal cavity.[27] DCR preserves the active drainage mechanism. It can be done via external access or endoscopic nasal access. Usually, endoscopic access requires general anesthesia. Transcanalicular laser-assisted dacryocystorhinostomy is performed by inserting a small laser fiber into the canaliculi and may be done under local anesthesia. It involves less tissue removal compared to standard techniques, but the success is lower than standard DCR techniques.[28](B3)

When the obstruction is in the canaliculi, the procedures discussed above will not work. A conjunctivodacryocystorhinostomy may be indicated. This procedure involves a complete by-pass of the lacrimal drainage obtained, inserting a Pyrex glass tube (Jones tube). Periodic removal and cleaning of the Jones tube, followed by immediate replacement, may be needed.[26] It has been shown that the device can be tolerated for at least four decades.[29] Some authors suggest that the application of antimetabolites at the time of DCR increases the functional and anatomic success of DCR.[30](A1)

Opening of the obstructed nasolacrimal ducts in adults with an antegrade dilatation has been suggested, but sufficient studies proving the efficacy of this procedure have not been completed.[31]

Differential Diagnosis

The most common presentation of dacryostenosis is epiphora.[16] However, as mentioned above, in some instances, other signs and symptoms may be present. In the presence of eye redness and discomfort, conjunctivitis, foreign bodies, end corneal abrasion must be ruled out.

Prognosis

In children, spontaneous resolution is frequent and occurs by six months of age in approximately 90 percent of patients.[11] If the obstruction persists more than the age of one year, spontaneous resolution is unlikely.[11] In adults with acquired dacryostenosis, spontaneous resolution is rare. When surgery is needed, the prognosis depends on the technique and associated conditions.

Success rates of external and internal DCR are similar and reported to be more than 90% in most studies in the literature. The endoscopic approach may be preferred because it offers the advantage of allowing the surgeon to identify and correct intranasal abnormalities, which are the most common causes of DCR failure.[32]

Complications

Dacryostenosis can evolve into an infection of the lacrimal sac (dacryocystitis), which, if left untreated, can cause complications such as endophthalmitis and orbital cellulitis. Signs and symptoms of acute dacryocystitis (erythema, swelling, warmth, tenderness of the lacrimal sac, and/or purulent discharge) must be identified. There is evidence that a relationship exists between congenital nasolacrimal duct obstruction and subsequent refractive error disorders in children. In particular, 10% of children with congenital nasolacrimal duct obstruction may develop anisometropia (with or without amblyopia).[33]