Anatomy and Embryology

Lacrimal system anatomy is covered in detail in Chapter 1. In brief, the lacrimal drainage system begins proximally with the upper and lower puncta located in the medial aspect of the eyelids. These vertical structures turn horizontally and run medially to form the upper and lower canaliculi, which in about 90% of individuals join to form the common canaliculus (internal common punctum) before entering the lacrimal sac. The lacrimal sac lies within the lacrimal sac fossa formed by the maxilla and lacrimal bone. The medial canthal tendon splits to wrap around the lacrimal sac. This important anatomic landmark provides attachment of the eyelids to the facial bones and must be preserved during lacrimal surgery. The lacrimal sac connects to the nasolacrimal duct, which runs within the maxilla to open into the inferior meatus of the nose, beneath the inferior turbinate. The valve of Hasner lies at the junction of the nasolacrimal duct and the nasal mucosa and is the most common site of congenital nasolacrimal obstruction. ¹⁰ There is most often a persistent membrane in this area, which can be disrupted with a probe to eliminate the obstruction. This is in contrast with acquired lacrimal obstruction, in which the site of obstruction is frequently the lacrimal sac or sac–duct junction, and the management paradigm is completely different.

An understanding of the embryology of the lacrimal system is helpful in clinically predicting the anatomy of patients with lacrimal anomalies. The development of the lacrimal system begins with surface ectoderm cells forming a ridge at the naso-optic fissure. These cells, at about 12 weeks’ gestation, dive into the nearby mesoderm to form a solid ridge. The cells spread both superiorly toward the puncta and inferiorly toward the nose, while canalization of the solid rod is complete by about 6 months’ gestation. The canaliculi become patent in the eyelid margin at about 7 months’ gestation, just prior to the eyelids separating. ⁵

While canalization of the ectodermal rod should be complete by 6 months’ gestation, a persistent membrane often results at the junction with the nose. One study found that more than 70% of stillborn infants have congenital lacrimal obstruction at birth, which is many times higher than that noted in live births. ¹⁰ Similarly, infants born via cesarean section have been noted to have an almost double risk of congenital lacrimal obstruction. ^{11,​ 12} It is thought that perinatal breathing, sucking, and crying likely play a significant role in the rupture of these persistent membranes.

Other less common lacrimal anomalies may occur as a result of embryologic dysgenesis at any stage of development. If portions of surface ectoderm fail to invaginate, agenesis of this section of the lacrimal system will result. Incomplete separation of the ectoderm from the surface may result in lacrimal fistulas or supernumerary puncta ( ▶ Fig. 4.1). These are rare and may be treated, if symptomatic, with excision or ablation. Incomplete ridge canalization may result in stenosis in any affected portion of the lacrimal outflow system.

4.3 Evaluation and Considerations in the Tearing Infant

Congenital lacrimal obstruction may be unilateral or bilateral, and parents may not recognize the problem until the child is a few weeks of age. Observations often include epiphora, elevated tear lake, mucopurulent discharge, and occasionally a visibly swollen lacrimal sac. Symptoms may not be present at birth since tear production in infants is not fully operational until about 3 weeks of age.

It is important during the examination to keep in mind other possible etiologies of tearing in infants. The first distinction is to determine if there is overproduction of tears versus obstruction of outflow. Hypersecretion in infants may be a result of trichiasis, entropion, foreign body, corneal abrasion, congenital glaucoma, or other anterior segment pathology. Careful evaluation and consultation with a pediatric ophthalmologist is indicated if there are any concerns, as these etiologies may affect visual development, resulting in amblyopia.

Lacrimal system patency in infants is evaluated in several ways. First, the tear film is observed for elevation and presence of mucopurulent discharge. The eyelid skin and lashes are examined for erythema and crusting from chronic epiphora. The lacrimal sac is palpated for fullness and ability to express discharge through the puncta. Next a modified fluorescein dye disappearance test is performed. Fluorescein with topical anesthetic solution is placed into the inferior fornix of both eyes and the excess liquid is blotted. After 5 minutes, involving minimal manipulation of the eyes and eyelids, a cobalt blue filtered light is used to assess for presence of dye. In cases of normal lacrimal outflow, there should be no residual fluorescein present at 5 minutes. ¹³ A prospective study of 80 infants concluded that this test is 90% sensitive and 100% specific in the presence of nasolacrimal obstruction. ¹⁴ The presence of residual fluorescein is suggestive of lacrimal obstruction, although it does not specify which anatomic portion of the lacrimal system is affected. Hence, the history is important, as most parents can report when the obstruction began. Some children will have acquired lacrimal obstruction, which may occur after an episode of conjunctivitis, for example. The obstruction in this situation is likely to involve the canaliculi or lacrimal sac and is managed in a different manner than the child thought to have a persistent congenital membrane at the valve of Hasner. See Chapter 5 for a discussion of acquired lacrimal obstruction.

Infants may also present with a mass in the lacrimal sac area suggestive of dacryocele, also known as dacryocystocele or amniotocele when thought to be filled with amniotic fluid. ¹⁵ This dilatation of the lacrimal sac results from an obstruction not only distally at the valve of Hasner, but also proximally at the valve of Rosenmüller, creating a closed system. This condition is more common in females (78%) ^{16,​ 17} and unilateral in 84 to 100% of cases. ^{16,​ 17,​ 18,​ 19} If large, these masses can result in astigmatism and amblyopia. ¹⁶ Conservative treatment with warm compresses and massage has reported success rates of 17 to 80%. ^{16,​ 17,​ 19}

The trapped fluid is often sterile in young children, but there is a reported 14 to 75% risk of infection resulting in dacryocystitis with surrounding erythema and tenderness. ^{16,​ 17,​ 18,​ 19} This preseptal cellulitis can spread to involve the orbit and other structures; hence, close monitoring is indicated. Hospital admission with intravenous antibiotics should be considered in cases of fever, orbital cellulitis, or severe preseptal cellulitis. Culture of the infectious material may be beneficial in selecting antimicrobial coverage, as is consultation with an infectious disease specialist. The most common organisms include Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenza. ²⁰ Once the acute infection is improved with systemic antibiotic therapy, a definitive procedure such as probing should be performed, as will be discussed later in this chapter.

Care must be taken to identify other potential causes of medial canthal masses in children. Concern should be especially high in those masses that are centered above the medial canthal tendon. Such etiologies include meningoencephalocele, capillary hemangioma, dermoid cyst, pneumatocele, lymphangioma, primary lacrimal sac tumor, rhabdomyosarcoma, and nasal glioma. ^{21,​ 22,​ 23,​ 24,​ 25,​ 26,​ 27,​ 28,​ 29} If there are findings on examination causing concern about a diagnosis other than lacrimal obstruction, then imaging should be considered prior to surgical exploration so that there are proper expectations and planning. Radiographic imaging is discussed in Chapter 3.

It is important to be aware of the entity of congenital nasolacrimal obstruction associated with intranasal cyst formation, first described by Raflo et al in 1982. ³⁰ This is most often recognized in the neonatal period when infants show signs of respiratory obstruction and distress, as they are obligate nose breathers. This rare entity requires a high level of suspicion and rapid intervention with nasal endoscopy and definitive treatment to rupture or marsupialize the cysts. ^{31,​ 32,​ 33,​ 34,​ 35,​ 36}

4.4 Treatment

4.4.1 Conservative Management: Crigler’s Massage

A conservative approach to the young infant with congenital lacrimal obstruction is often appropriate, as the majority of these obstructions will resolve spontaneously or with minimally invasive measures. The mainstays of conservative management are topical antibiotic as needed for discharge and lacrimal sac massage. Crigler described a technique for lacrimal sac massage in 1923 that involves placing a finger over the common canaliculus to block upward flow of contents and then stroking downward along the lacrimal sac in an effort to increase hydrostatic pressure to rupture the membrane at the junction of the nasolacrimal duct and nasal mucosa. ³⁷ Parents may report a popping sensation if the massage is successful, followed by resolution of symptoms. Several reports show high success rates ranging from 85 to 94.7%, especially in very young patients. ^{19,​ 38,​ 39,​ 40}

4.4.2 Probing and Irrigation

If conservative measures fail and the child is approaching 1 year of age, consideration must be given to more aggressive intervention. Most clinicians and investigators recommend lacrimal probing and irrigation as the next intervention.

Probing may be performed either in the office setting in very young infants using a papoose device or at any age in the operating room under general anesthesia. The procedure begins with inspection of the anatomy including the puncta, medial canthus, and nasal cavity. Irrigation is performed next, prior to placement of probes in the lacrimal system, to confirm impatency of the system. Next, a punctal dilator is used to enlarge the lower punctum. A lacrimal probe is placed vertically into the punctum and then turned horizontally and advanced through the canaliculus until the “hard stop” of the lacrimal sac fossa bone is felt. The probe is then turned 90 degrees inferiorly and very slightly posteriorly to advance through the nasolacrimal duct into the inferior meatus of the nose ( ▶ Fig. 4.2). Occasionally, a popping sensation may be noted as the obstructing membrane is ruptured. Irrigation is repeated to confirm patency of the system. The same procedure should then be performed via the upper punctum and canaliculus. Some experts advocate using progressively larger probes to dilate the system.

The most common complication of nasolacrimal probing is creation of a false passage. The surgeon must exercise caution by passing the probe slowly and stop the procedure if a “soft stop” is encountered, suggesting that there is a proximal obstructive problem in the common canaliculus or lacrimal sac.

Because of the high rate of spontaneous resolution of lacrimal obstruction, often quoted at 96% by 1 year of age, ⁴ there has been much discussion in the literature regarding the optimal time for surgical intervention. Arguments for early intervention include early relief of symptoms (although these are usually more bothersome to the parent than the child) and avoidance of complications of lacrimal obstruction such as conjunctivitis, dacryocystitis, and cellulitis as well as chronic fibrosis of the lacrimal system. In addition, early probing may be performed in the office without the need for general anesthesia. This may be somewhat traumatic to parent and child, but one survey showed that 95% of parents found the procedure to be easier than expected and 81% were happy with their decision for early intervention. ^{41,​ 42} The disadvantage of early probing is that there is a high chance of resolution over time without surgical intervention.

Many experts strike a balance by advocating for probing under general anesthesia as soon as the child reaches 1 year of age. Anesthesia is thought to be safest by this age ^{43,​ 44} and numerous studies have shown a decreasing rate of success of probing with increasing age after 1 year. ▶ Table 4.1 lists studies with 50 or more patients, showing various rates of decline. ^{42,​ 45,​ 46,​ 47,​ 48,​ 49,​ 50,​ 51} It is logical that the more complex anatomic problems persist without spontaneous improvement and therefore older children have lower success rates with probing.

When probing and irrigation fail to resolve symptoms of lacrimal obstruction, many advocate a second probing and irrigation. Reported success rates for repeated probing procedures are variable, with one study of 1,748 patients up to 4 years of age showing 100% success, ⁵² while other studies are more typical of the Katowitz and Welsh report showing 54% success for second probing in 18- to 24-month-old children and 33% success in those older than 2 years. ⁴⁵ Adjunctive procedures that may be beneficial at the time of the second probing include silicone bicanalicular intubation, infracture of the inferior turbinate, balloon catheter dilation, and nasal endoscopic evaluation.

4.5 Silicone Bicanalicular Intubation

Placement of silicone tubing in the lacrimal system at the time of probing is common practice, particularly after one failed probing. The tubing stents and dilates the newly opened lacrimal passage to prevent adhesion and restenosis. This procedure preserves the normal anatomy and is typically performed before other more invasive surgeries are considered. Quickert and Dryden first described this technique in 1970. ⁵³ Under general anesthesia, a vasoconstricting agent such as oxymetazoline is placed in the inferior meatus of the nose. A silicone tube with metal probes at both ends is fed first through one punctum and canaliculus to the hard-stop, turned inferiorly and directed into the inferior meatus of the nose. A second probe is similarly placed through the ipsilateral punctum. The probes are retrieved from the nose with a hook and fixated at a tension that allows for some tube movement but not significant tube prolapse ( ▶ Fig. 4.3). Fixation may be via a foam bolster, a series of knots, or suture fixation to nasal wall.

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