A number of variations of CNLDO were described way back in 1976 by Jones and Wobig [8]. These variations are seen in the lower end of the NLD, and the most common one described is the duct that fails to open through the nasal mucosa and stops at the vault of the anterior end of the inferior nasal meatus (Fig. 12.4a–f). The other variations include the NLD extending lateral to the nasal mucosa, extending up to the floor, complete absence of the duct or the impacted anterior end of the inferior turbinate, etc. (Fig. 12.4a–f).

Kushner first described the types of CNLDO into simple and complex based on intraoperative findings during probing [9]. In cases of simple obstruction, there is lack of resistance in passing the probe through the NLD until a point of membranous obstruction can be perforated. Simple obstruction also includes cases of canalicular valves, where resistance is encountered while bypassing them although there may not be true obstruction. Complicated obstruction can be those associated with any of the variations described earlier like a buried probe, a bony obstruction, nondevelopment of nasolacrimal duct, NLD opening into the inferior turbinate, and anlages.

The characteristic triad includes watering, discharge, and matting of eyelashes. In 95 % of cases, the onset of epiphora is within the first month of age [2]. The condition can be unilateral or bilateral. Symptoms may worsen with occurrence of upper respiratory tract infection. Other signs include increased tear meniscus height, positive fluorescein dye disappearance test (FDDT), and regurgitation on pressure over the lacrimal sac (ROPLAS). A spectrum of presentation can rarely include acute dacryocystitis, dacryocele, mucopyocele, and preseptal and orbital cellulitis (Fig. 12.5a–f).

Dacryocystoceles or simply dacryoceles are bluish cystic lacrimal sac swelling typically present below the medial canthal tendon, filled with secretions from epithelial lining and tears (Figs. 12.5b and 12.6). It is an uncommon manifestation of CNLDO occurring in 1 in 3,900 live births [8]. Nasolacrimal duct obstruction when combined with either functional obstruction of the proximal lacrimal system or common canaliculus leads to accumulation of secretions in the lacrimal sac. This leads to distortion of the common canaliculus and creates a ball-valve mechanism at the valve of Rosenmuller which allows ingress of tears into the sac but interferes with egress [10]. Dacryocystocele can be bilateral in 25 % of cases and can complicate into superadded infection and respiratory distress [5, 11]. Associated intranasal cyst (Fig. 12.7) can be small or large (if >50 of the nasal cavity) and, if large, can cause respiratory insufficiency because infants are nasal breathers, which can be life-threatening in cases of bilateral pathology [11]. Infection can lead to preseptal cellulitis, orbital cellulitis, and sepsis, therefore indicating early management of this condition. In the absence of intranasal cysts, dacryocele can be managed conservatively, and success rate achieved with sac compression alone was 76 % in one of the series [12]. In non-resolving cases and associated intranasal cyst, it is preferable to marsupialize the intranasal cyst early. Ali et al. [13] defined and classified the intranasal cysts as small and large and described a new technique of cruciate marsupialization for large intranasal cysts with good results on long-term follow-up.

Lacrimal fistula (anlage duct) is seen in 1 in 2,000 births [14]. It can cause epiphora (seen from the fistulous opening), discharge, dermatitis, and ascending infection causing acute or chronic dacryocystitis (Figs. 12.5f and 12.8). There are many theories postulating its formation; the most accepted one is that lacrimal fistula is an aberrant canaliculus which often originates from a common canaliculus or canaliculus and lined by a nonkeratinized stratified squamous epithelium resembling a canaliculus [14, 15]. Other associated lacrimal anomalies include CNLDO, absent canaliculus, supernumerary/absent punctum, and total agenesis of the lacrimal system [16]. A careful fistulectomy is performed when the lacrimal system is patent, but in cases of CNLDO, the authors prefer probing first and to wait for 6 months for a spontaneous closure of the fistula secondary to no flow. However if fistula persists, a fistulectomy can be performed.

Syndromic associations include Down’s syndrome (trisomy 21), Crouzon syndrome, Treacher Collins syndrome, Klinefelter syndrome, and Rubinstein-Taybi syndrome [14]. Associated craniofacial abnormalities include: cleft lip/palate, facial cleft, hypertelorism, bifid uvula, hemifacial microsomia, preauricular skin appendages, deformed external ears, and laryngeal stenosis (Fig. 12.9) [16].

A thorough knowledge and understanding of the natural history of CNLDO is a must for making a decision regarding the management as well as explaining the prognosis to the parents. In the landmark study by MacEwen and Young published in 1991, a large cohort of 1,019 eyes of infants were observed to determine the incidence and natural history of epiphora during the first year of life [2]. In 95 % of cases, the onset of epiphora was within the first month of age and thereafter 3 % in the second month and less than 1 % in the third and fourth months of age. Spontaneous resolution was observed throughout the year from the first month, and by 1 year of age, overall spontaneous resolution rate was 96 %. The authors also provided the probability of spontaneous resolution, i.e., the percentage of infants at each month, who on follow-up, resolved before age 12 months. Table 12.1 reflects the rounded up figures, making it easy to remember. This study provided the evidence that the probing should ideally be delayed until 1 year of age but did not provided the optimum age at which probing should be considered.

In subsequent study by the same researchers on CNLDO during the second year of life, it was noted that at 15 months of age, probing is superior to “no treatment” with statistical difference, but at the age of 24 months, there was no statistical difference between the two groups (74 % resolution in the probing group versus 60 % in the observation group) [17]. Spontaneous resolution remains a common occurrence during the second year of life with about 50 % rate (among the residuals) between 13 and 18 months and 23 % between 19 and 24 months of age. Appropriate time of probing recommended was 18 months of age if there are no signs of resolution.

Paediatric Eye Disease Investigator Group (PEDIG) studied the resolution of CNLDO with 6-month observation for infants presenting between 6 and <10 months old [18]. In this age group, more than half of the eyes (~66 %) resolved.

The most common outcome of CNLDO is the spontaneous resolution without the surgical intervention. Topical antibiotics are needed when there is purulent discharge and conjunctivitis or associated acute dacryocystitis. However, some surgeons prefer antibiotics more so for their additional anti-inflammatory actions as well. Various treatment options in CNLDO are conservative with compression over the lacrimal sac area, probing, intubation, balloon catheter dilation, endoscopic-assisted correction of associated nasal abnormalities, and, as a last resort for recalcitrant cases, an endoscopic or external dacryocystorhinostomy (DCR).