Congenital nasolacrimal duct obstruction — branching viva

Branch 1 — The diagnosis and the mimic

The candidate should identify congenital nasolacrimal duct obstruction from the white, quiet, watering eye with reflux on sac pressure and a normal red reflex and cornea, and immediately name congenital glaucoma as the must-not-miss mimic that also waters but adds photophobia, blepharospasm, a large or cloudy cornea and Haab striae. [4]

Probe the candidate on the mechanism: persistence of the membranous valve of Hasner at the distal duct opening, the last segment to canalise, backing up tears and mucus to overflow as epiphora. Ask why the eye stays white (the infection is confined to the drainage sac and tear film, not the conjunctiva) and why colds worsen it (nasal congestion swells the mucosa around the distal opening). [4]

Branch 2 — The first-line management and the probing-timing controversy

The candidate should prescribe Crigler lacrimal-sac massage — firm downward pressure over the medial canthus, about ten strokes, three or more times a day — combined with lid hygiene, and explain that topical antibiotics are not routine because the discharge reflects stasis rather than active infection. Reassure the family that most cases resolve spontaneously in the first year. [4]

Push the candidate into the controversy. The Cochrane review found insufficient evidence on optimal timing; the natural history favours waiting through the first year, while the falling success of probing with age limits open-ended deferral. The synthesis is to observe conservatively first and to offer probing from around twelve to eighteen months if the obstruction persists, individualising earlier for complex and syndromic cases. Office-based probing suits younger infants; older children usually need general anaesthesia. [2] [5]

Branch 3 — The photophobic infant and the newborn with a medial canthal mass

Introduce the second infant with photophobia and a large hazy cornea. The candidate should recognise congenital glaucoma and arrange urgent ophthalmology referral for tonometry, gonioscopy and definitive angle surgery, explaining that treating this as a blocked duct with massage is the error that blinds. [4]

Introduce the newborn with a blue-grey medial canthal mass and slow feeding. The candidate should recognise a congenital dacryocystocele, prioritise the airway and feeding assessment (the obligate neonatal nasal airway can be compromised by intranasal extension), and arrange combined ophthalmology and ENT review for early probing or decompression rather than watchful waiting. End on the safety-net: photophobia, a red or swollen eye, fever, and neonatal breathing or feeding difficulty. [10]