What is the most common cause of a blocked nasolacrimal duct in an infant and how should it be initially managed (lacrimal sac massage, warm compresses, topical erythromycin, oral amoxicillin‑clavulanate if infected, and criteria for referral for probing)?

Blocked Tear Duct in Infants

Most Common Cause

Congenital nasolacrimal duct obstruction (CNLDO) is caused by a membranous blockage at the distal nasolacrimal duct, affecting 5-20% of infants in the first year of life. 1, 2 This obstruction prevents normal tear drainage, resulting in excessive tearing (epiphora) and mucoid discharge that typically appears within the first weeks of life. 2

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Initial Conservative Management

First-Line Treatment: Lacrimal Sac Massage

Lacrimal sac massage combined with observation is the recommended initial approach for infants under 1 year of age. 1 The massage technique aims to increase hydrostatic pressure within the nasolacrimal system to rupture the membranous obstruction. 2

• Spontaneous resolution is common: 66% of cases in infants aged 6 to <10 months resolve within 6 months using only massage and observation, without requiring surgical intervention. 3
• Conservative management should continue through the first year, as most obstructions resolve spontaneously. 1, 2

Topical Antibiotics: Only When Infected

Topical antibiotic drops should be prescribed ONLY when signs of secondary bacterial conjunctivitis develop, such as purulent discharge or conjunctival injection. 4

• Do not prescribe antibiotics prophylactically or for simple tearing alone. 2
• Topical erythromycin or other antibiotic drops are reserved exclusively for active infection. 4
• Antibiotics as needed during the observation period help manage intermittent infectious episodes. 3

Oral Antibiotics: Reserved for Severe Infection

Oral antibiotics such as amoxicillin-clavulanate are indicated only for dacryocystitis (infection of the lacrimal sac) with systemic signs. 4

• Signs requiring oral antibiotics include: pain, swelling, erythema over the lacrimal sac area, and fever. 4
• Simple mucoid discharge or tearing does NOT warrant oral antibiotics. 4

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Red Flags Requiring Urgent Referral

Immediate Ophthalmology Referral Needed For:

• Dacryocystitis with fever, erythema, and swelling over the lacrimal sac — this represents acute infection requiring urgent treatment. 4
• Corneal involvement or ulceration — any corneal compromise demands immediate specialist evaluation. 4
• Severe purulent discharge suggesting gonococcal or other serious bacterial infection — requires prompt evaluation and treatment. 4

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Criteria for Elective Probing Referral

Timing of Surgical Intervention

For infants who fail conservative management, probing is most commonly performed between 6-12 months of age, though the optimal timing remains somewhat controversial. 1, 5

• Refer for probing consideration if: Symptoms persist beyond 6-12 months of conservative management with massage and observation. 1, 5
• Evidence on immediate vs. deferred probing: Children with unilateral NLDO may benefit from earlier office-based probing (RR 1.41 for treatment success), though 66% resolve without surgery during 6 months of observation. 5, 3
• After age 1 year: Nasolacrimal probing successfully addresses most persistent obstructions. 1

Probing Procedure Details

• Probing can be performed either in-office without anesthesia or under general anesthesia in the operating room. 5
• Success rates are high, though 9-13% may require secondary procedures. 5
• Potential complications include false passage creation, injury to the nasolacrimal system, bleeding (occurs in 20% of probings), laryngospasm, or aspiration. 5

Refractory Cases

For persistent epiphora and mucous drainage refractory to initial probing, consider: 1

• Repeat probing
• Silicone tube intubation
• Balloon catheter dilation
• Dacryocystorhinostomy (surgical creation of new drainage pathway)

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Clinical Monitoring During Conservative Management

At each visit, evaluate for: 4

• Tear film pooling
• Mucoid or purulent discharge
• Conjunctival injection
• Signs of dacryocystitis (pain, swelling, erythema over lacrimal sac, fever)

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Common Pitfalls to Avoid

• Do not prescribe prophylactic antibiotics — reserve them strictly for active conjunctivitis or dacryocystitis. 4, 2
• Do not rush to probing — two-thirds of cases resolve spontaneously with conservative management in infants 6-10 months old. 3
• Do not miss dacryocystitis — this requires urgent treatment with systemic antibiotics and possible urgent probing. 4
• Do not overlook corneal involvement — any corneal compromise requires immediate ophthalmology referral. 4