FCPS TOACS Mock Test · Nasolacrimal Duct Obstruction (NLDO)

❓ Q1. Describe the findings in the image. What is the most likely diagnosis?

✅ Model Answer:
• Findings: Left eye – epiphora (tears flowing onto cheek), mucoid discharge along lower lid, no conjunctival injection (white conjunctiva), no periorbital swelling.
• Diagnosis: Congenital nasolacrimal duct obstruction (NLDO) – also called dacryostenosis.
• Why not red eye: Absence of conjunctival hyperemia rules out infective conjunctivitis. White conjunctiva + constant tearing since birth points to anatomic obstruction, not infection.

❓ Q2. Describe the anatomy of the nasolacrimal drainage system. Where is the commonest site of obstruction in congenital NLDO?

✅ Model Answer:
• Anatomy: Tears drain from eye → puncta → canaliculi → common canaliculus → lacrimal sac → nasolacrimal duct → inferior meatus of nose (valve of Hasner at distal end).
• Commonest site of obstruction (>70%): Distal valve of Hasner – persistent membrane at distal end near inferior turbinate.
• Incidence: 5-10% of newborns; bilateral in 20-30%.

❓ Q3. What are the important differential diagnoses for a teary eye in a newborn?

✅ Model Answer:
• Congenital NLDO (most common, 90%).
• Neonatal conjunctivitis (redness, purulent discharge, periorbital edema, bilateral).
• Congenital glaucoma (photophobia, corneal clouding, enlarged corneal diameter >11 mm, increased IOP).
• Corneal abrasion/ulcer (trauma, pain, photophobia, fluorescein uptake).
• Key discriminating feature: White conjunctiva + constant tearing since birth = NLDO. Redness suggests infection/glaucoma.

❓ Q4. What are the typical clinical features of congenital NLDO? How is the diagnosis made?

✅ Model Answer:
• Features: Epiphora from birth, mucoid/mucopurulent discharge (intermittent), white eye, worse when lying down, positive regurgitation test.
• Diagnosis: Primarily clinical. Fluorescein dye disappearance test – if dye still present after 5 minutes → obstruction.
• Nasal endoscopy rarely needed.

❓ Q5. What is the first-line conservative management for congenital NLDO? Describe the Crigler massage technique.

✅ Model Answer:
• First-line: Lacrimal sac massage (Crigler technique) + warm compresses + cleaning discharge.
• Crigler massage: Place index finger at medial canthus (over lacrimal sac). Apply gentle downward pressure ("rolling" or "milking" motion) towards nose. Perform 5-10 strokes, 2-3 times daily.
• Goal: Increase hydrostatic pressure to rupture distal valve of Hasner membrane.
• Antibiotic drops NOT indicated for uncomplicated NLDO.

❓ Q6. What is the natural history of congenital NLDO? What percentage resolve spontaneously?

✅ Model Answer:
• High spontaneous resolution: >90% resolve by 12 months.
• Timeline: By 6 months (60-70%), by 8-9 months (80-90%), by 12 months (>95%).
• Mechanism: Spontaneous rupture of Hasner valve membrane.
• Indications for intervention: Persistent symptoms beyond 12 months (or earlier if severe discharge/recurrent dacryocystitis).

❓ Q7. When is nasolacrimal duct probing indicated? At what age is it typically performed?

✅ Model Answer:
• Indications: Persistent epiphora/discharge beyond 12 months, recurrent/acute dacryocystitis, dacryocystocele.
• Typical age: 12-14 months (some centers 6-9 months, but most wait until after first birthday).
• Success rate: >90% for first probing under GA.
• Procedure: Passage of fine metal probe through puncta → canaliculus → lacrimal sac → nasolacrimal duct → inferior meatus; often combined with irrigation.

❓ Q8. Describe the nasolacrimal duct probing procedure and its success rate.

✅ Model Answer:
• Procedure (by ophthalmologist under GA): Dilate punctum → pass lacrimal probe through lower punctum → "bump" sensation at valve of Hasner (30-40 mm depth) → irrigate saline → saline appears in nose confirms patency.
• Success rate: First probing >90%, second probing 50-70%.
• Complications: Rare – false passage (canalicular laceration), nasal bleeding, infection.

❓ Q9. What is the role of silicone intubation (bicanalicular intubation) in NLDO? When is it indicated?

✅ Model Answer:
• Indications: Failed primary probing, complex NLDO (tight strictures, canalicular stenosis), dacryocystocele with intranasal cyst, age >24 months at first procedure.
• Procedure: Silicone tubes through both puncta into nasolacrimal duct, tied in nose. Kept for 3-6 months.
• Advantages: Prolonged stenting, prevents reclosure.
• Disadvantages: Second procedure for removal. Success rate 80-90%.

❓ Q10. What is dacryocystitis? How do you recognize and manage it?

✅ Model Answer:
• Definition: Infection of lacrimal sac due to stasis in NLDO. Pathogens: Staph aureus, Strep pneumoniae, H. influenzae.
• Recognition: Painful, red, warm swelling at medial canthus, purulent discharge from punctum, fever, irritability.
• Management: Oral/IV antibiotics (amoxicillin-clavulanate or cephalexin; severe: IV vancomycin + cefotaxime), warm compresses. If not improving within 24-48 hours or abscess forms → ophthalmology referral for probing/drainage.
• Recurrent dacryocystitis indicates probing even before 12 months.

❓ Q11. What are the red flags that require urgent ophthalmology referral in a child with suspected NLDO?

✅ Model Answer:
• Urgent referral (24-48h): Acute dacryocystitis with systemic symptoms/preseptal/orbital cellulitis, dacryocystocele (respiratory obstruction risk), corneal clouding/photophobia/enlarged corneal diameter (congenital glaucoma), eye redness with severe pain/photophobia.
• Non-urgent referral: Persistent NLDO beyond 12 months, recurrent dacryocystitis without systemic toxicity, failed conservative management.

❓ Q12. How do you differentiate congenital nasolacrimal duct obstruction from congenital glaucoma?

✅ Model Answer:
• NLDO: White conjunctiva, mucoid discharge, normal corneal diameter, normal IOP, positive regurgitation test.
• Congenital glaucoma: Corneal clouding (edema), photophobia, blepharospasm, enlarged corneal diameter (>11 mm), elevated IOP, optic disc cupping.
• Glaucoma is an emergency – urgent ophthalmology referral. NLDO is benign.

⚕️ FCPS Paediatrics TOACS · Mock Test