What is the likely cause and recommended management for a six‑month history of non‑purulent clear watery discharge (epiphora) from a single eye?

Chronic Unilateral Epiphora: Evaluation and Management

A six-month history of non-purulent clear watery discharge from one eye requires systematic evaluation for nasolacrimal duct obstruction, conjunctival chalasis, or paradoxical tearing from ocular surface disease, with the most critical first step being fluorescein staining to rule out corneal involvement and assessment of the lacrimal drainage system.

Primary Differential Diagnosis

Nasolacrimal Duct Obstruction (Most Likely)

• Unilateral chronic epiphora lasting months is the hallmark presentation of acquired nasolacrimal duct obstruction, particularly in adults 1
• The tear drainage system can become obstructed at any point from the puncta through the nasolacrimal duct, preventing normal tear clearance 2
• When tear clearance is impaired, even normal tear production results in overflow tearing 1

Conjunctival Chalasis

• Redundant conjunctiva can occlude the inferior puncta, mechanically blocking tear drainage and causing chronic epiphora 3
• This condition presents with eyelid margin overhang and is chronic in nature 3
• Previous eye surgery, dry eye, and meibomian gland dysfunction are predisposing factors 3

Paradoxical Tearing from Dry Eye

• Dry eye can paradoxically present as epiphora, particularly outdoors or in windy conditions 4
• The mechanism involves reflex tearing in response to ocular surface irritation from inadequate baseline tear film 4
• This typically presents as "dry eye indoors and tearing outdoors" 4

Critical Initial Examination Steps

Rule Out Vision-Threatening Conditions First

• Perform fluorescein staining immediately to detect any corneal involvement, ulceration, or epithelial defects that would indicate more serious pathology 5
• Examine for eyelid vesicles or dermatomal rash that could indicate herpes simplex or varicella zoster virus, which can cause unilateral watery discharge with devastating complications including corneal perforation 5
• Assess visual acuity to establish baseline and detect any vision loss 5

Assess the Lacrimal Drainage System

• Inspect the puncta for stenosis, occlusion, malposition, or keratinization 3
• Perform the dye disappearance test: instill fluorescein and observe whether dye clears from the tear lake within 5 minutes (normal drainage) or persists (obstruction) 1
• Palpate over the lacrimal sac area to check for mucocele or dacryocystitis 1
• Examine for conjunctival chalasis by looking for redundant conjunctiva that may overhang the eyelid margin 3

Evaluate for Ocular Surface Disease

• Check tear breakup time to assess tear film stability (normal >10 seconds) 6
• Perform Schirmer testing to measure tear production 1
• Examine the conjunctiva for injection, follicles, papillae, or scarring 3
• Assess meibomian gland function, as dysfunction increases tear evaporation and can cause compensatory reflex tearing 1, 7

Examine Eyelid Position and Function

• Evaluate for ectropion, entropion, or eyelid laxity that could impair tear drainage 3
• Check blink completeness and frequency, as incomplete blinking interferes with tear distribution 1
• Look for trichiasis or distichiasis that could cause reflex tearing 3

Management Algorithm

If Nasolacrimal Duct Obstruction is Confirmed

• Refer to ophthalmology for probing and irrigation to confirm the level of obstruction 1
• Definitive treatment typically requires dacryocystorhinostomy (DCR) for complete nasolacrimal duct obstruction 1
• Temporary measures include warm compresses and massage over the lacrimal sac 1

If Conjunctival Chalasis is Present

• Mild cases: artificial tears without preservatives to lubricate the redundant tissue 3
• Moderate to severe cases with punctal occlusion: surgical excision of redundant conjunctiva or conjunctivoplasty 3
• Avoid preserved artificial tears, as preservatives accumulate when tear clearance is impaired 1

If Paradoxical Tearing from Dry Eye

• Initiate aggressive tear substitution therapy with preservative-free artificial tears, used frequently (every 1-2 hours initially) 4
• Consider punctal occlusion to retain existing tears once the ocular surface is stabilized 4
• Treat underlying meibomian gland dysfunction with warm compresses and lid hygiene 1, 7
• For severe cases, topical cyclosporine may address the inflammatory component 7

If Medication-Induced

• Review all topical eye medications for potential causative agents, particularly glaucoma medications, NSAIDs, and preserved drops 3
• Switch to preservative-free formulations when possible 3
• Consider that gradual worsening with continued use is characteristic of medication-induced disease 3

Critical Pitfalls to Avoid

• Never assume watery discharge is benign without corneal examination: HSV can present with minimal discharge and unilateral watery eye, but untreated corneal involvement leads to scarring and perforation 5
• Do not overlook bilateral disease presenting asymmetrically: many chronic conditions like ocular mucous membrane pemphigoid present bilaterally but asymmetrically 3
• Recognize that symptoms alone are unreliable: less than 60% of patients with objective evidence of dry eye disease are symptomatic, so objective testing is essential 6
• Avoid preserved artificial tears when tear clearance is impaired: preservatives and inflammatory cytokines accumulate in the conjunctival sac when drainage is compromised, worsening ocular surface disease 1

When to Refer Urgently

• Any corneal staining or epithelial defect detected on fluorescein examination 5
• Presence of eyelid vesicles or dermatomal rash suggesting HSV or VZV 5
• Rapid visual acuity decline or severe ocular pain 5
• Signs of dacryocystitis (erythema, swelling, tenderness over lacrimal sac) 1
• Progressive conjunctival scarring or symblepharon formation 3