Causes of Epiphora (Watery Eye)
Epiphora is primarily caused by either excessive tear production or inadequate tear drainage, with nasolacrimal duct obstruction being the most common cause in approximately 33% of cases. 1
Etiological Classification
1. Tear Drainage System Obstruction
- Nasolacrimal duct obstruction - Most common cause (33% of cases) 1
- Can be congenital or acquired
- May result from inflammation, trauma, or age-related changes
- Punctal stenosis or occlusion
- Canalicular obstruction
- Dacryolithiasis (tear duct stones) 2
2. Eyelid Abnormalities
- Eyelid malposition 3
- Ectropion (outward turning of the eyelid)
- Entropion (inward turning of the eyelid)
- Eyelid laxity
- Incomplete blinking - Associated with increased screen time and evaporative dry eye 3
- Conjunctival chalasis (redundant conjunctiva) 3
- May occlude the inferior puncta
- Often follows previous chemosis
- Associated with previous eye surgery, dry eye, and meibomian gland dysfunction
3. Lacrimal Pump Dysfunction
- Neuromuscular disorders affecting blinking 3
- Parkinson's disease
- Bell's palsy
- Orbital/eyelid surgery complications 3
- Radiation-induced damage 3
- Trauma to the lacrimal system 3
4. Excessive Tear Production (Reflex Tearing)
- Ocular surface disorders 2
- Dry eye syndrome (paradoxical tearing)
- Blepharitis
- Conjunctivitis
- Keratitis
- Trichiasis (inward-turning eyelashes)
- Foreign bodies
- Corneal abrasions or ulcers
5. Medication-Related Causes
- Topical medications 3
- Glaucoma medications
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Antibiotics
- Antivirals
- Preservatives in eye medications
- Systemic medications
- Dupilumab (for atopic dermatitis) 3
6. Systemic Disease-Related Causes
- Thyroid disease 3
- Thyroid-associated ocular disease
- Hashimoto's thyroiditis
- Post-radioactive iodine therapy for thyroid cancer 4
- Autoimmune conditions 3
- Sjögren's syndrome
- Ocular mucous membrane pemphigoid
- Stevens-Johnson syndrome
- Viral infections 3
- HIV/AIDS
- Epstein-Barr virus
- Hepatitis C
Clinical Pearls and Pitfalls
Age consideration: Epiphora is predominantly present in elderly patients, often due to age-related changes in the lacrimal system 2
Paradoxical epiphora: Dry eye syndrome can paradoxically cause watery eyes due to reflex tearing - this is a common pitfall in diagnosis 3
Screen time impact: Increased screen time (computers, phones, TVs) reduces blink rate and can exacerbate dry eye, leading to reflex tearing 3
Post-treatment epiphora: Radioactive iodine therapy for thyroid cancer can cause nasolacrimal duct obstruction through inflammation and fibrosis of the lacrimal drainage system 4
Diagnostic approach: When evaluating epiphora, it's crucial to determine whether the cause is excessive tear production or inadequate drainage, as this dictates treatment approach 5
Referral considerations: Ophthalmologists make the most appropriate referrals for surgical intervention (82% surgical candidacy) compared to family physicians (55%) 1
Management Considerations
Treatment should target the underlying cause:
Obstructive causes: May require surgical intervention like dacryocystorhinostomy (DCR) 5
Ocular surface disorders: Treat with appropriate topical medications 2
Eyelid abnormalities: Surgical correction of malpositions 3
Medication-induced: Consider medication changes or preservative-free alternatives 3
Alternative approaches: Acupuncture has shown some efficacy for lacrimal duct dysfunction in limited studies 6
Understanding the specific cause of epiphora is essential for effective treatment and to prevent potential complications like chronic irritation, infection, and vision impairment.