What are the causes and treatment options for conjunctival edema in a patient with a history of allergies and potential underlying systemic conditions such as heart failure or kidney disease?

Causes of Conjunctival Edema (Chemosis)

Conjunctival edema (chemosis) results from fluid accumulation in the conjunctiva and has multiple etiologies including allergic reactions, infectious conjunctivitis (particularly viral), mechanical/irritative causes, medication side effects, and systemic conditions affecting fluid balance such as heart failure or kidney disease. 1

Primary Etiologic Categories

Allergic Causes

• Allergic conjunctivitis is the most common cause of chemosis, presenting with bilateral eyelid edema, conjunctival injection, chemosis, watery discharge, and characteristic itching 1, 2
• Seasonal/perennial allergic conjunctivitis affects 6-40% of the general population and is associated with environmental allergens (grasses, pollens), climate factors, and outdoor air pollution 1
• The ocular surface inflammation is typically mast cell-driven, resulting in lid and conjunctival edema-redness during the acute phase, with potential late-phase response involving eosinophilia 2

Infectious Causes

• Viral conjunctivitis (particularly adenoviral) commonly presents with chemosis, along with bulbar conjunctival injection, watery discharge, follicular reaction, and eyelid swelling that can resemble orbital cellulitis 1
• Bacterial conjunctivitis can cause chemosis when severe, though purulent discharge is more characteristic than the watery discharge seen with viral or allergic etiologies 3, 4
• Herpes simplex virus and varicella zoster virus can cause unilateral chemosis with distinctive vesicular rash or ulceration of eyelids 1

Mechanical and Irritative Causes

• Contact lens-related keratoconjunctivitis causes conjunctival injection and variable papillary hypertrophy as a reaction to mechanical irritation, chronic hypoxia, or preservatives 1
• Foreign body trauma (such as grass seeds) can cause severe localized conjunctival edema and inflammation resembling chemical injury 5
• Floppy eyelid syndrome and giant fornix syndrome are mechanical causes listed in the differential 1

Medication-Induced Chemosis

• Calcium channel blockers, particularly amlodipine besylate, can cause chronic conjunctival chemosis along with bipedal pitting edema as a known side effect 6
• Medication-induced/preservative-induced keratoconjunctivitis should be considered in patients on chronic topical medications 1

Chronic Localized Conjunctival Chemosis (CLCC)

• CLCC is diagnosed when localized conjunctival edema persists for ≥6 months without definitive signs of local inflammation 7
• Biopsy specimens show chronic tissue inflammation or lymphangiectasia, suggesting the condition results from scarring and structural alteration of conjunctival lymphatics that irreversibly affects fluid distribution 7

Systemic Conditions

• Heart failure and kidney disease cause chemosis through systemic fluid overload and impaired venous/lymphatic drainage, though the provided guidelines focus primarily on local ocular causes 1
• Thyroid disorders may be associated with superior limbic keratoconjunctivitis, which can present with conjunctival inflammation 1
• Autoimmune conditions (Sjögren's syndrome, Hashimoto's, IgG4-related disease) are associated with conjunctival lymphoma presenting as chemosis 1

Treatment Approach Based on Etiology

For Allergic Chemosis

• Topical antihistamines and mast cell stabilizers are first-line treatment, with topical corticosteroids reserved for severe cases 3
• Cold compresses and preservative-free artificial tears provide symptomatic relief 3, 4
• Allergen avoidance and environmental control measures are essential 1

For Viral Chemosis

• Supportive care with cold compresses and preservative-free artificial tears is the mainstay, as viral conjunctivitis is self-limited 3, 4
• Patient education on hand hygiene is critical to prevent transmission 3, 8

For Severe Refractory Chemosis

• Topical adrenaline (1:1000) has been reported effective for severe tarsal conjunctival chemosis when conservative therapies fail, avoiding the need for examination under anesthesia or invasive intervention 9

For Medication-Induced Chemosis

• Discontinuation of the offending medication (such as amlodipine) typically results in resolution, though it may take up to 6 months 6

Red Flags Requiring Immediate Ophthalmology Referral

• Visual loss, moderate to severe pain, corneal involvement, severe purulent discharge, conjunctival scarring, or lack of response to therapy mandate urgent ophthalmology evaluation 1, 3
• History of HSV eye disease or immunocompromise requires prompt referral 1

Critical Pitfall to Avoid

• Do not empirically prescribe antibiotics for chemosis with watery discharge, as most cases are viral or allergic, self-limited, and antibiotic use promotes resistance without providing benefit 4
• Evaluate for medication side effects (particularly calcium channel blockers) and systemic conditions before attributing chemosis solely to local ocular disease 6