Chemosis (Conjunctival Swelling with Pupil Sparing)
The presentation of conjunctival swelling with sparing of the pupils—known as chemosis—requires immediate assessment for red flag features (pain, photosensitivity, vision loss, corneal involvement) to distinguish self-limited conditions from sight-threatening emergencies, with management ranging from supportive care for viral/allergic causes to urgent ophthalmology referral for severe cases. 1
Immediate Red Flag Assessment
Before determining the underlying cause, evaluate for features requiring urgent ophthalmology referral within 24 hours 2:
- Decreased visual acuity (self-assessed worsening) 2
- Ocular pain (not just irritation—true pain suggests significant inflammation or corneal involvement) 1
- Photosensitivity/photophobia (indicates corneal involvement, commonly seen with adenoviral keratoconjunctivitis or herpes simplex virus) 1
- Visible corneal damage on examination 2
- Unilateral presentation (very unlikely to be simple viral/allergic conjunctivitis and warrants investigation for other pathology) 2
If any red flags are present, refer immediately to ophthalmology or eye casualty for same-day assessment 2.
Differential Diagnosis Based on Clinical Features
Viral Conjunctivitis (Most Common Cause)
The triad of watery discharge, photosensitivity, and pain strongly suggests viral conjunctivitis rather than bacterial or allergic etiologies 1:
- Presentation: Abrupt onset, often sequentially bilateral, bulbar conjunctival injection, watery discharge, follicular reaction of inferior tarsal conjunctiva, chemosis, eyelid swelling 2
- Distinctive signs: Preauricular lymphadenopathy, petechial/subconjunctival hemorrhage, follicular reaction on inferior tarsal conjunctiva 2
- Natural history: Self-limited with improvement within 5-14 days 2
Allergic Conjunctivitis
Itching is the most consistent sign distinguishing allergic from infectious causes 3:
- Presentation: Mucoid white discharge with itching, bilateral presentation, papillary reaction on superior tarsal conjunctiva 4
- Associated factors: History of atopy, seasonal pattern, exposure to allergens 5
- Chemosis can be prominent in acute allergic reactions 5
Bacterial Conjunctivitis
Less likely with chemosis alone, but consider if 3:
- Creamy/mucopurulent discharge with matted eyelids on waking 4
- Lack of itching and absence of prior conjunctivitis history 3
- Often unilateral initially 4
Parinaud Oculoglandular Syndrome
Consider in cases with 2:
- Unilateral granulomatous follicular conjunctivitis with chemosis 2
- Ipsilateral regional lymphadenopathy (preauricular/submandibular), fever 2
- Associated with cat scratch disease (Bartonella henselae), tularemia, sporotrichosis 2
Management Algorithm
For Cases WITHOUT Red Flags
Mild Cases (Minimal Symptoms, Mild Redness)
Supportive care is the initial management for viral conjunctivitis, as it is self-limited and does not benefit from antibiotics or antiviral therapy in most cases 1:
- Artificial tears for symptomatic relief 1
- Cold compresses to reduce inflammation and discomfort 1
- Strict hand hygiene to prevent transmission to others and the contralateral eye 1
- Avoid touching eyes, sharing towels, pillowcases, or eye cosmetics 1
Moderate to Severe Cases or Suspected Bacterial Component
If corneal fluorescein staining is present or symptoms are moderate to severe 4:
- Broad-spectrum topical antibiotic such as moxifloxacin or levofloxacin four times daily 4
- Gatifloxacin 0.5% ophthalmic solution dosed for 5 days demonstrated clinical success (resolution of conjunctival hyperemia and discharge) in 58% versus 45% for vehicle 6
Important caveat: Topical antibiotics are not indicated for viral conjunctivitis, as they only shorten bacterial conjunctivitis duration by approximately 1 day and promote resistance 1
Allergic Conjunctivitis Management
For cases with prominent itching 5, 3:
- Topical antihistamines and mast cell stabilizers alleviate symptoms 3
- For severe acute exacerbations: Loteprednol etabonate (C-20 ester corticosteroid) provides effective anti-inflammatory relief with improved safety profile compared to traditional corticosteroids (less likely to elevate intraocular pressure or cause cataracts) 5
For Cases WITH Red Flags
Urgent ophthalmology referral within 24 hours for 2, 1:
- Worsening visual acuity
- Ocular pain or photosensitivity
- Visible corneal damage
- Unilateral presentation (unlikely to be dupilumab-related or simple viral/allergic)
- Recent ocular surgery
- Vesicular rash on eyelids or nose (suggests herpes zoster)
Special Considerations
Contact Lens Wearers
Must be evaluated for corneal ulcer, which can progress rapidly 4:
- Immediate discontinuation of contact lens wear
- Broad-spectrum topical antibiotics
- Urgent ophthalmology referral
Chronic or Recurrent Chemosis
Consider conjunctivochalasis (redundant conjunctival folds) in elderly patients 7, 8:
- Bilateral condition causing loose, redundant conjunctival tissue overlying lower eyelid margin 9
- Associated with aging, tear film instability, delayed tear clearance 8
- Medical treatment: Enhanced lubrication and anti-inflammatory medications 7
- Surgical options for refractory cases: Conjunctival cauterization or excision 7, 8
Chronic Unilateral Presentation
Biopsy indications to exclude malignancy 4:
- Unifocal recurrent lesions
- Resistance to therapy after 4-6 weeks
- Focal lash loss
- Chronic unilateral presentation unresponsive to treatment
Common Pitfalls to Avoid
- Do not prescribe topical antibiotics reflexively for all cases of chemosis—viral conjunctivitis does not benefit and this promotes resistance 1
- Do not miss herpes simplex virus conjunctivitis, which requires topical antivirals (not routine antibiotics) when distinctive signs are present 1
- Do not overlook unilateral presentation as a red flag requiring investigation beyond simple conjunctivitis 2
- Do not delay referral when red flags are present—corneal involvement can progress rapidly, especially in contact lens wearers 4
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