What should I do if I have a painful, watery swelling of one eye with periorbital swelling?

Immediate Evaluation for Orbital Cellulitis

You must immediately evaluate this patient for orbital cellulitis, which is a sight-threatening and potentially life-threatening emergency that requires urgent imaging and treatment. 1

Critical Distinguishing Features to Assess NOW

The combination of painful, watery swelling with periorbital edema raises immediate concern for orbital cellulitis rather than simple preseptal cellulitis or viral conjunctivitis. You need to rapidly assess for the following red flags:

Signs Indicating Orbital (Postseptal) Cellulitis - EMERGENCY

• Proptosis (forward displacement of the eyeball) 1, 2
• Limitation or pain with extraocular movements (ophthalmoplegia) 1, 2
• Relative afferent pupillary defect (RAPD) 2
• Vision loss or decreased visual acuity 1
• Severe, rapidly progressive eyelid erythema and edema 1
• Fever (often present, though not always) 2

If ANY of These Features Are Present:

Obtain CT orbit with contrast immediately - this is the imaging modality of choice to differentiate preseptal from orbital cellulitis and identify complications like subperiosteal abscess. 1

Start IV antibiotics without delay - vancomycin plus a third-generation cephalosporin or piperacillin-tazobactam for comprehensive coverage including methicillin-resistant organisms. 3

Obtain urgent ophthalmology and otolaryngology consultation - orbital cellulitis often arises from ethmoid sinusitis and may require surgical drainage. 3, 1

If Orbital Features Are ABSENT - Consider Alternative Diagnoses

Viral Conjunctivitis (Adenoviral)

If the patient has:

• Watery discharge with follicular reaction on the inferior tarsal conjunctiva 3
• Bulbar conjunctival injection (redness) 3
• Chemosis (conjunctival swelling) 3
• Recent exposure to someone with "pink eye" or upper respiratory infection 3
• NO proptosis, NO limitation of eye movements, NO vision loss 3

This is likely adenoviral conjunctivitis, which can present with significant eyelid swelling and even "resemble orbital cellulitis on exam." 3 This is self-limited (5-14 days) and does not require antibiotics. 3

Herpes Simplex Virus (HSV) Conjunctivitis

Look for:

• Vesicular rash or ulceration of the eyelids 3
• Dendritic epithelial keratitis on fluorescein staining 3
• Usually unilateral presentation 3
• Palpable preauricular lymph node 3

This requires antiviral therapy (topical and/or oral acyclovir/valacyclovir) to prevent corneal complications. 3

Common Pitfall to Avoid

Do NOT assume this is simple preseptal cellulitis and treat with oral antibiotics alone if you have not definitively ruled out orbital involvement. 2 A 10-year-old treated initially as preseptal cellulitis developed worsening proptosis and restricted movements within 3 days, ultimately requiring IV antibiotics and endoscopic sinus surgery. 2 Delay in diagnosis can lead to vision loss, cavernous sinus thrombosis, optic nerve injury, and intracranial complications. 1, 2

Immediate Action Algorithm

1. Check visual acuity in both eyes 1
2. Assess for proptosis (compare to fellow eye) 1, 2
3. Test extraocular movements (pain or limitation?) 1, 2
4. Check pupils (RAPD present?) 2
5. Measure temperature 2

If ANY abnormality in steps 2-4: → CT orbit with contrast NOW + IV antibiotics + Urgent subspecialty consultation 1, 2

If ALL normal: → Consider viral/HSV conjunctivitis, examine for vesicles, perform fluorescein staining, and manage accordingly 3