How should periorbital swelling be evaluated and managed?

Evaluation and Management of Periorbital Swelling

The critical first step is to distinguish preseptal (periorbital) cellulitis from postseptal (orbital) cellulitis, as this distinction determines whether outpatient oral antibiotics suffice or immediate hospitalization with IV antibiotics is required. 1

Immediate Clinical Assessment

Examine specifically for the following features that indicate true orbital cellulitis requiring emergency intervention:

• Proptosis (forward displacement of the globe) 1, 2
• Impaired or painful extraocular movements 1, 2
• Ophthalmoplegia (paralysis of eye muscles) 1
• Decreased visual acuity or vision changes 1, 2
• Relative afferent pupillary defect (Marcus Gunn pupil) 3

Additional risk factors suggesting postseptal involvement include high neutrophil count, absence of infectious conjunctivitis, gross periorbital edema, age >3 years, and previous antibiotic therapy. 2

Diagnostic Imaging Algorithm

Obtain CT orbits with IV contrast immediately if any orbital signs are present (proptosis, impaired extraocular movements, decreased visual acuity, or ophthalmoplegia). 1, 2

• CT with contrast is the first-line imaging study, providing 97% accuracy for detecting subperiosteal abscesses, orbital abscesses, bone erosion, cavernous sinus thrombosis, and intracranial complications. 2
• Fat stranding on CT reliably separates true orbital cellulitis from preseptal disease. 2
• Do not delay CT imaging when any orbital signs are present—this is a critical pitfall that can lead to vision loss or death. 1, 2

Upgrade to MRI head and orbits with and without contrast when:

• Multiple cranial nerve palsies are present (suggesting orbital apex syndrome or cavernous sinus thrombosis) 2
• Intracranial extension is suspected (severe headache, altered mental status, focal neurologic findings) 2, 3
• The patient is immunocompromised (to rule out invasive fungal sinusitis, which carries 50-80% mortality) 2, 3

Management Based on Diagnosis

Preseptal (Periorbital) Cellulitis - Outpatient Management

High-dose amoxicillin-clavulanate is the first-line oral antibiotic for outpatient treatment. 1

Outpatient criteria (all must be met):

• Eyelid less than 50% closed 1
• No proptosis or visual changes 1
• No systemic signs of infection 1
• Reliable follow-up available 1

Mandatory reassessment within 24-48 hours is required—failure to reassess can allow progression to orbital involvement. 1

Treatment duration is typically 5-7 days but should be extended if infection has not improved. 1

Postseptal (Orbital) Cellulitis - Immediate Hospitalization

All patients with orbital cellulitis require immediate hospitalization with IV broad-spectrum antibiotics. 1

Empiric IV antibiotic regimens:

• IV ceftriaxone plus clindamycin (provides comprehensive coverage of Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes, Moraxella spp, and anaerobes) 1, 3
• Add vancomycin if MRSA risk factors are present (prior MRSA infection, nasal colonization, injection drug use) 1, 3

Urgent ophthalmology and otolaryngology consultation is mandatory for potential surgical drainage if subperiosteal or orbital abscess is identified on imaging. 2

Daily assessment of visual function and extraocular movements is required. 1

Life-Threatening Complications to Monitor

Catastrophic complications of orbital cellulitis include:

• Raised orbital pressure causing retinal artery occlusion and permanent vision loss 2
• Superior ophthalmic vein thrombosis 2
• Cavernous sinus thrombosis (potentially fatal) 1, 2
• Intracranial extension (subdural empyema, meningitis, brain abscess) 1, 2

Critical Differential Diagnoses

Idiopathic Orbital Inflammatory Syndrome (IOIS)

IOIS mimics orbital cellulitis but is non-infectious and requires corticosteroids rather than antibiotics. 2, 3

Distinguishing features include absence of fever, lack of sinus opacification, normal white blood cell count, and no bone erosion on imaging. 2

IgG4-Related Orbital Disease

This accounts for a significant percentage of previously "idiopathic" orbital inflammation and requires immunosuppressive treatment. 2

Imaging typically shows soft-tissue enlargement without bone erosion. 2

Invasive Fungal Sinusitis

In immunocompromised or diabetic patients, maintain a low threshold for MRI to rule out invasive fungal infection, which carries 50-80% mortality and requires urgent systemic antifungal therapy plus surgical debridement. 2, 3

Additional Considerations When Photophobia is Present

When photophobia accompanies periorbital swelling, examine for corneal involvement (bacterial keratitis), which presents with pain, redness, blurred vision, corneal infiltrates or ulcerations, and discharge. 3

Do not patch eyes in contact lens wearers with corneal abrasions, as this increases the risk of bacterial keratitis. 3