What is the diagnosis and management for a 50-year-old female patient presenting with eye pain, redness, protrusion, diplopia (double vision), and fever of 2 days duration?

Orbital Cellulitis: Diagnosis and Management

Probable Diagnosis

This patient has orbital cellulitis, a sight- and life-threatening infection characterized by inflammation of orbital contents posterior to the orbital septum. 1, 2

The constellation of proptosis (eye protrusion), diplopia (double vision), pain, redness, and fever in a 50-year-old woman over 2 days is pathognomonic for orbital cellulitis rather than preseptal cellulitis, which would not cause proptosis or diplopia. 1, 3

Clinical Features

Cardinal Signs Present in This Patient

• Proptosis (exophthalmos): Forward displacement of the globe due to orbital inflammation and edema 1, 3
• Diplopia: Results from restricted extraocular muscle movement due to inflammation and edema of orbital contents 1, 2
• Pain: Severe orbital pain, often worse with eye movement 1, 3
• Eyelid erythema and edema: Marked periorbital swelling and redness 1, 3
• Fever: Systemic manifestation of infection 1, 3

Additional Features to Assess

• Visual acuity: Must be documented immediately, as vision loss can occur from optic nerve compression or ischemia 4, 5, 1
• Chemosis: Conjunctival edema and injection 1, 3
• Restricted extraocular motility: Pain with eye movements and mechanical restriction 1, 2
• Relative afferent pupillary defect (RAPD): Indicates optic nerve compromise requiring urgent intervention 5, 2
• Increased intraocular pressure: Can occur from orbital congestion 1

Critical Pitfall

Never assume absence of severe vision loss means the optic nerve is safe—permanent vision loss can occur rapidly even with treatment if intervention is delayed. 5, 1

Investigations

Immediate Imaging (Within Hours)

• Contrast-enhanced CT of orbits and sinuses: First-line imaging to identify orbital abscess, subperiosteal abscess, and source of infection (typically sinusitis) 6, 1
• CT is preferred over MRI initially because it is faster, better demonstrates bony anatomy and sinus disease, and is more readily available in emergency settings 6, 1

Laboratory Studies

• Complete blood count with differential: Leukocytosis with left shift expected 1, 2
• Blood cultures: Obtain before antibiotic administration 1, 2
• Inflammatory markers: ESR and CRP to assess severity and monitor response 1

Microbiological Studies

• Culture of any drainable abscess or sinus discharge: To guide antibiotic therapy 1, 2
• Most common organisms: Streptococcus species, Staphylococcus aureus (including MRSA), and anaerobes from sinus origin 1, 3, 2

Ophthalmologic Assessment

• Immediate ophthalmology consultation: Required for all suspected orbital cellulitis 4, 1, 2
• Visual acuity testing: Any vision worse than 20/40 mandates urgent specialist evaluation 4
• Pupillary examination: Check for RAPD indicating optic nerve involvement 5, 2
• Extraocular motility assessment: Document degree of restriction 1
• Fundoscopic examination: Assess for optic disc edema or central retinal artery occlusion 5, 1

Treatment Algorithm

Immediate Management (Within 1 Hour)

Broad-spectrum intravenous antibiotics must be initiated immediately—do not wait for imaging or culture results. 1, 3, 2

• Empiric IV antibiotic regimen: Vancomycin 15-20 mg/kg every 8-12 hours PLUS either ceftriaxone 2g every 12 hours OR piperacillin-tazobactam 4.5g every 6 hours 1, 2
• Vancomycin covers MRSA, which is increasingly common in skin and soft tissue infections 3, 2
• Add metronidazole 500mg IV every 8 hours if anaerobic infection suspected (foul-smelling discharge, dental source) 1, 2

Surgical Intervention Indications

Immediate surgical drainage is required if: 1, 2

• Orbital or subperiosteal abscess identified on CT (most critical indication)
• Vision deterioration despite 24-48 hours of IV antibiotics
• Optic nerve compromise (decreased vision, RAPD, or optic disc changes)
• Large abscess (>10mm) or complete ophthalmoplegia
• Frontal sinusitis (high risk of intracranial extension)

Monitoring Requirements

• Visual acuity checks every 4-6 hours initially: Any deterioration requires immediate surgical consultation 5, 1, 2
• Pupillary examination every 4-6 hours: Development of RAPD is surgical emergency 5, 2
• Clinical reassessment at 24-48 hours: Lack of improvement mandates surgical drainage 1, 2
• Repeat CT if clinical deterioration or no improvement at 48-72 hours 1, 2

Duration of Therapy

• IV antibiotics for minimum 7-10 days, then transition to oral antibiotics for total 2-3 week course 1, 2
• Adjust antibiotics based on culture results when available 1, 2

Critical Pitfall

Oral antibiotics alone are inadequate for orbital cellulitis in adults—IV therapy is mandatory. Preseptal cellulitis in healthy adults can be managed with oral antibiotics, but orbital involvement (proptosis, diplopia, vision changes) requires hospitalization and IV therapy. 2, 7

Complications

Vision-Threatening Complications

• Permanent vision loss from optic neuropathy: Can occur from direct compression, ischemia, or optic neuritis—reported even with treatment 5, 1, 2
• Central retinal artery or vein occlusion: From increased orbital pressure 5, 1
• Exposure keratopathy: From severe proptosis preventing lid closure 1, 2

Life-Threatening Complications

• Cavernous sinus thrombosis: Presents with bilateral eye involvement, cranial nerve palsies (III, IV, VI), and altered mental status 1, 2
• Intracranial abscess: Brain abscess, subdural empyema, or epidural abscess from direct extension 1, 2
• Meningitis: From spread through orbital foramina 1, 2
• Death: Mortality was significant in pre-antibiotic era; still possible with delayed treatment 1, 2

Ocular Complications

• Chronic diplopia: From extraocular muscle fibrosis or cranial nerve damage 1
• Restrictive strabismus: Permanent motility restriction requiring surgical correction 1
• Ophthalmoplegia: Complete loss of eye movement 1, 2
• Globe perforation: Rare complication from abscess rupture 1

Common Pitfall

Assuming improvement in eyelid swelling means the infection is resolving—orbital signs (proptosis, motility restriction, vision) are more important indicators of treatment response than external appearance. 1, 2