Periorbital cellulitis

1. History

• Onset and laterality: Acute unilateral eyelid swelling, erythema, warmth, and tenderness
• Precipitating event: Recent insect bite, skin abrasion, laceration, puncture wound, hordeolum, chalazion, conjunctivitis, dacryocystitis, dental abscess, or upper respiratory infection/sinusitis [3][5]
• Symptom characterization: Ask about degree of swelling, ability to open the eye, pain location (surface vs. deep/retro-orbital), and progression over hours vs. days
• Key negatives to elicit: Absence of pain with eye movements, no diplopia, no vision changes, no proptosis — these help exclude orbital cellulitis [1][6]
• Systemic symptoms: Fever (present in ~20% of preseptal cases vs. ~82% of orbital cases), malaise, rhinorrhea [6-7]
• Vaccination history: Pneumococcal and H. influenzae type b vaccination status (relevant in pediatrics) [1]

2. Alarm Features

These features suggest orbital cellulitis or complications and require urgent escalation:

• Pain with extraocular movements [1][6]
• Proptosis [2-3]
• Ophthalmoplegia / restricted eye movements [3][7]
• Decreased visual acuity [1][8]
• Chemosis (conjunctival edema) [3]
• Diplopia [6-7]
• High fever with toxic appearance [6]
• Bilateral involvement or rapid progression despite antibiotics
• Signs of cavernous sinus thrombosis: severe headache, altered mental status, bilateral eye findings, cranial nerve palsies [3][9]
• Failure to improve within 24–48 hours of appropriate antibiotics [8]

3. Medications

Inpatient treatment (moderate-severe or suspected orbital involvement):

• IV ampicillin-sulbactam, or IV ceftriaxone ± metronidazole (if anaerobic coverage needed) [1][12]
• IV vancomycin added if MRSA suspected [1]
• Transition to oral antibiotics when clinically improving; total duration approximately 10–14 days [12]

4. Diet

• No specific dietary triggers or restrictions
• Ensure adequate hydration, especially in febrile patients or children
• No acute or long-term dietary management required

5. Review of Systems

• HEENT: Nasal congestion, rhinorrhea, facial pain/pressure (sinusitis), dental pain, ear pain
• Ophthalmologic: Vision changes, diplopia, eye pain with movement, tearing, discharge
• Neurologic: Headache, altered mental status, neck stiffness (meningeal signs)
• Constitutional: Fever, chills, malaise, poor oral intake (especially pediatrics)
• Dermatologic: Recent skin trauma, insect bites, rashes, herpetic vesicles

6. Collateral History and Family History

• Collateral: Confirm timeline of swelling onset, any witnessed trauma or insect bite, recent URI symptoms, prior episodes
• Pediatric patients: Immunization status (PCV, Hib), daycare attendance, sick contacts
• Family history: Generally not contributory; however, recurrent periorbital infections may prompt evaluation for immunodeficiency
• Social context: Exposure to insects/outdoor activities, recent dental procedures, IV drug use (adults)

7. Risk Factors

• Sinusitis — the most common predisposing factor overall (56% in one series); sinusitis was present in 100% of orbital cellulitis cases [6][13]
• Local skin trauma: Insect bites, abrasions, lacerations, puncture wounds [3]
• Conjunctivitis — leading etiology in preseptal cases (28%) [6]
• Dacryocystitis — most common predisposing factor in adults (15–30%) [5]
• Hordeolum/chalazion [5]
• Dental abscess [3]
• Age: More common in children; orbital complications more frequent in older children (9–18 years) [7][14]
• Immunocompromised states, poorly controlled diabetes (risk for mucormycosis) [3]

8. Differential Diagnosis

• Orbital cellulitis — the most critical cannot-miss diagnosis; distinguished by pain with eye movements, proptosis, ophthalmoplegia, decreased visual acuity [1-2]
• Subperiosteal or orbital abscess (Chandler III–IV) [1]
• Allergic reaction / angioedema — bilateral, non-tender, no erythema, no fever
• Chalazion / hordeolum — focal, well-circumscribed lid lesion
• Dacryocystitis — swelling localized to medial canthus/lacrimal sac
• Herpes zoster ophthalmicus — vesicular rash in V1 distribution
• Periorbital trauma / hematoma — history of injury, ecchymosis
• Idiopathic orbital inflammatory syndrome (orbital pseudotumor)
• Rhabdomyosarcoma or other orbital tumor — painless proptosis, subacute course
• Cavernous sinus thrombosis — bilateral findings, cranial nerve palsies, toxic appearance [3][9]
• Mucormycosis — immunocompromised/diabetic patients, black eschar, rapidly progressive [3]

9. Past Medical History

• Prior episodes of periorbital or orbital cellulitis
• History of chronic sinusitis or nasal polyposis
• Recent sinus or dental surgery
• Immunodeficiency (primary or acquired)
• Diabetes mellitus (risk for fungal orbital infections)
• Chronic skin conditions (eczema, impetigo)
• Vaccination history

10. Physical Exam

Vital signs: Temperature, heart rate (tachycardia may indicate systemic toxicity)

11. Lab Studies

• Mild preseptal cellulitis: Labs often unnecessary for straightforward outpatient cases
• Moderate/severe or diagnostic uncertainty:
  • CBC with differential — leukocytosis more pronounced in orbital cellulitis [6][13]
  • CRP — significantly elevated in orbital cellulitis; a CRP >120 mg/L has been proposed as a cutoff suggesting orbital involvement [7][14]
  • Blood cultures — obtain if febrile, toxic-appearing, or immunocompromised [10]
  • Wound/drainage cultures — culture any open wounds, purulent drainage, or conjunctival discharge; commonly yield S. aureus (including MRSA), β-hemolytic streptococci, S. pneumoniae, H. influenzae [1][3]
• Procalcitonin — may be considered but not well-validated for this indication

12. Imaging

• Mild preseptal cellulitis with clear clinical diagnosis: Imaging is not routinely necessary [8]
• CT orbits with IV contrast — indicated when:
  • Orbital cellulitis cannot be excluded clinically (pain with EOMs, proptosis, decreased vision) [1][4]
  • Failure to improve on antibiotics within 24–48 hours [8]
  • Severe presentation or toxic appearance
  • Identifies subperiosteal abscess, orbital abscess, sinusitis, intracranial extension [1][6]
• MRI brain and orbits with contrast — superior soft tissue resolution; used when CT is non-diagnostic or intracranial complications suspected (cavernous sinus thrombosis, intracranial abscess) [4]
• Key imaging findings: Subperiosteal abscess (most common complication, typically medial), orbital fat stranding, sinus opacification, intracranial extension [7][14]

13. Special Tests

• Chandler classification — staging system for severity: [1]
  • I: Preseptal cellulitis
  • II: Orbital cellulitis
  • III: Subperiosteal abscess
  • IV: Orbital abscess
  • V: Cavernous sinus thrombosis
• Point-of-care ultrasound (POCUS): May help differentiate preseptal from orbital cellulitis by identifying retro-orbital fluid collections, but cannot exclude intracranial extension [4]
• Intraocular pressure measurement if orbital compartment syndrome suspected

14. ECG

• Not routinely indicated
• Consider if sepsis or systemic toxicity is present, or if the patient is on QT-prolonging antibiotics (e.g., fluoroquinolones)

15. Assessment

Periorbital (preseptal) cellulitis is the most common form of periorbital infection, accounting for ~90–95% of cases in pediatric series. [6][13] It typically follows a milder clinical course than orbital cellulitis and responds well to antibiotics. However, preseptal cellulitis can progress to orbital cellulitis, making clinical vigilance essential. [2]

16. Treatment Plan

17. Disposition

18. Follow Up / Return Precautions

Return precautions — instruct patients/caregivers to return immediately for:

• Worsening swelling despite antibiotics
• New onset of pain with eye movements
• Vision changes (blurring, double vision, loss of vision)
• Eye bulging forward (proptosis)
• Inability to move the eye normally
• High fever, severe headache, or altered mental status
• Inability to tolerate oral medications