What is periorbital cellulitis?

Periorbital Cellulitis: Definition and Clinical Approach

Periorbital cellulitis is an infection of the eyelid and surrounding tissues anterior to the orbital septum, characterized by eyelid erythema, edema, warmth, and tenderness, with normal extraocular movements and vision. 1

Clinical Characteristics

Periorbital cellulitis presents with:

• Eyelid erythema, edema, warmth, and tenderness
• Normal extraocular movements
• Preserved visual acuity
• No proptosis
• No pain with eye movement

Etiology and Predisposing Factors

Periorbital cellulitis usually arises from:

• Localized trauma to the periorbital area 2
• Bacteremia 2
• Upper respiratory tract infections (68% of cases) 3
• Skin lesions such as insect bites 1
• Preexisting skin infections like impetigo 1

Microbiology

The most common pathogens involved in periorbital cellulitis include:

• Staphylococcus aureus 2, 3
• Streptococcus pyogenes 2
• Streptococcus pneumoniae 2, 3
• Staphylococcus epidermidis 3

Distinguishing from Orbital Cellulitis

It is crucial to differentiate periorbital cellulitis from orbital cellulitis, as the latter involves the contents of the orbit posterior to the orbital septum and can lead to serious complications:

Feature	Periorbital Cellulitis	Orbital Cellulitis
Location	Anterior to orbital septum	Posterior to orbital septum
Extraocular movements	Normal	Restricted
Vision	Normal	May be affected
Proptosis	Absent	Present
Pain with eye movement	Absent	Present
Age prevalence	More common in children <5 years [3]	More common in children >5 years [3]
Common cause	Upper respiratory infections, trauma [3]	Sinusitis (79% of cases) [3]

Diagnostic Approach

1. Clinical evaluation is the first step in diagnosis

2. Imaging is not routinely required for typical periorbital cellulitis, but indicated when:

   • Clinical findings are insufficient to distinguish from orbital cellulitis
   • Poor response to initial therapy
   • Suspicion of abscess formation or deeper infection 1

3. Preferred imaging modality:

   • CT orbits with IV contrast is the most useful imaging for suspected orbital infection 2
   • MRI with contrast is preferred when intracranial complications are suspected 2, 1

Warning Signs Requiring Urgent Referral

• Pain with eye movements
• Movement restriction or diplopia
• Proptosis
• Vision changes 1

Management

1. Antibiotics:

   • Oral antibiotics active against streptococci and staphylococci for mild cases
   • Options include dicloxacillin, cephalexin, clindamycin, or amoxicillin-clavulanate 1
   • A 5-day course is as effective as 10 days if clinical improvement occurs 1
   • For more severe cases, intravenous antibiotics may be required

2. Hospitalization criteria:

   • Suspected progression to orbital cellulitis
   • No improvement within 24-48 hours of outpatient treatment 1

3. Surgical intervention is rarely needed for periorbital cellulitis alone (only about 3% of cases) 4, but indicated for:

   • Subperiosteal or orbital abscess formation
   • Inadequate response to medical therapy
   • Evidence of bone erosion on imaging 1

Complications

Potential complications include:

• Progression to orbital cellulitis
• Vision loss
• Intracranial infection
• Cavernous sinus thrombosis 1

Follow-up

• Daily follow-up is essential for patients with periorbital cellulitis treated as outpatients until definite improvement is noted 1
• Worsening symptoms despite 24-48 hours of antibiotic therapy suggests progression to orbital cellulitis 1

Clinical Pearls

• Misdiagnosing orbital cellulitis as periorbital cellulitis can lead to vision-threatening complications 1
• Clinical findings alone may not be specific enough to distinguish preseptal from orbital infections in all cases 1
• Blood and skin cultures are often negative in periorbital cellulitis 3
• Some evidence suggests that adding intranasal decongestants and steroids may reduce the need for surgical intervention in cases secondary to sinusitis 5