Periorbital cellulitis
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Periorbital cellulitis (preseptal cellulitis) is a bacterial infection of the soft tissues anterior to the orbital septum, typically causing eyelid swelling and erythema without involvement of the orbit.
Aetiology
- Local skin infections: impetigo, insect bites, trauma-related infections.
- Spread from adjacent structures: sinusitis, dacryocystitis.
- Haematogenous spread: less common, seen in bacteraemic illnesses.
- Common pathogens: Staphylococcus aureus (including MRSA), Streptococcus pyogenes, Haemophilus influenzae (in unvaccinated children).
Pathophysiology
- Bacterial invasion leads to soft tissue inflammation and oedema.
- Unlike orbital cellulitis, there is no involvement of the deeper orbital structures.
- If untreated, may progress to orbital cellulitis or abscess formation.
Risk Factors
- Recent sinusitis or upper respiratory tract infection.
- Skin trauma or insect bites near the eye.
- Unvaccinated status (H. influenzae type B).
- Immunosuppression (e.g., diabetes, HIV).
Signs and Symptoms
- Eyelid erythema, warmth, and swelling.
- No proptosis or ophthalmoplegia (distinguishes from orbital cellulitis).
- Normal visual acuity and painless eye movements.
- Mild fever and systemic symptoms may be present.
Investigations
- Clinical assessment: differentiates from orbital cellulitis.
- CT orbit with contrast: if orbital cellulitis or complications are suspected.
Management
1. Mild Cases (No Systemic Symptoms, No Orbital Signs):
- Oral antibiotics (co-amoxiclav or clindamycin if penicillin-allergic).
- Cold compresses and analgesia.
- Close monitoring for worsening symptoms.
2. Moderate to Severe Cases (Fever, Worsening Swelling, Systemic Symptoms):
- Hospital admission for IV antibiotics (co-amoxiclav or ceftriaxone + metronidazole).
- Ophthalmology review if symptoms worsen despite treatment.
3. Referral:
- Ophthalmology: if worsening despite treatment or if orbital involvement is suspected.
- Paediatrics: for children requiring IV antibiotics.
- ENT: if underlying sinusitis requires specialist management.