Periorbital Cellulitis
Periorbital (preseptal) cellulitis is infection of the eyelid and periorbital tissues anterior to the orbital septum, far more common and less dangerous than orbital cellulitis but requiring careful assessment to exclude posterior septal involvement.
Key Facts
Preseptal cellulitis involves tissues anterior to the orbital septum and is far more common than orbital cellulitis Most common in children <5 years, often following upper respiratory tract infection, insect bite, or minor trauma Key distinguishing features from orbital cellulitis: NO proptosis, NO ophthalmoplegia, normal visual acuity, normal pupil reactions Common organisms: Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae (post-Hib era, less common) Oral co-amoxiclav 625mg TDS for 7-10 days is first-line for mild-moderate cases in adults CT orbits with contrast indicated if clinical distinction from orbital cellulitis is uncertain Admit for IV antibiotics if child <1 year, systemically unwell, unable to examine eye adequately, or not improving on oral antibiotics Progression to orbital cellulitis occurs in approximately 5-10% of cases
Overview
Key Facts
Preseptal (periorbital) cellulitis is an infection of the eyelid and surrounding skin anterior to the orbital septum. It is far more common than orbital cellulitis, especially in children, and carries a much better prognosis. However, careful clinical assessment is essential to distinguish it from the sight-threatening orbital cellulitis.
Epidemiology
- Far more common than orbital cellulitis (3-5× more frequent)
- Peak incidence in children <5 years
- No significant sex preponderance
- More common in winter months (association with URTI and sinusitis)
Aetiology
- Local skin breaks: insect bites, minor trauma, impetigo, chalazion, dacryocystitis
- Extension from sinusitis (particularly ethmoid)
- Upper respiratory tract infection (especially in children)
- Post-surgical: after eyelid or periorbital surgery
- Common organisms: Staphylococcus aureus (most common), Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae type b (rare since vaccination)
Pathophysiology
- Infection involves subcutaneous tissue of the eyelid anterior to the orbital septum
- The orbital septum acts as a barrier preventing posterior spread in most cases
- Haematogenous spread can occur via valveless facial veins
- In children, the thin and incomplete orbital septum offers less protection, allowing easier posterior spread
Clinical Presentation
Typical Presentation
- Unilateral eyelid swelling, erythema, and warmth
- Eyelid tenderness
- Possible low-grade fever
- Often a visible entry point (insect bite, wound, chalazion)
- May have associated conjunctivitis
Importantly Normal Findings
- Visual acuity is normal
- No proptosis
- Full, painless range of eye movements
- Normal pupil reactions (no RAPD)
- No chemosis or retrobulbar involvement
Red Flags (Suggesting Progression to Orbital Cellulitis)
- Proptosis or resistance to retropulsion
- Painful or restricted eye movements
- Reduced visual acuity or colour vision
- RAPD
- Worsening swelling despite oral antibiotics
- High fever and systemic toxicity
Differential Diagnosis
| Diagnosis | Key Features | Investigation |
|---|---|---|
| Orbital cellulitis | Proptosis, ophthalmoplegia, reduced vision | CT orbits with contrast |
| Allergic reaction/angioedema | Bilateral, pruritus, no fever, rapid onset | Clinical, allergy testing |
| Insect bite reaction | Visible bite mark, pruritus, no fever | Clinical assessment |
| Chalazion/hordeolum | Localised eyelid lump, pointing, tender | Clinical assessment |
| Dacryocystitis | Medial canthus swelling, epiphora | Clinical, DCG if chronic |
| Nephrotic syndrome | Bilateral periorbital oedema, worse mornings | Urinalysis (proteinuria), albumin |
Diagnosis / Investigation
Bedside
- Visual acuity (should be normal)
- Pupil examination (should be normal)
- Eye movement assessment (should be full and painless)
- Temperature and observations
- Careful examination for entry wound
Bloods
- FBC: may show mild leucocytosis
- CRP: mildly elevated
- Blood cultures: if systemically unwell or child <1 year
Imaging
- CT orbits with contrast: only if clinical distinction from orbital cellulitis is unclear
- Shows pre-septal soft tissue swelling without post-septal involvement
- Normal extraocular muscles and orbital fat
- Not routinely required if confident clinical diagnosis of preseptal cellulitis
Special Tests
- Wound swab if obvious entry point
- Consider nasal swab in context of sinusitis
Management
Non-pharmacological
- Warm compresses to affected eyelid
- Good eyelid hygiene
- Follow-up within 24-48 hours to ensure improvement
Pharmacological
- Mild-moderate (outpatient management):
- Oral co-amoxiclav 625mg TDS (adults) or 25/3.1mg/kg TDS (children) for 7-10 days
- Alternative: oral cefalexin 500mg QDS + oral metronidazole 400mg TDS
- If penicillin allergy: oral clarithromycin 500mg BD
- Severe or not responding (inpatient management):
- IV co-amoxiclav 1.2g TDS (adults)
- OR IV ceftriaxone 2g OD (adults) / 50-80mg/kg OD (children)
- Switch to oral when clinically improving, apyrexial for 24-48 hours
Surgical
- Incision and drainage of associated abscess (e.g. eyelid abscess, chalazion)
- Rarely required
Referral Criteria
- Ophthalmology referral if any signs suggestive of orbital cellulitis
- Admission criteria: child <1 year, systemically unwell, unable to adequately examine eye, not improving after 48 hours oral antibiotics
- ENT referral if associated sinusitis
Prognosis
- Excellent prognosis with appropriate antibiotic treatment
- >95% resolve completely with oral antibiotics
- Progression to orbital cellulitis: 5-10% (higher in young children)
- Recurrence is uncommon
- Complications (rare): orbital cellulitis, abscess formation, skin necrosis
- No long-term visual sequelae if orbital involvement is excluded
Other Relevant Information
Preseptal vs Orbital Cellulitis — Summary
| Feature | Preseptal | Orbital |
|---|---|---|
| Swelling | Eyelid only | Eyelid + orbit |
| Proptosis | Absent | Present |
| Eye movements | Normal, painless | Restricted, painful |
| Visual acuity | Normal | May be reduced |
| RAPD | Absent | May be present |
| Fever | Low-grade/absent | Usually present |
| Management | Oral antibiotics (often outpatient) | IV antibiotics (inpatient) |
| CT findings | Pre-septal oedema only | Post-septal fat stranding ± abscess |
Admission Criteria for Preseptal Cellulitis
| Criterion |
|---|
| Age <1 year |
| Systemically unwell (high fever, tachycardia) |
| Unable to adequately assess eye/vision |
| Not improving after 48 hours oral antibiotics |
| Suspicion of orbital involvement |
| Immunocompromised patient |