We will discuss orbital cellulitis and preseptal/periorbital cellulitis…
Pathophysiology
Orbital cellulitis occurs due to infection of the fat and muscles posterior to the orbital septum. The orbital septum is a thin, fibrous membrane that acts as the anterior boundary of the orbit. Orbital cellulitis involves the orbit but not the globe.
It commonly occurs due to spread of an URTI from sinuses. It is a medical emergency and carries a high mortality rate.
🦠 Causative agents
These are the most common causative agents:
- Streptococcus
- S. aureus
- Haemophilus influenzae B
⚠️ Risk factors
- Childhood - commonly affects children 7-12 years old.
- Previous sinus infection - ethmoid sinus most commonly.
- Lack of Hib immunisation
- Recent eyelid infection
- Ear/face infection
😷 Presentation
- Swelling and redness around the eye.
- Severe ocular pain - worse with movement
- Eyelid oedema
- Exophthalmos (aka proptosis)
- Ptosis
- Reduced visual acuity
🔍 Investigations
- FBC
- WBC
- CRP
- Blood cultures and swabs
Looking for the symptoms mentioned above such as erythema, RAPD, oedema, proptosis, reduced acuity, ophthalmoplegia.
- CT with contrast - looking for inflammation of orbital tissue deep to septum, and also assessing for sinusitis.
🧰 Management
- IV antibiotics -for 7-10 days, therefore admission to hospital is needed. Empirical therapy to be started until confirmation.
- Cefotaxime
- + Vancomycin if MRSA is suspected
Preseptal cellulitis occurs when our infection is anterior to the orbital septum. It includes the eyelids, skin, subcutaneous tissue but not the orbit and its contents.
It is less severe than orbital cellulitis. However, it usually spreads to the surrounding structures and should be treated accordingly.
🦠 Causative agents
- S. aureus
- S. epidermidis
- Streptococcus
🏘 Epidemiology
It is more common in children, especially kids under <21 months.
More common in winter due to increased prevalence of RTIs.
😷 Presentation
- Acutely painful eye
- Red and swollen eye and surrounding tissue.
- Ptosis of the eye due to swelling.
📝 Differential diagnosis
- Orbital cellulitis - this is also a complication that may occur as the infection could spread posterior to the septum.
- Allergic reaction
🧰 Management
- Secondary care referral is needed for adequate assessment.
- Oral antibiotics are usually sufficient
- Co-amoxiclav
🔢 Classification
Chandler’s Classification of Orbital Infections:
- I - Preseptal cellulitis
- II - Orbital cellulitis
- III - Subperiosteal abscess
- IV - Orbital abscess
- V - Cavernous sinus thrombosis