Preseptal and Orbital Cellulitis
Preseptal and orbital cellulitis are acute infections of the tissues around the eye. Differentiating between them is a critical clinical skill, as preseptal cellulitis is a milder condition, while orbital cellulitis is a medical emergency that can lead to vision loss and intracranial complications. A thorough clinical assessment is key to distinguishing between the two.
Preseptal (Periorbital) Cellulitis
Preseptal cellulitis is an infection of the eyelid and periorbital soft tissue that remains anterior to the orbital septum.
Clinical Presentation
The child presents with a swollen, red eyelid and surrounding soft tissue.
They are often febrile, but importantly, their eye movements are normal, there is no pain with eye movement, and their visual acuity is unaffected.
There is no proptosis (forward displacement of the eyeball) or diplopia (double vision).
Aetiology
The infection usually arises from a local skin injury and is most commonly caused by Staphylococcus aureus or Group A Streptococcus. It can also spread from a dacrocystitis or upper respiratory tract infection.
Management
In mild, early cases, a trial of oral antibiotics like co-amoxiclav may be considered.
However, most UK paediatric guidelines recommend starting with intravenous antibiotics to ensure good tissue penetration. Co-amoxiclav is the first-line choice.
The child should be admitted for observation and reviewed within 24-48 hours.
Orbital Cellulitis
Orbital cellulitis is a much more serious infection of the orbital tissues posterior to the orbital septum. It is a medical emergency.
Aetiology
The most common cause is the spread of infection from an adjacent sinus, particularly the ethmoid sinus. The most common pathogens are Streptococcus pneumoniae, Haemophilus influenzae (less common now due to vaccination), Staphylococcus aureus, and anaerobes.
Clinical Presentation
The child is typically systemically unwell, febrile, and may be irritable or drowsy.
The hallmark features are signs of orbital involvement:
Proptosis (the eye is pushed forward).
Ophthalmoplegia (painful and restricted eye movements).
Chemosis (swelling of the conjunctiva).
Reduced visual acuity (often an early sign, with a loss of red-green colour discrimination).
Headaches, vomiting, or seizures may suggest intracranial spread.
Complications
Ocular: The infection can lead to a subperiosteal abscess, orbital abscess, and ischaemic retinopathy, potentially causing permanent vision loss.
Intracranial: The infection can spread to the brain, leading to meningitis, cerebral abscess, or cavernous sinus thrombosis.
Management
Urgent referral to a senior paediatrician, ophthalmologist, and ENT team is mandatory.
Urgent investigations:
CT scan of the orbits and brain is the preferred imaging modality to confirm the diagnosis, assess for an abscess, and rule out intracranial complications.
Blood tests, including FBC, CRP, and blood cultures.
Empirical antibiotics: Start intravenous ceftriaxone immediately. Clindamycin may be added if the child is very unwell or if MRSA is a concern.
Surgical drainage: An orbital or subperiosteal abscess may require urgent surgical drainage.
Monitor: Closely monitor for signs of neurological deterioration, such as changes in GCS or the development of focal neurological signs.