Contents
Introduction
The orbital septum is a fibrous connective tissue layer which divides orbital tissue from the eyelid, thus serving as a barrier against the spread of infection into the orbit. It extends from the orbital periosteum; is continuous with the tendon of levator palpebrae superioris superiorly and inserts into the tarsal plate inferiorly.
Inflammation and infection of muscle and fat anterior to the orbital septum is termed periorbital (also known as preseptal) cellulitis. As the inflammation is contained within the soft tissue layers superficial to the orbital septum, ocular function is preserved.
In orbital cellulitis, infection occurs posterior to the orbital septum and involves the orbital soft tissues. This is a sight-threatening emergency that warrants urgent hospital admission and senior review.
Aetiology
Both periorbital and orbital cellulitis are seen more commonly in children than adults, as the orbital septum has not fully developed, so it forms a weaker barrier to infection.
Many cases of periorbital cellulitis are due to a superficial insult, e.g., insect bite, chalazion, folliculitis. In children, it may also occur secondary to an underlying sinusitis.
Orbital cellulitis often reflects local spread from an upper respiratory tract infection, e.g., from the paranasal sinuses. It may also occur following the progression of periorbital cellulitis, orbital trauma, dental infections, or via haematogenous spread.
History and Examination
| Periorbital cellulitis | Orbital cellulitis | |
| History | Red, painful, swollen eyelidRecent insect bite | Red, painful +++, swollen eyelidFeverVisual disturbanceRecent acute sinusitis, orbital trauma, dental infection |
| Examination | Eyelid redness, tenderness and swellingNo proptosis or ophthalmoplegiaNormal visual acuity, colour vision and visual fieldsSystemically well | Proptosis (due to orbital swelling)Ophthalmoplegia (painful eye movements)Relative afferent pupillary defect (RAPD)Reduced visual acuityChange in colour visionNew visual field defect(s)Systemically unwell (fever, lethargy)CNS signs (indicate intracranial involvement): nausea and vomiting, headache, neck stiffness |
Investigations
Bloods are likely to show leucocytosis and an elevated CRP (this does not differentiate between periorbital and orbital cellulitis).
Blood cultures may demonstrate the causative organism (e.g., Streptococcus, Staphylococcus aureus, Haemophilus influenzae B), but should not delay administration of IV antibiotics.
Microbiology swabs from the conjunctiva and nasopharynx may be taken.
Contrast-enhanced CT sinus and orbits is the diagnostic modality of choice. Periorbital cellulitis is characterised by inflammation of periorbital structures anterior to the orbital septum. Inflammation of deep orbital tissues posterior to the orbital septum indicates orbital cellulitis.
If there is suspicion of an intracranial abscess or cavernous sinus thrombosis in a patient with new neurological signs, consider contrast-enhanced MRI head and orbits. Lumbar puncture may also be necessary if there are signs of meningeal involvement.
Management and Prognosis
Broad-spectrum antibiotics are the mainstay of treatment for both periorbital and orbital cellulitis.
Children with periorbital cellulitis should receive IV antibiotic therapy due to the risk of infection extending to cause orbital cellulitis. Clinically stable adults with periorbital cellulitis may be managed with oral antibiotics in the community if they are able to comply with appropriate follow up. Symptoms usually improve within 24-48h with treatment and most cases fully resolve.
Early hospital admission for empiric IV antibiotic therapy is essential for patients with suspected orbital cellulitis. Urgent ophthalmology and ENT review are required. Lack of clinical response to IV antibiotics after at least 24-48h suggests a potential orbital abscess and should be evaluated on repeat CT, especially if there is also optic nerve compromise. An abscess should be managed by surgical drainage and/or decompression. With prompt diagnosis and treatment, orbital cellulitis usually has a good prognosis. However, it is important to be aware of the potential complications which include visual loss, cavernous sinus thrombosis, intracranial abscess, meningitis and rarely death!
3 key points
- Perform a basic ophthalmology exam including visual acuity, colour vision, ocular movements and visual fields in a patient presenting with a red, painful and swollen eyelid.
- Urgently for early ophthalmology review if you suspect periorbital or orbital cellulitis.
- Initiate antibiotic therapy early for both periorbital and orbital cellulitis.
Further Reading
- Eyewiki
- Oxford Handbook of Ophthalmology
- BMJ Best Practice
- Lecture Notes in Ophthalmology
References
- Eyewiki – Preseptal Cellulitis
- Eyewiki – Orbital Cellulitis
- Geeky Medics – Periorbital and Orbital Cellulitis
- BMJ Best Practice – Periorbital and Orbital Cellulitis
- Radiopaedia – Orbital Septum
Periorbital and orbital cellulitis in children
Written by Dr Alice Wang (FY2) & reviewed by Mr Chris Ashton (Ophthalmology TSC External Fellow)
For more information, please see the our article on this topic in the ENT section of the website.
