PatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Background: the orbital septum
The orbital septum is a fibrous sheet which is attached peripherally around the margin of the orbit where it is continuous with the periosteum. Centrally, it fuses into the tarsal plates. It effectively separates the eyelids from the contents of the orbital cavity.
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Orbital cellulitis versus preseptal cellulitis
Orbital cellulitis is an extremely serious (potentially life-threatening) but uncommon ophthalmic emergency characterised by infection of the soft tissues behind the orbital septum.
Preseptal cellulitis refers to the much more common and far less serious infection anterior to the orbital septum. Very occasionally, preseptal cellulitis progresses to orbital cellulitis; this is more likely in children. Orbital cellulitis and preseptal cellulitis are not terms that can be used interchangeably.
Orbital cellulitis: pathophysiology
Orbital cellulitis usually occurs as a result of:
- Extension of an infection from the periorbital structures (usually the paranasal sinuses, especially ethmoid sinusitis) and also from the face, the globe, the lacrimal sac and dental infection (via an intermediary maxillary sinusitis).
- Occasionally, it may occur as an extension of preseptal cellulitis, particularly in young children in whom the orbital septum is not fully developed.
- Direct inoculation of the orbit from trauma (accidental or surgical - including orbital, lacrimal, strabismus and vitreo-retinal surgery). Post-traumatic orbital cellulitis tends to develop within 72 hours of the injury.
- Haematogenous spread from distant bacteraemia.
The pathogens most commonly involved are the aerobic, non-spore-forming bacteria - Streptococcus pneumoniae, Staphylococcus aureus, Streptococcus pyogenes and Haemophilus influenzae (the latter mainly found in children).
Mucormycosis associated with patients who have diabetic ketoacidosis or immunosuppression is also described. This very rare and rapidly spreading infection caused by fungi, is aggressive and often fatal.
There has recently been an emergence of Meticillin-resistant S. aureus (MRSA) in the organisms isolated; this is rare but the development is worrying. Orbital cellulitis may be complicated by spread to adjacent structures and to the central nervous system.
Preseptal cellulitis: pathophysiology
This may also arise in one of three situations:
- As a result of local skin trauma such as lacerations and insect bites.
- Due to spread from local infection such as dacrocystitis, hordeolum and paranasal sinuses.
- Spread from distant infections such as those outlined above as well as from the upper respiratory tract.
The most common pathogenic organisms are S. aureus, S. epidermidis, streptococci and anaerobes. MRSA has also been isolated.
The orbital septum limits spread to associated structures and notably to the central nervous system.
- Orbital cellulitis is much less common than preseptal cellulitis although data relating to the exact incidence are scant.
- Both conditions occur more commonly in the winter months as a result of the increased incidence of paranasal sinus infection.
- There is no predilection for gender or race (except in children where orbital cellulitis affects four times as many females).
- Both conditions are more common in children: orbital cellulitis more frequently affects those aged 7-12 years, whereas preseptal cellulitis occurs at younger ages (80% of patients are under 10 years of age and most are younger than 5 with a mean age of 21 months).
- Preseptal and orbital cellulitis have both been described following eyebrow piercing.
Differentiation between preseptal and orbital cellulitis is often difficult at the initial presentation.
- Acute onset of swelling, redness, warmth and tenderness of the eyelid.
- Fever, malaise, irritability in children.
- Sudden onset of unilateral swelling of conjunctiva and lids.
- Proptosis (bulging of the eye).
- Pain with movement of the eye, restriction of eye movements.
- Blurred vision, reduced visual acuity, diplopia.
- Pupil reactions may be abnormal - relative afferent pupillary defect (RAPD); see the separate article on Examination of the Eye.
- Fever, severe malaise.
- Orbital/preseptal cellulitis
- Necrotising fasciitis
- Allergic lid swelling
- Severe viral conjunctivitis
- Cavernous sinus thrombosis
- Other orbital conditions - eg, thyroid eye disease, orbital tumours/pseudo-tumours, orbital vasculitis
- Other conditions- eg, insect bite, angio-oedema, maxillary osteomyelitis
- Diagnosis is usually made based on the clinical findings and investigations are aimed at identifying the root cause of the infection - particularly in the case of orbital cellulitis. Investigations are carried out in the hospital setting.
- FBC frequently shows a leukocytosis (>15 X109) but blood cultures are frequently negative in adults. They cannot be counted on to differentiate between preseptal and orbital cellulitis.
- Any discharge from skin breaks should be swabbed and sent to microbiology. Throat swabs and samples of nasal secretions may also help diagnosis.
- CT of the sinuses as well as the orbit ± brain:
- CT is usually indicated only for children (unless the child is very well and the episode is mild) or if orbital cellulitis is suspected in an adult.
- if an intracranial abscess is suspected, CT is the gold standard imaging modality, carried out to identify any subperiosteal abscesses, paranasal sinusitis or cavernous sinus thrombosis (all needing multi-speciality input).
- It is also valuable in assessing trauma where there may be concerns about a retained orbital or intraocular foreign body.
- MRI may complement the CT in diagnosing a cavernous sinus thrombosis.
- If cerebral or meningeal signs develop, the patient may need a lumbar puncture. However a lumbar puncture is contra-indicated for suspected orbital cellulitis until a CT scan has ruled out raised intracranial pressure.
Emergency referral to secondary care is required for:
- All children
- Any patient with any indication of possible orbital cellulitis
- All patients who are systemically unwell
- Occasions where there is doubt over the diagnosis
- A patient not responding to treatment; or
- When drainage of a lid abscess is required
Most children are initially admitted to hospital (even for preseptal cellulitis) unless there is good reason not to. This may be just for 24 hours. Children should be considered to have orbital cellulitis until proven otherwise (ie repeated examinations normal, good response to antibiotics in first 24 hours and normal CT scan).
- Oral co-amoxiclav may be used for both adults and children as long as there is no allergy to penicillin. Clinical improvement should occur over 24-48 hours.
- Hospital management may involve intravenous therapy (eg, intravenous ceftriaxone until response is seen) and further investigation to confirm that this is indeed a simple preseptal cellulitis and that there are no unusual organisms involved.
- ENT will be involved if sinusitis is found.
- Hospital admission under the joint care of the ophthalmologists and the ENT surgeons is mandatory.
- Intravenous antibiotics are used (eg, cefotaxime and flucloxacillin) in addition to metronidazole in patients over 10 years old with chronic sinonasal disease.
- Clindamycin plus a quinolone such as ciprofloxacin are used where there is penicillin sensitivity. Vancomycin is also an alternative.
- Optic nerve function is monitored every four hours (pupillary reactions, visual acuity, colour vision and light brightness appreciation).
- Treatment may be modified according to microbiology results and lasts for 7-10 days.
- Surgery is indicated where there is CT evidence of an orbital collection, where there is no response to antibiotic treatment, where visual acuity decreases and where there is an atypical picture which may warrant a diagnostic biopsy. Surgery often concurrently warrants drainage of infected sinuses.
- Progression of infection to orbital cellulitis, especially in young children.
- Unusually, lagophthalmos (inability to close the eyelids completely over the globe), lid abscess, cicatricial ectropion and lid necrosis may also occur.
- Ocular: exposure keratopathy (which can lead to visual loss through permanent damage to the cornea), raised intraocular pressure, central retinal artery or vein occlusion, endophthalmitis, optic neuropathy.
- Orbital abscess: more often associated with post-traumatic orbital cellulitis. Blindness can occur through direct extension of the infection to the optic nerve.
- Subperiosteal abscess: usually located along the medial orbital wall. This may progress intracranially.
- Intracranial (rare): meningitis, brain abscess, cavernous sinus thrombosis.
Prompt diagnosis and treatment should result in an uncomplicated course and full recovery.
Early recognition and appropriate treatment should carry a good prognosis, particularly in the absence of complications. However immunosuppressed individuals are more susceptible to complications and fungal cellulitis can be associated with a high rate of mortality.
Haemophilus infection: Haemophilus influenzae type b (Hib) vaccination.
Prophylactic antibiotics are prudent in the management of surgical and accidental trauma to the lid. Chloramphenicol ointment is a good first choice, applied qds to the clean wound for a week. Traumatic lid laceration also benefits from a review a 48-72 hours down the line to help identify any emerging preseptal cellulitis early.
There is no definitive preventative management other than the optimal treatment of any precipitative factors such as sinusitis.
Further reading & references
- Rimon A, Hoffer V, Prais D, et al; Periorbital cellulitis in the era of Haemophilus influenzae type B vaccine: predisposing factors and etiologic agents in hospitalized children. J Pediatr Ophthalmol Strabismus. 2008 Sep-Oct;45(5):300-4.
- Clinical management guidelines: Cellulitis preseptal and orbital; The College of Optometrists (2011)
- Orbital Cellulitis; Handbook of Ocular Disease Management
- Moorfields Manual of Ophthalmology (2nd Ed), 2014
- Clinical Ophthalmology: A Systematic Approach (7th Ed) 2011.
- Witherspoon SR, Blomquist PH; Methicillin-resistant Staphylococcus. Ophthalmology. 2007 Jul;114(7):1420-1.
- Denniston AKO, Murray PI; Oxford Handbook of Ophthalmology, Oxford University Press, 2009
- Preseptal Cellulitis; Handbook of Ocular Disease Management
- Sadovsky R; Distinguishing periorbital from orbital cellulitis. American Family Physician, March 2003
- Carelli R, Fimiani F, Iovine A, et al; Ocular complications of eyebrow piercing. J Pediatr Ophthalmol Strabismus. 2008 May-Jun;45(3):184-5.
- Botting AM, McIntosh D, Mahadevan M; Paediatric pre- and post-septal peri-orbital infections are different diseases. A retrospective review of 262 cases. Int J Pediatr Otorhinolaryngol. 2008 Mar;72(3):377-83. doi: 10.1016/j.ijporl.2007.11.013. Epub 2008 Jan 11.
- Clinical practice guidelines: Periorbital and Orbital Cellulitis; The Royal Children's Hospital, Melbourne
- The Wills Eye Manual (6th ed), 2012
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Olivia Scott
Dr Colin Tidy
Dr Olivia Scott