01OverviewDefinition, clinical context and the essential points that orientate the chapter.
The orbit contains the globe, muscles, nerves, vessels and fat within a relatively rigid bony enclosure. A rapidly expanding haemorrhage or swelling can exceed the ability of those tissues to accommodate additional volume. Pressure then compromises ocular and optic nerve perfusion. Retrobulbar blood seen on CT is not automatically orbital compartment syndrome: some collections remain small and do not threaten vision. Conversely, a clinically tense orbit with deteriorating visual function requires action before imaging proves a collection.
Common settings include blunt facial trauma, orbital surgery and periocular anaesthetic injection. Anticoagulant treatment or a bleeding disorder can increase risk, and symptoms may emerge after an initially reassuring examination. Pain, proptosis, tight swollen lids, restricted movement and visual deterioration should be assessed together. An afferent pupillary defect is particularly concerning for compromised afferent visual function. A patient who is sedated, unconscious or distressed may not report visual loss, so inspect the orbit and pupil responses rather than requiring a verbal complaint before considering the diagnosis.
The urgency comes from perfusion failure rather than the cosmetic appearance of swelling. Severe permanent loss can develop within approximately two hours, sometimes sooner, and there is no safe waiting allowance based on that figure. Record the time of the precipitating event and observed deterioration while treatment is organised. An orbital fracture does not guarantee that pressure has been adequately relieved. A very swollen but soft eyelid after a superficial contusion differs from a tense orbit with proptosis and deteriorating function; the complete pattern matters.
Initial assessment should be focused and fast. Record acuity at the available level, pupil responses and eye movements, and inspect for signs of an open globe. Pressure measurement can support the diagnosis when globe integrity permits and equipment is immediately available, but it should not delay action in a convincing clinical emergency. Do not press on a possibly ruptured globe to estimate firmness. There is no single numerical pressure threshold that safely replaces the combined assessment of visual function, pupil findings and orbital tension.
Emergency treatment releases the lateral canthus and the constraining tendon components, usually through lateral canthotomy with inferior cantholysis. It is a procedure for a suitably capable clinician working within an emergency response, with immediate senior and specialist involvement. A skin incision alone may not achieve adequate decompression. The treating clinician must confirm release and promptly reassess the physiological effect. Do not move the patient to a scanner or wait for a distant specialist when a capable clinician is available to relieve a clinically threatened orbit.
After release, improvement in pressure, lid tension, pain, pupillary function or vision helps indicate the response, although the recovery of vision can be incomplete or delayed. Persistent compromise may require further release or operative orbital decompression and control of the bleeding source. CT then helps define fractures, retained material and the remaining collection. Review anticoagulants, coagulation and the need for reversal with the relevant specialists. Pressure-lowering medicines can be selected as adjuncts, but waiting to see whether they work is inappropriate when mechanical decompression is already indicated.
An open globe complicates this pathway because contact procedures can worsen extrusion and the surgical risks of canthal release differ. Seek immediate experienced ophthalmic and trauma judgement, protect the eye and avoid assuming that one visible injury excludes the other. After emergency treatment, the patient needs monitored transfer or admission, serial visual assessment and definitive management of the original trauma. Explain the uncertainty of visual recovery without declaring the treatment futile because some time has already passed; persistent pressure should still be urgently addressed.
Key points
- Retrobulbar haemorrhage describes blood behind the eye; orbital compartment syndrome describes the dangerous pressure and perfusion effect, so the terms are not interchangeable.
- Assess vision, pupils, colour perception when feasible, proptosis, lid tension and eye movements immediately after a concerning injury or procedure.
- The diagnosis of a threatened orbital compartment is clinical; CT is useful after initial treatment or when uncertainty can be resolved without delaying necessary care.
- Lateral canthotomy alone may not sufficiently release pressure; cantholysis releases the relevant tendon support and effective decompression must be confirmed.
- Obtain help from a clinician capable of emergency release; calling ophthalmology should run alongside the immediate response rather than create a waiting period.
- Avoid pressure-producing assessment if open-globe injury is suspected; simultaneous globe rupture creates a complex emergency requiring immediate senior judgement.
- Reassess vision, pupils and orbital tension after release and escalate persistent compromise; medicines and anticoagulant reversal do not substitute for needed decompression.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Traumatic orbital bleeding
Blunt facial injury can tear orbital vessels and produce an expanding retrobulbar collection, with or without an associated wall fracture.
Procedural haemorrhage
Periocular needle placement and orbital operations can injure vessels within a confined space, occasionally producing abrupt pressure elevation after the intervention.
Impaired haemostasis
Anticoagulants and bleeding disorders can increase the size or persistence of an orbital collection and contribute to delayed expansion.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Limited compartment compliance
Bony walls and anterior soft-tissue restraints restrict expansion, so added volume can cause a rapid increase in pressure around the globe.
- 2Compromised ocular perfusion
High orbital pressure impairs blood flow to the retina and optic nerve, creating an ischaemic mechanism for sudden visual dysfunction.
- 3Mechanical motility restriction
Haemorrhage, oedema and pressure restrict the normal movement of the globe and extraocular tissues, contributing to proptosis and painful ophthalmoplegia.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
The eye protrudes with markedly tight lids and restricted movement, suggesting pressure within the orbit rather than uncomplicated external bruising.
Falling acuity, impaired colour perception or a relative afferent pupillary defect supports threatened retinal or optic nerve function and increases urgency.
Severe pain and rapidly enlarging orbital swelling after injection or surgery should prompt immediate assessment even when the procedure initially appeared uncomplicated.
Sedation, unconsciousness or concurrent head injury may conceal pain and visual loss, requiring active observation of pupils, globe position and orbital tension.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Immediate visual and pupil assessmentFirst step - Why
- Identify evolving afferent dysfunction during the first clinical assessment.
- Interpretation and limitations
- Use achievable acuity categories and pupil responses without prolonged testing; unavailable detailed measurements must not prevent action on a convincing emergency pattern.
- 02
Globe integrity and orbital examination - Why
- Distinguish pressure-threatening proptosis from rupture or isolated external swelling.
- Interpretation and limitations
- Look for a wound or distorted globe and avoid contact if rupture is possible; assess movement and lid tension without repeated forceful manipulation.
- 03
Selective intraocular pressure measurement - Why
- Support assessment of a tense orbit when contact examination is safe.
- Interpretation and limitations
- An elevated reading strengthens concern but is not a prerequisite for emergency release, and tonometry is inappropriate with suspected open-globe injury.
- 04
Post-decompression CT and coagulation assessment - Why
- Define the source, associated injuries and factors sustaining haemorrhage.
- Interpretation and limitations
- Imaging and blood tests guide definitive treatment after the immediate threat is addressed; they must not displace required decompression from the first response.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Uncomplicated orbital haematoma
A collection can exist without clinically important compression; preserved function and lack of progressive tension distinguish it from a threatened compartment.
Traumatic optic neuropathy
Optic nerve injury can produce visual loss and an afferent defect without the tense proptosis characteristic of orbital pressure compromise.
Open-globe injury
A disrupted eye wall may cause visual loss with an abnormal pupil or visible wound; its pressure-sensitive examination risks differ from those of an intact globe.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01Recognise and actTreat the clinical perfusion emergencyFirst stepRapid visual compromise occurs with a tense protruding eye after trauma or an orbital procedure.+
- 1Call senior emergency, ophthalmic and surgical support, documenting the onset and essential acuity and pupillary findings while preparing immediate treatment.
- 2Have a clinician capable of the procedure perform urgent lateral canthotomy and appropriate cantholysis when clinically indicated, without waiting for CT or transport.
- 3Maintain analgesia, physiological support and observation, recognising that pressure-lowering medication cannot replace release of a mechanically threatened compartment.
02Assess the responseConfirm effective pressure releaseEmergency canthal release has been performed but the degree of restored perfusion remains uncertain.+
- 1Repeat acuity, pupil assessment and orbital tension promptly, with pressure measurement where safe and useful to judge the effect of release.
- 2EscalationSeek immediate specialist escalation if tension or visual compromise persists, considering incomplete cantholysis, ongoing bleeding or a need for more extensive decompression.
- 3DefinitiveRecord the procedure, its timing and response, then obtain imaging and definitive surgical planning without allowing recurrent compression to go unnoticed.
03Ongoing careControl the cause and protect recoveryThe immediate orbital pressure threat has been treated and the patient requires continued management.+
- 1Assess associated facial and ocular injuries and review anticoagulants or bleeding disorders with specialists, arranging reversal or haemostasis where indicated.
- 2Admit or transfer with monitoring and serial eye observations, providing a clear handover of visual function before and after decompression.
- 3Arrange repair and follow-up of the canthal wound, pressure, ocular surface and visual function, including rehabilitation if a lasting deficit remains.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Permanent visual loss
Sustained interruption of retinal or optic nerve perfusion can produce irreversible severe visual impairment despite subsequent control of the haemorrhage.
Corneal exposure injury
Proptosis and impaired lid closure can leave the ocular surface exposed, causing epithelial breakdown and additional discomfort or infection risk.
Persistent orbital or lid dysfunction
The initial trauma, muscle damage and emergency tissue release can leave diplopia or eyelid malposition requiring further specialist management.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Reassess visual function and pupils immediately after decompression and repeatedly according to the acuity of the situation, rather than judging success from bleeding alone.
- Watch for recurrent tense swelling or increasing pain, which can indicate continued haemorrhage despite an initially successful release.
- Monitor the consequences of associated trauma, anticoagulant reversal and any adjunct medicines alongside the ophthalmic observations.
- Follow corneal exposure, eyelid position and wound healing after canthal release, with definitive specialist repair and visual rehabilitation as needed.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Blood on CT is not the syndrome
Imaging demonstrates anatomy, whereas the emergency decision concerns pressure and threatened function; a collection without compromise has a different management context.
Canthotomy must achieve release
Opening the lateral skin is not sufficient evidence of effective decompression if tendon restraint and orbital tension remain.
A fracture is not protection
Orbital wall disruption can coexist with dangerous pressure, so the presence of a fracture cannot cancel concerning visual and pupil findings.
Delay is not a futility test
Late recognition worsens prognosis but does not justify leaving a persistently tense, visually compromised orbit without urgent specialist assessment and treatment.
11Common pitfallsFrequent interpretation and management errors.
- 01
Sending a clinically obvious orbital compartment syndrome to CT before arranging available emergency decompression.
- 02
Waiting for an intraocular pressure number when deteriorating vision, pupillary change and tense proptosis already indicate the emergency.
- 03
Treating the haemorrhage with medication alone while delaying a necessary mechanical release.
- 04
Assuming the procedure succeeded because a skin incision was made without reassessing vision, pupils or residual tension.