Ultrasound - Ocular
To assess and exclude the presence of:
Raised intracranial pressure
Consider in the following presentations:
Suspected raised ICP
Facial trauma (especially if lid swelling inhibits eye opening)
Contraindications (absolute in bold)
Globe rupture (if suspected on eye examination without ultrasound)
Airway management or resuscitation required
Standard eye examination with slit lamp and fundoscopy
Consent is not required if the patient lacks capacity or is unable to consent
Brief verbal discussion is recommended if the situation allows
Less complex non-emergency procedure with low risk of complications
Failure to visualise structures (gas in tissue, pain)
Failure of image interpretation (false negative or positive)
PPE: non-sterile gloves
Ultrasound machine and sterile gel
Linear ultrasound probe (high-frequency)
Positioning (marker descriptions for phased array cardiac probe)
Eyes closed in neutral position (looking straight head)
Large pillow of ultrasound gel directly on eyelid
Rest one end of the probe on nasal bridge or forehead (minimising pressure on the eye)
Sequence (general scanning)
Begin on the affected side
Set gain to create a hypoechoic posterior chamber
Scan in two planes with the eyes static and moving in all direction (kinetic echography)
Repeat on the unaffected side comparing anatomy
Sequence (specific signs in pathology)
Retrobulbar haematoma: hyperechoic structure in the retrobulbar area
Optic nerve oedema (raised ICP): sheath diameter >5mm, 3mm behind globe (nerve sides parallel)
Retinal detachment: retina visible as a thin serpentine echogenic line separate from there posterior globe
Subretinal haemorrhage: hyperechoic shifting fluid collection separated from the vitreous by the retina
Vitreous haemorrhage: hyperechoic structures in vitreous swirling on kinetic echography
Fibrinous vitreous bands: an asymptomatic bilateral finding that are seen increasingly with age
Globe rupture: anterior chamber collapse, buckling of sclera, decreased globe size, circular contour lost
Lens dislocation: disrupted lens position compared to unaffected eye
Foreign body: hyperechogenic structure with shadowing or comet tail artefact
Clean ultrasound gel from patient
Consider further assessment (ophthalmology review, CT of orbits)
Complete clinical assessment combining results with clinical history, exam and other investigations
Non-sterile ultrasound gel carries a risk of causing conjunctivitis and should be avoid
The optic nerve diameter can be overestimated if measures when its sides are imaged not parallel
Foreign bodies cannot be excluded by ultrasound (sensitivity 90%)
Ultrasound evaluation of the eye is particularly useful in trauma when swelling limits direct visualisation and evaluation of the eye and surrounding structures. Assess for retrobulbar haemorrhage, optic nerve oedema, retinal detachment, vitreous haemorrhage, globe rupture and foreign bodies.
Bedside ocular ultrasound is a reliable technique to detect elevated ICP in traumatic and non-traumatic presentations. Intracranial pressure is transmitted to the subarachnoid space surrounding the optic nerve, causing optic nerve sheath diameter expansion.
Posterior vitreous detachment appears similar to retinal detachment. It occurs increasingly with age and is usually an asymptomatic process but may presents with flashes of light. It appears thinner and less echogenic than a retinal detachment and is not tethered to the optic nerve (unlike a retinal detachment). Posterior vitreous detachment may become more symptomatic when it causes a tear in the retina resulting in haemorrhage and a retinal detachment.
This guideline has been reviewed and approved by the following expert groups:
Emergency Care Institute
Please direct feedback for this procedure to ACI-ECIs@health.nsw.gov.au.
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