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Ultrasound - Ocular

Indications

To assess and exclude the presence of:

Retinal detachment

Vitreous haemorrhage

Raised intracranial pressure

Retrobulbar haematoma

Globe rupture

Lens dislocation

Foreign body

Consider in the following presentations:

Visual loss

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

Alternatives

Standard eye examination with slit lamp and fundoscopy

Informed consent

Medical emergency

Consent is not required if the patient lacks capacity or is unable to consent

Brief verbal discussion is recommended if the situation allows

or

Verbal consent

Less complex non-emergency procedure with low risk of complications

Potential complications

Failure to visualise structures (gas in tissue, pain)

Failure of image interpretation (false negative or positive)

Procedural hygiene

Standard precautions

PPE: non-sterile gloves

Area

Any bed

Staff

Procedural clinician

Equipment

Towel

Ultrasound machine and sterile gel

Linear ultrasound probe (high-frequency)

Positioning (marker descriptions for phased array cardiac probe)

Semi-recumbent

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

Post-procedure care

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

Tips

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%)

Discussion

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.

Peer review

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.

References

Emergency ultrasound imaging criteria compendium. Ann Emerg Med. 2016;68(1):e11-e48. doi:10.1016/j.annemergmed.2016.04.028

Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges’ clinical procedures in emergency medicine and acute care. 7th ed. Philadelphia, PA: Elsevier; 2019.

Dunn RJ, Borland M, O'Brien D (eds.). The emergency medicine manual. Online ed. Tennyson, SA: Venom Publishing; 2019.

Dawson M, Mallin M. Introduction to bedside ultrasound: volume 1. New York NY: Apple Books; 2013.

Dawson M, Mallin M. Introduction to bedside ultrasound: volume 2. New York NY: Apple Books; 2013.

Gardiner M (2020): In: UpToDate. Waltham (MA): UpToDate.: Approach to eye injuries in the emergency department

Manoj P, et al (2019): In: UpToDate. Waltham (MA): UpToDate.: Emergency ultrasound in adults with abdominal and thoracic trauma

Kilker BA, Holst JM, Hoffmann B. Bedside ocular ultrasound in the emergency department. Eur J Emerg Med. 2014;21(4):246-253. doi:10.1097/MEJ.0000000000000070

Gottlieb M, Holladay D, Peksa GD. Point-of-care ocular ultrasound for the diagnosis of retinal detachment: a systematic review and meta-analysis. Acad Emerg Med. 2019;26(8):931-939. doi:10.1111/acem.13682

Munawar K, Khan MT, Hussain SW, et al. Optic nerve sheath diameter correlation with elevated intracranial pressure determined via ultrasound. Cureus. 2019;11(2):e4145. Published 2019 Feb 27. doi:10.7759/cureus.4145

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