OCULAR ULTRASOUND BY DR LUKE PHILIPS
FACEM, MBBS, BSC(BIOMED)(HONS), CCPU
EMERGENCY CONSULTANT - ALFRED HEALTH
CO-DIRECTOR OF EMERGENCY MEDICINE TRAINING (THE ALFRED HOSPITAL)
CO-CHAIR OF THE EMUGs BOARD OF DIRECTORS.
75yo Female presents to the ED with sudden onset right visual loss.
Denies flashes/floaters and has no history of stroke/TIAs in the past. She denies any symptoms of polymyalgia rheumatica or temporal arteritis.
Pt has a past history:
Cataracts but no surgery. Wears glasses for reading.
Hypertension
Type 2 Diabetes
Atrial fibrillation – on Xarelto.
Non-smoker.
On exam:
Pupils equal, normal shape and reactive, normal eye movements
Normal visual acuity in left eye and unable to see anything from right eye
Normal eye pressures, no corneal abrasions and sclera not injected.
Non tender temporal artery with easily palpable pulse.
Investigations:
Normal ESR/CRP.
CT Brain – age related changes. No stroke, masses or intra-cranial haemorrhage.
I took over from overnight staff and reviewed the patient in the morning. A point of care ocular ultrasound was performed.
The Ultrasound
The Ultrasound demonstrates a macular off rentinal detachment. The thick undulating hyperechoic membrane in the posterolateral globe is always attached to the optic nerve posteriorly & the ora serrata anteriorly – Almost like a towel pegged on each end to a clothes line. The differential diagnosis is a vitreous detachment which tends to be more mobile, less uniform and is not attached to the optic nerve.
Ultrasound has a 97-100% Sensitivity for detecting retinal detachment & is 83-100% Specific in a recent meta-analysis. Use as a rule in test. If not visualised you may need to investigate further by dilating the pupil and looking at the retina with opthalmoscope or pan-optoscope.
The Time to diagnosis after I saw the patient was less than 10 minutes and the patient was referred for an urgent ophthalmology opinion.
How to Perform an Ocular Ultrasound
Machine settings:
Linear Probe
Ocular setting (nerve if ocular unavailable)
PRO TIP: Turn up Gain to ensure subtle findings are not missed.
Ensure barrier protection for eye – tegaderm over eye or probe cover
Use a large amount of ultrasound gel and hover the probe over the closed eye without exerting too much pressure on the globe.
Use with caution in patients with elevated eye pressures or globe rupture/suspected penetrating injuries.
Start in transverse in the mid-line.
Fan probe up and ask patient to look up
Fan probe down and ask patient to look down
Rotate Probe Longitudinally and Start in the mid-line.
Fan probe to left and ask patient to look left
Fan probe to right and ask patient to look right.
Further Resources
Ultrasound of the Week – Case 12
POCUS Toronto – Seeing Cleared With Ocular Ultrasound
The Diagnostic Accuracy of Bedside Ocular Ultrasonography for the Diagnosis of Retinal Detachment: A Systematic Review and Meta-analysis Vrablik, Michael E. et al. Annals of Emergency Medicine , Volume 65 , Issue 2 , 199-203.e1. https://doi.org/10.1016/j.annemergmed.2014.02.020
5min Sono – Retinal vs Vitreous Detachment
Read: Introduction to Bedside Ultrasound Vol 2 – Chapter 16 (Free E-Book)