Ocular US

Question 1

Setup

Answer 1

• Pt supine w both eyes closed
• Probe: linear 7-10MHz or phased array 1-5MHz
• pillow: under shoulders if req to assist w viewing
• get Pt to look up & down slowly: rule out ‘swirling’ haemorrhage & assess for retinal detachment

Question 2

Indications

Answer 2

• decreased or loos of vision
• suspected foreign body
• ocular pain
• eye trauma
• head injury w suspected intracranial pressure
• follow up melanoma after laser Rx
• degenerative disorders
• asymptomatic loss of vision

Question 3

Retinal detachment

Answer 3

• most important finding!! Must ensure retina is attached
• occurs due to vitreous liquid moving through retinal layer due to small tears
• acute phase: appears as a thin to mild thickening of membrane anchored by the optic disc
• chronic phase: membrane is quite thickened & has reduced or absent flow on colour Doppler
• dynamic movement: will often cause membrane to flutter, confirming RD
• perf* can still be present under colour Doppler
• not to be confused w Lens or Vitreous detachment

Question 4

Foreign body trauma

Answer 4

• if global rupture suspect - NO US! Collapse of anterior chamber with extrusion of vitreous fluid
• metal/plastic/glass - can be echogenic w shadowing
• wood - hyperechoic
• check for metal if suspected instead of MRI - as unsuitable
• US has greater sensitivity for FB than CT
• assess vitreous component as haemorrhage can sometimes be present depending on the severity of the puncture

Question 5

Pathologies of anterior chamber

Answer 5

• hyphema - blood in the fluid at the anterior chamber (often trauma related)
• not always a Dx, can be an indicator for underlying pathology
• assess the integrity of the pupil & cornea
• assess size of fluid space & compare w contralateral side

Question 6

Pathologies posterior chamber

Answer 6

• cataracts can be assessed under US; usually ageing related not trauma
• assess lens: can show calcification w posterior acoustic shadowing (can mimic FB, check Hx)
• important to understand the appearances of diff pathologies to rule out sinister findings

Question 7

Vitreous haemorrhage

Answer 7

• blood has leaked or pooled in the vitreous humour
• causes: trauma, diabetic retinopathy & underlying pathology - retinal tears
• Pts generally complain to floaters unilateral & some associated loss of vision - if leakage is significant than it can be seen visibly
• important to know Pt Hx: cause & acute Vs chronic
• get Pt to move eye R to L to visualise swirling motion

Question 8

Ocular tumours

Answer 8

• multiple tumours can be detected under US
• most arise from the choroid as it is highly vascular
• benign or mal*: haemangioma is most common mass detected (benign)
• retinoblastoma: most common intraocular tumour detected in children (echogenic masses, heterogeneous & vascular)
• choroidal metastatic carcinoma (CMC) are the most common location for ocular mets: primary in women - breast, primary in men - lung
• CMC appears uniform & echogenic w vascularity
• these tumours will generally be incidental in nature