BloodSweatxED
PRN Education · No. 009 · POCUS Series

Ocular
Ultrasound.

Ocular ultrasound evaluates the posterior segment of the eye that a fundoscopic exam often cannot — through a closed lid, in a supine patient, without dilation. It identifies retinal detachment, vitreous hemorrhage, lens dislocation, and indirect evidence of elevated intracranial pressure.

The exam is performed with a closed eye, a generous gel layer, and no pressure on the globe.

Source

Curated from the POCUS 101 Ocular Ultrasound Made Easy: Step-By-Step Guide. The video clips of retinal detachment and vitreous pathology in motion are essential viewing — these are dynamic diagnoses.

When to scan

Indications and one firm contraindication

Indications

  • Acute vision loss, new floaters, flashes, or a visual field defect
  • Ocular trauma without suspected globe rupture
  • Suspected lens dislocation
  • Suspected elevated intracranial pressure (optic nerve sheath diameter)
  • Assessment of pupillary response when the lids are swollen shut

Do not scan

  • Suspected globe rupture is a contraindication to any pressure on the eye. If it must be imaged, float the probe on a thick gel layer with no contact pressure, or defer entirely.
  • Do not delay definitive ophthalmology consultation for a positive or equivocal scan.
  • Use an ocular or orbital preset where available — it limits acoustic output (mechanical/thermal index) appropriately for the eye.

Setup

Protect the eye, then image it

Probe

Linear, high-freq

Ocular/orbital preset if the machine has one. Depth set so the globe fills most of the screen with the optic nerve visible posteriorly.

Patient

Supine, eyes closed

A transparent adhesive dressing over the closed lid keeps gel out of the eye. Apply a generous gel mound so the probe rests on gel, not lid.

Hand position

Anchored

Brace your hand on the patient's forehead or nasal bridge so probe pressure cannot transmit to the globe.

The scan

Static, dynamic, then the nerve
GLOBE · AXIAL SECTION cornea lens vitreous detached retina tethered at the disc optic nerve ONSD here 3 mm behind the globe >5 mm suggests high ICP 3 mm
Fig. 1 — A detached retina stays anchored at the optic disc; the sheath is measured 3 mm posterior to the globe, perpendicular to the nerve.

Survey the globe in two planes

Transverse and sagittal · fan through the entire globe

Identify the anterior chamber, the lens, the anechoic vitreous, and the retina as the bright posterior boundary. Fan completely through the globe in both planes — peripheral pathology is missed by a single midline slice.

Increase the gain

Slowly raise gain from low to high

Subtle vitreous pathology — hemorrhage, posterior vitreous detachment — is often invisible at low gain and only appears as gain is increased. Examine the vitreous at both low and high gain before calling it clear.

Dynamic exam

Patient looks left-right and up-down with eyes closed

Eye movement differentiates the membranes. A detached retina moves stiffly with a tethered undulation; a posterior vitreous detachment is a thinner, more freely mobile membrane; vitreous hemorrhage swirls with eye movement and settles when still.

Key discriminator: a retinal detachment remains attached at the optic disc and the ora serrata. A membrane that crosses over the optic disc is not retina.

Optic nerve sheath diameter

Optic nerve in long axis behind the globe · measure 3 mm posterior to the retina

Identify the hypoechoic optic nerve extending posteriorly from the globe. Measure the sheath diameter 3 mm behind the posterior globe wall, perpendicular to the nerve. Average measurements from both eyes.

Interpretation: ONSD greater than ~5 mm in adults correlates with elevated intracranial pressure. It is a supporting data point, not a standalone diagnosis — correlate clinically and with definitive imaging.

Calling it

Differentiating the membranes
FindingAppearanceAction
Retinal detachmentThick, echogenic membrane tethered to the optic disc; stiff undulation with eye movement; may form a funnel shapeEmergent ophthalmology consultation
Posterior vitreous detachmentThin, low-echogenicity membrane, freely mobile, may cross the disc; often needs higher gain to seeUrgent ophthalmology follow-up; can coexist with retinal tears
Vitreous hemorrhageMobile echogenic material swirling within the vitreous on eye movementOphthalmology referral; search carefully for underlying detachment
Lens dislocationLens displaced from its position behind the iris, seen within the vitreousOphthalmology consultation; assess for associated trauma
ONSD> ~5 mmSupports elevated ICP in context; correlate with CT and clinical picture
Globe rupture signsLoss of globe contour, decreased globe volume, intraocular hemorrhageStop scanning; shield the eye; emergent ophthalmology

Pearls & pitfalls

Common failure points
Pearl

The disc is the reference point

Attachment at the optic disc is what separates retinal detachment from posterior vitreous detachment. Always image the disc and trace the membrane's insertion before naming it.

Pitfall

Low gain hides pathology

Vitreous hemorrhage and PVD are low-amplitude echoes. At default gain the vitreous can look clear. Sweep the gain up before declaring a normal exam.

Pitfall

A static exam is half an exam

The membranes are distinguished by how they move. If the patient has not moved their eyes during the scan, the differential between detachment types has not been assessed.

Pearl

Pupillary assessment through swollen lids

In periorbital swelling, image the pupil in transverse while shining a light in the contralateral eye — the consensual response is visible on ultrasound when the lids cannot open.

Pitfall

Pressure on a suspicious globe

If the mechanism or exam suggests rupture, the risk of extruding intraocular contents outweighs the diagnostic value. Shield the eye and involve ophthalmology first.

Pearl

ONSD is a screen, not a verdict

Sheath diameter varies between patients and measurement technique matters. Use it to raise or lower suspicion of intracranial hypertension alongside imaging — not to replace it.

Sample Epic documentation

Copy · edit · attest

A starting template for the POCUS note. Text in brackets [ ] and pick-lists in { } are fields to complete. Save it as a SmartPhrase, then edit every field to match the actual study.

.pocusOcular
POINT-OF-CARE ULTRASOUND: OCULAR

Indication: {vision loss : floaters / flashes : trauma : ? elevated ICP}
[side ***]
Exam type: Focused / limited, closed lid, no globe pressure
Operator: @ME@   Interpretation: independent, real-time
Probe: linear (ocular preset)
Globe rupture suspected: {no : yes - exam deferred / limited}

FINDINGS ([right : left])
- Retina: {attached : detachment tethered at disc}
- Vitreous: {clear : posterior vitreous detachment : hemorrhage}
- Lens: {in position : dislocated}
- Optic nerve sheath diameter (3 mm behind globe): *** mm
- Pupillary response (if assessed): {normal : ***}

IMAGE QUALITY: adequate / limited by [***]
Images saved and archived to [PACS / Qpath / ***].

IMPRESSION: [***]. Ophthalmology {consulted : not indicated}.

I personally performed and interpreted this study.
Electronically signed: @ME@  @TD@ @NOW@

Sample template only — not a validated institutional SmartPhrase. Verify wording, image-archival, and attestation requirements against your department's POCUS credentialing, coding, and compliance policies before clinical use. Documentation supports, but does not replace, the medical record and QA workflow.

PRN Education · POCUS Series

Keep scanning