Ultrasound Teaching Atlas
Draft — not yet peer-reviewedadvancedHead / EyeOcular

Ocular Ultrasound

Assess the globe for retinal detachment, vitreous hemorrhage, and lens dislocation, and measure the optic nerve sheath diameter.

This module is a content/teaching-structure draft. Images shown are illustrative schematics — real, de-identified, license-verified ultrasound clips replace them before peer review.

Learning objectives

  • Safely scan the closed eye with a high-frequency linear probe and the ocular preset.
  • Identify retinal detachment, vitreous hemorrhage, and lens dislocation.
  • Measure the optic nerve sheath diameter (ONSD) 3 mm posterior to the globe.

Maps to

  • Resident: ACEP Emergency Ultrasound — Ocular: Image Acquisition
  • Resident: ACEP Emergency Ultrasound — Ocular: Pathology recognition
  • Tech: Ophthalmic / POCUS ocular assessment

Acquisition — getting the view

Probe
linear
Patient position
Supine or semi-recumbent, eye closed.
Orientation convention
radiology
Probe placement
Over the closed upper eyelid
Marker direction
Indicator to patient's right (transverse), then sagittal

Probe placement (3D)

Over the closed upper eyelid

Structures in the imaging plane (near → far): Eyelid · Anterior chamber · Lens · Vitreous chamber · Retina · Optic nerve sheath

Step by step

  1. Select the ocular preset (low acoustic output), apply a tegaderm over the closed lid, and a generous layer of gel.
    Why: The ocular preset limits energy to the eye; the tegaderm keeps gel off the lid.
  2. Rest the linear probe gently on the closed lid with NO pressure on the globe; scan in transverse and sagittal planes.
    Why: Pressure is avoided, especially with suspected globe rupture.
  3. Have the patient move their eyes to assess mobility of any membrane or opacity.
    Why: A detached retina or vitreous moves characteristically with eye movement.

Troubleshooting

Hard to see subtle findings in the vitreous.
Increase the gain — low-level vitreous hemorrhage becomes visible at higher gain.
Suspected globe rupture.
Minimize or avoid scanning; any pressure is contraindicated.

Findings: normal

Normal globe

Anechoic vitreous, a thin posterior wall, and a hyperechoic lens anteriorly, with no membranes or opacities.

Schematic of a normal globe on ultrasound
Schematic: normal anechoic vitreous, lens anteriorly.
Original schematic, dedicated to the public domain (CC0).

Findings: pathology

Retinal detachment

A hyperechoic membrane in the vitreous, tethered at the optic disc, that undulates with eye movement and does not cross the optic nerve.

Signs: Membrane tethered at the optic disc; Undulates with eye movement

Schematic of retinal detachment
Schematic: detached retina tethered at the optic disc.
Original schematic, dedicated to the public domain (CC0).

Raised intracranial pressure (by ONSD)

An optic nerve sheath diameter measured 3 mm behind the globe that exceeds ~5–6 mm suggests elevated intracranial pressure.

Signs: ONSD > 5 mm (measured 3 mm posterior to globe)

Interpretation practice

A bright, mobile membrane in the posterior vitreous is tethered to the optic disc and sways as the patient moves their eye. What is it?

Mobile membrane tethered at the optic disc
Mobile membrane tethered at the disc — interpret.
Original schematic, dedicated to the public domain (CC0).

Measurement practice

Measure the optic nerve sheath diameter 3 mm posterior to the globe.

ONSD measurement 3 mm behind the globe
Place calipers across the sheath, 3 mm behind the retina.
Original schematic, dedicated to the public domain (CC0).
mm

Check your understanding

At what distance behind the globe is the ONSD measured?

What probe and setting are used for ocular ultrasound?

References

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