Ocular Ultrasound Exam Techniques

FIXME

B-Scan

Three probe positions

Transverse scan: probe marker oriented either vertically or nasally (depending on position on globe- should always see nerve at the start i.e. when looking at nasal retina probe should be vertically oriented), held at superior, inferior, medial and lateral and rotated as far anterior as possible looking at opposite side of eye Longitudinal scan: probe marker always pointing at the limbus, described in clock hours where the top of the image is oriented: 9 o'clock longitudinal scan includes the macula, optic nerve, Axial scan: probe on center of eye, vertical and horizontal images

Sequence of Exam

  1. Survey 4 quadrants with transverse probe position
    1. Superior quadrant scan using horizontal transverse probe position
      1. Marker is nasal and the patient is looking superiorly to expose more of the eye
      2. Place probe on the inferior limbus and identify the optic nerve (superior in the image will be nasal)
      3. Sweep the probe down pointing the tip up to see the superior globe
    2. Inferior quadrant scan using horizontal transverse probe position
      1. Marker is nasal and the patient is looking inferiorly
      2. Place probe on the superior limbus and find the optic nerve
      3. Sweep the probe up, pointing the tip down to see the inferior globe (superior in the image will be nasal)
    3. Nasal quadrant scan using a vertical transverse probe position
      1. Marker is placed superiorly (vertical) and the patient eye is adducted (nasal rotation)
      2. Place the probe on the temporal limbus and find the optic nerve
      3. Sweep the probe temporally to visualize the nasal retina from the optic nerve anteriorly (superior in the image will be superior)
      4. In this quadrant the image can be very anterior including the iris
    4. Temporal quadrant scan using a vertical probe position
      1. Marker is placed superior and the patient has their eye abducted (temporal rotation)
      2. Place the probe on the nasal limbus and find the optic nerve
      3. Sweep the probe nasally to visualize the temporal retina from the optic nerve anteriorly (superior in the image will be superior)
  2. Use Tranverse scans to better image and localize pathology at the meridians or other clock hour positions
    1. Probe marker is pointed to the limbus and the patient looks away from the probe position
    2. The top of the image is the anterior retina and the bottom of the image is the optic nerve (when the probe is at 9:00) or the posterior retina
  3. Use Axial scans to document the position of the lens to the optic nerve (often more aberration of the image due to the crystallin lens or IOL)
    1. Horizontal axial- orient the probe marker nasally and image directly into the pupil (superior in the image will be nasal)
      1. The optic nerve will be in the center and the macula just inferior
      2. This view can be used to measure the axial eye length
    2. Vertical axial (less useful)- orient the probe marker superior and image directly through the pupil (superior in the image is superior)
      1. If the optic nerve is in the image, the macula is not visible.

A-Scan

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