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Stereo Imaging Tutorial

NOTE: You will need to use stereo viewers to view the image examples in the below links.

Stereo imaging is the process of capturing two images that when viewed as a pair create a 3 dimensional quality in the resulting image. It is very useful to physicians in helping them to determine within what layer of the retina pathology exists.

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Joy Stick Positions

Stereo imaging in ophthalmic photography can be done in fundus photography or in fluorescein or ICG angiography. The effect is created by taking 2 sequential images while using the camera joystick to shift the fundus camera from the left edge of the pupil to the right edge of the pupil.

Center

First, position the camera centered in the patient's pupil.

 

Left

Next, using the joystick, move the camera to the left side of the pupil and take an image.
 
Right

Then, using the joystick, shift to the right side of the patient's pupil and take the second image of the stereo pair.

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Shadow and Arc

Shifting of the camera results in artifacts, i.e. shadowing or "arc" from the pupil.

This red free stereo pair demonstrates both shadow (moderate) and arc (minimal).

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Less Artifact

These artifacts can be kept to a minimum with some pathology and adequate stereo still be maintained.

Red-Free Less Artifact
This red-free stereo pair demonstrates good stereo with less shadow and arc.

Less Artifact
This mid-phase fluorescein stereo pair of the same eye stereos well with minimal artifact.

Minimal Artifact

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FA and ICG

More shifting to the edge of the patient's pupil will result in more arc or shadow; however, it also yields an increased stereo effect.

FA Example
This mid-phase stereo disc pair demonstrates more arc, which obscures the edges of the image. This is acceptable because the emphasis is on the optic disc.

ICG Example
Stereo ICG images do not show as much artifact, even though the photographer must move the camera more than in fluorescein angiography (shifting left, shifting right) to obtain stereo effect.

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Early, Mid, and Late Phases: FA and ICG

Stereo images are part of the DARC protocol for red-free as well as early, mid, and late phases of fluoroscein and ICG angiography. More joystick movement to side of pupil is required to obtain stereo in ICG.

Early FA

Mid FA

Late FA
 

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Early ICG

Mid ICG

Late ICG

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For more detailed information regarding stereo imaging, refer to:
  • Stereoscopic Atlas of Macular Diseases: Vol. I - IV. J. Donald Gass.
  • Stereo Atlas of Fluorescein and Indocyanine Green Angiography. Stevens, Saine & Tyler.
  • Stereo Fundus Photography: Principals and Techniques. Tyler, ME. 10/1996 Vol 18:2 p 68.
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