Friday, January 3, 2014

Tech Demo - Strabismus correction in the Rift

Strabismus is the condition of having divergent eyes, also known colloquially as being cross-eyed or wall-eyed.  To some extent it can be corrected for with glasses, and in more extreme cases, surgery.  Those afflicted who cannot get full correction with glasses or surgery are often at least partially stereo-blind, unable to use the differing parallax of objects to resolve their depth, and are forced to rely on other clues for depth perception.  Fortunately the brain is very good at generating a sense of depth from both parallax caused by moving the head and from cues such as known sizes for common objects.

I myself have divergent eyes.  My eyes diverge about 5° vertically and about 10° laterally.  I wear prismatic glasses that compensate to some degree, but not completely.  In fact, since I've started wearing the glasses the divergence has increased, as the glasses now do some of the work, allowing the eyes to work less hard to compensate, a situation my optometrist refers to as 'eating the prism'.

Since the release of the Rift I've been excited about the prospect not only of using it for immersive VR applications and games, but to allow me to correct for the divergent eyes.  While the Oculus VR SDK doesn't (yet) natively support measuring and correcting for this condition, doing so is actually pretty simple.  In fact I've created a small tech demo that does precisely that.

The tech demo is located here and is built for 64-bit Windows platforms.  I will soon be uploading Mac & Linux versions, as well as uploading the source code to my GitHub repository here.

If you have issues with perceiving depth, or wear glasses for correcting strabismus, I suggest you give it a try.


  1. Interesting. Can you see depth from disparity only (i.e., are you not stereo-blind?).

  2. I have Esophoria and was thinking the Rift would be a great tool for ocular muscle training / strengthening. Playing games would be much more fun than looking at wood balls tied to a string.

    Do you know if there is a way to adjust the camera angle used while gaming with the Rift to compensate for our condition? I wear prism glasses and I see double when playing games on the Rift. At the eye doctor there is an exercise where you turn dials to align a vertical and horizontal bar into a cross, it seems something like that would be possible to add to the Rift preferences UI.

    1. The mechanism of the demo is very similar to what you describe, but rather than using dials, you use head movement to align the views. You can try out the most recent version from Oculus Share if you have a Rift: