What happens to Listing's plane during convergence?

When looking about on a near surface (e.g. at the pattern on a bowl close to the face) eye position
1) remains constrained to Listing's plane
2) but Listing's plane (LP) in each eye turns temporally as does the eye's Primary Position (PP).

As the vergence increases the temporal rotation of Listing's plane increases.

This means that the eyes become intorted (int) when looking up and extorted (ext) when looking down.


Copyright © 1996 Tutis Vilis and Douglas Tweed
University of Western Ontario
London Ontario Canada
Updated October 28, 2005

Comments welcome. Email to tutis.vilis@schulich.uwo.ca