Measurement of interpupillary distance with chromostereopsis.

Chromostereopsis is a perceived depth difference between coplanar objects of different color and can be used for highly accurate measurement of interocular separation (PD). A survey of PD measurement with chromostereopsis and with the PD rule on 83 subjects shows that these methods on average result in the same PD, indicating that chromostereopsis is a valid technique for PD measurement. Repeated PD measures by these 83 individuals on the authors, using the PD rule and chromostereopsis, shows that the chromostereopsis result is far more repeatable than the PD rule. Suggestions are made for the use of the chromostereopsis technique in optometric practice.