Binocular single vision may be defined as a single mental impression perceived  in  free  space,   resulting   from   the   fusion    of   two   similar   images, one falling on the corresponding area of eachretina.


The field of  binocular   single  vision  (FBSV)   is  that  area  where  bifoveal   fusion   of   the  object   of   re­gard  occurs.  Normally,  the  field  of  BSV  is  delimited  partly  by  the  extent  of  the  ocular  rotations  and  partly  by  the  patient's   facial features.