Vision  may,  as  I  have  seen,  be  sometimes  impaired  alone,  almost  always
on  one  side.  There  may  be  absolute  loss  of  sight,  or  only  great  amblyopia
and  reduction  of  the  field  to  a  small  area  around  the  fixing  point.  The  iris
still  acts  perfectly  to  light,  and  the  fundus  oculi  is  normal.  The  loss  is
usually  sudden ;  sometimes  it  follows  a  hysteroid  fit.  It  is  usually  transient,
passing  away  in  a  few  days  or  weeks.  An  instance  of  more  permanent  loss
of  sight  of  this  character  is  mentioned  on  p.  590 ;  in  this,  such  unilateral
amblyopia  has  now  lasted  for  six  years,*  sometimes  improving  a  little,  and
then  relapsing,  still  without  change  in  the  action  of  the  pupil  or  in  the
fundus.    Very  rarely  hysterical  patients  have  transient  bilateral  loss  of  sight.
Hearing  is  involved  in  the  hemianaesthesia,  but  scarcely  ever  alone.  The
loss  is  usually  greater  for  sounds  conducted  through  the  bone  than  for  those
conducted  through  the  air.f  The  nerve  also  loses  its  normal  sensitiveness
to  electrical  stimulation.
Motor  Symptoms. — Paralysis  is  very  common,  and  may  involve  almost  any
part  of  the  motor  apparatus.  The  onset  may  be  sudden  or  gradual ;  it  may
follow  a  convulsive  seizure,  or  may  be  excited  by  emotion.  Some  transient
palsy  may  follow  each  fit,  paraplegia  after  one,  hemiplegia  after  another.
