DW> However, there is a problem with middle-distance. This is one
 DW> of the reasons why I now wear graduated-focal glasses. By
 DW> looking through the right part of the lens, I can see
 DW> close-up, distance, or anywhere in between perfectly clearly.
 DW> They took a while to get used to, but now I love them.

I'm the same way.  One of the problems getting used to these lenses is
caused by poor fitting.  The lenses can be raised or lowered by moving the
nose pads in or out, respectively.  This is critical for those of us who
have a lot of trouble getting used to these lenses.  If the positive part
of the lens interferes with a level line of sight, I get a headache. 
Moving the nose pads apart just a millimeter or less lowers the lenses,
relieving the effect.  Of course, if the lenses were cut improperly, this
adjustment must be made to too large an extent.  In that case, return to
the place where they were bought and they'll have to cut you some new ones.

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