Low abbe materials reduce the crisp edges of objects when viewed through the prism of the lens periphery. The effect, exaggerated here, causes a smearing of the edges of letters or the small details of distance vision through the lens periphery.
Few patients notice but some are sensitive enough to say “I just don’t think I see as well as my other glasses”. What they might be noticing is the slightly reduced field of clear view. Of course, low abbe lens materials are also high index so any small reduction in the clear field of vision is offset by as much as a 50% reduction in thickness and the comfort for lenses 40% lighter.