I didn't mention " visual circuit" you guys dreamt that one up!
‘Visual approach’ means an approach when either part or all of an instrument approach procedure is not completed and the approach is executed with visual reference to the terrain.
The original question was in regards to the missed approach following a circle ( or part circling) procedure.
Please read more carefully the previous answer and all will become clear.
Bloggs of course you can have a lower vis for a visual approach segment following an instrument approach than required for a circle. check any Jepp or Aerad .
Groucho, nope! if the chart specifies more vis then you go by the chart, Vienna, Innsbrook, Chambery, all require more than 2400m. I.e at MDA you must have the required in flight Vis to continue the manoeuvre.