A little confused by what you're referring to. Do you mean minimum visual conditions for a VFR flight (with a caveat in Australia allowing authorisation for "Special VFR"). Or are you referring to the criteria by which approach/tower can authorise you to make a Visual Approach (both IFR and VFR)?
My understanding of Visual Approaches is that they may be authorised and conducted ()at least in Australia):
1)By Day:
Within 30nm of the Aerodrome and not below MSA/LSALT/appropriate DME Step/Procedure MDA.
Clear of Cloud
In sight of ground or water
Flight VIZ not less than 5000 meteres.
2)By Night:
As above, but in addition;
Be within the circling area OR
Within 5nm of an AD (7nm for RWY with ILS) established not below "On Slope" of PAPI/VASI and on the RWY centreline OR
Within 10nm of an AD established not below "On Slope" of the ILS with less than full scale deflection.
Convoluted way of saying that minimum VIZ day or night must not be less than 5000metres with the ground/water in sight.
Any less? Expect Instrument Approach!