A Visual approach doesn't have to be in VMC if your IFR. Under all EASA regs (CAT,NCC,NCO,SPO) minimum visual reference is 800m for a visual approach. I would barely do a hand flown ILS in that vis let alone a visual somehow. But thats what its says. ICAO PANS-OPS does not reference Contact approaches. If Japan, Canada and the states do it I would image it came from TERPS.