Not necessary to see the field under vanilla ICAO rules. ICAO says:
An IFR flight may be cleared to execute a visual approach provided the pilot can maintain visual reference to the terrain and:
a) the reported ceiling is at or above the approved initial approach level for the aircraft so cleared; or
b) the pilot reports at the initial approach level or at any time during the instrument approach procedure that the meteorological conditions are such that with reasonable assurance a visual approach and landing can be completed.