Circular shaped venetian blinds will have their slats handcrafted to the angle of their head rail. This means that the slats will tilt from the open position to, either backwards away from the room, or forwards into the room. Porthole blinds can be made so that the bottom section of slats rise up to the centre point (ideal if there’s a window handle to access or for cleaning the window).
There are a range of shutter options for round windows. Wooden plantation shutters are available in various finishes.