A lens device for an illumination assembly. The lens device has light-entry and light-exit surfaces and comprises at least one ring region. Each ring region extends along a circumferential direction about a central axis of the lens device, and comprises a plurality of area segments. Each area segment forms a circular arc portion of a respective ring region and comprises a first end in the circumferential direction and a second end opposite to the first end in the circumferential direction. At the first end, the light-exit surface is inclined in the direction of the central axis by an arbitrary first angle in relation to the light-entry surface, and at the second end, the light-exit surface is inclined in the direction of the central axis by an arbitrary second angle in relation to the light-entry surface differing from the first angle.