An optical device for modifying a light distribution pattern of a light source is presented. The light source radiates first light beams to a first geometric quarter-space and second light beams to a second geometric quarter-space, where the first and second quarter-spaces are defined by mutually perpendicular geometric planes one of which constitutes a boundary between the first and second geometric quarter-spaces. The optical device may include a lens-section for modifying a light distribution pattern of the first light beams and a reflector surface for reflecting at least a part of the second light beams from the second geometric quarter-space to the first geometric quarter-space. The reflector surface is shaped to resemble a wedge that points towards the first geometric quarter-space so as to provide total internal reflection and to direct the reflected second light beams to sideward directions.