A lighting assembly includes a light guide to propagate light by total internal reflection and having a light output region on a major surface thereof. The lighting assembly also includes an optical adjuster having a major surface juxtaposed with and conforming to the light guide's major surface. The optical adjuster has a first region and a second region, the first region having a light modifying characteristic. The optical adjuster and light output region are variably positionable relative to one another to selectively apportion light emitted from the light output region between the first region and the second region. In this way, light apportioned to the first region is modified by the light modifying characteristic so that light output from the lighting assembly is modified based on relative positioning of the optical adjuster and the light guide.