A lens for distribution of light from a light emitter having an axis, the lens including a (1) base forming a substantially rectangular opening to an emitter cavity defined by an inner surface, (2) a main output surface transverse the axis, (3) a reflecting surface positioned to reflect light received from the inner surface toward the main output surface, the reflecting surface including front and back curvatures and a pair of substantially-identical lateral curvatures each adjoining the front and back curvatures. Configuration of the lateral curvatures differs from configurations of the front and back curvatures, which differ from one another.