Abstract: An optical fiber of cylindrical construction provides a lateral light outflow. The optical fiber, which is adapted to convey a light flow from one of its ends, the inlet end (6), to the other end, the outlet end (8), comprises at least on a given area (2) of its outer surface a large number of closely spaced degradations (4) of very small size in relation to the fiber diameter, each of said degradations (4) causing the outflow of conveyed light through the point so that the fiber seems globally illuminated. The surface density of the degradations (4) varies in accordance with the direction of propagation of the light flow, which is thus substantially uniformly discharged over the entire length of the fiber.