Lens for a lighting device of a motor vehicle includes a rear face designed to be oriented toward a light source of the lighting device, and a convex front face designed to be oriented toward the roadway being illuminated. The lens has a median vertical plane designed to be substantially orthogonal to the roadway, the front face having a first zone of diffusion with microstructures adapted to diffuse the light emitted by the light source, the first zone of diffusion extending in the median vertical plane. The front face furthermore includes at least two second zones of diffusion each one having microstructures adapted to diffuse the light emitted by the light source, the two second zones of diffusion being situated on either side of the median vertical plane. The microstructures of the two zones of diffusion have a depth absolutely greater than the depth of the microstructures of the first zone of diffusion.