Thermoplastic composition comprising a (meth)acrylic (co)polymer and particles of hollow glass spheres--or a mixture of particles of hollow glass spheres and particles of a mineral and/or organic compound--the said particles scattering light: having a mean size of 0.5 .mu.m to 200 .mu.m; possessing a refractive index different from that of the transparent thermoplastic by at least .+-.0.05; and being used in an amount of 5 ppm to 1000 ppm by weight with respect to the total composition. Corresponding fashioned articles, especially sheets for backlight units.