Antireflective films are described comprising a light transmissive substrate and a low refractive index layer disposed on the light transmissive substrate. The low refractive index layer comprises the reaction product of polymerizable resin composition comprising at least 20 wt-% fumed silica. In one embodiment, the polymerizable resin is ethylenically unsaturated. In a favored embodiment, the low refractive index layer increases in porosity from the light transmissive substrate interface to an opposing porous surface.