Optical element with a porous low refractive index layer having a protection layer

An optical article comprising:

• a first optical element comprising a polarizing film, a diffusing film, a reflecting film, a retarder, a light guide or a liquid crystal display panel;
• and
• a second optical element comprising:
• (a) a low refractive index layer having an effective refractive index of 1.3 or less disposed on the first optical element, the low refractive index layer comprising:
• a binder;
• a plurality of particles of fumed silica or fumed alumina dispersed in the binder;
• wherein the low refractive index layer comprises a plurality of interconnected voids and has a thickness of 1 to 20 micrometers;
• and
• (b) a water resistant polymeric protective layer formed from polymers having an average molecular weight of greater than 50,000 g/mol disposed on the low refractive index layer, wherein the polymeric protective layer has a thickness of 1 to 15 micrometers, said polymers comprising:
• organomodified silicones selected from the group consisting of (meth)acrylate modified silicones, silicone modified (meth)acrylates, silicone-polyureas, silicone-polyurethane-polyureas, silicone polyamides, and silicone polyoxamides;
• or thermoplastic silicone acrylate copolymers;
• and
• wherein the polymeric protective layer does not increase an effective refractive index of the second optical element by greater than 10% as compared to a second optical element having no polymeric protective layer.