NOVELTY - The optical coating has a hydrophilic binder and porous silica nanoparticles in which the pores are randomly oriented. The pores have an internal surface at least partially comprising a hydrophobic layer. The binder is tetraethoxysilane or a siloxane-based hardcoat comprising 3-glycidoxypropyltrimethoxysilane. At least 50 percent of the volume of the pores is air.    USE - Optical coating, e.g. anti-reflective coating, used in different applications. Uses include but are not limited to fiber optics; ophthalmics, e.g. ophthalmic elements such as lenses (claimed), displays, including both emissive and reflective displays, e.g. LCD backlight, LED and E Ink display used e.g. in Amazon Kindle; solar collection, including solar cells (claimed), e.g. silicon solar cell; lighting components (claimed); windows (claimed), e.g. windows for buildings, vehicle windows, e.g. automotive, laser windows, self-cleaning windows, antistatic windows such as zinc oxide aluminum, indium tin oxide (ITO) or transparent coated windows; glass for protecting pictures and paintings; display cases; fish tanks and aquaria, and instrument display panels. Can also be used for other optical components, such as solar concentrators, used for collecting and directing sun light to a photovoltaic cell, general displays and window applications, e.g. for thermal management of buildings and in ophthalmic elements, e.g. spectacle lenses.    ADVANTAGE - Provides strength and flexibility by virtue of each particle having multiple contact points with surrounding particles. Eliminates brittle failure and film delamination under impact and renders the film suitable for outdoor applications such as solar cells and eyewear.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a solution for forming an optical coating comprising a solvent and porous silica nanoparticles;    (2) a method of fabricating an optical coating;    (3) a combination of a substrate and an optical coating; and    (4) a use of porous silica nanoparticles.    DESCRIPTION OF DRAWING(S) - The drawing shows the graph of the reflectance curve in the visible wavelength range showing the anti-reflective performance of the optical coating.