A coating composition includes a first polymer and a second polymer that are incompatible and non-reactive with one another. The absolute value of the difference between the refractive index of the first polymer and the refractive index of the second polymer is about 0 to about 0.01. The first polymer and the second polymer are soluble in a carrier liquid that is a good solvent for the first polymer and a poor solvent for the second polymer. The carrier liquid is removed from the coating layer to spinodally decompose the mixture of the first polymer and the second polymer in an amount sufficient to form a substantially continuous first phase with a predominant amount of the first polymer and a substantially discontinuous second phase with a predominant amount the second polymer. At least 70% of the second phase includes droplets with an aspect ratio, when viewed in the plane of the surface of the substrate, of less than about 3.