Solid state CMOS active pixel sensor devices having unit pixels that are structured to provide improved uniformity of pixel-to-pixel sensitivity across a pixel array without the need for an additional light shielding layer. For example, unit pixels with symmetrical layout patterns are formed whereby one or more lower-level BEOL metallization layers are designed operate as light shielding layers which are symmetrically patterned and arranged to balance the amount of incident light reaching the photosensitive regions.