An image sensor having shield structures and methods of forming the same are provided. Generally, the image sensor includes: (i) substrate having at least one photosensitive element formed therein; (ii) a dielectric layer overlying the substrate and the photosensitive element; and (iii) an annular reflective waveguide disposed in the dielectric layer above the photosensitive element to reduce cross-talk between adjacent elements of the sensor while increasing sensitivity of the sensor. In certain embodiments, the sensor further includes a photoshield disposed in the dielectric above the photosensitive element and about the waveguide to further reduce the possibility of cross-talk. Other embodiments are also disclosed.