A method for modifying the refractive index of an optical, hydrogel polymeric material. The method comprises irradiating predetermined regions of an optical, polymeric material with a laser to form refractive structures. To facilitate the formation of the refractive structures the optical, hydrogel polymeric material comprises a photosensitizer. The presence of the photosensitizer permits one to set a scan rate to a value that is at least fifty times greater than a scan rate without the photosensitizer in the material, yet provides similar refractive structures in terms of the observed change in refractive index. Alternatively, the photosensitizer in the polymeric material permits one to set an average laser power to a value that is at least two times less than an average laser power without the photosensitizer in the material, yet provide similar refractive structures.