A method to determine the optimum laser parameters for maximizing laser induced refractive index change (LIRIC) while avoiding exceeding the damage threshold for different materials with high water content (in particular, polymers such as hydrogels or the human cornea) is proposed. The model is based upon two previous independent models for LIRIC and for laser induced optical breakdown (LIOB) threshold combined in a simple manner. This work provides qualitative and quantitative estimates for the parameters leading to a maximum LIRIC effect below the threshold of LIOB.