The structure and dynamics of highly charged colloidal silica systems has been investigated at low concentrations by means of light scattering. The index of refraction of the colloidal particles was matched using a mixture of water/glycerol. By simultaneously measuring the dynamic and static properties of the colloidal systems, we were able to extract the hydrodynamic function H(Q) at different concentrations. Our results are in excellent agreement with theoretical calculations over a large concentration range.