We report on a study of protein-free and protein-containing AOT water-in-oil microemulsions with isooctane and decane as solvents by using static and dynamic light scattering measurements. In a first step, using a model of polydisperse layered spheres, we show that we can determine the size polydispersity gamma of the microemulsion droplets with very high precision because the variation of both the scattering intensity as well as the hydrodynamic radius with the water content are very sensitive to gamma in the vicinity of the optical match point of the microemulsion particles. In a second step, we then focus on the size and structural perturbations induced in the reverse micellar system upon solubilization of the enzyme alpha-chymotrypsin by using optical contrast variation techniques. In particular, we show that light scattering experiments close to the optical match point can be used as a very sensitive method in order to quantitatively test the currently existing theoretical models for protein solubilization in microemulsions.