The sharp resonances in reflectance difference spectroscopy (RDS) data at the critical points of the dielectric function of bulk semiconductors have been assigned to surface-bulk transitions. photon localization, or optical transitions from bound dimer states to excited dimer states. For the case of ZnTe, CdTe, and ZnSe, we present experimental data indicating that a uniaxial in-plane stress component induces sharp resonances at these critical points by lifting the degeneracy of the optical transitions at the A and Gamma points due to the resulting anisotropic strain. Even small stresses of about 1-5 MPa, or strains on the order of 1 X 10(-5) can be detected with RDS.