  We study paraxial beam propagation parallel to the screw axis of a dislocated
amorphous medium that is optically weakly inhomogeneous and isotropic. The
effect of the screw dislocation on the beam's orbital angular momentum is shown
to change the optical vortex strength, rendering vortex annihilation or
generation possible. Furthermore, the dislocation is shown to induce a weak
\textit{biaxial} anisotropy in the medium due to the elasto-optic effect, which
changes the beam's spin angular momentum as well as causing precession of the
polarization. We derive the equations of motion of the beam and demonstrate the
optical Hall effect in the dislocated medium. Its application with regard to
determining the Burgers vector as well as the elasto-optic coefficients of the
medium is explained.

Optics