  Black hole shadows and photon spheres offer valuable tools for investigating
black hole properties. Recent observations by the Event Horizon Telescope
Collaboration have confirmed the existence of rotating black holes. Black hole
parameters influence the observed shadow size. This paper explores the impact
of geometrical deformations on black hole shadow size using gravitational
decoupling applied to axially-symmetric spacetime. We find the results are more
complex than the spherically-symmetric case. We compare shadows in well-known
models with those of an Kerr black hole. Our approach suggests that the
influence of an accretion disc on the observed shadow shape can be accurately
described despite negligible impact on the black hole geometry itself.
