  The concept of energy-dependent forces in quantum mechanics is re-analysed.
We suggest a simplification of their study via the representation of each
self-adjoint and energy-dependent Hamiltonian H=H(E) with real spectrum by an
auxiliary non-Hermitian operator K which remains energy-independent. Practical
merits of such an approach to the Schroedinger equations with energy-dependent
potentials are illustrated using their quasi-exactly solvable example.
