  The purpose of this comment is to present the perturbation approach proposed
by Maiz J. Math. Phys. 60, 012103 (2019) in a clearer way. The results of our
straightforward procedure agree with those obtained by that author except for
one case in which we obtain the exact result while he obtained an approximate
one. In addition to it, we show that for sufficiently deep double-well
potentials the perturbation approach deteriorates considerably.
