  We propose a Ginzburg-Landau phenomenological model for the dependence of the
critical temperature on microscopic strain in tetragonal high-Tc cuprates. Such
a model is in agreement with the experimental results for LSCO under epitaxial
strain, as well as with the hydrostatic pressure dependence of Tc in most
cuprates. In particular, a nonmonotonic dependence of Tc on hydrostatic
pressure, as well as on in-plane or apical microstrain, is derived. From a
microscopic point of view, such results can be understood as due to the
proximity to an electronic topological transition (ETT). In the case of LSCO,
we argue that such an ETT can be driven by a strain-induced modification of the
band structure, at constant hole content, at variance with a doping-induced
ETT, as is usually assumed.
