  We propose a unified approach for describing the carrier localization,
metal-insulator transitions (MITs) and stripe formation in high-$T_c$ cuprates.
The ground-state energy of a carrier interacting with a defect and with lattice
vibrations is calculated within the continuum model and adiabatic
approximation. At low doping levels, hole carriers in $\rm{La}$-based systems
with large-radius dopants are localized near the dopants with the formation of
hydrogenic impurity centers.
