  The metal-insulator (MI) transition in BaVS$_3$ has been studied at ambient
pressure and under hydrostatic pressure up to $p=26 $kbar in the frequency
range of $20-3000 $cm$^{-1}$. The charge gap determined from the optical
reflectivity is enhanced, $\Delta_{ch}(p)/k_BT_{MI}(p)\sim 12$. This ratio is
independent of pressure indicating that the character of the transition does
not vary along the $p-T$ phase boundary. Above the critical pressure,
$p_{cr}\sim20$ kbar, metallic spectra were recorded in the whole temperature
range, as expected from the shape of the phase diagram. Our results exclude the
opening of a pseudogap above $T_{MI}$ at any pressure. Below $T_{MI}$ an
unusually strong temperature dependence of the charge gap was observed,
resulting in a $\Delta_{ch}(T)$ deviating strongly from the mean field-like
variation of the structural order parameter.
