An imprint lithography method is disclosed for reducing a difference between an intended topography and an actual topography arising from a part of a patterned layer of fixed imprintable medium. The method involves imprinting an imprint lithography template into a layer of flowable imprintable medium to form a patterned layer in the imprintable medium, and fixing the imprintable medium to form a patterned layer of fixed imprintable medium. Local excitation is applied to the part of the patterned layer to adjust a chemical reaction in the part of the patterned layer to reduce the difference between the intended topography and the actual topography arising from the part of the fixed patterned layer of imprintable medium when this is subsequently used as a resist for patterning the substrate. An imprint medium suitable for imprint lithography with the method is also disclosed.