Modelling of liquid crystal optics is commonly based on variants of matrix-type solvers, which are ideally suited for addressing light wave propagation in stratified anisotropic media. Liquid crystal devices with complex director structures on the micron scale require more rigorous methods Tur predicting their optical response. Two potential candidate methods exist: the Beam Propagation Method and the Finite-Difference Time Domain Method. The scope of this paper is to apply the former and assess its accuracy against the latter, which is considered to be more general. The analysis and assessment is focused on Zenithal Bistable Nematic devices.