By applying the previously established model of molecular nanofilm crystalline structures, in this paper we theoretically investigated and studied changes in optical properties due to the presence of boundaries of ultrathin film samples. With founded exciton dispersion law and theory of system's response to an external perturbation, the relative dynamic permitivity and the optical properties (absorption, refraction, reflection and transparency indices) of these ultrathin dielectric films were determined. The results have shown that boundary perturbation parameters could change refraction, appearance of discrete transparency and absorption as well as that could change position and number of absorption peaks.