The paper describes the results of investigations in a rapidly progressing area of modern physics - singular optics. Basic properties of optical vortices (wave front dislocations), which are the principal objects of the investigation, are presented. The vortices peculiarities connected with the coherent light propagation in an inhomogeneous medium are determined. Initiation of the vortices is caused by the occurrence of isolated intensity zeros in an optical beam cross section that is the necessary condition of their existence. New theoretical approaches to the problem of dislocations are proposed, which is especially topical due to the necessity of improvement of atmospheric optical systems. An efficiency of adaptive optics functioning is evaluated under conditions of strong intensity fluctuations in the turbulent atmosphere.