Yes, those with active hallucinations or under the influence of drugs or some medications. More commonly, some people need to depart from traditional styles of practice to accommodate special needs. Various forms of trauma often manifest with a difficulty feeling safe with eyes closed so a soft focus approach can be helpful. Individuals with psychotic symptoms should approach meditation slowly and with close supervision as they sometimes find their symptoms become exasperated with close attention. For these reasons it is helpful to find an experienced teacher who can work with each student individually.