Re psoriasis

johnny has psoriasis on his knees and on the back of his legs, and scalp that really hurts at times. he sees a derm. who has him on clobetasol 0.05,dovonex0.05 ,derm smoothe fs (for his hair)none of these work. the doctor now wants to put him under a uv light 3 xs a week. i have said i am afraid of the future out come of this light. does any others suffer from psoriasis? and what have you tried for it? ty