It's a short novel by Jean Rollin (1938-2010). Rollin is better known in the English-speaking world as the director of strange surreal erotic horror movies with the emphasis on the surrealism and with a twisted fairy tale feel to them. In his native France he enjoyed more success as a novelist, working in the fantasy and horror genres.
Little Orphan Vampires is the tale of two young blind orphan girls who may or may not be vampires but they are certainly killers. Whether or not they are evil is also open to debate.
My full review can be found at my Cult Movie Reviews blog. Here's the link.