Described is a method for the specific modulation of the expression of target genes in cells and/or tissues of the CNS and/or eye, wherein a composition comprising one or more doubled stranded oligoribonucleotides (dsRNA) is introduced into the cell, tissue or organism outside the blood-brain or blood-retina barriers. Furthermore, a method for the identification and validation of the function of a gene is provided, wherein the method provides a test cell, test tissue or test organism, which allow information to be gained on the function of the target gene. In addition, compositions and kits are described useful for those methods. In particular, components and methods for the diagnostic use and/or therapy of disorders related to the CNS and/or eye are provided which are based on RNA interference.
