The invention relates to nanoparticles for the systemic or topical delivery of lipophilic diagnostic or therapeutic agents to a subject in need thereof. The nanoparticles of the invention comprise a water soluble polymer and at least one of a biocompatible lipid and a lipophilic agent. The invention further relates to ophthalmic treatment using the nanoparticles of the invention. In addition, the invention pertains to compositions and formulations comprising the nanoparticle of the invention. Such formulation may be an eye drop formulation.