The present invention is directed to a liposomal formulation for ocular drug delivery comprising (i) liposomes comprising at least one lipid bilayer, and (ii) a prostaglandin drug and/or a prostaglandin derivative associated in the liposomes, wherein the liposomes have a mean diameter of less than 2 μπι. The present invention is also directed to a pharmaceutical comprising the liposomal formulation and a method of producing the liposomal formulation for ocular drug delivery. Additionally, the present invention is directed to a method of treating or preventing an ocular disease, comprising administering the liposomal formulation or the pharmaceutical composition to a subject in need thereof.