The present invention relates to lens assembly for an illumination device comprising a number of optical lenses and a lens holder comprising a mounting plate having a number of holes, said number of holes being adapted to accommodate said lenses. At least one of said holes is at least partially surrounded by a number of resilient fingers extending backward from the mounting plate, said resilient fingers being adapted to engage with one of said lenses and secure said lens in said holes. The present invention relates also to an illumination device comprising such lens assembly and a method of manufacturing the illumination device.