The present invention is related to a pigment epithelium-derived factor (PEDF) for use in a method for treatment and/or prevention of a disease, wherein the method comprises administering PEDF to a subject and wherein treatment and/or prevention of a disease comprises inhibiting labyrinth capillary formation, inducing growth of choriocapillaris, tightening choriocapillaris, inhibiting extracellular matrix formation, protecting choriocapillaris, and/or guiding vessel development.