In 2012 and 2013 he was a visiting researcher with the Doheny Eye Institute of the university of Southern California (USC) in Los Angeles (USA), where he is primarily investigating the potential of a human embryonic stem cell transplantation for the therapy of dry AMD. Together with the principal investigator, Prof Mark Humayun, he is additionally evaluating the surgical feasability of the next epiretinal prosthesis for the treatment of retinitispigmentosa.
Prof. Dr. Koss has organized and participated in numerous wet and dry labs at the German academy meeting (DOG), the German meeting of ocular surgeons (DOC) and the Frankfurt-Marburg Retina meeting since 2005. He has helped profoundly to develop the current software of the EyeSi (VRMagic) with his mentor and long term teacher Prof. Dr. Frank Koch.
He is a current Fellow of the European and German Board of Ophthalmology. Being an active member of ARVO, the ASRS and the EVRS, he also serves as a editor for Graefes Archives of Ophthalmology.