Challenges, facilitators and barriers to screening study participants in early disease stages-experience from the MACUSTAR study oleh Jan Henrik Terheyden, Charlotte Behning, Anna Lüning, Ludmila Wintergerst, Pier G. Basile, Diana Tavares, Beatriz A. Melício, Sergio Leal, George Weissgerber, Ulrich F. O. Luhmann, David P. Crabb, Adnan Tufail, Carel Hoyng, Moritz Berger, Matthias Schmid, Rufino Silva, Cecília V. Martinho, José Cunha-Vaz, Frank G. Holz, Robert P. Finger, on behalf of the MACUSTAR consortium