The punch to Michael's face broke his cheek bone which gave him a long lasting black eye (and brought about his sinuses to continually run - that's why the usage of a handkerchief continuously) till he obtained again to The us and had medical procedures to repair it (Freddie states, https://bookmarkworm.com/story18757996/5-tips-about-7-reason-why-the-godfather-master-piece-you-can-use-today