Madness

Madness is a 1994 Italian giallo film directed by Bruno Mattei. The film is about Giovanna Dei who is the creator of the comic series Doctor Dark, a character with a split personality. After a series of murders begin to happen in a similar fashion to how Doctor Dark's fictional murders. Dei defends herself against any criticism of the violence in her comics and later finds that the murderer is leaving the eyeballs of her victims in her apartment.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.