Here's everything I remember, some things more vivid than others.
The story starts with the protagonist outside of this prison/facility.
Within the story the prison/facility is seen as normal from the outside but on the inside it is evil.
The protagonist is sent there for some reason.
There is a sadistic scientist/guard who tries to break the prisoners and does experiments on them (the whole facility may be based on human experimentation).
There are abnormally strong guards in black suits that keep the prisoners in check and work for the sadistic scientist/guard.
The protagonist is forced to watch gruesome scenes on a screen with his eyes peeled open as some form of torture
I remember vividly the protagonist is then strapped down and injected or forced to take some medication which causes him immense agony. When he wakes up he feels different, including greatly enhanced vision. The author describes how he can see things in great definition and clarity like the pores on skin or all the cracks in the walls.
The book was written in English, and I read the book approximately 5 years ago.