Will is blind, but that's not tonight's medical mystery. Everyone already knows about it, for one thing. It wouldn't take very long for the team to figure it out. They'd pretty quickly run through all the obvious alternatives: "Are the lights out? Are his eyes closed? Is he just facing in the wrong direction?" He's also got an ex-girlfriend who loves him and a current girlfriend who sells him LSD-laced ice cream and kind of gets forgotten about in the second half of the episode. In the end, his problem is that he breathed in some deadly spores at some point. They can cure him, but it will involve destroying his hearing. And that's the happy ending!
Meanwhile, House's mother Blythe has stopped by to check on him. And she brought Billy Connolly, who may or may not be House's biological father! After some shenanigans, all is revealed and it turns out that Blythe knows all about House going to jail. She claims she's been reading the Princeton police blotter ever since House moved there. That's a pretty good idea! Oh, and Billy Connolly isn't really House's biological father.
Having said all that, this episode will actually be remembered, if at all, for Park's acid trip in which she sees everyone as rabbits who are trying to kiss her.