Both the unflipped manga and the anime show his right as the artificial eye, though I agree neither of them look exactly human.

There's also the flashback to Tsuzuki in the hospital with a bandage covering his left eye. The few other anime characters I can think of whose left eyes are covered/blinded are all "good guys" for whom the injury was not self-inflicted (which I just remembered is the case with the characters in Weiss Kreuz and Saiyuki, and would not surprise me is the case with Muraki and Tsuzuki) and for whom the injury often seems to represent prior blindness to some form of evil which led to the literal blinding.