The exact episode in which Zoro loses his eye is not clear from the search results. However, it is established that Zoro suffered an injury to his eye during a training session with the members of the Straw Hat crew during the two-year time skip. The injury resulted in a distinctive scar on his left eye, which he intriguingly keeps closed, eliciting curiosity among readers and enthusiasts. The mystery surrounding how Zoro lost his eye continues to tantalize viewers, sparking fervent discussions.