I saw sometimes と indicating a topic. Like in the sentence: そんな既視感に戸惑いを感じていると、こちらを見つめる視線に気が付いた ( My attempt of tranlation is "I felt confused by that deja vu feeling by noticing the line of sight looking in this direction"). I think it have the 「そんな既視感に戸惑いを感じている」as the topic of the sentence, and then say that the person had that feeling of deja vu by noticing a line of sight. Is that it or did I got all wrong?
Anothe exemple sentence is: 僕らの存在こんなにも単純だと 笑いに来たんだ (beggining of the opening "UNINSTALL" of the anime ぼくらの). My teatcher said it means "Came laughing of the fact that our existence is simple this way" (tried to make a more literal translation)
In this last case, it seems that the と have the same role as the particle に, indicanting the element of which someone is laughing.