I dunno. This guy I know only uses visine after he gets done smoking and his eyes has never been severly red. Me on the other hand though never get red eyes unless I take my contacts out when high or if it's late in the night and I'm just smokin..I'm glad because my eyes never get red, but then on the other hand my eye lids make me look asian when high which I hate because that gives away your highness more than the red eyes lol! For some reason the people I smoke with that get red eyes their eyes never really get extremely low, I don't know why mines does that .