Welcome, John.
Have you seen this post?
It sounds like you guys are setting the standard for serious O2 exposure. I have had what appeared to be O2-induced myopia after a two week CCR trip in the Galapagos in 2005, where I was doing about 6 hours underwater a day, at 1.2-1.5 PO2. But the myopia did not last more than a week. Perhaps it was due to the fact that I wore contact lenses...and drank a lot of antioxidant yerba mate tea. I have no idea, really.
Thanks for the "insight" on the Carcharhinus, by the way.