yeh its basically the same as the Valsalva ,you blow to to clear your middle ear ,could the pressure of the blow cause the blood shot as i also use this method to clear my middle ear when i am not diving and could the pressure have an effect on the pigments in the iris resulting in a discoloration of the iris? thank you Dr
Frenzel??? Is this to clear your mask of water...blowing air out of your nose, thus forcing water out of the mask? Is this what you mean, or is this a maneuver where your forcefully blow out, but no air comes out (like to clear your middle ear) aka Valsalva? It's normal for you to feel some pressure. It's also normal for your eyes to be bloodshot after salt water or chlorine. Maybe you need to go see your local Eye MD (ophthalmologist) and get a check up? Have fun SCUBA diving and be safe.
Best wishes,
Timothy D. McGarity, M.D.
www.tmcgaritymd.com