I think that in addition to this, they reduce oxygen in the environment. The level of oxygen in an environment greatly influences what can grow there.

(I may be wrong though, but I think I heard it creating a stagnant, oxygen poor enviornment that did it.)

That would make sense. In which case the real risk might be from rising the lens and then inserting it. Getting exposed to water when already inserted in the eye (ie. shower or swimming) might be less risky, unless the water somehow penetrates under the lens.

Anyway, this is a good PSA.