I dive with soft, disposable contacts. I have horrible myopia and mild astigmatism, so a prescription mask would have been inconvenient because of needing to wear the mask whenever not wearing glasses (on the boat, dock, beach, etc.). Plus, glasses don't correct my astigmatism but contacts do (something about the shape of the contact naturally holding my eyeball in the right shape).
Diving in saltwater, I have needed to take the contacts out and give them a rinse between dives, especially if my mask floods. Also, after a week of diving, I replace the lenses out of an unfounded belief that there may still be salt stuck to them. I always bring along plenty of spare pairs (about 4 or 5) because I'm a little paranoid.
I usually let my dive buddy know I'm diving with contacts just in case anything does happen. Then they'll know why I'm running into things and squinting (at very close range) at my gauges.