For what it's worth: USN has been doing PRK waivers/acceptances since late 90's.
Do you know what interesting side effect this has had?
It's been much harder to recruit navigators/backseaters of the same high quality as previously. Any number of folks with marginal vision used to get into aviation as RIOs or BNs. Now, a considerable portion of that motivated class of young people get the PRK and are recruited as pilots.
This led, a few years back, to an interesting "quality spread" in the navigator candidates.