As for needing a prescription <1 year old, if your vision hasn't changed, just edit the date in the PDF. Same for contact lens prescriptions.
As part of the regular eye exam, they generally use an autorefractor machine on your current glasses and/or eyes to get a baseline before they manually fine tune with the 1/2 on the eye chart test. But yeah, you can't just get the quick prescription from the autorefractor like you talked about in Japan.
Eat some berries and nuts
"Paleo" diet doesn't even include that much meat in it