Wow. Rosacea of the eyes sounds excruciating. Mine was facial, and it was awful. I am pale everywhere else, which just made it look worse. Taking pictures was a nightmare- I'd cover up the redness with heavy makeup, but if there was flash and I hadn't applied my "Neutralizing green" facial primer, I would look like a burn victim. I went to multiple dermatologists, and never got dietary reccs, actually. Just advice not to wear makeup.
I noticed a difference- I'd say up to 50% improvement-within a week of trying the PB. Within a month, I could wear red again. (red face+red shirt= no bueno.) It was a totally unexpected, but very welcome surprise!
I suspect that mine was triggered by undiagnosed celiac/gluten intolerance- if I have a biggish "slip-up", I will wake up the next morning with bright red nose and cheeks, and a really attractive acne break-out around my mouth. (Not to mention gastric distress: so sex-ay! Excellent incentive to behave myself.) Maybe you could get him to just ditch grains, and see if that would do it?