I dunno about the eyes part, I've had close encounters with many critters, several with elk, deer and turkeys, if you blink or move your eyes and they're close and looking at you, they'll spook just like any movement will spook them, but just seeing your eyes isn't enough to do it normally, not in my experience. I've been wearing full camo including face mask and gloves whether I'm big game or turkey hunting for many years, everything is covered except my eyes and I wear regular glasses, have for 50yrs since I was 10yrs old, no contacts.
Back in the 70s before I started with the camo, I had a close encounter with a small herd of 18 elk during deer season in late October, I was wearing a blaze camo coat and a red baseball cap, I heard these elk moving towards me, they're noisy when feeding, so I just stood still in front of a small tree or bush to break my outline, they fed right up to within just a few feet of me, the closest cow kept looking at me, but she'd go right back to eating. Finally, I got real nervous cuz there were so many around me and they'd get my wind any time, didn't want to get trampled if they spooked, so I just shrugged my shoulders, those closest didn't bolt right away, but if elk eyes could get any bigger, I'd be surprised, they had saucer sized eyes when I did that!! They stepped away waiting for the lead cow to get them moving, then they filed away in proper elk formation.
Tim