I've heard this as well. I have blue eyes and extreme sensitivity to light, much moreso than my partner w/ brown eyes. I can't be outside without sunglasses for instance, and I've noticed polarized lens's are far more effective at reducing my pain point than normal tinted glasses. I also can't just flick on the lights in the morning when I wake up, I have to gradually introduce my eyes to light.

I'm not sure of a relationship there, but I recall reading reports for a long time that red-heads felt less pain than other people - as a red-head this amuses me, but I have no personal data to share.

Random source is random:

http://sciencenordic.com/redheads-feel-different-kind-pain

My dentist told me that people with red hair are less susceptible to the effects of novicane. I have red in my beard and always need a second injection when getting drilled. She said this is the cause.