I thought I may supplement to this old thread as it bears relevance to my experience yesterday.

I have recently gone raw paleo again, eating rib eye steak and milk keffir. Yesterday I got it in my head to try some processed fat in the form of mascarpone. I woke up with a blood shot scratchy eyes. I wasn't sure what to do for the rest of the day. As it hadn't improved by evening I decided to try eating a punnet of blueberries and raw cream. Within 5 minutes I felt some relief so I had another punnet with cream. This morning all the pain is gone along with the redness. I also have this oddly intense clear focus - like I have eagle vision.

The associations I have build over the years with bloodshot eyes is excess in eating the wrong carbs(probably the milk keffir in this case though the onset seemed linked to the mascarpone), lack of carbs and somehow a lack of oxygen in the eye. Usually it is only one eye that goes red.

I stopped raw paleo 5yrs ago on account of dry aging skin especially on my legs and face and the onset of rosacea. The capilaries in my cheeks and nose would bust and the the skin peal. A pore on the side of my nose where an old girlfriend had squeezed a black head became inflamed and would peal every 3/4 days and if I scratched it it would bleed excessively.

It took me along time to figure out that it was the keffir that was the problem. Even today I get very heavy legs from eating it, so I have dropped it in the realization that it seems to cause some sort of histamine response.

Perhaps the bloodshot eye is in response to free radical damage or excessive histamines or salycilates. It seems to depend on what you eat and the relation that carbs have to it.

In my view find the carb responsible and treat for oxidative stress.