I used to get ocular migraines a couple of times a year, but I haven't one in over four years since getting on a wheat and yeast-free diet. I started the diet to try and fix an autoimmune disease. It worked perfectly and also got rid of migraines as a bonus. I spent some time trying to find out why and I think the reason is simple, although I'm nowhere close to being a biologist. It might work like this: 1) Migraines and are known to be caused by inflammation. 2) Yeast is known to cause an inflammatory response in humans via innate immune system (dectin-1, mannose receptors). 3) Yeast beta-glucans (that trigger immune response via dectin-1) can pass through the intestines. Therefore, eating yeast contributes to migraines.