Until a year ago I have had abnormally sharp vision. This last year a B1 deficiency reached a critical point and I have chronic tinnitis and was getting double vision for about 2 months before I started to get a reasonable amount of relief by taking hella B complex. The cause being that I don't eat grains due to allergy, and that's where you find B1. Not anywhere else. Not energy drinks, none of them have B1 or B2 in them, and it's hard to find it by itself, even though the damage it can cause is severe. Long term memory loss too. It's a big part of the mechanism behind the damage of alcohol abuse.