If you have dark brown eyes, the news is bad. You are more apt to experience pain resulting from dental cavity preparation than a blue-eyed person. In a study conducted by Dr. Phillip R N. Sutton at the University of Melbourne Dental School in Australia, it was shown that the subjects with the least reaction to pain had blue, green, or hazel eyes.
Pain intensified slightly in light and medium brown eyes, with a marked reaction by those subjects with dark brown eyes.
Seeing (or not seeing) colors
Protans are commonly called "red-defective." they confuse certain reds, grays and bluish-greens and have a reduced sensitivity in the red end of the visible spectrum. Deutans are commonly called "green-defective;" they confuse certain greens, grays and purplish reds.