According to literature records, Iridology has been studied for at least 300 years, but was not structured in a systematic and detailed way until about 150 years ago. During the past century, the methodology has been used primarily by chiropractors, nutritionists, and herbalists. There are an estimated 10,000 practitioners of Iridology in the U.S. Although Iridology is given considerable scientific attention in Europe, it has not yet found widespread acceptance among the scientific and medical communities in the U.S.