There are many authors who have published works on Iridology. Most of these are medical doctors or naturopathic doctors. The most comprehensive book to date is by Dr. Bernard Jensen called "The Science and Practice of Iridology in the Healing Arts, Volume II". Dr. Jensen lived and practiced iridology and nutrition for 50 years on his ranch in California. There he helped over 350,000 people to heal from their conditions and taught about natural healing.
Older texts by Jensen on Iridology are, "The Science and Practice of Iridology in the Healing Arts", and "Iridology Simplified". Other authors titles include,"Information From Structure and Color", published by the Felke Institute, and "Disease Signs in the Iris", by Theodor Kriege and A. W. Priest. Both these books are written by German Iridologists and are translated to English. Germany, as well as other European countries, have a fairly rich history in Iridology.