Iridologists generally use equipment such as a flashlight and magnifying glass, cameras or slit-lamp microscopes to examine a patient’s irises for tissue changes, as well as features such as specific pigment patterns and irregular stromal architecture. The markings and patterns are compared to an iris chart that correlates zones of the iris with parts of the body. Typical charts divide the iris into approximately 80-90 zones. For example, the zone corresponding to the kidney is in the lower part of the iris, just before 6 o’clock. There are minor variations between charts’ associations between body parts and areas of the iris. According to iridologists, details in the iris reflect changes in the tissues of the corresponding body organs. One prominent practitioner, Bernard Jensen, described it thus: “Nerve fibers in the iris respond to changes in body tissues by manifesting a reflex physiology that corresponds to specific tissue changes and locations.” This would mean that a bodily condition translates to a noticeable change in the appearance of the iris. For example, acute inflammatory, chronic inflammatory and catarrhal signs may indicate involvement, maintenance, or healing of corresponding distant tissues, respectively. Other features that iridologists look for are contraction rings and Klumpenzellen, which may indicate various other health conditions, as interpreted in context.