Iridology is the study of a persons internal health levels via  examination of the iris constitution. This incorporates iris colour, the pupil shape and it's border, iris structure, iris diathesis and observation of various sclera signs.   


Iridology is able to reveal locations within the human body which  manifest degrees of inflammation prior to a diagnosis of disease.


For example:

If a lacuna or another form of indicator was to be observed within the kidney / liver or brain region, this would suggest an underlying issue has been manifesting for some time.    


The process of Iridology is carried out with non invasive observation of a person's eyes using a specially designed magnifying lens as a diagnostic tool.


Another method of iris observation is by close photography of the eye.