Iridodonesis is abnormal iris tremor as the eye moves. Such a symptom arises at moments of constriction or dilation, as well as at any other pupillary movement. The pathology develops as the iris has a weak connection with the crystalline lens, which is behind it, and thus is not held in its place during movement. Generally, this symptom is difficult to detect without special equipment. It is possible to observe the abnormality while using a slit lamp.