Aniridia is a rare genetic disorder characterised by the absence of the iris. The iris of patients with aniridia is hardly visible from the outside and is often only detected with a special examination, also known as genioscopy, using a special contact lens prism. Since the natural aperture stop of the eye, the iris, is absent, it is no longer possible to control the amount of light entering the eye, which results in glare. Patients are often also extremely sensitive to light (photophobia) and have involuntary eye movements (nystagmus). They also have an increased risk of developing glaucoma (increased pressure in the eye) or cataracts (clouding of the lens of the eye).