These optical devices, typically made of soft hydrogel or silicone hydrogel materials, alter eye appearance by covering the iris with a white opaque layer. A theatrical example would be their use to create the effect of blindness or a supernatural gaze.
Beyond cosmetic and theatrical applications, these lenses can sometimes be used for managing certain eye conditions, such as aniridia or albinism, by reducing light sensitivity and improving vision. Historically, advancements in materials and manufacturing processes have significantly improved their comfort and safety. This evolution has expanded their use from purely medical necessities to a wide range of aesthetic choices.