Spiral scratches on contact lenses can turn them into multifocals

Inscribing a spiral in the centre of a contact lens seems to create optical vortices that interact so that the lens provides a clear image of objects at all distances

​Inscribing a spiral in the centre of a contact lens seems to create optical vortices that interact so that the lens provides a clear image of objects at all distances Inscribing a spiral in the centre of a contact lens seems to create optical vortices that interact so that the lens provides a clear image of objects at all distances