Lines that do not increase their width under a magnifying glass.
D006801:Humans; D007088:Illusions; D007909:Lenses; D008027:Light; D055095:Optics and Photonics; D010786:Photoreceptor Cells / Q000502:physiology; D012160:Retina / Q000502:physiology; D014785:Vision, Ocular