The eyes of chameleons lie outside the bony protection of the orbits. This prominent position gives them a much wider potential field of vision than any other creature though this depends on the eyes also having a wide range of movements for the visual field of each eye is narrow. In order to scan the landscape around them they move their eyes jerkily as we would move our heads if we were looking through a rolled-up newspaper. The 'turret' in which the eye lies evolved from the upper and lower eyelids, now fused together except for a narrow aperture, through which the eye, well set back, peers. The lids are also fused to the outer layer of the eye. Protection of the eye comes from the horny skin of the eyelid below which there is a layer of muscle and a bony plate. The eyes move independently ('uncoupled') until the chameleon fixates upon an object whereupon the eyes come together providing stereoscopic vision. So chameleons cannot blink.