Snake

Snakes have infamously poor eyesight, which is why they resort to sticking out their tongues all the time to get a sense of their surroundings. ... Like all other snakes and many other reptiles, coachwhip snakes don't have eyelids but rather a transparent scale called a spectacle that covers and protects the eye. The fluid between the retinas and the spectacles is produced by tear glands behind the lenses. A pair of nasolacrimal ducts drain the fluid into spaces in the roof of the mouth. Because the spectacles are attached to the skin, the tears cannot overflow from their eyelids as they do in mammals.