Since amphibians have been around a long time, and have adapted to a 
variety of environments, their eye structures vary slightly for different environments. The frog has large, bulging eyes, which sit at the top of its head. Its eyes bulge out so far that it can see in nearly all different directions, which is helpful for an animal that can’t turn its head. A transparent inner eyelid called the nictitating membrane protects the frog’s eyes when the animal is underwater. A frog can also shut its eyes completely. To do this, the frog pulls its eyeballs deep into their sockets. This closes the upper and lower eyelids together.
Most species of salamanders view their world with colour vision, but they see in the ultraviolet range, which is impossible for the human eye. Salamanders use this special vision adaptation to hunt prey. Some species of amphibians, such as the Texas blind salamander, live their entire lives underground in places like caves. These amphibians do not have eyes, since they live in complete darkness.