Chameleons have the most distinctive eyes of any reptile. Their upper and lower eyelids are joined, with only a pinhole large enough for the pupil to see through.
They can rotate and focus separately to observe two different objects simultaneously, which lets their eyes move independently from each other.
This gives them a full 360-degree arc of vision around their body. When prey is located, both eyes can be focused in the same direction, giving sharp stereoscopic vision and depth perception.
Chameleons have very good eyesight for reptiles, letting them see small insects from a long (5–10 m) distance.