Did you know that frogs focus their eyes not by changing the shape of the lens but by moving it, much like a modern accommodating intraocular lens?1 Frog eyes can be brown, green, red, bronze, silver, and even gold; pupils can be round, horizontal, or vertical, triangular, star-shaped, or even heart-shaped! The large, protruding eyes of most frogs give them a very wide field of vision, which is useful for looking around without moving and scaring off prey (Figure). Frogs have good night vision and depth and movement perception. Unfortunately, they cannot see stationary objects well and can starve even when surrounded by insects if they are not moving.2 Another fascinating fact is that a frog retracts its eyes down toward the oropharynx when swallowing. When a frog swallows, its eyes help push food down its throat, since there is no bone between the eyes and the esophagus.3
Rozenbaum I, Ritch R. Eye on the Web. Arch Ophthalmol. 2007;125(12):1634. doi:10.1001/archopht.125.12.1634
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