Chameleon vision from the head, giving the lizard panoramic sight. An eyelid fused to the pupil protects the eyes, leaving only a small part exposed. With a negative (nearsighted or concave) lens and a positive (farsighted or convex) cornea, chameleons use a method of monocular focusing to judge distance called corneal accommodation. Each eye focuses independently, which is achieved by the chameleon eye’s unique anatomy of separated nodal and center points of the eye. Finally, “striated rather than smooth ciliary muscle in sauropsids” allows for rapid focusing. Chameleon eyes feature a negative lens, meaning that the lens is concave. This increases retinal
Lens (optics) object off the optical axis of the lens is imaged, where rays pass through the lens at an angle to the axis θ. Rays that pass through the centre of a lens of focal length "f" are focused at a point with distance from the axis. Rays passing through the outer margins of the lens are focused at different points, either further from the axis (positive coma) or closer to the axis (negative coma). In general, a bundle of parallel rays passing through the lens at a fixed distance from the centre of the lens are focused to a ring-shaped