Final answer:
The anterior-most structure of the eye, part of the fibrous tunic, is called the cornea, which functions to protect the eye and focus light onto the retina.
Step-by-step explanation:
The clear, anterior-most structure of the eye, part of the fibrous tunic, is called the cornea. The fibrous tunic is the outermost layer, and it includes both the white sclera and the clear cornea. The cornea functions as a protective covering for the eye and plays an essential role in focusing incoming light onto the retina. The fibrous tunic's function is primary protection and light transmission, with the cornea specifically allowing light to enter the eye and contributing to the eye's focusing power.