What is the function of the 'sclera'?

The sclera is indeed the protective outer covering of the eye. It is a tough and fibrous layer that maintains the shape of the eyeball and provides a sturdy attachment for the muscles that control eye movement. This outer layer plays a critical role in safeguarding the more delicate internal structures of the eye, such as the retina and choroid.

While other structures within the eye have specific functions—like the lens, which focuses light onto the retina, or muscles that control eye movement—none of these roles pertain to the primary purpose of the sclera. Its composition and location are what make it integral for protection and structural support, distinguishing it from other components involved in the function of vision.