Which part of the eye is considered the outer layer?

The outer layer of the eye is the sclera. This tough, protective layer is composed of dense connective tissue and forms the white part of the eyeball. The sclera provides structural support and serves as an attachment site for the eye muscles, allowing for the movement of the eye. Additionally, it helps maintain the shape of the eyeball, ensuring that the internal components remain properly positioned.

In contrast, the retina, choroid, and ciliary body are all parts of the middle or inner layers of the eye. The retina is responsible for light reception and conversion into neural signals, the choroid contains blood vessels supplying nutrients to the eye and absorbs light to prevent scattering, and the ciliary body plays a role in controlling the shape of the lens for focusing. Each of these components has a specific function that is vital for vision but does not form the outer protective layer of the eye.