Which part of the eye spreads tears across the eye to keep the cornea and conjunctiva moist?

The eyelids play a crucial role in maintaining eye health and comfort by spreading tears across the surface of the eye. When you blink, the eyelids close and then reopen, which helps distribute the tear film evenly over the cornea and conjunctiva. This action not only keeps these surfaces moist but also ensures that any debris or irritants are cleared away, providing a protective function.

Tears contain essential components that nourish the cornea and prevent dryness, making the eyelids vital in facilitating this process. The cornea itself is a transparent layer that benefits from this tear film but does not contribute to the spreading of tears. The conjunctiva is the membrane that lines the eyelids and covers the white part of the eyeball; while it is involved in eye moisture, it does not actively spread the tears. Eyebrows, on the other hand, serve primarily a protective role by preventing sweat and debris from entering the eyes, but they do not interact with the tear film in the same way that eyelids do.