What helps maintain the shape of the eyeball?

The sclera, which is the outermost layer of the eye, plays a crucial role in maintaining the shape of the eyeball. It is a tough, white, fibrous tissue that provides structure and support to the eye, preventing it from collapsing under pressure. The sclera also serves as an attachment point for the muscles that move the eye, contributing to its overall stability and positioning.

In contrast, the iris is responsible for controlling the amount of light that enters the eye through the pupil and does not have a direct role in maintaining the eyeball's shape. The cornea is the transparent front part of the eye that helps focus light but is not primarily involved in maintaining the overall structure. The pupil is the opening in the center of the iris and also does not contribute to the shape of the eye. Thus, the sclera's rigidity and supportive nature are essential for keeping the eyeball in its proper form.