What causes the shape of the eyeball to change?

The shape of the eyeball can change due to various factors, with the most common being the contraction or relaxation of the ciliary muscles surrounding the lens. This can lead to adjustments in the shape of the lens, allowing the eye to focus on objects at different distances. In conditions such as myopia (nearsightedness) or hyperopia (farsightedness), the shape of the eyeball may be naturally elongated or shortened, affecting how light is focused on the retina.