Final answer:
The cornea does not change shape to focus on objects; that role is played by the lens of the eye, which adjusts its focal length. For myopia correction, the cornea should be flattened, whereas for hyperopia it should be made more curved.
Step-by-step explanation:
The statement that the cornea must modify its shape to focus on an object is false. Instead, it is the lens behind the cornea that changes shape, thanks to the surrounding muscles, allowing the eye to focus on objects at various distances. The cornea has a fixed shape and does not flex; its main role in vision is to help focus light as it enters the eye because it has a greater refractive index than air. When it comes to correcting vision issues, reshaping of the cornea through surgical means or with contact lenses is indeed possible.
To correct myopia (nearsightedness), the cornea's curvature should be made smaller. By flattening the cornea, light rays can be focused further back, aligning with the retina rather than in front of it. On the other hand, hyperopia (farsightedness) is corrected by increasing the curvature of the cornea, making it more powerful so that light rays come to a focus more readily upon the retina.