Why should the lens of a normal eye be fatter to look objects and thinner to look at distant objects?

The lens of a normal eye adjusts its shape to focus light properly on the retina, a process known as accommodation. When viewing nearby objects, the lens becomes thicker (fatter) to increase its curvature, allowing it to bend light more sharply to focus the image. Conversely, for distant objects, the lens flattens (becomes thinner), reducing its curvature and enabling the light to focus accurately on the retina without distortion. This dynamic adjustment ensures clear vision across varying distances.