3 Answers
Since the size of eyes cannot increase or decrease, the image distance remains constant. When we increase the distance of an object from the eye, the image distance in the eye does not change. The increase in the object distance is compensated by the change in the focal length of the eye lens. The focal length of the eyes changes in such a way that the image is always formed at the retina of the eye.
The size of the eye can change, so the image distance is fixed when we increase the distance if the eye does not change, due to power of accommodation of the eye, focal length of the eye lens is changed, which compensates the increase in object distance. Hence image distance remains fixed and image is formed on the retina of the eye.
Lens of our eye become thin and its focal length increases and no image is formed on the ratina. So we cannot see distant objects.