How can we get same image distance for various positions of objects ?

Explanation

1) The ciliary muscle which attached with eye lens and helps to change the focal length of eye lens.
2) When the eye is focussed on a distance object, these are relaxed. So the focal length of eye lens increases to its maximum value.
3) The parallel rays coming from a distance object are focussed on the retina with 2.5 cm image distance (`f_(max) =2.5 m u=oo , v= 2.5 cm`)
4) when the eye is focussed on a nearer object the muscles are strained , So the focal length of the eye lens decreases its maximum value.
5) The rays from an object (u=25 cm) at L (point of least distance of distinct vision) are focussed on the retina with 2.5 cm image distance .(`f_(min) = 2.27 cm, u= 25 cm , v=2.5 cm`)