Question

how can change of size of eyeball be one of the reason for
(1)myopia
(2)hypermetropia
compare the size of eyeball with that of normal eye in each case how does these change of size affect the position of image

Answer 1

In a normal eyeball, the lens bends the incoming rays and converges them exactly on the yellow spot of the retina.
In a myopic eye, the eye ball is big and the rays converge in front of the retina.
In a hypermetropic eye, the eyeball is small and the rays converge behind the retina.