Hypermetropia actually forms a stage in normal development of the eyes. Hypermetropia therefore represents an imperfectly developed eye when it persists in adult life. Most primitive peoples and many of the lower animals are hypermetropic, carnivora for example, are almost constantly so. Hypermetropia can also occur due to change in refractive index of the crystalline lens of the eye, as in cataract, or due to injury to the eye with dislocation of the crystalline lens of the eye. Another form of Hyperopia is Presbyopia , which affects individuals after or near 40 years of age.
Presbyopic persons complain of blurring of text specially after some time.
Young children with significant hypermetropia can also develop a convergent squint. Rays reflected off an object in front of the eye focus in front of the retina. In the great majority of cases the cause of myopia is an increased length of the eyeball. But it may also be due to an increase in the curvature of the cornea or the surfaces of the crystalline lens. Cataract can also produce myopia due to a change in the refractive index of the crystalline lens of the eye.