How does it happen for a person to have both nearsightedness and farsightedness?

[Bloomington]

How does it happen for a person to have both nearsightedness and farsightedness in each of the eyes?

I just can't understand this,as nearsightedness and farsightedness are two very dissimilar eye conditions to me.

[Bloomsburg]

It is quite common that people with one eye nearsighted and with the other farsighted. In this case, people need different correction in both eyes. Bifocal glasses are not suitable for them because they won't help you see far with left eye and see near with right eye, they only allow you see far from the top and see near from the bottom. So people should get contacts with one for far and the other for near.

[Bloomsbury]

It is called anisometropia in which there is a difference in the refractive powers between both eyes. About 6% of children 6-18 have this problem. With a major degree of anisometropia, the brain cannot able to reconcile the difference in images coming from the two eyes. It develops a preference for the image coming from one eye and suppresses the image from the other eye and, in time, the brain loses the ability to "see" the image from that eye.