Focusing Problems:
Hyperopia:
Also known as farsightedness, hyperopia is an eye condition in which the eye has problems focusing on nearby objects. In a normal eye, the light is focused directly onto the retina, but an eye with hyperopia focuses the light beyond the retina. A converging lens (glasses) can be used to fix this problem.
Presbyopia:
This is a seeing condition that is mainly caused by age, in which the eye has problems focusing on small objects such as text. This can also be solved by a converging lens.
Myopia:
Also known as nearsightedness, this seeing problem results in the eye having difficulty seeing far-away objects. The focused light falls short of the retina. A diverging lens (glasses) is used to correct it. 
Contact lenses are another form of correcting eye problems; in this case, a lens is placed directly onto the eye.
