Normal Vision

All light rays converge at a single point on the retina.

Myopia (Nearsightedness)

In this visual disorder, near objects are seen clearly because light rays focus at a point before reaching the retina, but distant vision is blurred.

Hyperopia (Farsightedness)

This is a visual defect in which both distant and near images focus at a point behind the retina; that is, parallel light rays reach the retina out of focus. In this case, both visions, especially near vision, are blurred.

Astigmatism

Caused by structural or surface defects in the cornea or lens that produce blurriness. Light rays passing through the cornea focus on different points of the retina.

Presbyopia

A visual problem that occurs around and after the age of 40, in which near vision becomes difficult. This is caused by the hardening of the lens and, consequently, the difficulty of the focus muscles to achieve near focus.