If the eye under converges and light rays focus behind the retina, this is called farsighted person. A farsighted person can see distant objects very clear, but nearby objects such as words in a book is very fuzzy. Convex lenses are helping farsighted people to correct their vision. They are thicker in the middle than at the edges. The following are the diagram to show you how the convex lenses work.

Another vision problem is - Presbyopia a vision problem created by the stiffening of the crystalline lens. People with presbyopia have poor near vision. This happen usually after people after 45.

Multiple Lens On One Glasses

One glasses with three different kinds of lens that you can see objects from farsight, middle place, and nearsight. This kind of glasses is very useful for people who have different kinds of problem on their eye.