Prism eyeglasses are not normal glasses. They are not designed to improve the vision of one or both eyes, and they do not help a person see better at a distance or close up. They are used when an individual is having trouble keeping his eyes working together. In other words, the eyes are looking at two different points instead of the same point. Generally this will cause double vision, if the eyes are extremely bad, or blurred vision if they are looking close to the same point. An eye doctor is needed to diagnose the issue, and prism glasses are the normal remedy.
Manipulate the Eyes
Prism glasses are used as a way of bringing the middle point between the two eyes into focus by distorting the glasses themselves. They focus the eyes by directing them toward a middle ground. This lets the eyes see the same thing, and fools the brain into thinking the eyes are working together. The glasses are not needed forever if used in conjunction with some eye exercises to build the muscles needed to help keep the eyes from wandering away from centre.
The prism in eyeglasses bends light. It is placed in the glasses so that as the eyes look through them, the objects are pulled into focus. It is similar to a triangle or cone. The focus occurs because the bottom of the prism is on the outside of the glasses. It pulls the object in and narrows its focus as it makes its way up the prism. The object visualised is pulled together in both lenses to a closer point, creating a clearer picture. This makes the vision clear, without forcing the eyes to work as one.