Which lens type is used primarily to treat hyperopia?

Hyperopia, commonly known as farsightedness, is a condition where distant objects can be seen more clearly than close objects due to the eye's inability to focus properly. This happens when the eye is too short or the cornea has too little curvature, causing light to focus behind the retina.

To correct hyperopia, a convex lens is used. Convex lenses are thicker in the center and thinner at the edges, which converges light rays before they enter the eye. This helps to bring the focal point forward, allowing images to be focused directly on the retina rather than behind it, thus improving vision for near tasks.

The other lens types serve different purposes: concave lenses are used for myopia (nearsightedness), cylindrical lenses correct astigmatism by compensating for irregular curvatures of the eye, and multi-focal lenses accommodate presbyopia, allowing users to see at multiple distances. Each of these lenses addresses different vision issues, which is why they are not suitable for treating hyperopia.