What type of lens is typically used for reading glasses?

Reading glasses are designed to assist with near vision, primarily for tasks such as reading or other close-up work. When a person has difficulty focusing on nearby objects, which is common as a result of presbyopia (the natural aging of the eye), a convex lens is used in reading glasses.

A convex lens is thicker at the center than at the edges and converges light rays, allowing the viewer to focus on close objects more easily. By bending the light rays inward, the lens helps bring the image into clearer focus on the retina, compensating for the decreased ability of the eye's lens to focus on near objects due to age.

In contrast, concave lenses are generally employed for correcting myopia (nearsightedness) and diverge light rays, which wouldn't be suitable for reading. Flat lenses do not alter the vision and thus are not used for correction. Fresnel lenses are used in specific applications like lighthouses or certain types of eyeglasses, but they are not typically prescribed for standard reading glasses.