what purpose do bifocal spectacles serve

Bifocal spectacles serve the purpose of correcting vision for both distance and up-close reading. They contain two lens powers, with the top part of the lens correcting distance vision and the bottom part correcting near vision. Bifocals are commonly prescribed to people over the age of 40 who have presbyopia, a condition where the eyes lose the ability to naturally change focus due to age. When wearing bifocal lenses, you look up and through the distance portion of the lens when focusing on points farther away, and you look down and through the bifocal segment of the lens when focusing on reading material or objects within 18 inches of your eyes. Bifocal lenses are available in various shapes and sizes, and they can provide various vision benefits, including near-vision correction for reading or similar close-up activities.