Chelsea Havana 50-20-140

Progressive lenses are line-free multifocals that have a seamless progression of added magnifying power for intermediate and near vision.The power of progressive lenses changes gradually from point to point on the lens surface, providing the correct lens power for seeing objects clearly at virtually any distance.Bifocals, on the other hand, have only two lens powers — one for seeing distant objects clearly and a second power in the lower half of the lens for seeing clearly at a specified reading distance. The junction between these distinctly different power zones is defined by a visible “bifocal line” that cuts across the center of the lens.