Single vision lenses have one prescription that is throughout the entire lens. This lens is prescribed for one purpose. Some people may require several different prescriptions for different tasks.
Lined bifocals or trifocals allow the wearer to see at two or three distances using the same lens. As the name implies, there will be visible lines in the lens defining the different sections. Lined style lenses are often used for small children or for those desiring wide peripheral vision and who are willing to sacrifice range to get it.
Progressive lenses are also called a no-line bifocal. The very top part of the lens works well for distance. The bottom portion gets progressively stronger ending with the strongest portion at the very bottom for reading.
A progressive lens allows the wearer to use a portion of the lens to see clearly at nearly any distance. They allow a seamless transition between the powers rather than the sudden “jump” that occurs between powers in a lined lens. Additionally, from a cosmetic standpoint, no one else needs to know you are wearing one because they are virtually invisible!
HD or digital lenses are available for either multifocal or single vision lens wearers. This technology is very similar to your HDTV in the sense that it makes your picture clearer, colors brighter and allows clearer vision to the edges of your “screen”. These lenses are customized to each patient by sophisticated computers.