Levels of Progressive Lenses

Progressive lenses, also known as no-line bifocals, resemble single lenses, but are actually multifocal lenses without the lines of a trifocal or bifocal lens. Compared to bifocals and trifocals, progressive lenses -- which combine several optical strengths into a single lens -- generally cost significantly more and can cause visual distortions. Progressive lenses come in two different levels.

Advantages

• Progressive lenses are more effective in naturally correcting presbyopia -- a visual condition appearing at middle age that makes it difficult to read fine print -- than prescription eyeglasses, bifocals or trifocals are. Dr. Rachel J. Bishop of the National Eye Institute says presbyopia is "like having a camera with no multifocal option." With progressive lenses, the lens power progressively increases when the wearer views distances. Moreover, with progressive lenses, users can transition from focusing from far to near without any image jump.

Soft Design

• One level of a progressive lens is the soft design. This type of progressive lens offers a longer and wider field for viewing moderate distances. A soft design progressive lens also offers a more natural vision with less areas of soft focus, or peripheral unusable areas of the lens. A soft focus progressive lens is ideal for better vision at 18 to 30 inches, for larger eyeglass frames and for individuals over the age of 50 or individuals who cannot adapt to the hard/short corridor design.

Hard/Short Corridor Design

• The second level of a progressive lens is the hard/short corridor design. This type of progressive lens offers enhanced clarity of distance vision with virtually no areas of aberration, or distorted or blurred vision. The hard/short corridor design is ideal for better vision at 14 to 18 inches, for individuals between the ages of 40 and 48 and for individuals who prefer a smaller eyeglass frame.

Adapting

• A new wearer of a progressive lens may initially feel a difference in peripheral vision that will diminish in time. Typically, most people will adapt to their new lenses within a few hours; however, the adaptation can take up to a few weeks. To experience a natural transition to progressive lens glasses, stop wearing the old glasses immediately and wear the new glasses high on the nose and close to the face.