As their name suggests, bifocal eyeglass lenses have two lens powers — one for distance and one for near.
The lower half of a bifocal lens contains the near segment for reading and other close-up tasks. The rest of the lens is usually a distance correction, but sometimes has no correction at all in it, if you have good distance vision.
The Franklin bifocal design remained in style for more than a century. Then in the early 1900s, the invention of fused bifocals offered thinner and more attractive lenses.
In a fused bifocal, a small lens segment for near vision is attached (fused) to a full distance lens.
| || |
The most popular fused bifocal today has a D-shaped near segment rotated 90 degrees so that the flat part of the "D" is facing up. For this reason, D-seg bifocals also are called "flat-top" (FT) or "straight-top" (ST) bifocals.
Flat-top bifocals are further described by the width of the near segment, measured in millimeters (mm). The most popular FT bifocal is the FT-28, a flattop bifocal with a near seg that is 28 mm wide.
FT-28 offers a wide field of forward vision and allows the user to see objects at close range without changing spectacles. This lens gives the wearer a wide range of long-distance vision and, at the same time, allows viewing of objects at close range such as meters, navigation screens and expressway tickets. This type can also be used for sports such as golf.
Two different segment sizes to meet individual requirements
Reduced reflections due to curved segment top
Segment fusing or molding on front surface and inner toric surface design ensure excellent optical quality and cosmetically attractive lenses
Wide selection available: various material, photochromic bifocal lenses and sunglass lenses
Aogang bifocals are made from one of the highest quality materials, in Uncoated, Hard-Coated and Hard-Multi-Coated varieties.