Middle-index 1.56 Flat-top Uncoated Prescription Bifocal Lenses for Presbyopes
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Middle-index 1.56 Flat-top Uncoated Prescription Bifocal Lenses for Presbyopes

  • Bifocal
  • Aogang
  • 9001509900
  • 1.56
  • 70/28mm
  • NK55, imported from Japan
  • 42
  • 1.15
  • > 97%
  • UC
  • SPH: -3.00~+3.00 ADD: +1.00~+3.50

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Product Description

Refractive IndexMonomerPlace Of Origin


1.56NK55, imported from JapanChina


Abbe ValueSpecific GravityTransmission




DiameterFlat Top Segment

Power Range


SPH:0.00~+3.00,0.00~-3.00, ADD:+1.00~+3.50

Product Features

  • What Are Bifocal Lenses?

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.

  • Flat Top Lenses

flat top 3.JPG

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.

  • The Advantages Of Wearing Flat Top Bifocal Lens

flat top 9.JPG

  1. Two different segment sizes to meet individual requirements

  2. Reduced reflections due to curved segment top

  3. Segment fusing or molding on front surface and inner toric surface design ensure excellent optical quality and cosmetically attractive lenses

  4. Wide selection available: various material, photochromic bifocal lenses and sunglass lenses

  5. Aogang bifocals are made from one of the highest quality materials, in Uncoated, Hard-Coated and Hard-Multi-Coated varieties.

Contact Us

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