Back-surface progressive + Back-surface Aspheric Design

Back-surface progressive + Back-surface Aspheric Design

Combination of a <progressive power surface>, <astigmatism-corrective surface> and <aspheric surface> together on the back surface, enables production of a uniform curve on the front surface resulting perfect optical performance.

Back-surface progressive + Back-surface Aspheric Design

Principle of Back-surface progressive + Back-surface Aspheric Design

Distortion and blurring are features of progressive lenses that are mainly caused by "changes in magnification" due to:
① Changes in the lens power
② Changes in the front lens surface curve

"Changes in the lens power" are unavoidable with the structure of conventional progressive lenses that provide suitable levels of eyesight through progressive changes in power.

In addition, the problem of "changes in the front surface curve" cannot be resolved with progressive lens types that achieve added power by changing the front surface curvature.

However, the «Back-surface progressive + Back-surface Aspheric Design» that combines all design elements such as "added power," "spher power," "astigmatic power," "astigmatic axis," "prism power," "inset of the near zone" and "aspheric surface correction" on the back lens surface only, results in a uniform front surface curve that reduce the causes of distortion and blurring, enabling production of a lens featuring radically improved optical performance with low levels of a sense of swaying, distortion and blurring.

Effects of Back-surface progressive + Back-surface Aspheric Design

1. Reduced distortion and blurring

Because the front surface curve is uniform due to the Back-surface progressive + Back- surface Aspheric Design, there is no difference between the change ratio for near and far distances resulting from changes in curvature. This results in the reduction of distortion and blurring that tends to occur at the sides of the near-distance segment of the lens.

  • Conventional progressive lenses
  • Back-surface progressive + Back-surface Aspheric Design lens

The photograph shown is an image of differences in the field of vision.

Description Comparison image

2. Expanded field of vision

In addition to reducing the degree of distortion and blurring, bringing the progressive refracting power surface closer to the eyes by the thickness of the lens expands the field of view and achieves clarity of vision.

  • Conventional progressive lenses
  • Back-surface progressive + Back-surface Aspheric Design lens

The photograph shown an image of differences in the field of vision.

Description Image of enlarged field of vision

Back-surface progressive + Back-surface Aspheric Design has been incorporated for:

SEIKO Individual Lens SuperiorP1
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SEIKO Individual Lens SuperP-1 NEO
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SEIKO Individual Lens PursuitNV
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SEIKO Individual Lens PursuitEV
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SEIKO Individual Lens Synergy
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SEIKO Individual Lens VisioDS
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SEIKO Individual Lens IndoorLD
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SEIKO Individual Lens IndoorMD
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SEIKO Individual Lens Indoor100/200
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SEIKO Individual Lens IndoorPC
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