Multifocal

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Geometry

  • Multifocal spherical front optic zones
  • Distance or Near in center
  • Spherical back optic zones
  • 3 different back optic variants:

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  • 1 aspheric flattening
  • Eccentricity: 0.30 -> 0.80
  • corneal toricity < 3/10 mm

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  • 2 aspheric flattenings
  • Eccentricity: 0.10 -> 0.90
  • Aspheric zone 2: standard (−) or sharp (+) opening
  • corneal toricity < 4/10 mm

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  • 3 spherical flattenings
  • Spherical zones 1 and 2: r1 = rO + 0.60 mm, r2 = rO + 1.20 mm
  • Spherical zone 3 standard (−) (rO + 3.50 mm) / open (+) (rO + 4.50)
  • strong toricity, irregular topography, special biometry

bSA  bS2A bS3S

Multifocal Variations:

  • Bifocal (Bf): two spherical concentric optic zones distant / near
  • Simple Progressive (Sp): spherical and aspheric concentric zones: distant / intermediate / near

Technical data

  • Total diameter: 7.50 -> 12.00 mm
  • Base curve: 6.00 -> 9.00 mm
  • Sphere: -40.00 -> + 40.00 dpt
  • Addition: +0.50 -> +4.00 dpt
  • Central optical zone Zoc: 1.00 -> 4.50 mm

steps 0.01 mm / 0.01 dpt / 1°

First fitting

  • Total diameter: = corneal diameter – 2.00 mm
  • Base curve:
  • SA: rO = flacher Hornhautradius (rcfl)
  • S2A: rO = flacher Hornhautradius (rcfl)
  •  S3S:
    • ( rcfl – rcst) ≤ 0.30 mm -> rO = rcfl – 0.05
    • (rcfl – rcst) ≤ 0.40 mm -> rO = rcfl – 0.10
    • (rcfl – rcst) ≤ 0.50 mm -> rO = rcfl – 0.15
  • Flattening:
    • SA:  eccentricity (En) = eccentricity of the cornea at 30° rounded up to the next 1/10
    • S2A:
      • 1st zone: eccentricity (En) = eccentricity of the cornea at 30° rounded up to the next 1/10
      • 2nd zone: begin with (−) Standard
    • S3S: begin with (−) Standard

Materials

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