The FlexCone spherical RGP lens for Keratoconus cases are available in 2 different back surface geometries as Aspherical and Multicurve. This promise an optimal fit and increase the customer comfort.



FlexCone ASP

  • Aspheric Design
  • Spherical center
  • 1 aspheric flattening
  • Eccentricity: 0.10 -> 0.90
  • Early Keratocone

FlexCone SMS

  • Multicurve Design
  • Spherical center
  • 3 spherical flattenings adjustable comparing to cornea eccentricity
  • Eccentricity: 0.10 -> 0.90
  • Advanced Keratocone

Other variants:

  • FlexCone K12: Spherical and fixed multicurve flattening for early stages
  • FlexCone K34: Spherical and fixed multicurve flattening for advanced stages
  • FlexMCone P: Multifocal versions
Multifocal Variations

Bifocal (Bf)

Bifocal Bf
  • 2 concentric Optical zones far/near
  • CD or CN

Simple progressive (Sp)

Simple progressive Sp
  • 3 concentric Optical zones far/ intermediate / near
  • CD or CN

Technical Data

Total diameter10.00 mm12.00 mm0.01 mm
Base curve6.00 mm9.00 mm0.01 mm
Sphere-40.00 dpt+40.00 dpt0.01 dpt

Další informace





Correction type

, ,

Lens Type

Designed by


Fitting advice

  • Total diameter: = corneal diameter – 2.00 mm
  • Base curve:
    • ASP: r0 = Kflat (rcfl)
    • SMS:
      • ( rcfl – rcst) ≤ 0.30 mm -> BC = rcfl – 0.05
      • (rcfl – rcst) ≤ 0.40 mm -> rO = rcfl – 0.10
      • (rcfl – rcst) ≤ 0.50 mm -> rO = rcfl – 0.15
  • Flattening: ASP & SMS: eccentricity (En) = eccentricity of the cornea at 30° rounded up to the next 1/10

Fitting guide

flatten BCsteepen BCflatten Peripherysteepen PeripheryIncrease Diameterdecrease Diameter
Lens riding low
Lens riding high
Aptical Staining
3 & 9 Staining
Sup. limbal Staining
Fluo edge too wide
Fluo edge too narrow
Ghosting or cloudy
Poor Acuity
Bubbling / dimple veiling
Pooling at cone base
Early Cone
Advanced Cone

Fluoreszein pattern

optimal fit

flat central fit

decrease BC -0.10 mm

steep central fit

increase BC +0.10 mm

peripheral flat fitting

decrease EN -0.1

peripheral steep fitting

increase EN +0.1

First contact lens choice

Progression system and central optic zone (Zoc)

Reading zone choice

Determine if the vision is alternate (change of optic zones by translation) or simultaneous (change of optic zones by visual cortex selection):

  • Alternate vision: reading zone in periphery (most of the cases)
  • Simultaneous vision: reading zone in centre
RequirementsBifocal BfSimple progressive Sp
Myopia Addition < 1.75 dpt
Myopia: Addition ≥ 1.75 dpt
Priority in distance vision
Priority in near visiondominant eyenon dominant eye
Good contrast
  • Distance vision depends on centering, near vision on the movement (translation).
  • For a good translation, a movement from 1 to 2 mm is needed. It is affected by rO and ØT.
  • The fluoroscopy must show good optic zone alignment. 

Central optic zone, position and diameter:

Recommendations for the 1st choice: standard pupil (3.50–4.00 mm) with normal lighting

Bifocal BfBifocal BfSimple progressive SpSimple progressive Sp
PositionCentre near (CN)Centre Distance (CD)Centre near (CN)Centre Distance (CD)
Dominant eye2.253.752.504.00
Non-dominant eye2.753.253.003.50

For non standard pupil size or for distance/near preference, fit the Zoc in steps of 0.25 mm

Rigid Contact Lens Materials


Boston XO

Optimum Comfort

Boston EO

Optimum Classic

Boston ES

Contaperm F2 low

DK Fatt ISO 9913-1









Wettability angle49° (2)6° (3)49° (2)12° (3)52° (2)

19° (3)

Hardness (4)79.979838385.4


Refractive index1.4151.4371.4291.451.443


Handling tintblue red green lilablue greenblueblue greenblue green





Resistance deformation (5)++++++++++++


Long term wearing+++++++++


Tear film with lipid++++++++++


Tear film with protein++++++++++




* ×10-11 (cm2/sec) [ml 02/(ml × mm Hg)]

** ×10-11 (cm2/sec) [ml 02/(ml × hPa)]

2 Wettability angle = CLMA method 

3 Receding contact angle (DCA)

4 Shore D 

5 Corneal astigmatism

More information about the product features (Article by Boston Materials)

Default material: Optimum Classic Blue

Quality assurance

These materials are in conformity with the standard ISO 10993-1 defining the biocompatibility of materials.

SwissLens manufacturing process warrants this biocompatibility even after the manufacturing process, in particular without adding polish material. This standard is required by the quality assurance system of SwissLens.

Boston Materials


Material Training with Martin Conway from Contamac