RelaxFlex Myopia

The Relax contact lens is developed and CE approved for the indication of myopia management in children between 8 and 18 years of age with the indication of progressive myopia.

Relative peripheral hyperopia is corrected with the proven technology of optimized Hyperopic Defocus Control (HDC). This ensures optimized imaging of the entire retina, including the periphery. Since single vision lenses do not correct this peripheral defocus, the focal plane is located peripherally behind the retina and could, therefore, be a stimulus for longitudinal growth.

The structure is similar to that of a concentric multifocal lens, whereby the distance is exclusively in the center. For myopia management, polynomial progression with Hyperopic Defocus Control (HDC) is located in the periphery of the contact lens.

The size and the beginning of the HDC zone are variable.

The unique Relax Design is available in a Soft lens design Relax, and a special OrthoK design for Children wit progressive Myopia NightFlex Relax


Image surface without Relax

Image surface with Relax


  • Spherical front and back optic zones
  • 3 different back optic variants like OrbiFlex

Technical Data

Total diameter7.50 mm12.00mm0.01 mm
Base curve6.00 mm9.00 mm0.01 mm
Sphere (CL)-0.25 dpt-40.00 dpt0.01 dpt
Defocus Addition+0.50 dpt+9.00 dpt0.01 dpt
Distance optic zone diameter ZOC2.00 mm6.00 mm0.01 mm

Additional information



Correction type

Lens Type

Designed by


Fitting advice

Use fitting advice for BC and Diameter like for corresponding unifocal design Orbis, Toris or OrbiFlex below

  • HDC: start with default value (Add +1.50 dpt / ZOC 4.50 mm) or use additional measurements
Optimising HDC:

Central optical zone for distance vision (Zoc) by measuring Pupil size in room lighting

  • small Pupil (< 5.00 mm): Zoc = 4.00 mm
  • medium Pupil (5.50 to 6.50 mm): Zoc = 4.50 mm
  • large Pupil (> 6.50 mm): Zoc = 5.00 mm

Peripheral Hyperopic Addition

2 possibilities to measure: 

  • Near Lag of Accommodation – measured with MEM Retinoscopy
    • Position yourself 33-40 cm away from the patient (2.50 -3.00 D accommodative demand). Have them either look at your nose or a near fixation card attached to your retinoscope. Use ±1.00, ±1.50 and ±2.00 flippers and start with looking at the reflex without a correcting lens, sweeping quickly along the horizontal and vertical, checking right then left eyes and then repeating. Try the +1.00 flippers first, and if you still see ‘with’ movement, quickly change to +1.50. If the reflex reverses, you get your answer at +1.25. Once you have got neutralisation or reversal, your last lens is your answer. See how this measurement works on youtube:
  • Near Lag of Fixation – measured with Thorington or Schober Cross
    • Use the Thorington Method or Schober test (or other similar) to measure the needed Addition to bring the cross into the center of the circle.
      Patient hold the test in 33-40 cm in front of the eyes in normal gaze position. Use a red/green or polarisation filter, depending on the test. Ask the patient to look at the cross and circle and let them explain where they are. Try with the binoculars flipper plus power so long until the cross is in the middle of the circle.
      If the disparity indicates an exophoria, then this is not useful and probably the Relax lens will not work as expected.

Fitting advices

  • 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 advices for gas permeable contact lenses


  • Insert trial lens for a minimum duration of 30 minutes. Ask patient to focus on the floor to minimise the foreign body sensation.
  • Evaluation of the subjective comfort.
  • Over-refraction
  • Slit lamp examination:
    • Dynamic evaluation with diffuse illumination:
      • Eye in primary gaze and blinking normally.
      • Movement (speed) and position after blink and during eye movements:
        • Vertical movement
        • Horizontal movement
        • Centration
        • A good fitting lens will be evenly centered on the cornea (±0.5 mm)
        • The movement should be pronounced but not too big (1-2 mm)
  • Static evaluation with fluoroscopy:
    • Evaluation when patient is looking straight ahead and the lens is centered on the cornea without impact of the eyelids on the lens: Evaluation of the tear film thickness under the lens; tear film < 10μm = no florescein is visible.
      • central optic zone with alignement fluorescein pattern
      • inter-peripheral zone with small amount of fluorescein
      • peripheral zone with a band of increased fluorescein which will be needed for a good tear film exchange
Advice for Toriflex

The optimal fluorescein pattern shows a small fluor lake in the center and a larger fluor ring in the periphery (env. 0.75 mm).
Vertical movement should be around 1 mm. In case of too much movement, decrease both central back curves (r0fl and r0st) with -0.10 mm. In case of low riders, increase both central back curves (r0fl and r0st) with +0.10 mm or in case the upper lid is pushing the lens down, increase the total diameter ØT.

In case of high riders, decrease total diameter ØT

For Toriflex TP only:

In case of instable stabilisation and/or high riders, increase the prism to 2.0 cm/m.

WARNING: the stabilisation prism induce an optical prism. This should be adjusted on both eyes.

Publication on Relax

Enhancing the optical zone of custom made myopia prevention contact lenses

Several domestic and international health institutions such as The World Health Organisation (WHO)[1], the Brien Holden Institute[2] and the British Association of Optometrists (AOP)[3] have published recommendations for the use of myopia control contact lenses. Even though research into peripheral refraction in connection with myopia control is still ongoing [4], multiple studies have clearly indicated that multifocal contact lenses, as well as orthokeratology contact lenses, have a positive effect on the slowing of myopia progression. Walline[5] reviewed the peer-reviewed literature of studies which used the currently available standard lens geometries and found that the progression of myopia can be reduced by up to 50%.

Aller’s research [6] however, shows a success rate of over 70% in myopia reduction. A closer look into Aller’s work shows that it is important to not only test the binocular vision when fitting multifocal or orthokeratology contact lenses, but to take this into account in order to improve this success rate and this is borne out in other studies too[7-10].
Aller’s research[6] however, shows a success rate of over 70% in myopia reduction. These studies raise the questions: Why do not all children and adolescents respond positively to these products? How can we improve the products so that myopia prevention has a positive effect on everybody?

Figure 1: Meta-Analysis of data collated in Lisa-Maria Mathys Bachelor‘s thesis 2016 ‘Effektive Kontrolle der Myopieprogression: Erstellung einer Metaanalyse und deren Ableitung auf Handlungsmöglichkeiten für Optometristen‘

Is this the key to more effective myopia control?

Binocular vision investigations which influence the success rate would include measuring the AC/A ratio, accommodative lag and any heterophoria together with an assessment of its compensation.

A high accommodative convergence movement occurring with the accommodative effort (a high AC/A ratio) or a decompensating ‘phoria deserves special attention. A Malaysian study showed that children with a significant near esophoria are more likely to develop myopia[11] and this can be tested with the Schober Test, or a fixation disparity test, at the habitual reading distance. The aligning sphere can be used to indicate which near addition would be optimal for myopia control. Furthermore, an accommodative lag has also been shown to trigger myopia progression and seems to be more prevalent in myopes than in emmetropes[10]. In accommodative lag, the image shell would not be formed on the retina but would be relatively hypermetropic (i.e. behind the retina) and this has been shown to be a stimulus for a progression of the myopia[12]. By having a relatively hyperopic power in the periphery of the contact lens, the effect of the accommodative lag can be overcome. Further aspects which influence the progression of myopia include aberrations caused by both the pupil itself and the size of the optical zone of the contact lens in relation to the pupil diameter [13]. They describe how the pupil diameter also influences which lens design might be more beneficial and this is taken into account in our individualised lens designing.

What does SwissLens offer?

SwissLens provides an online calculation tool available at where you can enter additional measurements in order to obtain the ideal parameters needed for a customised near zone, maximizing the opportunity to achieve the best possible hyperopic defocus control result.
The Relax soft contact lens has been on the market for 9 years with proven effectiveness[14] and the feedback from our customers has been extremely positive. This product is available in spherical as well as toric options, with an almost limitless choice of diameters and base curves to ensure a perfect fit. Depending on the quality of the tear film, we offer different materials, including Definitive74 Silicon, and you can choose between 3 or 6-month replacement schedules. Since 2015, our Relax contact lens has also been available in RGP materials and at the moment we are also developing an orthokeratology version. The combination of our online tool, additional test recommendations and our Relax products will allow a more precise myopia management.
Ongoing studies will also lead to a better understanding of the relationship between binocular vision, the pupil size, the prescription variations and the mechanisms of the longitudinal growth of the eye.


[1]         Bastian Cagnolati, Periphere Refraktion und Myopieentwicklung – Update, die Kontaktlinse, 7-8/2016

[2]         Walline JJ 2016, Myopia Control: A Review.

[3]         Thomas A. Aller, et al., Myopia Control with Bifocal Contact Lenses: A Randomized Clinical Trial

[4]         Whatham, A., Influence of accommodation on off-axis refractive errors in myopic eyes

[5]         Goss DA, Grosvenor T. Rates of childhood myopia progression with bifocals as a function of nearpoint phoria: consistency of three studies. Optom Vis Sci 1990;67:637Y40.

[6]         Fulk GW, Cyert LA, Parker DE. A randomized trial of the effect of single-vision vs. bifocal lenses on myopia progression in children with esophoria. Optom Vis Sci 2000;77:395Y401.

[7]         Gwiazda JE, Hyman L, Norton TT, Hussein ME, Marsh-Tootle W, Manny R, Wang Y, Everett D. Accommodation and related risk factors associated with myopia progression and their interaction with treatment in COMET children. Invest Ophthalmol Vis Sci 2004; 45:2143Y51.

[8]         Chung, K.M. and E. Chong, Near esophoria is associated with high myopia. Clin Exp Optom, 2000. 83(2): p. 71-75.

[9]         Charman, W.N., et al., Peripheral refraction in orthokeratology patients. Optom Vis Sci, 2006. 83(9): p. 641-8.

[10]       Gifford, K. Myopia Profile – Measuring near lag of accommodation. 2015

[11]       Gwiazda, J., et al., A dynamic relationship between myopia and blur-driven accommodation in school-aged children. Vision Res, 1995. 35(9): p. 1299-304.

[12]       W.N. Charman, Aberrations and myopia, 2005

[13]       Michaud Langis;


Rigid Contact Lens Materials


Optimum Infinite

Boston XO

Optimum Comfort

Boston EO

Optimum Classic

Boston ES

Contaperm F2 low

DK Fatt ISO 9913-1

180*/ 135**











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

19° (2)

Hardness (4)




Refractive index




Handling tint

blue red green clear

blue red green lilablue greenblueblue greenblue green

blue green clear






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

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