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 www.swisslens.ch/toolbox 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.
References:
[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; https://www.clspectrum.com/issues/2016/march-2016/defining-a-strategy-for-myopia-control[14] A. van der Heide, DATA ANALYSIS OF THE EFFECTIVENESS OF THE RELAX CONTACT LENS FOR REDUCING MYOPIA PROGRESSION 2019
