Dispensing, Feature

Myopia management for dispensers by Grant Hannaford – Part 1

Myopia’s prevalence has driven the development of innovative interventions, including spectacle lens options. GRANT HANNAFORD explains how dispensers can fit into the myopia management treatment plan.

Myopia management is a rapidly developing field, with spectacle lens interventions advancing significantly. The risk for developing additional conditions such as cataract, retinal detachment and myopic maculopathy is elevated in myopia and risk is linked to power. Consequently, myopia represents one of the most significant challenges for optometry today, perhaps more so since the challenges raised by the COVID-19 pandemic and myopic development.

Grant Hannaford.

These articles will look at dispensing in practice regarding myopia management. Part 1 is an overview for the dispenser, while Part 2 assesses specific lenses and their applications. References cited are available at www.aaoo.net.au/MFD1 and listed below. While treatment pathways encompass various techniques including pharmaceutical and contact lens options, this discussion is limited to spectacle lenses. In November, we will also provide a more detailed overview in the Myopia Management for Dispensers webinar via the AAOO CPD program (www.aaoo.net.au).

The growth of the eye during childhood is dependent on coordinated development between the refractive and physiological components of the eye, interruptions to which may result in the emergence of refractive error. Myopia can be considered as an excess in power of the refracting elements of the eye or an eye length that is too long for the refracting power of the eye. It is somewhat relative so using standard values for ages we can reach broad definitions for causes for myopia of ‘refractive’ or ‘axial’.

Click here to open a a six-point checklist for optical dispensers and myopia management. 

The sensitivity of this emmetropisation phase to interruption represents the time of greatest risk for the emergence of refractive error, for the same reason it is also an ideal time to attempt to influence the ocular development to optimise refractive outcomes. While generalisations are always risky, many of the interventions in use at this time rely on manipulation of blur at the retina, either overall or in the periphery, to try and influence growth and refractive development. The range of spectacle lens families have been studied with relation to myopic development.

Following is a brief look at lens concepts that may be useful for dispensers talking to patients:

  • Single vision – no evidence to support wear influences refractive development (1), consequently this often provides our reference for the efficacy of other treatments.
  • Multifocals (bifocals, PPL/PALs) – create areas of competing focus in the eye with the plane formed by the ‘add’ triggering a slowing of axial growth. The efficacy of these varies with lens type. Practitioners may also examine binocular vision function which may lead to prescribing prism control bifocals. (2, 3)
  • Myopia correcting lenses – aspheric single vision lenses incorporating a treatment zone consisting of areas or rings of aspheric lenslets. The two main designs in this field create either areas or volumes of competing focus in the eye to slow ocular growth. (4-9)

While the effectiveness of these options varies, a range of factors will influence the outcomes, from binocular vision criteria to wearing patterns, so not every option will be appropriate for a given patient. Once a design has been selected by the practitioner, dispensers will be vital for implementation of treatment, education and follow up/compliance.

Implementation – after prescribing by the practitioner, the dispenser will need to ensure the lenses are correctly implemented. This includes the selection of an appropriate frame in terms of not only fitting, but also lens requirements. All relevant lens options have specific requirements such as minimum fitting heights/depths, tilts, wraps and MSU. The dispenser should be familiar with the requirements of the lens design to ensure optimal outcomes.

Education – children and parents will require coaching on how to use the spectacles and performance expectations. Designs may have zones of lower effective acuity which need to be explained to avoid rejection. Remember, the patient is engaging in a treatment regime, so 6/6 is not necessarily going to be the best visual outcome for them at that point in time. Similarly, do not change the lens design without practitioner consultation. Lens designs for myopia control may not be interchangeable.

Follow up – the patient should engage in regular reviews to evaluate the effectiveness of the treatment. It may be necessary to modify the lenses periodically and the dispenser can ensure patients are compliant with lens usage and attending reviews as required.

The next article will look at the specific fitting requirements for lenses mentioned here and their features and limitations.

ABOUT THE AUTHOR: Grant Hannaford is the co-founder and director of the Academy of Advanced Ophthalmic Optics. He owns the private practice Hannaford Eyewear and is a senior lecturer at the UNSW SOVS. He is currently a doctoral candidate at the School of Optometry Aston University researching ocular biometry and development.

References 

  1. Ong, E., et al., Effects of spectacle intervention on the progression of myopia in children. Optom Vis Sci, 1999.76(6): p. 363-9.
  2. Cheng, D., et al., Randomized trial of effect of bifocal and prismatic bifocal spectacles on myopic progression: two-year results. Arch Ophthalmol, 2010. 128(1): p. 12-9.
  3. Cheng, D., G.C. Woo, and K.L. Schmid, Bifocal lens control of myopic progression in children. Clin Exp Optom, 2011. 94(1): p. 24-32.
  4. Lam, C.S.Y., et al., Effect of Defocus Incorporated Multiple Segments Spectacle Lens Wear on Visual Function in Myopic Chinese Children. Transl Vis Sci Technol, 2020. 9(9): p. 11.
  5. Zhang, H.Y., et al., Defocus Incorporated Multiple Segments Spectacle Lenses Changed the Relative Peripheral Refraction: A 2-Year Randomized Clinical Trial. Invest Ophthalmol Vis Sci, 2020. 61(5): p. 53.
  6. Li, Y., et al., Evaluating the myopia progression control efficacy of defocus incorporated multiple segments (DIMS) lenses and Apollo progressive addition spectacle lenses (PALs) in 6- to 12-year-old children: study protocol for a prospective, multicenter, randomized controlled trial. Trials, 2020. 21(1): p. 279.
  7. Lam, C.S., et al., Myopia control effect of defocus incorporated multiple segments (DIMS) spectacle lens in Chinese children: results of a 3-year follow-up study. Br J Ophthalmol, 2021.
  8. Bao, J., et al., One-year myopia control efficacy of spectacle lenses with aspherical lenslets. Br J Ophthalmol, 2021.
  9. Li, X., et al., Influence of Lenslet Configuration on Short-Term Visual Performance in Myopia Control Spectacle Lenses. Front Neurosci, 2021. 15: p. 667329.
  10. Gwiazda, J., et al., A randomized clinical trial of progressive addition lenses versus single vision lenses on the progression of myopia in children. Invest Ophthalmol Vis Sci, 2003. 44(4): p. 1492-500.

More reading

A brief guide to frame adjustment – Part 1

Practical frame adjustment guide – Part 2

Importance of accurate measurements – Nicola Peaper