How to set goals for myopia management - Q&A with Prof Hakan Kaymak

A few years ago, we started prescribing MiYOSMART spectacles for myopic patients. From the publication, the clinical study showed that MiYOSMART spectacle lenses could slow down myopia progression on average by 60% when measured by axial length.¹ The treatment results among my patients were obvious: we have many satisfied patients and parents. However, emmetropic (i.e. physiological) eye growth among children makes a 100% reduction of myopia progression nearly impossible. Hence, I tried to think of other ways of measuring the treatment results of myopia management. I plotted the efficacy data of several common myopia management treatments and contrasted it with an emmetropic eye growth curve² and started to use this to set treatment goals for myopia management – that is, bringing myopic eyes to the level of emmetropic eye growth. We are happy that certain treatments can achieve this goal.³ Gradually, this concept evolved into the AMMC module.

AMMC stands for Age-Matched Myopia Control. This tool is based on periodic axial length measurements, with each data point representing a 6-month  axial length growth rate. The axial length growth rate captured in the biometry device of patients will be plotted and compared with age- and gender-matched emmetropic axial length growth rate. 

The AMMC module relies on three basic concepts to manage myopia control:     

1. Myopia, its onset, and its progression rate are assessed by axial length measurement. 
2. The axial length growth rate (mm/yr) of myopic patients is compared to the average normal growth pattern of children that are the same age and gender who become or remain emmetropic in adulthood. The assessment is based on the difference in “excessive” (i.e. myopic) growth and emmetropic eye growth.³
3. Under treatment, the reduction of myopic eye growth is the measurement of the treatment effect. In practical terms, if a myopia management treatment brings the annual growth rate of a myopic eye to a full return of the age-matched emmetropic axial growth rate, the treatment is considered to have 100% efficacy.³

With the introduction of specially designed spectacle lenses to inhibit myopia progression in children, the portfolio of myopia management treatment has been expanded with an easy-to-use and non-invasive option that can be prescribed by ophthalmologists and optometrists. However, there is yet to be a consensus on the specific goal of myopia treatment, what criteria should be used to monitor the treatment success, and when an adjuvant treatment should be administered. The AMMC module was therefore developed to enable the evaluation of the treatment results of each individual child, simplify the monitoring process, and support parent-practitioner communication.

The normative data that defines emmetropic growth has been extracted from epidemiological studies and is subject to refinement as further epidemiological data becomes available. Major parts of the normative data are based on the studies by Truckenbrod and colleagues in a German cohort,² my observations in German schools,³ and Sanz Diez and colleagues in an East Asian cohort.⁴ As juvenile axial growth is highly age-dependent,^5-6 the tool therefore considers the patient’s age when assessing a treatment effect.

The aim is to create a comprehensible and generally accepted system with which the success of myopia treatments can be easily assessed. Based on this approach of age-matched myopia control, a tool with a graphical user interface was developed. The module classifies the axial length growth rates into several tiers which are correlated to the modelled emmetropic axial length growth rates in an age-specific manner. Thus, practical information about the individual efficacy of a myopia treatment can be obtained, and treatment recommendations can be given. The use of this tool is viable for ophthalmologists as well as optometrists since the introduction of new biometers enables everybody to monitor axial length growth.

The AMMC module classifies a patient’s myopia development into “Fast progression”, “Moderate progression”, “Slow progression” and “Emmetropic growth” according to the axial length growth rates and thus provides information about the efficacy of the current treatment and practical instructions for further treatment. Figure 1 below is an example of what the AMMC module looks like on the biometric device. The treatment results are very straightforward. 

The AMMC module is easy to use and can be effectively implemented in clinical practice. With the AMMC, it is possible to tell the parents clearly what we want to achieve with our treatment, and thus helps to reduce chair time thanks to a more explicit explanation. It also supports improved compliance and adherence, especially when we use atropine eye drops. It is nice for parents and as well as for children to see that they reach the treatment goal and are thus further motivated.