One of the most difficult challenges in myopia control is identifying whether or not patients are receiving a significant therapy benefit. This has been a problem because patients of different ages progress at varying rates, and we can never truly know how far an individual patient would have advanced if they hadn’t received treatment.
A good example of this is the typical 7-year-old non-Asian patient progressing by –1.00D in refractive error and 0.35mm in axial length per year, but the average 12-year-old non-Asian patient progresses by –0.40D in refractive error and 0.21mm in axial length per year.
Individuals of Asian descent make slightly more progress than patients of non-Asian descent. The prevalent thinking that a myope develops 0.50D per year on average only holds true for people of a specific age and racial group (those under the age of ten).
In addition, it is crucial to remember that emmetropic patients might have a neutral refractive error while still experiencing around 0.1mm of axial length advancement per year.
Recently published evidence suggests that the maximal axial length slowing experienced by a myope treated with a multifocal soft contact lens may be similar to that seen by an emmetrope in some cases.
As a result, it is unlikely that we will be able to completely halt axial length growth in children who are still growing. In addition, it is vital to remember that these are averages, which means that certain patients will progress more rapidly than the average myope.
What can we do with this information to determine the effectiveness of myopia management treatments? Efficacy is determined by observing that individuals progress less than the mean value for their age and race after undergoing a particular treatment.
While this is not a perfect sign of effectiveness, it does provide us with some foundation for determining whether a treatment is helpful, and we will most likely continue to rely on this type of data until studies that speak to the effectiveness of treatments in individual patients are conducted.
We discuss with families the potential benefits of combination therapy after at least one year of treatment. Nonetheless, it is up to the parents, after they have been educated, to decide whether or not to change the course of therapy.