February 15, 2023
By Dwight Akerman, OD, MBA, FAAO, FBCLA, FIACLE
In this editorial, Bullimore and Brennan explore a vexing research question: Can results from myopia control studies on East Asian children be applied to Western children and vice versa?
It is well established that the prevalence of myopia is higher in East Asian countries but is increasing worldwide, with a few exceptions. Second, myopia progresses 30% faster in East Asian than non-East Asian children, but both show the same exponential slowing with age — 15% per year. In contrast, myopia progression is strongly related to the degree of axial elongation in all races, and the ratio of progression to elongation seems independent of race. Likewise, the relationship between the degree of myopia and the risk of eye disease seems to be the same.
Myopia control interventions are typically evaluated in single-center studies with limited racial diversity. Multicenter studies of myopia control are rare, and clinical trials involving multiple countries are even rarer, but there are exceptions. The authors believe that the metric Cumulative Absolute Reduction in axial Elongation (CARE) is preferred for expressing efficacy and comparing treatments and studies. Expressing efficacy in absolute terms is independent of patient age and incorporates a reduction of efficacy over time.
Bullimore and Brennan’s analysis failed to find evidence of a difference between East Asians and non-East Asians in terms of myopia control treatment effect. They acknowledge that their observations are not derived from rigorous clinical study designs and that “absence of evidence is not evidence of absence.” None of the individual examples are statistically robust to detect differences and should thus be considered inconclusive rather than negative. Nonetheless, the consistency across two multi-country clinical trials and three sets of between-trial comparisons supports the proposition that no difference exists.
The authors conclude that, based on available evidence, the efficacy of individual myopia control treatments is largely independent of race. More generally, in terms of slowing axial elongation, treatment efficacy is independent of the progression rate. It does not matter whether the child is progressing faster because they are younger rather than older or East Asian rather than of European descent. The benefit of any myopia control modality seems to be the same.
Efficacy in Myopia Control: Does Race Matter?
Bullimore, Mark A. MCOptom, PhD; Brennan, Noel A. MScOptom, PhD
The range of available myopia control modalities is increasing rapidly. Likewise, the number of studies assessing these various approaches is increasing exponentially. Unfortunately, established and emerging therapies are typically evaluated in single-center studies with limited racial diversity. Here we evaluate the extent to which results on one race can be extrapolated to others; specifically, can results from studies on East Asian children be applied to Western children and vice versa?
Bullimore, M. A., & Brennan, N. A. (2023). Efficacy in Myopia Control: Does Race Matter?. Optometry and Vision Science, 100(1), 5-8.