Our results showed the age at stabilization and the level of myopia at stabilization to be strongly correlated and influenced by similar factors. The age at stabilization (
P < 0.0001) and the amount of myopia stabilization (
P = 0.02) both varied significantly across ethnic groups. African Americans were more likely to have an earlier age at peak myopia deceleration (approximately 1 year earlier than the other ethnic groups), have stable myopia at earlier ages (13.8 years compared with approximately 16 years in the other ethnic groups), and have less myopia at stabilization (−4.36 D compared with approximately −5.0 D in the other ethnic groups). The ethnic differences in myopia stabilization observed in the COMET are not unexpected because differences in myopia progression among ethnic groups were observed previously in this cohort. During the first 3 years of the COMET, myopia progression was significantly slower in African Americans than in the other ethnic groups, a finding that is consistent with their lower amount of myopia at stablilization.
25
Asian children in the COMET showed the most myopia at stabilization and had significantly faster progression than African American COMET children during the first 3 years of the study.
25 While to the best of our knowledge data from other studies are not available on myopia stabilization in Asian children, rates of progression similar to those of the COMET children were found in studies conducted among Asian children in Hong Kong,
26 Singapore,
27 and the Shunyi district in China.
28 A report from the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error Study,
29 a multicenter observational investigation of refractive error in four ethnic groups from four different locations in the United States, found Asian children to have the highest prevalence of myopia. Prevalence studies among adults have also identified Asian populations as having more myopia
30,31 and African Americans as having less myopia.
2,32 Therefore, ethnic variation has been observed for all phases of the course of myopia. The differences in myopia prevalence among ethnic groups seem to be explained by a combination of genetic factors and environmental factors because increases in myopia prevalence have been observed across different ethnic groups among the same populations
2 (Saw SM, et al.
IOVS 2011;52:ARVO E-Abstract 2490) and because myopia prevalence for children of the same ethnic origins varies depending on where the children live and the environments to which they are exposed.
33 For example, children of Chinese origin living in Australia had lower levels of myopia than their counterparts living in Singapore.
34 Therefore, the ethnic differences in myopia stabilization may be influenced by factors in the visual or social environment that can occur during the different phases of myopia progression and slowing (e.g., changes in reading or studying patterns and time spent outdoors).