Xiangui He, MD, PhD
Shanghai Eye Disease Prevention & Treatment Center
Myopia, characterized by onset and rapid progression in childhood, is already a global health threat in East and Southeast Asia, with nearly half of school students aged 12 years and older myopic.1, 2 Myopia can be corrected with spectacles, contact lenses, or refractive surgery, and its progression often slows down in late childhood or early adulthood. However, the increasing trend of myopia manifesting at an earlier age is increasing the risk of an individual reaching high myopia.3 Some regions in Asia are already witnessing an epidemic of high myopia in children and young adults.2, 4, 5 Several ocular complications occur in patients with high myopia at older ages. One such complication, myopic maculopathy, is now the leading cause of irreversible and usually bilateral visual impairment among working populations in East Asia.6-8 Therefore the presence of high myopia will inevitably lead to the substantial reduction of life quality in both children and adults, and it will considerably increase the economic burden in managing them.9, 10
Although the exact mechanism underlying the onset of myopia is unclear, research indicates an interaction between genetic and environmental factors.11
A higher correlation in refractive error between monozygotic twins than dizygotic twins and a higher risk of children with parental myopia developing into myopia was observed, indicating the role hereditary factors play in the development of myopia.12, 13 But whether these family correlations are the reflection of shared environment or shared genes needs further verification. Mutations or variations of numerous genetic loci have been demonstrated to be associated with early-onset or familial high myopia. However, determinant genes that could be applied practically as intervention methods to delay its onset have not been discovered yet.14, 15 On the other hand, evidence of the critical, influential effect of environmental factors is increasing with decreased outdoor activity and increased educational burden as some of the likely factors underlying the rising trajectory of school myopia.11, 20
