Having parents with myopia increases the chances of a child developing myopia. Studies have found that identical twins are more likely to have similar prescriptions and eye length than non-identical twins. The heritability of eyeball length is also high, at over 90%. East Asian children have a higher incidence of myopia compared to European Caucasian children, which suggests that there may be a genetic component to the development of myopia.
Children who spend less time outdoors and have less exposure to natural lighting are more likely to develop myopia. Research has found that outdoor activity reduces the prevalence of myopia in children. Studies have also found that high population density and smaller homes are associated with increased eyeball elongation and childhood myopia, which suggests that the environment in which a child grows up may also play a role in the development of myopia.
Prolonged near tasks such as reading and using electronic devices at close distances have become more prevalent in today's digital age, which has led to an increase in the incidence of myopia. A study found that the COVID-19 pandemic and the resultant increased screen time have led to an increased prevalence of myopia in children. Another study also found that increased screen time and decreased outdoor time during the pandemic were associated with an increased risk of myopia in children.
