Less time than whom? From that article, “According to reports published in recent years, the prevalence of myopia in China is now more than 80% of the population.”. I’d be wiling to use “the behaviors of 80% of the population” as a proxy for the level of exposure that’s in some way ‘normal’ for that group.
The total number of myopia doesn’t matter for looking at the difference. Myopia also doesn’t automatically mean glasses. It can also mean contact lenses which are worn less by nerds.
Less time than whom? From that article, “According to reports published in recent years, the prevalence of myopia in China is now more than 80% of the population.”. I’d be wiling to use “the behaviors of 80% of the population” as a proxy for the level of exposure that’s in some way ‘normal’ for that group.
The total number of myopia doesn’t matter for looking at the difference. Myopia also doesn’t automatically mean glasses. It can also mean contact lenses which are worn less by nerds.