I didn't bother registering to view the rest of the article, but am I right that it is screen time as the cause?

I was in senior high school in China there were only 4 classmates out of 35-ish including me don't wear glasses. This was like 2007, before the smartphone took off in China.

I have no idea how come did this happen but one of my assumptions is the ruthless study plan for young kids.

Several studies have linked lack of exposure to sunlight to short sightedness. One specifically identified UVB radiation as important in preventing it.

It's probably lack of going outside on a clear day that's causing it rather than what they're looking at indoors.

sounds like they need to better plan for the future

I always thought the term was near-sighted. "Short-sighted" means "done without consideration for the future."

In the US, most people do say "near-sighted", but in the UK "short-sighted" is common. For example, on the NHS website: https://www.nhs.uk/conditions/Short-sightedness/

The reason you can use "short-sighted" as an adjective to suggest that someone isn't thinking about the future is by analogy to this condition. The same thing is true for "myopic".