[coldtea]

>Could it be the prevalence of ophthalmologists instead?

It's orthogonal. More doctors would mean more diagnosis. But more short distance indoors fixed focus screen work stress on the eyes would also mean more patients.

Too little time outdoors

Research has found that spending time playing outside as a child may reduce your chances of becoming short-sighted, and existing short-sightedness may progress less quickly.

This may be related to light levels outdoors being much brighter than indoors. Both sport and relaxation outdoors appear to be beneficial in reducing the risk of short-sightedness.

Excessive close work

Spending a lot of time focusing your eyes on nearby objects, such as reading, writing and possibly using hand-held devices (phones and tablets) and computers can also increase your risk of developing short-sightedness.

An "everything in moderation" approach is therefore generally recommended. Although children should be encouraged to read, they should also spend some time away from reading and computer games each day doing outdoor activities.

https://www.nhs.uk/conditions/short-sightedness/causes/