Doesn't necessarily has to be DNA. Prevalence of fixed focus work, screens and monitors and reading, has made more people need glasses, in earlier ages, than 100 or 200 years ago for example...
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.