50% of the world’s population is expected to be short-sightedness by 2050, according to an Opthalmology journal. 60 years ago, only 15% of the Chinese teenagers need to wear glasses. Now 90% of teenagers and young adults have difficulties reading far objects. 95% of teenagers in South Korea are short sighted.
I don’t know how accurate these figures are but I bet it won’t be too far off the reality in developed cities where everyone uses smart phones and computers every day. I haven’t worn any glasses for a long time (except for sun glasses) so I rarely walk into optical shops which are not designed for casual browsing.