Count the hours your eyes spend on screens today. Now count the hours they spend looking at something far away. For many of us, the second number is shrinking. A widely cited projection published in Ophthalmology in 2016 estimated that 49.8% of the world's population, about 4.76 billion people, will be myopic by 2050, up from 22.9% in 2000.

The researchers pointed to lifestyle changes, mainly less time outdoors and more near work, and urged regular eye exams for children, preferably each year. It is a projection rather than a certainty, but it explains why eye care is suddenly everyone's business.