And with nine out of 10 university students in those cities having less than 20-20 vision, glasses or contact lenses are now par for the course. The picture is much the same in places like Taiwan. The study was small, involving only 68 children. But wearing those glasses, it seems, can significantly slow the rate of shortsightedness. Among those given progressive lenses, vision deteriorated at only half the rate of the other kids.
Shortsightedness occurs when the eyeball becomes too long or the lens becomes too thick.
This causes the light from faraway objects to focus in front of the retina rather than on it. Hence the blurred images. Progressive lenses act like a series of bifocals, which are graduated to give the strongest light-bending power toward the top. The idea is to enable shortsighted people to focus clearly on distant objects, while reducing the lens power when looking at something up close. The Polytechnic University results surprised scientists because previous research failed to show significant benefit.