The glasses, by Essilor Stellest, are approved by the FDA to slow nearsightedness in 6- to 12-year-olds. For many children, the experience of getting their first pair of glasses is an inevitable milestone, the first in a lifetime of visits to the eye doctor.But what if those lenses could actually help preserve the child’s vision and reduce the chances for more serious eye problems in adulthood?That’s the promise of a new type of lens approved by the Food and Drug Administration in September. While the technology has previously been available in Europe, Asia and other parts of the world, it’s now rolling out in the U.S.Here’s what to know about the new approach.