(MONEY Magazine) – The people queue up by the hundreds and wait for hours, sometimes days. But, says Ron Cuevas, 41, "they're always happy to see us." Cuevas, an optometrist with LensCrafters, is part of a group of globetrotting eye doctors and technicians who bring free eye exams and recycled eyeglasses to the world's poor. "We think we're doing something simple, but to them, we're giving them the world."

Cuevas made his first trip, to Panama, in 1992. Toting $20,000 worth of equipment and donated glasses, the team set up a makeshift clinic under the watchful eye of a heavily armed military. Then, with a local priest as a guide, Cuevas and three volunteers loaded equipment into dugout canoes and paddled to an isolated camp in the remote San Blas Islands. "The jungle was filled with drug dealers," he remembers. "But we managed to examine 357 people."

Working in conjunction with Lion's Club International, which helps identify the neediest communities, Give the Gift of Sight International (GOS)--the philanthropic arm of LensCrafters that evolved in response to the volunteer effort--coordinates the collection and shipment of equipment, medicine, personnel and eyeglasses abroad. "Ron helped shape the program," says Susan Knobler, co-director of GOS. So far 1 million people have received exams and glasses.

Cuevas, who digs into his own pocket to cover some expenses, says he gets as much as he gives. The stories can be wrenching. "We've diagnosed fatal retinal tumors that we can't treat." But there are also miracles. "Imagine living 55 years not being able to see--then suddenly you can! It's an amazing thing to be part of." --E.M.