Superb surgeons have qualities that set them apart. In addition to the intelligence needed to practice good medicine, they possess dexterity, physical stamina and, equally important, supreme confidence in their skills and an insatiable desire to fix things. But few surgeons aspire to vanquish a disease from an entire region of the world. That was the dream of Sanduk Ruit, a brilliant Nepalese doctor born in one of his country’s poorest and most remote villages, who became a pioneering ophthalmologist, revolutionizing cataract surgery and creating a medical network to deliver the sight-restoring operation to blind people throughout the Himalayas and in other developing countries.

Watching Ruit carry out impeccable cataract extractions in a bare-bones clinic in rural Nepal was the experience that first made David Oliver Relin consider writing about him. “I’ve always loved watching any physical task performed flawlessly,” Relin notes. But Ruit’s determination to cure cataracts, the world’s leading cause of preventable blindness, on a massive scale convinced the co-author of Three Cups of Tea that he had to tell the surgeon’s story.

Ruit’s dogged personality and his remarkable accomplishments make Second Suns a compelling and inspiring book. Ruit’s mother lost three of her six children to treatable illnesses — diarrhea, fever, tuberculosis — and young Sanduk, sent away to boarding school in Darjeeling, India, at age 7, soon resolved to do his part to remedy the lack of health care that had led to his siblings’ deaths. “They died because resources the rest of the world had were not available to us,” he recalled. “I realized I had to become a doctor.”

As a foil to Ruit’s superhuman focus, Relin also traces the trajectory of his unconventional partner, Geoffrey Tabin, an American ophthalmologist who seems in the book’s early chapters like a caricature of a talented but overly privileged and self-centered young doctor. Athletic, hyperactive and risk-loving, Tabin repeatedly dropped out of Harvard Medical School and later left an orthopedics residency to join mountaineering expeditions, even abandoning medicine to spend a few years as a journalist and world-class climber. But while volunteering at a Himalayan clinic after summiting Mount Everest, Tabin witnessed a cataract operation and decided to become an ophthalmologist. Years later, fully trained, he arrived in Kathmandu to work with Ruit, who at first refused to take him seriously. “I chalked him up as just another one of those jokers,” Ruit recalled.

But Tabin was so inspired by Ruit’s surgical skill and altruism that he did whatever his mentor demanded, eventually becoming both an expert eye surgeon and the chief fundraiser and grant-getter for Ruit’s Himalayan Cataract Project. He also helped expand the program’s training of eye surgeons to serve other medically needy countries, including India, Ghana, Ethiopia and Rwanda.

Second Suns portrays heroic health care delivered under harrowing conditions: Ruit and his teams carry their equipment on multi-day treks up steep mountain trails, sometimes hiking at night with flashlights or head lamps, to reach settlements where they typically spend several days operating on hundreds of villagers in makeshift surgical theaters. They worked throughout Nepal’s decade-long civil war, operating on government sympathizers and Maoist rebels alike.