In the past two decades, medical trains funded by Lifeline Express, a charity in Hong Kong, have helped to restore the sight of thousands of rural residents with cataracts.

In 1997, Hong Kong returned to China after more than a century under British rule. To mark the handover, the central leadership and local governments sent lavish gifts to the city, including a landmark sculpture of a flower in Golden Bauhinia Square.

Ahead of the handover, Nellie Fong, a well-known healthcare activist, was chosen as a member of the Preparatory Committee for the Hong Kong Special Administrative Region, which was founded to implement the establishment of the SAR.

Fong was impressed by the gifts and eager to reciprocate. "A gift should be memorable, and I wanted mine to provide lasting benefits for my compatriots," she said, recalling how she founded Lifeline Express.

At the time, more than 4 million people in China had cataracts. Poverty condemned many to unnecessary blindness, robbing them of their livelihoods and perpetuating a cycle of misery.

Inspired by medical trains in India that are equipped like hospitals, Fong started Lifeline Express with the aim of providing free operations for cataract patients in rural areas. She also founded the Lifeline Express Hong Kong Foundation to fund the program.

"The program was acclaimed by people in Hong Kong. Many small and medium-sized businesses donated money over several years, and we even received donations from people in the low-income group," she said.

Many doctors showed their support by providing their services free of charge, and local stars, including Jackie Chan and Andy Lau, endorsed the charity by appearing at its events and fundraising activities, she added.

The charity's first train departed Kowloon Station for the mainland on July 1, 1997, the day Hong Kong returned to China. It carried volunteer doctors from large cities, including Beijing, Tianjin and Hong Kong, who stayed in several rural areas for about three months each. By the time they left, they had usually performed as many as 1,000 surgeries.

In addition, the doctors also provided training for their rural counterparts and donated surgical equipment, while the foundation paid for rural ophthalmologists to visit Hong Kong for training.

In 1999 and 2002, the charity donated two more trains, and a fourth, provided by businesspeople in the mainland, began operating in 2009.

In 2002, the Chinese Foundation for Lifeline Express was founded in Beijing. Along with its counterpart in Hong Kong, it enabled people in the mainland and Hong Kong to show their support for the program.

By the end of 2016, the four trains - all called Lifeline Express - had made about 160 stops in 28 provinces and regions, helping to restore the sight of more than 180,000 cataract patients.