Squinting under the blistering sun, 14-year-old Tzandwei breaks into a toothy smile as he sees his reflection on the small black screen of a camera for the first time in his life. Surrounded by scores of well-wishers, the shy teenage Tibetan regards his father closely, taking in the features on his weather-beaten face with barely constrained delight. Tzandwei is one of about 500 Tibetan patients who early this month received life-changing cataract surgery on the Lifeline Express, a mobile eye surgery clinic that made its first journey to Tibet. Perched on a high plateau with an average altitude of 4,900 metres, Tibet's bright ultraviolet light means the region has the highest incidence of cataract disease on the mainland, with some Tibetans developing the blindness-inducing eye disease when they are in their thirties or forties. With the launch of the Qinghai-Tibet railway service in July last year, the Hong Kong-founded Lifeline Express charity has extended its reach into the vast Tibetan autonomous region. 'With much of the railway trail at more than 4,000 metres above sea level, high pressure and thin air are two obstacles we had to overcome,' said Susan Dong Shuzhen , the train manager. 'Before our inaugural flight to Lhasa , we needed to reinforce the glass of the carriages and install oxygen-supplying systems on the train. 'Extra medical equipment is also needed as patients undergoing surgery at high altitudes will have higher blood pressure and need extra medical care,' said the Beijing native, who has travelled with the train to dozens of mainland cities since it took to the tracks. The hospital train was launched a decade ago with donations from Hong Kong entrepreneurs and the public. On the day of the 1997 handover, the first Lifeline Express left Hung Hom station for Anhui province . Its work was hailed a success and a second and a third train were inaugurated in 1999 and 2002 respectively. The trains have gone to 22 mainland cities and provinces, providing free cataract treatment to more than 68,000 impoverished patients. With a donation this year of HK$30 million from China Petroleum & Chemical Corporation (Sinopec), a fourth eye train is expected to be in service by the middle of next year. Lifeline Express has now grown into a collaborative service between the mainland and Hong Kong, with backing from Hong Kong philanthropists and Chinese state-owned enterprises. 'The Lifeline Express was a gift from Hong Kong people to China in celebration of the handover. Now there are two foundations in China and Hong Kong to raise funds to relieve the suffering of cataract sufferers in remote areas on the mainland,' said Nellie Fong Wong Kut-man, executive president of the Lifeline Express Committee. A survey by the Ministry of Public Health indicates there are about 4 million mainland cataract sufferers. That figure is estimated to rise by 400,000 every year. Coming from poverty-stricken areas, most sufferers cannot afford the operation, which costs 3,000 to 5,000 yuan on the mainland. Taking teams of professional ophthalmologists to the 'roof of the world' was an uphill task for the charity. Sinopec donated more than HK$2 million for a refit of the hospital train so that it could withstand the harsh elements and rugged terrain along the sinuous Qinghai-Tibet route. Extra doctors and nurses were also brought in as part of the 24-strong staff from Hong Kong, Beijing and Shantou , as the high altitudes mean oxygen levels fall below 70 per cent and medics can only work for short periods. The three Lifeline Express trains operate on an ongoing basis on the mainland. The Tibet train began its latest journey in March last year in Tieling , Liaoning province . It was in Xinging, Qinghai province , by the middle of last year before going through Hunan and then stopping for repairs. It arrived in Lhasa early last month and next month heads to Kashgar , Xinjiang . In the Tibetan capital, the four carriages were tucked away in a remote depot surrounded by rippling fields and craggy mountains near Neiqiong, on the city's outskirts. The train has two operating theatres, staff quarters and a waiting room for patients. Lying on the bunk beds in the waiting room were dozens of elderly Tibetans whose brown faces reflected years of backbreaking work under the scorching sun. Sixty-eight-year-old Nagchuka, her grizzled locks tied into braids, was one of the hundreds of Tibetan cataract sufferers who travelled hundreds of kilometres from remote mountain communities to seek help from Lifeline Express. Her left eye was blinded by cataracts years ago and the elderly woman left her home in Naqu with her 38-year-old son in the hope of restoring the sight in her cataract-racked right eye. 'We would never have the money to get treatment for my mother,' her son said through an interpreter. On the day of the operation, Nagchuka staggered out of the surgery room with her right eye covered by a bandage. As she emerged from surgery the deep furrows on her cheeks creased into a beaming smile. Grateful old faces are a common sight on the train. Tzandwei was one of the youngest patients. He travelled with his father to Lhasa to try their luck at Lifeline Express. Suffering from congenital cataract and amblyopia (also called lazy eye) in both eyes, the world was a blur of hazy shapes and abstract objects. After their arduous trek from Xigatse , a two-day drive from Lhasa, the father and son were devastated when they were told amblyopia disqualified the boy from being accepted for surgery. With priority given to those with the best chance of complete vision restoration, Lifeline Express screens out those with disabilities such as amblyopia and macular degeneration. 'Because of limited resources and the deluge of patients, we cannot treat everyone at our doorstep. Given the constraints, we have no choice but to turn away those patients who have minimal chances of restoring heavy eyesight after treatment,' said Medea Yip Wai-shan, general manager of Lifeline Express Hong Kong Foundation. But on this day fortune favoured the distraught son and father. Touched by the plight of the rheumy-eyed boy, the Hong Kong ophthalmologists on board the train made a collective plea to accept the teenager's case. After their intervention, it was agreed Tzandwei would receive treatment on the train. A day after the 15-minute operation, Hunter Yuen Kwok-lai, associate consultant of the Hong Kong Eye Hospital, conducted a post-operative check on the boy. 'Because of his inborn amblyopia, the child can only gain partial vision after treatment. While the images he saw before were a complete blur, he can now see rough outlines of objects,' Dr Yuen said. But any improvement was a godsend to Tzandwei and he and his father were overjoyed at the improvement in his eyesight. 'His severe eye disability has precluded him from leading a normal life from birth,' said the 38-year-old, whose shy and timid son clung to his arms throughout the interview. 'Confined to our house all day long, he couldn't even tend to his own basic sanitary needs. I felt sad when I saw him being bullied by my two younger daughters.' The three Hong Kong eye specialists on the train described their work on the Lifeline Express as fulfilling and enlightening. With streams of patients filing in and out of the operation room, the ophthalmologists said they were most impressed by the mainland doctors' efficiency and their assembly-line-like procedures. 'While a Hong Kong doctor has eight cataract operations at most a day, our mainland counterparts on Lifeline Express whip up over two dozen surgeries in quick succession in a single morning,' said Tsang Chi-wai, an eye specialist with the Hong Kong Eye Hospital. With a target of 1,000 operations for the journey, the eye train will leave Tibet at the end of July for Kashgar in Xinjiang. The severe cases of cataracts in the Tibetans also offered the surgeons a lesson in the severity of the disease. 'Many of the Tibetans we operated on suffered from the most severe forms of cataract which verged on blindness,' said Dr Yuen. 'The opaque crystalline lenses of some of the patients were so hardened that we had to use additional force to break them up during the cataract extraction surgery. We also had to make do with the cramped operation space and older models of medical equipment. 'Working in the rather stressful environment and operating on Tibetans who don't even have a smattering of Putonghua was a great challenge for us,' said Lulu Cheng Lu, a specialist in ophthalmology with the Prince of Wales Hospital. The train represented a meeting of minds for the Hong Kong and mainland eye experts. Operations took place with a video system transferring live footage to a screen in the conference room, to involve those engaged in observation sessions outside the theatres. 'With Hong Kong doctors on the train, we can exchange ideas and learn from their medical expertise,' said Zhang Shaobin , the lead surgeon of the 10-strong Shantou team. With Hong Kong and mainland doctors bringing together advanced medical equipment and skills in remote areas, the venture is also an inspiration for struggling health centres in mainland backwaters. 'To set the mobile hospital in motion, Lifeline Express has entered into business agreements with mainland enterprises which can speed up the economic and health care development of the places the trains visit,' said Gao Hucheng , vice-minister of the ministry of commerce.