Tibetans live in one of the highest inhabited regions in the world at an average 4,500m - and as altitude increases so does exposure to the ultra-violet radiation that damages eyesight.
About 2,000 people a year go blind from cataracts in Tibet, from a population of 2.2 million.
Michael Amendolia's pictures of attempts to combat blindness in Tibet won first prize in the science and technology section of the World Press Photo competition 1999 and went on show in the UK last month.
They document the work of the Nepal Eye Program which sends surgeons to train doctors in remote villages to perform cataract operations. So far 3,000 operations have been carried out.