PARIS - The world's blind will increase threefold from about 36 million today to 115 million in 2050 as populations expand and individuals grow ever older, researchers said on Thursday.

The number of people with a moderate to severe vision impairment - only those not corrected by glasses, contact lenses or an operation - will also near triple, from about 217 million to 588 million over the same period.

Most of those affected live in Africa and Asia, a team wrote in The Lancet Global Health journal.