The prevalence of blindness and vision impairment worldwide is set to triple from nearly 36 million to 38.5 million by 2020 and 115 million in 2050 due to an increase in the ageing population, a study has claimed.

The study, published in the journal Lancet Global Health, showed that in 2015 an estimated 36 million people were blind, 217 million were moderately or severely vision impaired, and 188 million had mild vision impairment.Near-vision impairment due to uncorrected presbyopia affected 1.09 billion people aged 35 years or older.Most of the blind people live in South Asia (11.7 million, 80 per cent), followed by East Asia (6.2 million) and Southeast Asia (3.5 million). Some parts of sub-Saharan Africa also have particularly high rates.

"There is an ongoing reduction in the age-standardised prevalence of blindness and visual impairment, yet the growth and ageing of the world's population is causing a substantial increase in number of people affected," said Rupert Bourne, Professor at the Anglia Ruskin University in the UK.Further, there are more than 200 million people with moderate to severe vision impairment, which is expected to rise to more than 550 million by 2050.For the study, the team estimated trends in prevalence of vision impairment and their uncertainties, by sex, for 188 countries in the 21 Global Burden of Disease (GBD) regions, from 1990 to 2015.Even mild visual impairment can significantly impact a person's life. For example, reducing their independence... as it often means people are barred from driving," Bourne was quoted as telling the BBC.

Visual impairment also limits people's educational and economic opportunities, Bourne said.The study calls for better investment in treatments, such as cataract surgery, and ensuring people have access to appropriate vision-correcting glasses."Interventions provide some of the largest returns on investment. They are some of the most easily implemented interventions in developing regions," Bourne said."They are cheap, require little infrastructure and countries recover their costs as people enter back into the workforce," he added.