The study examined all population-based surveys of eye disease worldwide since 1980, Findings were compared to the World Health Assembly Global Action Plan, which aimed to reduce avoidable sight loss by 25% over the last decade.
Overall numbers of people both blind and vision impaired have increased. If accounting for the ageing of the population, there was a 15.4% decrease in avoidable blindness since 2010, but there was no significant decrease in moderate or severe vision loss.
Researchers found that the leading cause of blindness is cataract, accounting for 15 million people, around 45% of the 33.6 million cases of global blindness. It also causes severe vision impairment in 78 million people and is treatable by surgery.
Uncorrected refractive error, a condition easily treated with spectacles, is the biggest contributor to moderate or severely impaired distance vision, estimated to affect 86 million people across the globe. More than 500 million people are estimated to be living with uncorrected presbyopia, which is easily corrected with reading glasses.
Significant but less easily treatable causes of vision loss include glaucoma – the leading cause of vision loss in high-income countries; diabetic retinopathy; and age-related macular degeneration.
The study also noted an increase in vision loss due to diabetic retinopathy, which is of particular concern in younger, economically active age groups. This can be avoided by early detection and timely intervention.
Lead author Rupert Bourne, Professor of Ophthalmology at Anglia Ruskin University (ARU), said: “It is clear from the results of this study that efforts by eye care services across the world have failed to keep pace with the ageing and growth of populations, and have failed to reach targets set by the World Health Assembly. While prevalence of blindness has decreased, the number of cases has actually risen.
“If this continues, health infrastructure will continue to creak and fail to reach the people that need relatively simple solutions to their vision loss. The effect of COVID-19 is likely to exacerbate this issue, with research having already shown delays and an increasing backlog of people in need of eye care.
“It is absolutely vital that all nations have a robust public health strategy for dealing with avoidable sight loss, which costs healthcare services billions of pounds every year.”
A second report, also published by the same group in Lancet Global Health, warns that global blindness and severe vision impairment is set to double by 2050.
Serge Resnikoff, Professor at the University of New South Wales, and a senior author, said: “By 2050, vision loss is projected to affect 1.7 billion people because of population growth and ageing, especially in low- and middle-income countries. Significant additional investments and concerted actions are urgently needed to reverse this trend and provide quality services to everyone, including to the vulnerable and currently neglected populations.”
Theo Vos, Professor of Health Metrics Sciences at the Institute for Health Metrics and Evaluation (IHME) in Seattle, said: “Blindness and vision loss ranks eighth among all causes of disability in 50-69 year olds and fourth among those over the age of 70. The ability to prevent or treat blindness and vision loss is greater than top-ranking causes of disability in these age groups such as low back pain, age-related hearing loss and diabetes”.
Professor Bourne, of Anglia Ruskin University (ARU) leads the Vision Loss Expert Group, which informs the wider Global Burden of Disease project, co-managed by Professor Vos.
Both studies were funded by Brien Holden Vision Institute, Fondation Théa, The Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation, Sightsavers International and the University of Heidelberg.