Public health services across the world are failing to meet targets to reduce avoidable sight loss, according to a new study published today in The Lancet Global Health.
The study examined all population-based surveys of eye disease worldwide going back to 1980. Findings were benchmarked to the World Health Assembly Global Action Plan, published in 2013, which aimed to reduce avoidable sight loss by 25% over the last decade since 2010.
Researchers found that the leading cause of blindness was cataract, accounting for 15 million people, around 45% of the 33.6 million cases of global blindness. It also caused severe vision impairment in 78 million people and is treatable by surgery.
Uncorrected refractive error, a condition easily treated with spectacles, was 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 included glaucoma – the leading cause of vision loss in high-income countries; diabetic retinopathy; and age-related macular degeneration.
Overall numbers of people both blind and vision impaired have increased. However, if one accounts for the ageing of populations that has occurred, there was a 15.4% decrease in avoidable blindness since 2010, but there was no significant decrease in moderate or severe vision loss.
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) and Cambridge University Hospital, 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 WHA. 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 today in Lancet Global Health, warns that global blindness and severe vision impairment is set to double by 2050.
Hugh Taylor, Professor at University of Melbourne, and a senior author, said: “First it is wonderful to see all these data brought together to give such a strong picture of the worldwide progress being made in eye care and the work that still needs to be done. Second it shows that we do know how to address the needs, when the services are provided, they really do work, but more are needed.”
Jost Jonas, Professor at University of Heidelberg, and a senior author, said: “With an ageing and growing population global vision impairment needs to be an urgent health-care priority. The easiest, safest and most economical method to improve the situation is to provide adequate glasses correcting refractive errors for distant vision and near vision.”
Jaimie Steinmetz, Research Scientist at Institute for Health Metrics and Evaluation in Seattle, and co-lead on these papers, said “With the exception of glaucoma, the global prevalence of every major cause of age 50+ blindness and vision loss we estimate is higher in women than men. This includes cataract and uncorrected refractive error, both main contributors to avoidable vision loss. These findings underscore the need to consider gender inequity in vision research and policy.”
Serge Resnikoff, Professor at 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 leads the Vision Loss Expert Group, which informs the wider Global Burden of Disease project, co-managed by Theo Vos, Professor of Health Metrics Sciences at the Institute for Health Metrics and Evaluation (IHME) in Seattle.
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.