Leading causes of 'avoidable blindness' identified as cases set to increase

Global blindness is set to increase by 2020 due to the prevalence of refractive errors, glaucoma and cataracts, according to a new report.

The study shows that decades of declining rates of ‘avoidable blindness’ are plateauing, and are projected to start increasing between 2015 and 2020. Causes of avoidable blindness include cataracts, glaucoma and refractive errors – short- and long-sightedness and astigmatism.

The data is published today in The Lancet Global Health to coincide with World Sight Day.

A new paper by the Vision Loss Expert Group (VLEG) – led by Imperial College London’s Dr Seth Flaxman and Anglia Ruskin University’s Professor Rupert Bourne – identifies the leading causes of blindness and moderate and severe vision impairment (MSVI) in 2015.

Of the 253 million people worldwide who are blind or have MSVI, uncorrected refractive errors (123.8 million people) and cataracts (65.2 million) are the main causes, followed by age-related macular degeneration and glaucoma.

VLEG’s latest data show that progress between 1990 and 2015 resulted in some 90 million people globally being treated or prevented from becoming blind or moderately or severely visually impaired.

However, trends in an ageing and growing global population, coupled with the increase in myopia (short-sightedness) and problems related to diabetes, mean existing efforts are at serious risk of being overwhelmed.

The study projects a 5.6% increase in the prevalence of avoidable vision impairment by 2020, and a potential threefold increase in blindness by 2050.

Potential for gains

The new analysis brought together data from 288 different studies over three decades covering 98 different countries and almost four million individuals. Dr Flaxman, from the Department of Mathematics and the Data Science Institute at Imperial, led the data analysis effort using advanced statistical methods.

These allowed the team to make predictions and quantify uncertainties, despite a lack of data from over 100 countries. Dr Flaxman said: “Our best estimates point to progress over the last decades, and I actually see the uncertainty as an opportunity: there's the potential for more gains if we invest in healthcare.”

The data is mapped on the International Agency for the Prevention of Blindness (IAPB) Vision Atlas, launched for World Sight Day on 12 October. This looks at the possibility of achieving the World Health Organisation’s Global Action Plan target of a 25% reduction in avoidable vision impairment (blindness and MSVI combined) by 2019 (based on 2010 figures).

Urgent action needed

Professor Bourne, who co-ordinates the 100 collaborating ophthalmic epidemiologists involved in the VLEG, said: “Our study shows that in 2015, cataract and uncorrected refractive error accounted for 77% of the MSVI burden and 55% of blindness worldwide.

"Even in high income areas, preventable issues make up the majority of cases. Urgent action is called for to address this and provide adequate eye care services across the world.

“We are very supportive of the Vision Atlas initiative by the IAPB – this means the results of this scientific effort are now of practical value to everyone in supporting efforts to highlight, prevent, treat or rehabilitate those with vision loss in all countries.”

Peter Ackland, CEO of the IAPB, said: “The disturbing loss increase in numbers of people with vision loss worldwide show that our efforts at preventing vision loss are being eroded by an increasing and ageing global population.

"We believe the IAPB Vision Atlas will be an effective tool in understanding these trends and advocating for an increased commitment to eye health. The Atlas will help make vision count.”

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'Global causes of blindness and distance vision impairment1990–2020: a systematic review and meta-analysis' by Seth Flaxman, Rupert Bourne* et al. is published in Lancet Global Health.