Researchers say we're watching the world go blind

December 07, 2020

As the global population grows and ages, so does their need for eye care. But according to two new studies published in The Lancet Global Health, these needs aren't being met relative to international targets to reduce avoidable vision loss.

As 2020 comes to a close, an international group of researchers set out to provide updated estimates on the number of people that are blind or visually impaired across the globe, to identify the predominant causes, and to illustrate epidemiological trends over the last 30 years.

"This is important because when we think about setting a public health agenda, knowing the prevalence of an impairment, what causes it, and where in the world it's most common informs the actions that key decision makers like the WHO and ministries of health take to allocate limited resources," says Joshua Ehrlich, M.D., M.P.H., a study author and ophthalmologist at Kellogg Eye Center.

The study team assesses a collection of secondary data every five years, undertaking a meta-analysis of population-based surveys of eye disease assembled by the Vision Loss Expert Group and spanning from 1980 to 2018.

Creating a blueprint

A study like this poses challenges since regional populations vary in age.

"For example, the population in some Asian and European countries is much older on average than the population in many African nations. Many populations are also growing older over time. A direct comparison of the percentage of the population with blindness or vision impairment wouldn't paint a complete picture" says Ehrlich, who is also a member of University of Michigan's Institute for Healthcare Policy and Innovation, explains.

To address this issue, the study looked at age-standardized prevalence, accomplished by adjusting regional populations to fit a standard age structure.

"We found that the age-standardized prevalence is decreasing around the world, which tells us eye care systems and quality of care are getting better," says study author Monte A. Del Monte, M.D., a pediatric ophthalmologist at Kellogg Eye Center. "However, as populations age, a larger number of people are being affected by serious vision impairment, suggesting we need to improve accessibility to care and further develop human resources to provide care."

In fact, the researchers found that there wasn't any significant reduction in the number of people with treatable vision loss in the last ten years, which paled in comparison to the World Health Assembly Global Action Plan target of a 25% global reduction of avoidable vision loss in this same time frame.

Although findings varied by region globally, cataracts and the unmet need for glasses were the most prevalent causes of moderate to severe vision impairment. Approximately 45% of the 33.6 million cases of global blindness were caused by cataracts, which can be treated with surgery.

Refractive error, which causes a blurred image resulting from an abnormal shape of the cornea and lens not bending light correctly, accounted for vision loss in 86 million people across the globe. This largest contributor to moderate or severely impaired vision can be easily treated with glasses.

Also important, vision impairment due to diabetic retinopathy, a complication of diabetes that affects eyesight, was found to have increased in global prevalence.

"This is another condition in which we can prevent vision loss with early screenings and intervention," says study author Alan L. Robin, M.D., a collaborating ophthalmologist at Kellogg Eye Center and professor at Johns Hopkins Medicine. "As diabetes becomes more common across the globe, this condition may begin to affect younger populations, as well."

Looking to 2050

"Working as a global eye care community, we need to now look at the next 30 years," Ehrlich says. "We hope to take these findings and create implementable strategies with our global partners through our Kellogg Eye Center for International Ophthalmology so fewer people go blind unnecessarily."

In an effort to contribute to the WHO initiative VISION 2020: The Right to Sight, the researchers updated estimates of the global burden of vision loss and provided predictions for what the year 2050 may look like.

They found that the majority of the 43.9 million people blind globally are women. Women also make up the majority of the 295 million people who have moderate to severe vision loss, the 163 million who have mild vision loss and the 510 million who have visual impairments related to the unmet need for glasses, specifically poor near vision.

By 2050, Ehrlich, Del Monte, and Robin predict 61 million people will be blind, 474 million will have moderate and severe vision loss, 360 million will have mild vision loss and 866 million will have visual impairments related to farsightedness.

"Eliminating preventable blindness globally isn't keeping pace with the global population's needs," Ehrlich says. "We face enormous challenges in treating and preventing vision impairment as the global population grows and ages, but I'm optimistic of a future where we will succeed because of the measures we take now to make a difference."
-end-
Both studies were funded by Brien Holden Vision Institute, Fondation Théa, Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation, Sightsavers International and the University of Heidelberg.

Papers Cited: "Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study," The Lancet Global Health. DOI: 10.1016/S2214-109X(20)30489-7

"Trends in prevalence of blindness and distance and near vision impairment over 30 years: an analysis for the Global Burden of Disease Study," The Lancet Global Health. DOI: 10.1016/S2214-109X(20)30425-3

Michigan Medicine - University of Michigan

Related Vision Loss Articles from Brightsurf:

Discovery holds potential for reversing vision loss
Scientists at the Oklahoma Medical Research Foundation have identified a compound that could reverse the vision loss that occurs when blood vessels in the eyes of premature infants and adults grow out of control.

Researchers develop cell injection technique that could help reverse vision loss
University of Toronto Engineering researchers have developed a new method of injecting healthy cells into damaged eyes.

Exercise can slow or prevent vision loss, study finds
Exercise can slow or prevent the development of macular degeneration and may benefit other common causes of vision loss, such as glaucoma and diabetic retinopathy, new research suggests.

Vision loss influences perception of sound
People with severe vision loss can less accurately judge the distance of nearby sounds, potentially putting them more at risk of injury.

Estimating adults at high risk for vision loss, evaluating care use
The estimated number of US adults at high risk for vision loss increased from 2002 to 2017 in this observational study based on national survey data.

For aging patients, one missed doctor's visit can lead to vision loss
Visit adherence plays an important role in outcomes for patients with age-related macular degeneration, a Penn Medicine study found.

Concordian examines the link between cognition and hearing or vision loss
Concordia researcher Natalie Phillips and her colleagues found that poor hearing especially was linked to declines in memory and executive function in otherwise relatively healthy, autonomous, community-dwelling older adults.

Artificial intelligence predicts treatment outcome for diabetes-related vision loss
A new approach that uses artificial intelligence to analyze retinal images could one day help doctors select the best treatment for patients with vision loss from diabetic macular edema.

Disruption of glucose transport to rods and cones shown to cause vision loss in RP
Ophthalmology researchers at the University of Louisville have discovered the loss of vision in RP is the result of a disruption in the flow of nourishing glucose to the rods and cones.

Experimental drug delivers one-two punch to vision loss
In studies with lab-grown human cells and in mice, Johns Hopkins Medicine researchers have found that an experimental drug may be twice as good at fighting vision loss as previously thought.

Read More: Vision Loss News and Vision Loss Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.