As diabetes increases in sub-Saharan Africa, so will blindness

NAIROBI — People from all over the country travel to Comprehensive Community Based Rehabilitation in Tanzania, located in Dar es Salaam, for eye care. The health care organization is Tanzania’s largest provider of eye services. Increasingly, a larger number of patients are arriving with diabetic retinopathy — a complication of diabetes that can lead to permanent blindness.

But the problem is that many are arriving too late, said Dr. Cyprian Ntomoka, head of the organization’s ophthalmology department.

The patients, often not knowing they are diabetic, go when they already have an advanced stage of the disease. This means they are too late for early stage treatments, like lasers or injections, and only surgery can save them from blindness.

But Ntomoka’s team does not have the resources to conduct the surgery, so it refers patients to a private hospital, where he says the cost of the surgery can range between $2,500 and $4,000. His team refers between 10 to 20 patients per week for this surgery.

But many of his patients cannot afford this.

“Maybe this person could not even afford the transport fare to Dar es Salaam; maybe they got it from a friend. And now you tell that person that an operation costs $4,000. Instead, they go back to their village and declare themselves blind,” Ntomoka said.

“That’s what faces me every day, and I can assure you I go back home sad because I find myself useless,” he added.

Diabetes is on the rise globally, including in sub-Saharan Africa, fueled by the adoption of unhealthy diets and inactive lifestyles. A 143% increase is expected in the number of diabetes cases in Africa by 2045. Currently, 79% of people with diabetes live in low- and middle-income countries.

While the number of people living with diabetic retinopathy was 146 million in 2014, this could increase to 180.6 million over the next 10 years. By 2040, there will be an estimated 50% increase in the number of people that need regular screening for diabetic retinopathy.

About 15% of diabetics in Africa have diabetic retinopathy — a prevalence up to five times higher than that for European populations.

Globally, it is the leading cause of blindness in working age adults.

“That has implications for that person's ability to work, engage with society, and look after their family,” said Dr. Charles Cleland, a research fellow at the International Centre for Eye Health and the lead author of a study examining a screening program for diabetic retinopathy in Tanzania.

The COVID-19 pandemic has compounded this. The Comprehensive Community Based Rehabilitation in Tanzania had planned to conduct outreach screenings for diabetic retinopathy in hospitals in the areas around Dar es Salaam. But because of COVID-19, it was not able to undertake these activities — logistically and financially.

Additionally, patients may not go in for follow-up care due to fears of contracting COVID-19 and health systems are overburdened, said Imran Khan, global technical lead for eye health at Sightsavers. Type 2 diabetes increases a person's risk of having a severe case of COVID-19.

“We would expect, actually, diabetes and the complications of diabetes to get worse,” Khan said. “I think we've taken a step back because of COVID.”

Regular screenings

Proper management of diabetes — such as keeping hyperglycemia and high blood pressure under control — is key to preventing vision impairment from diabetic retinopathy.

Because people do not typically have symptoms in the early stages of diabetic retinopathy, diabetics should receive regular eye screenings. But many do not even know they have diabetes. Of the estimated 463 million people that have diabetes globally, 232 million do not know they have it.

Because of this, the disease might not be caught early enough for treatment to prevent irreversible blindness.

“There is a period, a window, in which you can treat it and maintain people's sight,” Dr. Philip Burgess, an ophthalmology specialist at the University of Liverpool who has worked with diabetic retinopathy patients in Malawi.

A big challenge to screening for this disease in resource-strained environments is that there are often a low number of ophthalmologists to take retinal pictures, analyze the imagery, and provide treatment. For example, in Tanzania, there is less than 1 ophthalmologist for every 1 million residents. The equipment needed for screening and treatment is also expensive.

“Basically, at the moment, nobody really knows how to make it cost-effective in a low-resource setting,” Burgess said.

Other challenges include educating people about the need for screening, as well as encouraging them to follow up for treatment.

A study that examined the success of a mobile screening program around Mount Kilimanjaro found that only about 42% of people went to a follow-up appointment at a hospital when problems were detected, Cleland said. Challenges included a poor understanding of the disease and treatment options, as well as how the referral process worked.

Diabetes can also cause cataracts, particularly at younger ages, but the treatment for that involves a one-time, low-cost surgery that can restore lost vision, so there is less of a need for screening to catch it early, Burgess said. However, there are still many barriers for people to access this surgery.

Artificial intelligence

The use of artificial intelligence technology could help make screenings for diabetic retinopathy more affordable, according to ophthalmologists.

Traditionally, diabetic retinopathy screenings require a person to sift through the imagery, but new technology allows automatic analysis of images.

“That's very helpful, especially in an environment where you don't have enough eye doctors,” Cleland said.

According to a study published last year in JAMA Ophthalmology, the performance of automated systems at two eye care centers in India was “equal to or exceeded” analysis by humans.

In Mexico, VisionQuest Biomedical Inc. has screened over 30,000 patients for diabetic retinopathy at the Clínicas del Azúcar using artificial intelligence software, which completes each analysis in less than one minute and has a sensitivity rate of over 90% in detecting the condition, according to the company.

AI technology could also reduce the number of people referred to hospitals. In the Tanzania study, researchers suspected there were people who were told to go for a follow-up appointment but did not really need it, Cleland said. Health workers were not quite sure whether they had detected an abnormality, but to err on the side of caution, they told patients to visit the hospital.

Holistic care

Traditionally, health services in low-income settings have been set up for one-off episodes of care, such as for pneumonia, childbirth, and malaria, Burgess said. While this alone is a challenge to provide comprehensively, care for chronic disease is a greater challenge.

In low- and middle-income countries, there is a transition from blindness due to infectious conditions like trachoma and river blindness, which is caused by a worm, to blindness that is caused by noncommunicable diseases like diabetes, Cleland said.

To best manage diabetic retinopathy, a holistic approach is needed to address the underlying cause, Sightsavers’ Khan said.

For example, in Pakistan, Sightsavers has a program that links diabetic retinopathy services at eye health facilities with general health facilities. Counselors encourage patients to take their medication, follow healthy diets, and exercise, as well as to return for regular follow-ups. Currently, the organization only has diabetic retinopathy programs in Pakistan and India but has plans to expand its programming in Africa moving forward.

“If someone has complications in the eye, we want to ensure that they're getting their diabetes under control to help prevent further damage inside the eye,” Khan said.

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