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Diabetic retinopathy: Implications for the health care sector

The practical relevance for health systems in knowing the magnitude of diabetic eye disease and the importance of public health in managing it.
The challenge of managing diabetic retinopathy can be compared to an iceberg. Above the water, the visible tip represents those people who have either become blind from diabetic retinopathy, or have some visual impairment. Below the surface, there are many more undetected cases of disease that need to be identified and managed before people become blind. The percentage of people who become blind from diabetic retinopathy varies across populations. But it is evident that health workers and health systems around the world are facing an overwhelming challenge to manage the disease.
It is therefore very important to take a practical and structured approach to planning services to identify, screen, and treat people who are at risk of developing diabetic retinopathy. A key first step is to measure the magnitude of visual loss from diabetic retinopathy in a given population. This is a major undertaking. To plan practical services for diabetic retinopathy in a particular health system or population, we need to estimate the overall prevalence of diabetic retinopathy, and the specific prevalence of proliferative diabetic retinopathy, diabetic macular oedema, and vision-threatening diabetic retinopathy.
Estimates from previous studies suggest that the overall prevalence of diabetic retinopathy amongst a population of people with diabetes will be about 34%. Of these, approximately 7% will have proliferative diabetic retinopathy, 7% will have diabetic macular oedema, and 10% will have vision-threatening diabetic retinopathy.
The number of individuals with vision-threatening diabetic retinopathy gives an important estimate of the number of patients who require treatment to prevent vision loss.
There are approximately 145 million people with diabetic retinopathy worldwide, and approximately 30 million have vision-threatening diabetic retinopathy. The prevalence of diabetic retinopathy has been found to be similar in men and women.
80% of people affected by diabetic retinopathy live in low and middle income countries. Regional differences are also observed, with diabetic retinopathy-related blindness found to be highest in West Africa, and moderate and severe vision impairment from diabetic retinopathy highest in South Asia. In some countries such as Sweden, Denmark, and the United States, the incidence of diabetic retinopathy is declining. This is due to improving patterns of care, especially screening, and tighter medical control of modifiable risk factors. Prevalence rates of diabetic retinopathy are higher in people with type 1 diabetes, and in those who have a longer duration of diabetes, or increased levels of glycated hemoglobin, HbA1c, blood pressure, and total serum cholesterol.
To prevent blindness from diabetic retinopathy in a population means public health action needs to be taken at multiple levels in the health system. Primary prevention aims to stop diabetic retinopathy from even occurring. We cannot implement effective action to prevent impact from unmodifiable risk factors, such as duration of diabetes, but health education and support services should be put in place to manage modifiable risk factors, such as unhealthy eating. Secondary prevention action limits the progression of diabetic retinopathy and prevents blindness from occurring. To do this, we provide good medical management of the blood sugars and blood pressure, and also establish a screening program to detect vision-threatening diabetic retinopathy in its early stages.
Tertiary prevention is the implementation of treatment as soon as possible to limit progression of vision-threatening diabetic retinopathy. In cases where blindness has occurred, we must also set up low vision or rehabilitative services. Public health education is crucial for preventing visual loss from diabetic retinopathy, and other diabetic eye diseases, such as glaucoma and cataract.
When a person is first diagnosed with diabetes is one of the best opportunities - to identify their modifiable risk factors and - introduce them to supportive measures and guidance which will enable them to actively manage their diabetes care by managing their blood sugar levels, blood pressure, and diet, - and to create an understanding of the ocular complications and highlight the importance of attending regular eye screening services.
People with diabetes need a multidisciplinary approach to manage the various complications that arise from the disease. Wherever possible, it is essential to invest in holistic methods of care, such as diabetes centers, where diabetic eye disease is included in education and support services for people with diabetes. Finally, it is important to emphasize the need for investment to deliver timely and effective diabetic retinopathy treatment facilities for everyone identified through screening as being at risk of vision loss.
In summary, The magnitude of diabetic retinopathy is estimated to be increasing as more people are diagnosed with diabetes, particularly in low and middle income countries. Early detection through screening programs and continuous management of modifiable risk factors can reduce the risk of vision loss from vision-threatening diabetic retinopathy by 60%. Public health interventions include patient education to manage their diabetes, establishing regular screening services, and investing in the delivery of timely treatment for vision-threatening diabetic retinopathy.

A recent systematic review of 35 population-based studies showed that the prevalence of diabetic retinopathy, proliferative diabetic retinopathy, diabetic macular oedema and vision threatening diabetic retinopathy amongst people with diabetes is 34.6%, 7.0%, 6.8%, and 10.2%, respectively (Yau et al. 2012).

By extrapolating these results to the global number of people with diabetes it is estimated that:

  • The number of people with diabetic retinopathy will grow from 126.6 million in 2011 to 191.0 million by 2030
  • The number of people with vision threatening diabetic retinopathy will increase from 37.3 million to 56.3 million if no urgent action is taken.

However, in high income countries specific public health efforts have contributed to a declining trend in the prevalence of diabetic retinopathy-related blindness amongst people with both type 1 and type 2 diabetes. For example, a 25 year follow up study from the Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) in the US, found that the annual incidence of proliferative diabetic retinopathy (PDR) was 3.5% between 1980 and 1992 but 1.5% between 1994 and 2007.

There are very few high quality incidence studies in Africa and Asia as yet. A recent study from Malawi found progression from no diabetic retinopathy to vision threatening diabetic retinopathy amongst participants with diabetes was 5 times higher than found in European studies (Burgess et al. 2017).

As you watch this video, consider what the explanation might be for the differences in the reported prevalence trends in diabetic retinopathy between high-income and low- and middle-income country settings?

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Diabetic Eye Disease: Building Capacity To Prevent Blindness

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