A recent study published in Ophthalmology and Therapy evaluated the patterns and trends in the burden of blindness due to diabetic retinopathy (DR) from 1990 to 2021 at the global, regional, and national levels.
Give me some background.
The global prevalence of diabetes has risen sharply over recent decades due to population aging, urbanization, unhealthy dietary habits, sedentary lifestyles, and obesity—posing a major public health challenge in the 21st century.
Moreover: DR is the most common microvascular complication of diabetes as well as the most prevalent cause of vision loss among the diabetic population—particularly in individuals of working age.
- In fact: It was estimated that 1.07 million people worldwide were blind due to DR in 2020.
While previous studies have investigated the burden of DR globally or in specific countries, the authors of this research noted that no study has yet comprehensively reported the burden and trends of DR-related blindness at the global, regional, and national levels simultaneously.
Now talk about the study.
Investigators performed a population-based analysis using the most recent data from the Global Burden of Disease (GBD) Study 2021.
- Note: The GBD 2021 uses over 328,000 data sources to generate more than 607 billion estimates, providing comprehensive assessments of the trends in 371 diseases and injuries across 204 countries and territories from 1990 to 2021.
The prevalence and number of cases of DR-related blindness were stratified by:
- Type of diabetes
- Sex
- Age
Sociodemographic index (SDI) level, wherein the countries and territories were divided into five SDI subgroups:
- High (e.g., United States)
- High-middle (e.g., China)
- Middle (e.g., Mexico)
- Low-middle (e.g., Cambodia)
- Low (e.g., Uganda)
Findings?
Globally: The number of people impacted by DR-related blindness increased by 326.0% from 1990 to 2021, with the age-standardized prevalence rate (ASPR) increasing from 7.59 to 15.28 per 100,000 population.
- Note: ASPR allows researchers to compare different time periods or geographic areas by either mathematically adjusting one population to match another or adjusting multiple populations to match a third population (called the standard population).
Regionally: Tropical Latin America had the highest ASPR in 2021, while South Asia and East Asia had the greatest number of prevalent cases.
- The number of individuals afflicted by DR-related blindness from South and East Asia accounted for 44.8% of the global total.
Additionally: The ASPR of DR-related blindness in Tropical Latin America was 161 times greater than that of the region with the lowest ASPR (Australasia).
What about on the country level?
India and China had the highest number of prevalent cases in 2021, while the Marshall Islands and Mauritius reported the highest ASPR.
The estimated prevalence of diabetes in adults aged 20-79 years in 2021 was 25.1% in the Marshall Islands and 26.5% in Mauritius, placing both among the countries with the highest diabetes prevalence globally—compared to a global average of 10.5%.
What factors impacted the prevalence of DR-related blindness?
In 2021, the middle SDI group had the greatest number of patients who became blind due to DR.
- Historically, diabetes was perceived as predominantly affecting affluent nations; however, over the past few decades, the prevalence of diabetes in middle-income countries has increased dramatically, reaching levels comparable to those in high-income countries.
Go on …
Females had a greater burden of DR-related blindness than males, which may be attributed to the following factors:
- Higher diabetes prevalence
- Less access to healthcare
- Different biological predispositions between sexes
The increased global burden of DR-related blindness between 1990 and 2021 was predominantly driven by:
- Population growth (significantly impacting individuals with type 1 diabetes)
- Population aging
- Epidemiological changes (significantly impacting individuals with type 2 diabetes)
Expert opinion?
“The projected increase in the ASPR and patient numbers by 2035 underscores the importance of addressing this issue now to prevent potentially catastrophic impacts on global vision health,” the study authors explained.
As for next steps: The investigators advised that policymakers continue investing in research, prevention, and treatment strategies to reduce the growing burden of DR-related blindness worldwide.
Noted. Any notable limitations of this research?
These included:
- In some underdeveloped countries, limited healthcare infrastructure may lead to misdiagnoses or underreporting of cases, potentially resulting in an underestimation of the burden of DR-related blindness
- The definition of blindness used in this study may not capture all cases of vision impairment due to DR
- The GBD 2021 estimates were derived from a wide range of data sources, including epidemiological surveillance, disease registries, and scientific literature, and remains dependent on the availability and quality of input data
- For countries with limited surveillance systems or scarce ophthalmologic data, estimates may be extrapolated based on covariates or regional patterns, which can introduce bias or increase uncertainty. Thus, country-level results are recommended to be interpreted with caution.
- Variations in diagnostic criteria, case definitions, and reporting practices for DR across countries may introduce heterogeneity into the underlying data, affecting the comparability and accuracy of estimates
- This study focused on population-level trends rather than individual-level risk factors or clinical outcomes, so findings should be interpreted as descriptive of epidemiological patterns useful for public health planning rather than as precise clinical data
Take home.
These findings suggest that the global burden of DR-related blindness has increased significantly over the past three decades, with notable disparities across regions, countries, and SDI groups.
There is an urgent need for targeted public health interventions in high-burden regions and countries to mitigate the growing impact of DR-related blindness.
- “Future research should focus on identifying effective interventions and policies to address the already-coming and upcoming challenges,” the study authors concluded.