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Blindness and vision loss prevalence among older adults decreased in the countries Brazil, Russia, India, China, and South Africa from 1990 – 2019— but blindness and vision burdens are expected to rise by the year 2040.1
Blindness and vision loss affects 2.2 billion people globally, commonly affecting older adults.2 Vision loss is associated with reduced health life expectancy and increased risk of depression, dementia, falls, hip fractures, hospitalizations, and death.
Currently, Brazil, Russia, India, China, and South Africa are transitioning to a market economy and experiencing an increase in economic, growth, population, aging, and noncommunicable diseases. But, as the population of older adults increases, the burden of blindness and vision loss will too.1
A new study, led by Jianqi Chen, MD, of State Key Laboratory of Ophthalmology at Sun Yatsen University in Guangzhou, China, sought to assess the national trends in the burden of blindness and vision among adults in Brazil, Russia, India, China, and South Africa between 1990 – 2018 and predict the burden by 2040. The investigators considered older adults as individuals aged >60 years old, and they studied trends by sex, age, and cause.
“To the best of our knowledge, this is the first study to examine the temporal trends and projections of [blindness and vision loss] prevalence rates and number of cases among older adults in [Brazil, Russia, India, China, and South Africa] countries,” the investigators wrote.
The investigators collected data on blindness and vision loss, as well its related causes, from the Global Burden of Disease 2019. From there, the team calculated the age-standardized prevalence rate. They also evaluated the temporal trends by calculating the average annual percentage change using joinpoint regression analysis. Moreover, the team performed a Bayesian age-period-cohort to predict the burden of blindness/vision loss and its related causes by 2040. Unlike other prediction models, the Bayesian age-period-cohort examined population aging, birth cohorts, and time periods.
The investigators studied 19 detailed blindness and vision loss causes. Chen and colleagues defined blindness and vision loss as a visual acuity of < 6/18 on the Snellen chart and defined near vision loss as a near acuity of < 6/12 distance equivalent.
The results found Brazil, Russia, India, China, and South Africa experienced a significant decrease in age-standardized prevalence rates (P < .05), with the most decrease in India (0.52; 95% CI, 0.54 – 0.50). Even now, the decreasing trends are projected to continue.
However, from 1990 – 2019, Russia had an increase in age-standardized prevalence rates (0.12; 95% CI, 0.11 – 0.14). In 2019, India had the highest age-standardized prevalence rates while Brazil had the lowest.
The age-standardized prevalence rates will continue to decrease in Brazil, India, China, and South Africa—all the countries except Russia, which will slightly increase by 2040. Also, by 2040, the number of blindness and vision loss cases are projected to increase by roughly 50% across the 5 countries. The predicted vision loss cases for each country are 192 million in China, 170 million in India, 25 million in Russia, 17 million in Brazil, and 7 million in South Africa. Except, blindness and vision loss causes are predicted to change in the future, specifically in India.
The investigators also found the age-standardized prevalence rates were higher in women than men in most of the 5 countries.
The average annual percent change in most age groups was <0>
Based on the Bayesian age-period-cohort model, age-standardized prevalence rates in Russia were predicted for near vision loss, refraction disorders, age-related macular degeneration (AMD), and diabetic retinopathy; in India it was predicted for refraction disorders, AMD, diabetic retinopathy, and other causes; in China, an increase was predicted for diabetic retinopathy but a decrease for cataract.
The investigators found India and Brazil had significant declines for most causes of vision loss, while Russia had significant increases for near vision loss (0.29; 95% CI 0.25 – 0.33). China had significant increases for cataract (0.51; 95% CI, 0.27 – 0.76), and South Africa had significant increases for AMD (0.3; 95% CI, 0.25 – 0.35) and diabetic retinopathy (1.18; 95% CI, 1.10 – 1.25).
“The different trends of [blindness and vision loss’ age-standardized prevalence rates] across [Brazil, Russia, India, China, and South America] may reflect the different stages of population health transition,” the investigators wrote.
For instance, over the past few decades, Brazil has had significant economic and structural changes, such as the start of the universal Brazilian Unified Health System, as well as improving pollution and tobacco control. Meanwhile, Russia had consistent increases in blindness and vision loss, and they still have a high prevalence of smoking; they also have a high mortality rate for workers. In China, they have a rapid increase in cataract prevalence. Furthermore, in India, they have controlled tobacco use; they also started new initiatives of clean cooking gas. Finally, South Africa’s still at the beginning of their transition, but they started tobacco control efforts.
“[Brazil, Russia, India, China, and South America] countries have undergone or committed to substantial health-system reforms designed to improve the quality of medical services and financial protection, with the ultimate goal of universal health coverage,” the investigators wrote. “The rapid rise in the number of [blindness and vision loss] cases among older adults in these countries is indicative of the need for provision of corresponding medical resources for eye diseases, and inclusion of [blindness and vision loss] prevention and control in future national strategies.”
References
- Chen J, Zhu Y, Li Z, et al. Temporal trends and projection of blindness and vision loss prevalence in older adults in BRICS countries. J Am Geriatr Soc. Published online November 13, 2023. doi:10.1111/jgs.18672
- Blindness And Vision Impairment. World Health Organization. August 10, 2023. https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment. Accessed November 28, 2023.
