Global pattern of blindness changes with success in tackling infectious disease and as population ages
16 December 2004 | Geneva - Success in tackling the infectious causes of blindness combined with changes in the world's population have caused a dramatic shift in the patterns of blindness around the world, according to new data published by the World Health Organization (WHO). Ten years ago, infectious diseases such as trachoma and onchocerciasis were among the leading causes of blindness. Today, these factors are far less important compared to chronic diseases such as diabetes, the new figures show.
Globally, based on the 2002 world population, more than 161 million people were visually impaired, of whom 124 million had low vision and 37 million were blind, including 1.4 million under the age of 15 years.*
The new figures illustrate the successful impact of efforts to eliminate the infectious causes of blindness. Worldwide, cataract - largely as a result of ageing - continues to be the leading cause of avoidable blindness. While cataract (which causes 47.8% of global blindness) still poses the major challenge in the effort to eliminate avoidable blindness -- particularly in developing countries -- other ageing-related conditions, such as glaucoma (12.3%), age-related macula degeneration, or AMD (8.7%), and diabetic retinopathy (4.8%) have now begun to predominate as causes of blindness. WHO’s current estimates indicate that globally, avoidable blindness from cataract and the above causes, constitutes approximately 75% of all blindness.
"Changes in the pattern of avoidable blindness can be attributed to significant achievements in the prevention and management of some causes of avoidable blindness," says Dr Serge Resnikoff, WHO Coordinator of Chronic Diseases Prevention and Management. "In addition, we now have much better data, which is giving us a more accurate estimate of causes."
The last decade has seen an upsurge in the intensity and efficiency of prevention of blindness activities in most parts of the world where blindness and visual impairment are public health problems. This has been achieved despite the competing demands on the limited resources of the governmental health sector from other public health priorities. The major reasons include:
- Eye care, integrated into the primary health care system, that has contributed to the decline in vision loss from trachoma, onchocerciasis, vitamin A deficiency, and even cataract, through comprehensive services including out-reach case finding and eye health education.
- Enhanced political commitment, as evidenced by the World Health Assembly Resolution of 2003.
- Increased professional commitment to and involvement in prevention and control of visual impairment activities
- Impressive successes with elimination of blindness efforts in, for example, India, Morocco, Nepal, Sri Lanka, Thailand and the Gambia.
However, an increasing number of people are at risk of visual impairment as populations grow and people live longer. Developing countries are already aging much faster than those in the developed world. In 2000 more than 248 million (59%), of the roughly 418 million persons aged 65 and over, lived in developing countries. By the year 2020 this is projected to rise to 67%. The UN estimates that by 2020 there will be a global elderly population of 698 million.
The Global Initiative for the Elimination of Avoidable Blindness -- "VISION 2020: The Right to Sight" -- was launched in 1999. This is a collaborative effort between WHO, and the International Agency for the Prevention of Blindness (IAPB). The goal is to help member countries plan and develop sustainable national capacity of their eye health systems as an integral part of the national health system, based on the principles and practice of primary health care.
The latest figures point towards a new agenda for this initiative. Interventions against cataract still need to be intensified to reach affected but so far un-serviced populations. In addition, health planners will need to include the means to manage the diseases that are now becoming more prevalent. Glaucoma, AMD, and diabetic retinopathy need to be addressed by making available existing as well as new treatment methods and drugs. Monitoring and evaluation must continue to play an essential part.
"Despite the recent achievements in the prevention and control of avoidable blindness, the emerging trend is a warning sign against complacency on the part of governments, WHO and other eye care providers" says Dr Ivo Kocur, WHO VISION 2020 Global Coordinator. "If the current level of maldistribution of resources is perpetuated, the global disparity and inequity in the availability of affordable eye health services, particularly for the elderly in the poorest parts of the world, will be compounded. VISION 2020's goal is as valid today is it was when the Global Initiative was launched."
*These figures do not include people having uncorrected refractive errors such as short or long sight or astigmatism.