This article is more than 5 years old. Information may no longer be current.
Eliminating cataract blindness: Rapid progress and the remaining agenda
Second in a series discussing the major causes of world blindness and the specific challenges and possible strategies for dealing with each.
Click Here to Manage Email Alerts
The problem of cataract is, in many ways, emblematic of the current state of world blindness: Accomplishments over the past two decades have been numerous, and in some cases extraordinary. Yet much remains to be done, often in places where it would seem that all the tools necessary for success are at hand.
Cataract, which can be cured with a 20-minute operation costing $25, remains the cause of one half of the blindness on the planet. As the large populations of Asia continue to age, much more will need to be done simply to keep pace with incident cases, let alone eliminating a global backlog of nearly 20 million people.
Outstanding accomplishments
| Nathan G. Congdon |
It is appropriate first to review the outstanding accomplishments in the field of cataract blindness over the past 20 years. Perhaps most striking among these has been India’s leap from a cataract surgical rate of about 300 cases per one million people per year to more than 4,000, which is close to that achieved by many European countries. This has been driven by the model of low-cost, high-volume, high-quality surgical programs, which are sustained financially by modest fees from patients eager to pay a month’s salary or two to regain vision and financial viability.
A corollary of the widespread success of this model on the subcontinent has been the worldwide availability of inexpensive, high quality IOLs, produced in facilities in India, China, Africa and elsewhere. With the ready availability of affordable IOLs, the promise of a good visual outcome is brought that much closer to the average patient in the developing world.
Models for the delivery of aid, where it is still needed, have evolved, as well. Increasing emphasis is placed by non-governmental organizations (NGOs), governments and organizations such as the World Health Organization (WHO) on local capacity building through training of surgeons, provision of equipment and collaboration with ministries of health and other local institutions. In many parts of the world, this has largely replaced “surgical expeditions” as the preferred approach to sustainable elimination of cataract blindness.
Technical advances have also played an important role. These include a wider use of A-scans in the developing world to select specific IOLs for each patient; a broader dissemination of refractive skills to ensure that eye glasses are recommended postoperatively when needed and the more common use of sutureless; manual cataract extraction, which can provide rapid visual rehabilitation without the recurrent expenses, and equipment maintenance problems associated with phacoemulsification or the cost and infection risk of sutures.
Remaining challenges
With all of these weapons in our armamentarium, why does cataract remain the leading cause of blindness throughout most of the developing world? For one thing, while some countries have rapidly implemented low-cost, high-volume cataract surgical programs on a wide scale, other large countries with equally well-developed ophthalmic infrastructures, such as China and Indonesia, remain with cataract surgical rates in the 300-to-500 range, a fraction of the level estimated by the WHO as necessary to eliminate large backlogs.
Although the reasons vary from area to area, they boil down, in essence, to a lack of affordable cataract surgery in rural areas where the majority of the population, nearly 80% in China, still resides. Throughout much of Asia, ophthalmologists are concentrated in urban areas, often focusing much of their attention on procedures such as refractive surgery, which do not directly address the problem of blindness. Many hospitals retain a high-cost, low-volume economic model of cataract surgery, often because of a lack of financial support from the government. A direct result of this low surgical volume is that visual results are often suboptimal. A pair of recent studies from China has reported that only 25% of patients had vision of 6/18 or better after cataract surgery, with 40% remaining blind postoperatively in both settings.
Even in areas where cataract surgery is, in principle, widely available, a variety of financial and socioeconomic reasons may lead to poor uptake of services. Population-based studies have shown unoperated cataract as the leading cause of blindness, even in such highly developed settings as Hong Kong and Baltimore.
In areas such as Africa, a variety of different factors have made sustainable cataract programs difficult to implement. The proportion of patients able and willing to pay even a modest amount for cataract surgery may be small. In many parts of Africa, population densities are low and transportation infrastructure may be poor, leading to practical problems in bringing surgeon and patient together, both for surgery and for follow-up. Cooperation among NGOs, still responsible for the majority of cataract surgeries in Africa, and between NGOs and government bodies, still leaves much to be desired. And of course, there is the threat of HIV/AIDS, already realized in Africa and growing rapidly in Asia, which continues to siphon off health care resources.
More to be resolved
Despite all of the scientific advances in the past 2 decades, many technical issues regarding the delivery of cataract surgical services remain to be resolved. For example, do A-scan measurements, with the attendant needing to maintain a larger stock of IOLs over a wide range of powers, deliver sufficient benefit to the average patient in terms of visual function to justify the expense?
Similar questions may be asked with regard to routine postoperative refraction. The answers may vary from setting to setting but are rarely directly addressed. Advances are still required in the area of training to optimize the efficiency of skill transfer, identify standard parameters for the well-trained surgeon and aid in more complete preoperative identification of comorbidities, which still account for a high proportion of suboptimal visual results in many areas.
It may only be hoped that a follow-up to this article written in 2020, at the culmination of the Global Vision 2020 program, will relate an even longer list of successes, and that the recitation of remaining problems will have shrunk proportionately.
For more information:
- Nathan G. Congdon, MD, MPH, is a professor in the Department of Ophthalmology and Visual Science, Chinese University of Hong Kong. He can be reached at ncongdon1@gmail.com.