Introduction to Geographic and Preventive Ophthalmology
HUGH R TAYLOR
Table Of Contents
|In 1991, Dr. Alfred Sommer, the initial editor of this section, wrote that “geographic” and “preventive” ophthalmology
share a common tradition and perspective, which explains the composition
of this section. Both are firmly rooted in public health disciplines
and public health pursuits; both are concerned with all aspects of
an ophthalmic problem, from its root cause to its prevention and cure. A
decade or more later, this is still true.|
He emphasized that the careful study of individual patients would continue to provide important scientific insights. However, increasingly, the application of powerful epidemiologic tools to “groups” and “populations” or individuals has enhanced the ability to identify factors responsible for disease: from racial and genetic variations in the risk of chronic open angle glaucoma1,2 and age-related maculopathy3,4 to environmental5,6 and dietary factors7,8 that may be responsible for cataract. These same techniques provide rigorous means for evaluating treatment modalities and their long-term impact.9–12 These approaches and their interpretation are discussed elsewhere in this text. All ophthalmologists can benefit from the review: it can improve the quality of research and, more importantly, the ability to interpret and assimilate reports published in the clinical literature.13–15
At a time of increasing concern with health care costs, access, and quality, the “population” perspective to ocular morbidity and visual impairment has become even more compelling. For the first time, we have begun to develop truly representative estimates of the distribution and magnitude of visual impairment and blindness in the United States.16–21 Other chapters in this book lay the groundwork for understanding these issues of measures of visual function and the latest population estimates.
These data provide guidance for future directions and useful baseline yardsticks against which we can assess progress. The “good news” implementation of recommendations for appropriate management and care of type 1 diabetics not only saves sight but also is highly cost effective: ideal care is less expensive than just the cost of social security payments to those who would otherwise have gone blind.13 The “bad news”? At a time when cataract surgery has reached new heights of sophistication and ever more patients receive and benefit from earlier surgery, the single greatest cause of blindness in East Baltimore remains unoperated cataract.3 A better understanding of the totality and distribution of eye disease and the obstacles patients face in receiving care is clearly essential in designing appropriate and equitable eye care programs and convincing an increasingly reluctant public to support them. Robust, rigorous protocols for screening (discussed elsewhere in this volume) and diagnosis is one approach to effective intervention.
If a more holistic approach is needed to reduce the burden of avoidable blindness in the United States, it is absolutely crucial for poorer nations. Not only are they affected by the same blinding conditions as the West, but in many countries, these conditions are more common (glaucoma is 5 to 10 times more frequent in black populations in Africa and the Caribbean22), and developing countries have far less resources to deal with them. It is no surprise that cataract accounts for half of all blindness.23 Some African nations have less than one ophthalmic surgeon per million population, compared with one per 10,000 to 20,000 in the United States.
Ten years ago, a vigorous debate raged over the relative merits of intracapsular cataract surgery and aphakic spectacles versus intracapsular or extracapsular surgery with intraocular lenses (IOLs). Detailed clinical trials confirmed the clinical impression that even in areas in developing countries, IOL surgery was superior.24 Low cost ($5 to $10/lens) factories have developed in some of the poorest parts of Asia, driving this surgical revolution.25 Now the debate is about extracapsular cataract extraction (ECCE) or small incision surgery in these developing areas.
In addition to Western diseases and limited resources, developing countries also suffer from the neglected diseases that have yielded, in the West, to improved nutrition (xerophthalmia) and hygiene (trachoma) or that rarely occur outside the tropics to begin with (onchocerciasis). Each of these is dealt with in detail in this text: each is in flux. With the discovery that improvement in vitamin A status dramatically increases child survival, xerophthalmia, once the “Cinderella” of childhood blindness, has assumed mainstream attention.26 Epidemiologic studies have revealed that repeated reinfection is the prerequisite for trachoma blindness,27 and an integrated strategy is advocated for trachoma control.28 Mectizan, the first practical, effective, and safe microfilaricide has dramatically improved prospects for treatment and prevention of river blindness.29 Ocular complications of leprosy await a “magic bullet”; in the meanwhile, insufficient appreciation of the risks to sight and the management of those risks remain the greatest obstacles to tackling the problem.
The additional burdens afflicting developing countries explain varying patterns of blindness around the globe—and their impact on the outlook, experience, and challenges faced by our colleagues.
The global impact of eye disease and vision loss will double over the next 20 years as the number and proportion of older people increases. In both developed and developing areas, vision loss increases dramatically with age, whether resulting from cataract in developing countries or macular degeneration in developed areas. Having recognized this, the World Health Organization and nongovernment organizations under the leadership of the International Agency for the Prevention of Blindness, launched a Global Initiative for the Elimination of Avoidable Blindness, Vision 2020 the Right to Sight.23 This global initiative is likely to have a major impact over the next 20 years as it aims to eliminate avoidable blindness by 2020.
The disease-specific chapters will be immensely interesting to Western ophthalmologists concerned about blinding disease in the developing world. Suggestions for innovative use of scarce resources can be found elsewhere.
The past decade has witnessed an explosion of interest and discovery in all areas addressed by this section. Its chapters and contents will continue to be revised as new and pertinent data become available or as emerging, generic concerns require urgent changes in clinical practice.
15. The COMS randomised trial of iodine 125 brachytherapy for choroidal melanoma, III: Initial mortality findings. COMS Report No. 18. The Collaborative Ocular Melanoma Study Group. Arch Ophthalmol 2001;119:969