Author reply to: Estimation of global visual impairment due to uncorrected refractive error

Letters CBulletin of the World Health Organization | August 2008, 86 (8) but we believe that the global estimate of 8.2 million blind persons due to un- corrected refractive error by Resnikoff et al. is an overestimate, largely due to the inclusion of an implausibly high estimate for India. While on the one hand we should not overlook blindness due to uncorrected refractive error as it can be addressed relatively easily, on the other hand we should be careful not to swing the pendulum in the other direction by overestimating it. Related to this issue, we have also published a proposal for revision of the definitions of blindness and visual impairment in the International Statistical Clas- sification of Diseases that would take into account the inclusion of refractive error as a cause of blindness and visual impairment.4 ■ Acknowledgements Both authors are equally affiliated with the George Institute for International Health in Sydney, Australia and in Hyderabad, India. Lalit Dandonaa & Rakhi Dandonaa References Resnikoff S, Pascolini D, Mariotti SP, Pokharel GP. 1. Global magnitude of visual impairment caused by uncorrected refractive errors in 2004. Bull World Health Organ 2008;86:63-70. PMID:18235892 doi:10.2471/BLT.07.041210 Dandona2. L, Dandona R. What is the global burden of visual impairment? BMC Med 2006;4:6 http://www.biomedcentral. com/1741-7015/4/6/. PMID:16539747 doi:10.1186/1741-7015-4-6 Murthy3. GV, Gupta SK, Bachani D, Jose R, John N. Current estimates of blindness in India. Br J Ophthalmol 2005;89:257-60. PMID:15722298 doi:10.1136/bjo.2004.056937 Dandona L, Dandona R. Revision of visual 4. impairment definitions in the International Statistical Classification of Diseases. BMC Med 2006;4:7 http://www.biomedcentral.com/1741- 7015/4/7/. PMID:16539739 doi:10.1186/1741- 7015-4-7 Author reply to: Estimation of global visual impairment due to uncorrected refractive error In response to the letter by L Dandona & R Dandona,1 we would like to point a George Institute for International Health, Hyderabad, India & School of Public Health, University of Sydney, NSW, Australia. Correspondence to Lalit Dandona (e-mail: LDandona@george.org.in). b Chronic Disease Prevention and Management, World Health Organization, 20 avenue Appia, 1211 Geneva 27, Switzerland. Correspondence to Silvio Mariotti (e-mail: mariottis@who.int). out that the study to which they refer (BMC Medicine 2006;4:6) – certainly a useful study in its own right – was not included in the references of our own paper as it informed neither the approach we took to our analysis nor the geographical scope of our work. Our study included data sources for all age groups from 68 surveys in 31 countries, chosen with epidemiological criteria different from those used by L Dandona & R Dandona, who de- rived their global estimates from nine surveys in eight countries. Our work presents an age-specific algorithm developed for missing data. May we also point out a misinter- pretation of our findings in this letter with regard to India. According to the estimated presenting and best-corrected blindness (visual acuity < 6/60) for people aged 50 years and older in 15 Indian states reported by Murthy et al.,2 the reduction of visual impairment after correction is 42% and not one-fifth. The authors themselves point this out by saying that “the blindness load could be nearly halved by correction”. We agree with L Dandona & R Dandona’s emphasis on the need for new definitions. This issue has been extensively discussed since a consulta- tion on refractive errors held by WHO in 2000. The International Council of Ophthalmology adopted a resolution in 2002, followed in 2003 by a WHO consultation on the development of standards for characterization of visual loss and visual functioning, which led to significant changes in definitions and categorizations.3 These have been subsequently integrated into the revi- sion of the 10th International Classifi- cation of Diseases. ■ Silvio Mariotti,b Serge Resnikoff b & Donatella Pascolini b References Dandona L, Dandona R. Estimation of global 1. visual impairment due to uncorrected refractive error. Bull World Health Organ 2008;86:656. doi:10.2471/BLT.08.053652 Murthy GV, Gupta SK, Bachani D, Jose R, John N. 2. Current estimates of blindness in India. Br J Ophthalmol 2005;89:257-60. PMID:15722298 doi:10.1136/bjo.2004.056937 Prevention of blindness and deafness. 3. Consultation on development of standards for characterization of vision loss and visual functioning. Geneva: WHO;2003 (WHO/ PBL/03.91). Country ownership and vertical programmes in health, health information and health research In the March 2008 issue, the Bulletin of the World Health Organization published two related items on the complex issue of ownership of health information in international health programmes and on the “vertical versus horizontal” nature of the health programmes responsible for generating this information.1,2 The first is an editorial by Sanjoy Bhattacharya of the Wellcome Trust, which highlights (once again) the divide between protagonists of vertical and horizontal health programmes, and makes a call for “adaptive verticality” to optimize the potential of international health programmes to integrate with primary health care systems in low- income countries and strengthen these in the process.1 The second is a news item: an interview with Sally Stansfield of the Health Metrics Network in which she calls for country-ownership of health information and for “verti- cal” health programmes to integrate with and strengthen national health information systems. These she argues should become the source of infor- mation for improved public-health decision-making and, at the same time, for information needed by donors and by specific (“vertical”) health pro- grammes.2 The problems raised by Bhattacha- rya and Stansfield are not confined to the health sector nor to health infor- mation. On the contrary, the issue of ownership of data and the practice of vertical programming is, in many ways, far worse in the domain of health research. In most low- and middle- income countries, foreign-funded initiatives determine national health research agendas, even in countries in which governments contribute sub- stantially to supporting national health