Philosophical direction of ‘ophthalmic epidemiology'

Abstract

Published in this second issue of Ophthalmic Epidemiology is a review article by Dr. David H. Sliney entitled ‘Epidemiological studies of sunlight and cataract: the critical factor of ultraviolet exposure geometry'. Ultraviolet radiation as a risk factor for cataract development is a hot and hotly debated controversy with conflicting results presented in a number of superb research studies by experienced ophthalmic epidemiologists. This review article by Dr. Sliney offers some insight as to why the results of these epidemiologic studies are not uniformly consistent; he points out some of the pitfalls associated with instruments we use to measure ultraviolet radiation in population-based studies, and the importance of considering the circumstances under which ultraviolet exposure to the human eye is measured, whether it be by direct measurement of ultraviolet light impinging upon the eye, questionnaire of ultraviolet light exposure history, tables of resident area of sunlight or ultraviolet A, B, or C exposure or by other modalities of ultraviolet determinations. Using the information provided by Dr. Sliney in this review article may help future investigators improve the precision of instruments used in epidemiologic studies to quantify ultraviolet light impinging upon the human eye. Improvement of the precision of collected data can only reduce the variance of findings among studies on the association of ultraviolet radiation as a cause of age-related cataract. A similar issue is raised by Christen and associates in the article published in this same issue of Ophthalmic Epidemiology, ‘Confirmation of self-reported cataract in the Physicians’ Health Study', a well-conducted and well-respected study, that points out the need for independent confirmation of self-reported cataracts as recorded by questionnaire, to improve the accuracy of diagnosis of a disease whose risk factors are under investigation. A dictum taught me by my mentors at Johns Hopkins University, Drs. Philip Sartwell and George Comstock, that because of the imprecision and variance of epidemiologic measurement instruments, it takes many studies ‘like swallows to make a spring’ to confirm risk-factor relationships to a given disease. The often cited, numerous controversial studies on the association of cigarette smoking and lung cancer which were published long before it became clear that cigarette smoking was the major risk factor in that disease, emphasize the role of multiple studies in confirming an association between risk factor and disease, even when it is readily obvious in hind sight. I personally feel that review articles, published in ophthalmic journals, serve an essential function in the advancement of ophthalmic research. Periodic review articles on a particular ocular disease, by summarizing the known infomation about that particular disease up to that point in time, help current investigators plan future research based upon the balanced review of past knowledge. No current ophthalmic or epidemiologic journal is committed to consistently publishing those review articles necessary to provide a readily available repository of critical information, presented in a balanced perspective by experts in the field, for citation by researchers to further future research advances in particular fields of ophthalmic epidemiologic investigation.

The stimulus for Dr. Sliney's article came from the recent World Health Organization Report of an Informal Consultation on ‘The Effects of Solar UV Radiation on the Eye', convened by the WHO Prevention of Blindness Programme and the w HO Division of Environmental Health. This consultative study was stimulated in part by substantiated observations of ozone depletion at both polar regions of the earth and the logical question of what the potential effect of increased ultraviolet radiation on the eye in these areas may be, based upon the known ultraviolet exposure data currently available. Dr. Thylefors, Head of the WHO Prevention of Blindness Programme, has allowed Ophthalmic Epidemiology to publish portions of this consultative report in order to disseminate, to the general ophthalmic community, this ‘state-of-the-art’ information on the relationship of ultraviolet radiation and potential ocular damage. The article by Dr. Sliney, who contributed to the WHO report, is just the first of several review articles to be published on this subject by Ophthalmic Epidemiology; the putative relationship of ultraviolet exposure to cataract development has importent environmental, social, economic and health-related importance. Dr. Paul Dolin, a member of the w HO consultative team, has written an article, accepted in the next issue of Ophthalmic Epidemiology, which provides suggested epidemiologic studies that might help us in further investigation of the relationship of ultraviolet radiation and cataract development. Professor Gordon Johnson, also a contributor to the WHO consultation, has submitted a review paper on ultraviolet light exposure and its overall effect on the eye and adnexa, except for cataract and macular degeneration, which will be published in a future issue of Ophthalmic Epidemiolgy.

One of the reasons I accepted the major undertaking necessary to bring ‘Yet another Journal’ into the field of ophthalmic information overload, comes from my exasperation from attending many meetings over my 25 years as an ophthalmic epidemiologist where I felt that important papers and posters were presented and I wished that I were able to review in detail the methodology, results and discussion of the research presented; papers that were stimulating, provocative, controversial, methodologic, with negative results, positive results, or otherwise, which I thought worthy of publication to advance the field of ophthalmic epidemiologic research. I have seen research on specific areas repeated by subsequent investigators because no such repository of knowledge, where past research, be it positive or negative, could be found, had been published. Most ophthalmic and epidemiologic journals cannot, with their wide obligations to broad areas of readership, publish all the ‘nuts-and-bolts’ articles essential to provide the repository of information necessary to ophthalmic epidemiologists. These are the articles that need to be published, review and original articles, that form the basic building blocks which current researchers in ophthalmic epidemiology can use as foundations for future investigations. Ophthalmic Epidemiology is committed to providing the repository of information upon which new ideas can evolve based upon the building blocks of the past. Part of this foundation is the depository provided by review articles, special topics, methodologic studies, and negative results which I will encourage, so that others in our footsteps do not repeat our repetitious failures and successes out of ignorance, but can use our past footsteps to lead the march to future advances in the conquest of world blindness.