Health and medical practice has been generically 'evidence based' since the emergence of the modern scientific disciplines of physiology, pharmacology, microbiology, biochemistry, pathology and human anatomy between the 17th and 20th Centuries. Before this, physicians relied on traditional treatments, often based in the historically resilient but scientifically untenable humoral dogma of Galen and Hippocrates. Despite the emergence of the basic medical sciences, the dominance of tradition over science in medical practice was aptly illustrated by the fact that the common use of phlebotomy ('bleeding') to treat respiratory ailments persisted well into the 19th Century. The more recent evidence-based movement in clinical practice focuses explicitly on the use of relevant research such as robust clinical trials to direct decisionmaking, as opposed to tradition, habit and 'expert opinion'. Evidence-based practice in health care has been defined as 'the conscientious, explicit and judicious use of current best evidence in decisionmaking'.2 While there has been some controversy and disagreement about the benefit of such an approach, 3 it has been adopted by other health professions and deserves to be investigated thoroughly as a possible aid to assist clinical decisionmaking in optometry. In this article, I examine the nature of this contemporary evidence-based philosophy of clinical practice and how it might be applied to primary-care optometry.
CLINICAL EVIDENCEIn relation to clinical practice, the term 'evidence' is used specifically to refer to sources of knowledge that are relevant to the practical solution for a clinical problem. Such problems may be very specific, such as a decision on which available treatment will provide the best outcome for a particular condition and patient, or they might be general, such as the choice of the best examination procedure to minimise risk of misdiagnosis or failure to detect disease.National health authorities recognise formal categories of clinical evidence and these are regularly reviewed and ranked in order of apparent strength. In Australia the National Health and Medical Research Council 4 (NH&MRC) recognises six different categories of clinical evidence, as shown in Table 1.A previous NH&MRC list included another item, 'opinion of respected authorities, based on clinical experience, descriptive studies or reports of expert committees', but this was discarded in 1999. Evidence-based practice in health care requires that treatment decisions be supported by high-quality clinical evidence, preferably involving well-designed large-scale clinical trials of the various treatment options. How does this relate to everyday primary-care optometry? This article provides a background to the emergence of the 'evidence-based' movement and investigates areas where the efficacy of clinical optometry might be improved by an evidence-based approach. It is argued that evidence-based practice is appropriate for all aspects of optometry but it may be most useful in the selection of treatments...