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Bill Harvey recommends the Cochrane Library as an essential resource with a refreshing absence of bias
I have long been wary of subjective rating based research. Asking a patient how they feel in a certain type of contact lens or how they rate the vision through a particular spectacle lens seemed to me fraught with potential pitfalls. The question itself will introduce bias ('is this more comfortable?' 'can you see better now?') and may mask external influences such as a free supply of the new lens/product. I assumed that objectivity had to be the key.
I have revised this view somewhat after hearing the story of Sir Ian Chalmers, an obstetrician who spent some time working in the Middle East. Here he noticed that much of what he had been taught and what had been learned from apparently evidence-based research did not seem to be borne out by his real-life experiences.
He noticed, for example, inconsistencies in the way that Caesarian section births were assumed by many to be the best method of delivering children. He noted how many of the methods 'proved' by research to be the best way of offering analgesia during birth were contradicted by statements of the women actually giving birth.
He noticed, in fact, a lack of input from patients and their views in general when researchers were looking at specific therapeutic interventions and that the outcomes were rarely measured in terms of patient satisfaction.
He was thus inspired to become a champion of better designed research, based on the ideal of randomised controlled studies and including all aspects of potential outcome including that of patient inference.
In 1992, Chalmers was appointed director of the UK Cochrane Centre. Subsequently, he became founding editor of the James Lind Library, which documents the history and evolution of fair trials of treatments, and helped to establish the James Lind Alliance, a non-profit organisation that 'aims to identify the most important gaps in knowledge about the effects of treatments'. The aim is to make sure there is ready access for professionals and patients to well-designed research about any particular topic. The online Cochrane resource publishes regular reviews and meta-analyses about a wealth of topics and allows you to view the summated evidence based on well-designed research. There are many that apply to optometry.
How to access findings
Simply go to www.thecochranelibrary.com and register your details and areas of interest. Whenever there is a review of the research in any particular area, you can access a summary. Of recent interest were three recent reviews by Professor John Lawrenson and colleague. The first looks at the effectiveness or otherwise of omega-3 supplementation on eye health and concludes: 'There is currently no evidence to support increasing levels of omega-3 LCPUFA in the diet for the explicit purpose of preventing or slowing the progression of AMD.'
The second report looked at the influence of supplementation on AMD progression and reports: 'People with AMD may experience delay in progression of the disease with antioxidant vitamin and mineral supplementation. This finding is drawn from one large trial conducted in a relatively well-nourished US population. The generalisability of these findings to other populations is not known. Although generally regarded as safe, vitamin supplements may have harmful effects. A systematic review of the evidence on harms of vitamin supplements is needed.'
Finally, how useful is supplementation at preventing AMD onset? 'There is accumulating evidence that taking vitamin E or beta-carotene supplements will not prevent or delay the onset of AMD. There is no evidence with respect to other antioxidant supplements, such as vitamin C, lutein and zeaxanthin, or any of the commonly marketed multivitamin combinations. Although generally regarded as safe, vitamin supplements may have harmful effects and clear evidence of benefit is needed before they can be recommended.' This tallies well with previous meta-analyses suggesting that supplementation may help reduce progression but there is still no evidence of a prophylactic effect when it comes to disease onset. ?