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Evolution and evidence based medicine
  1. R A Hill
  1. University of California, Irvine Department of Ophthalmology, UC Irvine, Irvine, CA92697-4375, USA; rahill{at}

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    A costly but necessary practice

    Evolution as a process has led inventors and glaucoma surgeons to sites distal to the pretrabecular, trabecular, and post-trabecular origins of difficult to treat glaucomas. Evolution as a process has also led investigators to the multicentre randomised trials of sufficient power to answer questions and advance medical knowledge in a stepwise fashion. “Evidence based medicine” is a costly but necessary practice. These studies are made successful by dedicated physicians and patients willing to participate in these studies. The monetary costs are supported by physician sacrifices, committed educational institutions, private foundations, and government sponsored agencies. Susanna and colleagues (994) are to be congratulated and thanked for their contribution to our fund of knowledge. These studies are arduous at best, requiring long term sacrifice and devotion. Susanna and coworkers have noted that the conjunctival and subconjunctival physiologies of the equator of the globe are different from that of the limbus. This is an ironic finding, as this is part of the reason that initially pushed inventors and glaucoma surgeons to shunt aqueous to this distal site. The next advancements and directions in aqueous drainage devices may be argued. Perhaps a bioerodible film on implants might be used to release antimetabolites and modulate wound healing of the filtering capsule over a longer period. Perhaps the answer might be in a better understanding of material-tissue interactions. Or, perhaps it is time for a paradigm shift away from the bigger is better theme. This new theme could be a functional and focal therapy based on a physiological approach similar to coronary artery bypassing and stenting. This year, clinical trials of smaller, ab externo and ab interno shunting and stenting devices will start. Both approaches will utilise aqueous outflow physiology. Time and evidenced based medicine will determine if they are new steps or mis-steps that need re-evaluation.

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