AbstractThese are commentaries on a Cochrane review, published in this issue of EBCH, first published as: Pringsheim T, Steeves T. Cochrane Database of Systematic Reviews 2011, Issue 4. Art. No.: CD007990. DOI: 10.1002/ 14651858.CD007990.pub2Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2012 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration