Amblyopia affects about 3-5% of the population. Occlusion therapy using an eye patch to cover the non-amblyopic eye for a couple of hours each day has been the principal means of treatment. The sensitive period in which vision loss can develop and be recovered is generally up to 6 years of age.1 In many European countries, population based screening and treatment by orthoptists has reduced the proportion of people with untreated or insufficiently treated amblyopia to about 1% of the population.2 3

The effectiveness of screening and treatment for amblyopia in the United Kingdom has been questioned because of insufficient evidence from randomised controlled trials,4 and an effort is now being made to assess its effectiveness and cost. In this week's BMJ, a randomised controlled trial by Stewart and colleagues compares the effect of prescribing six or 12 hours of occlusion each …