To overcome this, we have designed an instrument that permits us to measure occlusion: an occlusion dose monitor (ODM) which provides an objective record of how much occlusion a child actually receives. Recently we have observed that 75% of improvement induced by occlusion occurs in the first four weeks of treatment. In this study we explore the possibility that by intensive treatment the period of amblyopia therapy can be shortened – i.e. treatment will be more efficient, more effective, and more ‘family-friendly’. The study hypothesis is that 12 hours/day of patching is more effective than 6 hours/day.