Amblyopia exercises have been shown to be effective in Px over the age of 8 years of age (which is at the point that the visual system development becomes hard wired) however they are usually transient improvements. Basically when you stop the exercises the vision returns to is pre-exercise level. However the exercises don’t work with everyone. If you are trying to get from 6/12 to 6/9 which is not a huge improvement I would think the appropriate eye exercises would be worth trying – you just might have to do them every year for a month or so before each medical.