Obviously you should keep your diabetes under control but don't run it too tight if your diabetes has been uncontrolled for some time, sudden tightening of bg control can make retinopathy worse. You also need to keep your bp below the recommended levels as well as your cholesterol, apart from that make sure you eat a healthy balanced diet with plenty fruits and veg, my own Ophthalmologist said the darker the colour the better it is for eye health, as I say there's plenty of helpful advice on the link that I posted above.