Sorry to read that you have background retinopathy.
Good bg control is important but do be careful, if your diabetes hasn't been well controlled and you suddenly tighten things up it can make retinopathy worse, any changes should done gradually and if in doubt speak with your diabetes care team or ophthalmologist.
As Dave says you need to keep your bp below the recommended limit and monitor your cholesterol levels too, the following website has a wealth of information about diabetic retinopathy and is full of useful advice which you should find useful:
http://www.diabeticretinopathy.org.uk/back_diabetic_retinopathy.html