DMR guidlines
http://www.medscape.com/viewarticle/775150_1
ETDRS
The International Clinical Diabetic Retinopathy and Diabetic Macular Oedema Severity Scale, developed in 2001
Wilkinson CP, Ferris FL 3rd, Klein RE et al. Global Diabetic Retinopathy Project Group. Proposed international clinical diabetic retinopathy and diabetic macular edema disease severity scales. Ophthalmology 110(9), 1677–1682 (2003).