Receiver operating characteristic (ROC) curves for discriminating diabetic subjects without retinopathy from control subjects using a logistic regression model that combined contrast sensitivity (CS) values measured both in moderate and in dim lights. Receiver operating characteristic (ROC) curves for discriminating diabetic subjects without retinopathy from control subjects using a logistic regression model that combined contrast sensitivity (CS) values measured both in moderate and in dim lights. (A) ROC curve for a logistic model that includes CS values measured in response to all four spatial frequencies (black line) and (B) ROC curve for a model that includes CS to two spatial frequencies (3 and 6 cycles per degree). ROC for the model in photopic conditions is also indicated (gray traces, from figure 2). AUC, area under the curve; Accy, accuracy; cyc/deg, cycles per degree. Sare Safi et al. BMJ Open Diab Res Care 2017;5:e000408 ©2017 by American Diabetes Association