Fig. 1. Markov model of no screening group. A decision node (□) is the decision to test a contact by using the respective screening procedure. Branches from a change node (○) represent the possible outcomes of an event; terminal nodes (◃) are assigned the cost of a prior series of actions and events. Probabilities (p): see model specifications; #: complementary probability (all probabilities of chance node's branches to sum to 1.0). pNR, probability of no retinopathy; pNPDR, probability of NPDR; pPDR, probability of PDR; pCSME, probability of CSME; pNPDRobs, probability of remained NPDR; pNPDRtoPDR, probability of NPDR to PDR; pNPDRtoCSME, probability of NPDR to CSME; pPDRnolaserSVL, probability of PDR to SVL after no laser therapy; pCSMEnolaserSVL, probability of CSME to SVL after no laser therapy.