Fig. 3

An illustration of the subgroup stratifications used for further cost-effectiveness analysis. Patients were stratified by merging health state groups into what we loosely describe as ‘Late’ disease (severe or worse VF loss in the better eye) or ‘Non-Late’ (‘Early’) Disease (mild and moderate VF loss in better eye)). The former would be patients diagnosed with a level of vision loss that would likely be incompatible with the VF component for legal fitness to drive in the UK [34]. Age distribution was taken directly from that used in the FVFM model. In the model proposed practice was provided to each of the four individual groups in turn with the remaining groups being allocated to the current practice