Case-finding should be a continuing process and not a ‘one-time’ project. Much of the evidence that was given for diabetic retinopathy being an important condition that comes under these criteria above is presented in this guideline. Evidence of the cost effectiveness of screening came from a number of sources 6, 12 - 20 . In the Four Nations there is unequivocal support for the use of digital photography as the best method of screening. The use of selective mydriasis and the number of fields captured have been more controversial 6, 21 - 24 for evidence base for digital photography and required fields . It is important to recognise that screening acts as a sieve and, as with all screening programmes, not every case of sight threatening retinopathy will be detected with the screening test used. 8.4 ORGANISATION OF SCREENING SERVICES AND METHODOLOGIES USED IN THE UK The introduction of National Screening Programmes in England, Scotland, Wales and Northern Ireland demonstrated differences in the health care systems at that time. All Four Nations agreed a minimum specification for cameras to be used across the UK which is updated at approximately 3 yearly intervals. Any new cameras coming onto the market are tested to check that they comply with the relevant minimum standard. 67 The implementation of the English National Screening Programme is overseen by a Programme Advisory Committee. In the English Scheme guidance was given on recommended software to be used, the method of two field mydriatic digital photography, the minimum grading classification and further information is provided on a website1 . The screening test uses technician screeners or optometrists. Fixed locations are used or screening may be undertaken in a van based mobile unit transported to GP surgeries or other locations. It is recommended that screening in any area is overseen by a Programme Board that has representation from Ophthalmology, Public Health, Commissioners and the local Screening Team. In Scotland the DRS Collaborative has been formed to bring together individuals from all the NHS Boards in Scotland involved in the delivery of the retinopathy screening programme, including representatives of the various professions involved as well as patient representatives and other stakeholders. The aim of the DRS Collaborative is to facilitate the delivery of diabetic retinopathy screening across Scotland as part of a National Programme. The National Screening Programme in Scotland uses a three-stage process based on one field non-mydriatic digital photography, with the use of mydriasis and slit-lamps, where necessary. In 2010, NHS Quality Improvement Scotland recommended the use of automated grading for distinguishing retinopathy from no retinopathy, providing validated software is used (http://www.sign.ac.uk/pdf/sign116.pdf, 2011). The DRS Collaborative has since commenced implementation of automated grading within the National Screening Programme. In Wales, a Programme Board established by Cardiff and Vale NHS Trust oversee the Diabetic Retinopathy Screening Service for Wales which is centrally funded by the Welsh Assembly. The screening methodology in Wales is two field mydriatic digital photography using technicians travelling in mobile units to fixed locations across Wales. All grading in Wales is undertaken in a single centre. The Northern Ireland DRSP was implemented by a project board. The screening programme uses a mixed model, with the screening test delivered primarily in GP practices in the legacy Eastern, Northern and Southern Boards using mobile equipment, and in six fixed community sites in the legacy Western Board. The methodology is two field digital photography through dilated pupils, with selective mydriasis under the age of 50 years. All images are transferred and graded centrally at the screening programme centre at Belfast Health and Social Care (HSC) Trust. Monitoring of programme performance against a set of Quality Assurance standards is key to successful National Screening Programmes in all Four Nations. England has developed Quality Assurance Standards and Key Performance Indicators against which individual Screening Programmes are monitored. Wales and Northern Ireland are working to similar standards to the English Screening Programme. NHS Quality Improvement Scotland has produced a set of standards against which screening programmes in Scotland are monitored. Links to relevant documents are available from the English1 and Scottish2 websites. The key feature of these standards is rigorous quality control at all stages of the screening and assessment process. Screening services are required to produce annual reports and continuous internal and external monitoring of quality should enable year on year improvements to occur. 68 A key requirement for systematic DR screening in the UK is accurate identification in primary care of all those known to have diabetes and the transfer of this information to invite the target population for screening. This is essential to achieve full coverage. In Scotland, GPs register all people with diabetes on the SCI-DC Network, which, in addition to providing a single web based patient record for diabetes also registers patients on the national diabetes retinopathy screening system (Soarian). In England a system called GPtoDRS is being developed to allow electronic transfer of data from GP diabetes registers to screening programmes. With rapid advancements in technology new approaches to screening may prove effective including the use of computerised methods for detection and assessment of retinopathy25 26 or optical coherence tomography in the first line assessment of screen positive patients with diabetic maculopathy. When new technologies are assessed for use in the English Screening Programme they need to demonstrate: 1. That the device can match the sensitivity and specificity of digital photography in the detection of referable retinopathy in a screening programme environment where ungradable images are test positive. 2. That the device should be able to detect microaneurysms