The overarching aim of the National Institute for Health and Clinical Excellence (NICE) is to provide the National Health Service (NHS) and partner organisations with independent, authoritative and evidence-based guidance on the most effective ways to prevent, diagnose and treat disease and ill health, reducing inequalities and variation, while ensuring value for money.1 To this end, NICE has produced guidance for the NHS for over a decade, with Clinical Guidelines, Technology Appraisals (drugs) and Interventional Procedures Guidance each having directly influenced medical and surgical practice in ophthalmology. The extent to which NICE guidance applies varies between UK Nations with the above three forms applying specifically to the NHS in England and Wales, and elsewhere by implication and local agreement. In recent years the NICE portfolio has been expanded to include NHS Evidence, Pathways, Quality Standards and Commissioning Outcomes Framework Indicators.1 For clinicians working in the field of glaucoma and related conditions, NICE guidance has been particularly evident, with a Clinical Guideline published in 2009, Quality Standards in 2011, updated Commissioning Guidance for people at risk of Glaucoma in 2012 and a variety of Interventional Procedure Guidance statements over several years.2

The Glaucoma Clinical Guideline, CG85, was scoped around diagnosis and management of chronic open angle glaucoma (COAG) and ocular hypertension (OHT).3 As with NICE clinical guidelines generally, a 3–5-year phased implementation was advised. Immediately following publication of the guideline, however, an unintended consequence arose in the form of a dramatic change in case-finding behaviours and patterns of referrals from community optometrists. Criteria for diagnosis had been selectively extracted from diagnosis and management and transplanted across into primary care case-finding settings by …