1. Thyroid Research Group, Cardiff University School of Medicine, Cardiff, United Kingdom.
2. Faculty of Medicine, Universiti Sultan Zainal Abidin, Kuala Terengganu, Malaysia.
3. Department of Ophthalmology, University Hospital of Wales, Cardiff, United Kingdom.
4. Research Design Service-South West, University Hospitals Bristol NHS Foundation Trust, Bristol, United Kingdom.
5. Gloucestershire Research Support Service, Gloucestershire Royal Hospital, Gloucester, United Kingdom.