1. St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, UK
2. Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
3. Ophthalmology Unit of the Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
4. Schepens Eye Research Institute, Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA
5. Department of Medical and Surgical Specialties, Radiological Sciences, and Public Health, Ophthalmology Clinic, University of Brescia, Brescia, Italy