M Zarei-Ghanavati1,2, A Shalaby Bardan1,3,4, C Liu1,4,5. 1. Sussex Eye Hospital, Brighton and Sussex University Hospitals NHS Trust, Brighton, England. 2. Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran. 3. Faculty of Medicine, University of Alexandria, Egypt. 4. Brighton and Sussex Medical School, University of Sussex, Falmer, Brighton. 5. Tongdean Eye Clinic, Hove, England.