K Merchant1, M Nassar2,3, A Shafiq4, D Cottrell4. 1. Department of Ophthalmology, Royal Berkshire Hospital, Reading, UK. 2. Department of Ophthalmology, Dumfries and Galloway Royal Infirmary, Dumfries, UK. 3. 3Department of Ophthalmology, Faculty of Medicine, Minia University, Al-Minia, Egypt. 4. Newcastle Eye Centre, Royal Victoria Infirmary, Newcastle Upon Tyne, UK.