1. Department of Ophthalmology, The Queen's University of Belfast, N. Ireland, The Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts
2. Department of Ophthalmology, The Queen's University of Belfast, N. Ireland, School of Biomedical Sciences, University of Ulster, Coleraine, N. Ireland, The Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts
3. Department of Ophthalmology, The Queen's University of Belfast, N. Ireland
4. The Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts