1. Electron Microscopy, Clinical Sciences Building, Manchester Royal Infirmary, Manchester M13 9WL, UK
2. National Specialist Ophthalmic Pathology Service, Department of Histopathology, E Floor, Royal Hallamshire Hospital, Sheffield S10 2JF, UK
3. Cornea Clinic, Chittagong Eye Infirmary, PO Box 729, Pahartali, Chittagong 4000, Bangladesh
4. Department of Biological Sciences, Imperial College London, Silwood Park Campus, Ascot SL4 7PY, UK
5. Electron Microscopy Unit, Department of Histopathology, Northern General Hospital, Herries Road, Sheffield S5 7AU, UK