[1] Kings Coll Hosp London, Retinal Res Unit, Dept Ophthalmol, London SE22 8PT, England
[2] Univ London, Dept Ophthalmol, St Georges Hosp, London SW17 0QT, England
[3] Univ London, Sch Med, London SW17 0QT, England
[4] Univ London, Dept Histopathol, St Georges Hosp, London SW17 0QT, England