[1] Royal Victoria Eye & Ear Hosp, Dept Ophthalmol, Dublin, Ireland
[2] Univ Med & Hlth Sci, Royal Coll Surg Ireland, Sch Med, Dublin, Ireland
[3] Imperial Coll Healthcare NHS Trust, Dept Ophthalmol, London, England
[4] St Vincents Univ Hosp, Dept Radiol, Dublin, Ireland
[5] Beaumont Hosp, Natl Neurosurg Ctr, Dept Neurosurg, Dublin, Ireland
[6] Royal Victoria Eye & Ear Hosp, Adelaide Rd, Dublin 2, Dublin, Ireland