1 Department of Ophthalmology, Gloucestershire Hospitals NHS Foundation Trust, Cheltenham, United Kingdom. s.p.mamtora@hotmail.com.
2 Department of Ophthalmology, Gloucestershire Hospitals NHS Foundation Trust, Cheltenham, United Kingdom.
3 National Institute for Health Research (NIHR), Biomedical Research Centre based at Moorfields Eye Hospital, NHS Foundation Trust, London, United Kingdom.