Haziq R Chowdhury1, Geoffrey E Rose2, Daniel G Ezra2. 1. Lacrimal Clinic, Moorfields Eye Hospital, City Road, London, UK. 2. Lacrimal Clinic, Moorfields Eye Hospital, City Road, London, UK; UCL Institute of Ophthalmology, London, UK; National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.