Central foveal thickness (arrow) was defined as the distance between the vitreoretinal interface and the inner border of retinal pigment epithelium at the foveal centre, based on optical coherence tomography imaging at the centre of the fovea. Central foveal thickness (arrow) was defined as the distance between the vitreoretinal interface and the inner border of retinal pigment epithelium at the foveal centre, based on optical coherence tomography imaging at the centre of the fovea. Shohei Kitahata et al. BMJ Open Ophth 2018;3:e000107 © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.