From: The Effect of Hypercarbia and Hyperoxia on the Total Blood Flow to the Retina as Assessed by Magnetic Resonance Imaging Invest. Ophthalmol. Vis. Sci.. 2011;52(9):6867-6874. doi:10.1167/iovs.10-6762 Figure Legend: The sequential rebreathing system. The input (fresh) gas reservoir and the exhaled gas reservoir are connected to the face mask with separate one-way valves. The two reservoirs are connected via a positive end-expiratory pressure (PEEP) valve that allows the subject to rebreathe the exhaled gas when the fresh gas reservoir is emptied. Date of download: 10/11/2017 The Association for Research in Vision and Ophthalmology Copyright © 2017. All rights reserved.