Original StudyAREA OF PERIPHERAL RETINAL NONPERFUSION AND TREATMENT RESPONSE IN BRANCH AND CENTRAL RETINAL VEIN OCCLUSIONSinger, Michael MD*; Tan, Colin S. FRCSEd (Ophth)†,‡,§; Bell, Darren MD*; Sadda, Srinivas R. MD§Author Information *Medical Center Ophthalmology, San Antonio, Texas; †Department of Ophthalmology, Tan Tock Seng Hospital, Singapore, Singapore; ‡Fundus Image Reading Center, National Healthcare Group Eye Institute, Singapore, Singapore; and §Doheny Eye Institute, University of Southern California, Los Angeles, California. Reprint requests: Srinivas R. Sadda, MD, Doheny Eye Institute, 3623, 1450 San Pablo Street, Los Angeles, CA 90033; e-mail: [email protected] Presented in part at the annual meeting of the American Academy of Ophthalmology, Chicago, IL, November 2012. Supported in part by NIH Grant EY03040 and NEI Grant R01 EY014375 (S.S.) and the National Healthcare Group Clinician Scientist Career Scheme Grant CSCS/12005 (C.S.T.). M. Singer received grant support in terms of equipment and reading center support from Optos. S. R. Sadda receives research support from Carl Zeiss Meditec, Optovue Inc, and Optos. C. S. Tan receives travel support from Bayer. S. R. Sadda previously shared in royalties from intellectual property licensed to Topcon Medical Systems by the Doheny Eye Institute and also previously served on the scientific advisory board for Heidelberg Engineering. The remaining authors have no conflicting interests to disclose. Retina: September 2014 - Volume 34 - Issue 9 - p 1736-1742 doi: 10.1097/IAE.0000000000000148 Buy Metrics AbstractIn Brief Purpose: To evaluate the extent of peripheral retinal nonperfusion in retinal vein occlusion and to determine its effect on the severity of macular edema and response to treatment. Methods: This prospective clinic-based cohort study included 32 consecutive patients with retinal vein occlusion and refractory macular edema evaluated using spectral domain optical coherence tomography and wide-field fluorescein angiography. Areas of ischemia were calculated as a percentage of the total visible retina (ischemic index), which was evaluated when macular edema was present (foveal central subfield >300 μm) and when edema had resolved (foveal central subfield ≤300 μm). Ischemic index was the main outcome measure. Results: The mean ischemic index at study enrollment was 14.8% and was larger when macular edema was present compared with when edema had resolved (14.8 vs. 10.3%, P < 0.001). Compared with those with less nonperfusion, patients with ischemic index >10% had thicker mean foveal central subfield on optical coherence tomography (520.8 vs. 424.5 μm, P = 0.029) and worse visual acuity (56.3 vs. 59 letters) with the presence of macular edema and experienced greater decrease in optical coherence tomography (296.1 vs. 165.3 μm, P = 0.019) and gain in visual acuity (12.4 vs. 0.9 letters, P = 0.036) in response to treatment. Conclusion: The area of peripheral retinal nonperfusion is variable in patients with retinal vein occlusion and affects its clinical course and response to treatment. The area of peripheral retinal nonperfusion is highly variable in retinal vein occlusion and changes with the disease activity. It is larger when macular edema is present and decreases when macular edema has resolved. © 2014 by Ophthalmic Communications Society, Inc.