title: Area of peripheral retinal nonperfusion and treatment response in branch and central retinal vein occlusion.
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  The area of peripheral retinal nonperfusion is variable in patients with retinal vein occlusion and affects its clinical course and response to treatment.
authors.affiliation: *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.
authors.forename: Michael
authors.initials: M
authors.lastname: Singer
authors.forename: Colin S
authors.initials: CS
authors.lastname: Tan
authors.forename: Darren
authors.initials: D
authors.lastname: Bell
authors.forename: Srinivas R
authors.initials: SR
authors.lastname: Sadda
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020533:Angiogenesis Inhibitors / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use; D015331:Cohort Studies; D003907:Dexamethasone / Q000008:administration & dosage*; D004343:Drug Implants; D004359:Drug Therapy, Combination; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D058449:Intravitreal Injections; D007511:Ischemia / Q000503:physiopathology; D008269:Macular Edema / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D000069579:Ranibizumab; D012169:Retinal Vein / Q000503:physiopathology*; D012170:Retinal Vein Occlusion / Q000188:drug therapy* / Q000503:physiopathology*; D041623:Tomography, Optical Coherence; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors; D014792:Visual Acuity / Q000502:physiology
chemical_list: D020533:Angiogenesis Inhibitors; D061067:Antibodies, Monoclonal, Humanized; D004343:Drug Implants; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D003907:Dexamethasone; D000069579:Ranibizumab