title: Wide-field optical coherence tomography angiography using extended field imaging technique to evaluate the nonperfusion area in retinal vein occlusion.
abstract: OBJECTIVE
  Optical coherence tomography angiography (OCTA) is a newly developed technology which allows us to reconstruct the three-dimensional chorioretinal vasculature without dye injection. OCTA is a noninvasive, rapid, and reproducible method to assess retinal ischemia. However, one of its limitations is the size of scanning area. A novel yet simple technique to expand the scan length on optical coherence tomography has been reported as an extended field imaging (EFI) technique. It involves imaging the posterior pole through trial frames fitted with a +20 diopter lens. We applied this technique to OCTA to evaluate retinal vein occlusion.
  
  
  METHODS
  Ten eyes of nine patients with retinal vein occlusion were studied. The average age was 69.0 years (range: 49-93 years). We obtained OCTA images by using RTVue XR Avanti OCT with AngioVue(®). The images of OCTA with scan size of 8×8 mm were obtained with and without EFI, and then they were compared.
  
  
  RESULTS
  OCTA with EFI technique was performed successfully in all eyes. The nonperfusion area was well defined in superficial capillary plexus layer. The images with EFI were able to capture the larger area of the fundus by an average of 188.5% than those without EFI. The posterior pole inside the vascular arcade was well covered with this technique. The area of the fundus imaged by OCTA with EFI technique was even larger than that of fluorescein angiography using Heidelberg Retina Angiograph 2, which captured a 30° field.
  
  
  CONCLUSIONS
  Our results suggested that OCTA with EFI technique is very useful to evaluate the retinal ischemia in retinal vein occlusion.
authors.affiliation: Department of Ophthalmology and Visual Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Masayo
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Department of Ophthalmology and Visual Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Nozaki
authors.affiliation: Department of Ophthalmology and Visual Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Munenori
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Department of Ophthalmology and Visual Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Ogura
keywords: EFI; OCTA; RVO; extended field imaging; nonperfusion area; optical coherence tomography angiography; retinal vein occlusion; wide-field imaging