title: Retinal vessel calibre measurements by optical coherence tomography angiography.
abstract: To compare the vessel calibre measurements between optical coherence tomography angiography (OCTA) and colour fundus photography.
  
  
  
  In this retrospective comparative study, OCTA and colour fundus images of healthy eyes and eyes with optic atrophy were evaluated. The colour fundus image was registered manually using Image J software to the OCTA image of the optic disc. Two independent graders measured the vessel calibre of the widest vein and artery in each peripapillary quadrant on a 3.4 mm diameter circle centred on the optic disc in the same location on both images. The difference in vessel calibre between the two techniques was assessed.
  
  
  
  A total of 312 vessels from 29 healthy eyes and 20 eyes with atrophic optic discs were included. There was a high level of agreement between graders for measurement of vessel calibre in both colour fundus (intraclass correlation coefficient=0.93, coefficient of variation=0.07) and OCTA images (intraclass correlation coefficient=0.94, coefficient of variation=0.05). The mean vessel calibre in colour fundus images (94.5±23.2 µm) and OCT images (112.2±26.1 µm) was correlated (r=0.8, p<0.001), but the difference was statistically significant (mean difference: 17.6±1.5 µm, p<0.001). This difference was evident for both arteries (mean difference: 18.2±16.3 µm, p<0.001) and veins (mean difference: 15.1±16.2 µm, p<0.001) individually, with a similar magnitude of difference for both vessel types (p=0.08). In addition, the magnitude of difference between imaging modalities was similar in atrophic and healthy discs (17.1±15.9 vs 18.4±15.2 µm, respectively, p=0.4). The difference, however, was significantly higher in vessels with a calibre of ≤94.5 compared with larger vessels (19.3±16.3 vs 15.6±14.4 µm, respectively, p=0.02).
  
  
  
  Vessel calibre measurements were significantly larger in OCTA images compared with colour fundus photographs, particularly for smaller vessels. These differences may need to be accounted for when using OCTA-derived metrics.
authors.affiliation: Department of Ophthalmology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.|Doheny Eye Institute, Los Angeles, California, USA.|Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Khalil
authors.initials: K
authors.lastname: Ghasemi Falavarjani
authors.affiliation: Department of Ophthalmology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.|Doheny Eye Institute, Los Angeles, California, USA.
authors.forename: Mayss
authors.initials: M
authors.lastname: Al-Sheikh
authors.affiliation: Doheny Eye Institute, Los Angeles, California, USA.|Department of Ophthalmology, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Darvizeh
authors.affiliation: Department of Ophthalmology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.|Doheny Eye Institute, Los Angeles, California, USA.
authors.forename: Alfredo A
authors.initials: AA
authors.lastname: Sadun
authors.affiliation: Department of Ophthalmology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA.|Doheny Eye Institute, Los Angeles, California, USA.
authors.forename: Srinivas R
authors.initials: SR
authors.lastname: Sadda
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005451:Fluorescein Angiography / Q000379:methods*; D005654:Fundus Oculi; D006801:Humans; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D010781:Photography; D012171:Retinal Vessels / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods*; D055815:Young Adult
keywords: Imaging; Optic Nerve; Retina