title: Retinal thickness and volume measurements in diabetic macular edema: a comparison of four optical coherence tomography systems.
abstract: OBJECTIVE
  To compare different spectral domain optical coherence tomography devices regarding retinal thickness values in patients with diabetic macular edema and to correlate the results with conventional time domain Stratus OCT data.
  
  
  METHODS
  Thirty eyes of 30 consecutive patients with diabetic macular edema were included into a prospective study. The macula was examined by Spectralis HRA+OCT, Cirrus HD-OCT, 3D OCT-1000, and Stratus OCT. The procedures' sequence was performed by a single experienced technician in a randomized fashion according to a computer-generated list. In each eye, foveal thickness, foveal volume, and total macular volume were measured automatically. Intraclass correlation, coefficients of variance, and coefficients of repeatability were calculated.
  
  
  RESULTS
  Foveal thickness differed between the particular devices with a mean ± SD ranging from 359.97 ± 105.84 μm to 437.70 ± 115.84 μm. Correlation between the different OCT devices resulted in r > 0.7 (Pearson), and intraclass correlation was >0.9. Agreement of measurements was assessed showing a mean difference of foveal thickness values ranging from 19.2 μm to 77.7 μm (P < 0.05) and coefficients of repeatability ranging from 37.7 μm to 87.4 μm.
  
  
  CONCLUSIONS
  While intradevice reproducibility is satisfactory, retinal thickness and volume measurements should not be used interchangeably because measurements differed significantly between systems. The lack of interdevice agreement seems to be related to the different segmentation algorithm of thickness measurement and should be considered because it may strongly influence treatment decisions and conclusions.
authors.affiliation: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.
authors.forename: Jan
authors.initials: J
authors.lastname: Lammer
authors.forename: Christoph
authors.initials: C
authors.lastname: Scholda
authors.forename: Christian
authors.initials: C
authors.lastname: Prünte
authors.forename: Thomas
authors.initials: T
authors.lastname: Benesch
authors.forename: Ursula
authors.initials: U
authors.lastname: Schmidt-Erfurth
authors.forename: Matthias
authors.initials: M
authors.lastname: Bolz
mesh_terms: D000368:Aged; D000465:Algorithms; D003430:Cross-Sectional Studies; D003930:Diabetic Retinopathy / Q000175:diagnosis*; D005260:Female; D005584:Fovea Centralis / Q000473:pathology; D006801:Humans; D008266:Macula Lutea / Q000473:pathology; D008269:Macular Edema / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods