title: Quantification of external limiting membrane disruption caused by diabetic macular edema from SD-OCT.
abstract: OBJECTIVE
  Disruption of external limiting membrane (ELM) integrity on spectral-domain optical coherence tomography (SD-OCT) is associated with lower visual acuity outcomes in patients suffering from diabetic macular edema (DME). However, no automated methods to detect ELM and/or determine its integrity from SD-OCT exist.
  
  
  METHODS
  Sixteen subjects diagnosed with clinically significant DME (CSME) were included and underwent macula-centered SD-OCT (512 × 19 × 496 voxels). Sixteen subjects without retinal thickening and normal acuity were also scanned (200 × 200 × 1024 voxels). Automated quantification of ELM disruption was achieved as follows. First, 11 surfaces were automatically segmented using our standard 3-D graph-search approach, and the subvolume between surface 6 and 11 containing the ELM region was flattened based on the segmented retinal pigment epithelium (RPE) layer. A second, edge-based graph-search surface-detection method segmented the ELM region in close proximity "above" the RPE, and each ELM A-scan was classified as disrupted or nondisrupted based on six texture features in the vicinity of the ELM surface. The vessel silhouettes were considered in the disruption classification process to avoid false detections of ELM disruption.
  
  
  RESULTS
  In subjects with CSME, large areas of disrupted ELM were present. In normal subjects, ELM was largely intact. The mean and 95% confidence interval (CI) of the detected disruption area volume for normal and CSME subjects were mean(normal) = 0.00087 mm(3) and CI(normal) = (0.00074, 0.00100), and mean(CSME) = 0.00461 mm(3) and CI(CSME) = (0.00347, 0.00576) mm(3), respectively.
  
  
  CONCLUSIONS
  In this preliminary study, we were able to show that automated quantification of ELM disruption is feasible and can differentiate continuous ELM in normal subjects from disrupted ELM in subjects with CSME. We have started determining the relationships of quantitative ELM disruption markers to visual outcome in patients undergoing treatment for CSME.
authors.affiliation: Department of Electrical and Computer Engineering, University of Iowa, Iowa City, Iowa, USA.
authors.forename: Xinjian
authors.initials: X
authors.lastname: Chen
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Elliott H
authors.initials: EH
authors.lastname: Sohn
authors.forename: Kyungmoo
authors.initials: K
authors.lastname: Lee
authors.forename: Meindert
authors.initials: M
authors.lastname: Niemeijer
authors.forename: John
authors.initials: J
authors.lastname: Chen
authors.forename: Milan
authors.initials: M
authors.lastname: Sonka
authors.forename: Michael D
authors.initials: MD
authors.lastname: Abràmoff
mesh_terms: D001485:Basement Membrane / Q000473:pathology*; D003930:Diabetic Retinopathy / Q000150:complications*; D019773:Epiretinal Membrane / Q000175:diagnosis* / Q000209:etiology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008269:Macular Edema / Q000150:complications*; D010865:Pilot Projects; D012160:Retina / Q000473:pathology; D041623:Tomography, Optical Coherence; D014792:Visual Acuity / Q000502:physiology