title: Comparison of the clinical disc margin seen in stereo disc photographs with neural canal opening seen in optical coherence tomography images.
abstract: OBJECTIVE
  To compare neural canal opening (NCO) with the clinical optic disc margin (DM) seen and to investigate the planarity of the NCO in normal human optic nerve heads (ONH).
  
  
  METHODS
  Sixteen eyes were imaged. Twelve healthy eyes were selected for planarity and 9 for NCO and DM correspondence. All subjects were subjected to a visual field examination, stereo disc photograph (SDP), scanning laser ophthalmoscopy, clinical examination with a fellowship trained glaucoma specialist, and optical coherence tomography imaging. Three reviewers delineated the NCO and inner limiting membrane on optical coherence tomography images. The clinical DM was delineated by a glaucoma specialist while viewing SDPs. Plane error was calculated for NCO and for Bruch membrane (BM) at distances 80 and 120 μm from NCO.
  
  
  RESULTS
  The NCO segmentation interrater variability was low with an average coefficient of variation of 2.7%. A regional variation of the SDP and NCO correspondence was observed, wherein the temporal region had the largest coefficient of variation. The plane error of the NCO and BM were similar and was approximately 12 μm, which is small relative to an average DM diameter of 1.7 mm.
  
  
  CONCLUSIONS
  The BM opening has a good correspondence with the clinical DM seen in SDPs. NCO delineation seemed to be reliable. The BM and NCO are relatively planar in normal humans and can be further evaluated for longitudinal studies to observe stability.
authors: *School of Engineering Science, Simon Fraser University †Department of Ophthalmology and Visual Sciences, University of British Columbia, BC, Canada.
authors: Mei
authors: M
authors: Young
authors: Sieun
authors: S
authors: Lee
authors: Mahmoud
authors: M
authors: Rateb
authors: Mirza F
authors: MF
authors: Beg
authors: Marinko V
authors: MV
authors: Sarunic
authors: Paul J
authors: PJ
authors: Mackenzie
mesh_terms: D000293:Adolescent; D000328:Adult; D016570:Bruch Membrane / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008137:Longitudinal Studies; D008297:Male; D054259:Neural Tube / Q000033:anatomy & histology*; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000033:anatomy & histology*; D010781:Photography; D055213:Retinal Pigment Epithelium / Q000166:cytology; D041623:Tomography, Optical Coherence / Q000379:methods*; D014794:Visual Fields / Q000502:physiology; D055815:Young Adult