title: Retinal nerve fiber layer defect volume deviation analysis using spectral-domain optical coherence tomography.
abstract: OBJECTIVE
  To report the retinal nerve fiber layer (RNFL) defect volume deviation according to structural RNFL loss in RNFL thickness maps.
  
  
  METHODS
  Retinal nerve fiber layer defect is defined in RNFL thickness maps by the degree of RNFL loss. A 20% to 70% degree of RNFL loss was set with a 1% interval as the reference level for determining the boundary of RNFL defects. Each individual RNFL thickness map was compared with a normative database map and the region below the reference level was identified as an RNFL defect. The RNFL defect volume was calculated by summing the volumes of each pixel inside RNFL defect. The RNFL defect volume deviation was calculated by summing the differences between the normative database and the subject's RNFL measurements. To evaluate the glaucoma diagnostic ability, the areas under the receiver operating characteristics curves (AUCs) were calculated.
  
  
  RESULTS
  Retinal nerve fiber layer defect volume and RNFL defect volume deviation (0.984 and 0.986, respectively) had significantly greater AUCs than all circumpapillary RNFL thickness parameters (all P < 0.001). In the early stage of RNFL loss (under 31% loss of RNFL), RNFL defect volume deviation showed better diagnostic performance than the RNFL defect volume. In multivariate analysis, RNFL defect volume and RNFL defect volume deviation were significantly associated with the mean deviation in visual field tests.
  
  
  CONCLUSIONS
  Retinal nerve fiber layer defect volume deviation is a useful tool for diagnosing glaucoma and monitoring RNFL change. In early stage of RNFL loss, RNFL defect volume deviation is more sensitive for detecting glaucoma than the RNFL defect volume measurements.
authors.affiliation: Department of Ophthalmology, Hanyang University College of Medicine, Seoul, Korea.
authors.forename: Joong Won
authors.initials: JW
authors.lastname: Shin
authors.affiliation: Department of Ophthalmology, Hanyang University College of Medicine, Seoul, Korea.
authors.forename: Ki Bang
authors.initials: KB
authors.lastname: Uhm
authors.affiliation: Department of Ophthalmology, Hanyang University College of Medicine, Seoul, Korea.
authors.forename: Mincheol
authors.initials: M
authors.lastname: Seong
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D005901:Glaucoma / Q000150:complications / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk; D009901:Optic Nerve Diseases / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D012372:ROC Curve; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012189:Retrospective Studies; D041623:Tomography, Optical Coherence / Q000379:methods*; D058609:Visual Field Tests; D014794:Visual Fields
keywords: glaucoma; lost and remaining volume; retinal nerve fiber defect; spectral-domain optical coherence tomography