title: Retinal nerve fiber layer reflectance for early glaucoma diagnosis.
abstract: OBJECTIVE
  Compare performance of normalized reflectance index (NRI) and retinal nerve fiber layer thickness (RNFLT) parameters determined from optical coherence tomography (OCT) images for glaucoma and glaucoma suspect diagnosis.
  
  
  METHODS
  Seventy-five eyes from 71 human subjects were studied: 33 controls, 24 glaucomatous, and 18 glaucoma-suspects. RNFLT and NRI maps were measured using 2 custom-built OCT systems and the commercial instrument RTVue. Using area under the receiver operating characteristic curve, RNFLT and NRI measured in 7 RNFL locations were analyzed to distinguish between control, glaucomatous, and glaucoma-suspect eyes.
  
  
  RESULTS
  The mean NRI of the control group was significantly larger than the means of glaucomatous and glaucoma-suspect groups in most RNFL locations for all 3 OCT systems (P<0.05 for all comparisons). NRI performs significantly better than RNFLT at distinguishing between glaucoma-suspect and control eyes using RTVue OCT (P=0.008). The performances of NRI and RNFLT for classifying glaucoma-suspect versus control eyes were statistically indistinguishable for PS-OCT-EIA (P=0.101) and PS-OCT-DEC (P=0.227). The performances of NRI and RNFLT for classifying glaucomatous versus control eyes were statistically indistinguishable (PS-OCT-EIA: P=0.379; PS-OCT-DEC: P=0.338; RTVue OCT: P=0.877).
  
  
  CONCLUSIONS
  NRI is a promising measure for distinguishing between glaucoma-suspect and control eyes and may indicate disease in the preperimetric stage. Results of this pilot clinical study warrant a larger study to confirm the diagnostic power of NRI for diagnosing preperimetric glaucoma.
authors.affiliation: Departments of *Biomedical Engineering †Electrical & Computer Engineering, The University of Texas at Austin, Austin, TX ‡Imaging Physics, MD Anderson Cancer Center, The University of Texas, Houston, TX §Departments of Ophthalmology and Neurobiology, Duke University Medical Center, Durham, NC.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liu
authors.forename: Bingqing
authors.initials: B
authors.lastname: Wang
authors.forename: Biwei
authors.initials: B
authors.lastname: Yin
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Milner
authors.forename: Mia K
authors.initials: MK
authors.lastname: Markey
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: McKinnon
authors.forename: Henry G
authors.initials: HG
authors.lastname: Rylander
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D003430:Cross-Sectional Studies; D042241:Early Diagnosis; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009798:Ocular Hypertension / Q000175:diagnosis; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D010865:Pilot Projects; D012165:Retinal Ganglion Cells / Q000473:pathology*; D041623:Tomography, Optical Coherence