title: Effect of disease severity and optic disc size on diagnostic accuracy of RTVue spectral domain optical coherence tomograph in glaucoma.
abstract: OBJECTIVE
  To evaluate the effect of disease severity and optic disc size on the diagnostic accuracies of optic nerve head (ONH), retinal nerve fiber layer (RNFL), and macular parameters with RTVue (Optovue, Fremont, CA) spectral domain optical coherence tomography (SDOCT) in glaucoma.
  
  
  METHODS
  110 eyes of 62 normal subjects and 193 eyes of 136 glaucoma patients from the Diagnostic Innovations in Glaucoma Study underwent ONH, RNFL, and macular imaging with RTVue. Severity of glaucoma was based on visual field index (VFI) values from standard automated perimetry. Optic disc size was based on disc area measurement using the Heidelberg Retina Tomograph II (Heidelberg Engineering, Dossenheim, Germany). Influence of disease severity and disc size on the diagnostic accuracy of RTVue was evaluated by receiver operating characteristic (ROC) and logistic regression models.
  
  
  RESULTS
  Areas under ROC curve (AUC) of all scanning areas increased (P < 0.05) as disease severity increased. For a VFI value of 99%, indicating early damage, AUCs for rim area, average RNFL thickness, and ganglion cell complex-root mean square were 0.693, 0.799, and 0.779, respectively. For a VFI of 70%, indicating severe damage, corresponding AUCs were 0.828, 0.985, and 0.992, respectively. Optic disc size did not influence the AUCs of any of the SDOCT scanning protocols of RTVue (P > 0.05). Sensitivity of the rim area increased and specificity decreased in large optic discs.
  
  
  CONCLUSIONS
  Diagnostic accuracies of RTVue scanning protocols for glaucoma were significantly influenced by disease severity. Sensitivity of the rim area increased in large optic discs at the expense of specificity.
authors.affiliation: Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, California 92093-0946, USA.
authors.forename: Harsha L
authors.initials: HL
authors.lastname: Rao
authors.forename: Mauro T
authors.initials: MT
authors.lastname: Leite
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
authors.forename: Linda M
authors.initials: LM
authors.lastname: Zangwill
authors.forename: Luciana M
authors.initials: LM
authors.lastname: Alencar
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Sample
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Medeiros
mesh_terms: D000368:Aged; D019540:Area Under Curve; D005901:Glaucoma / Q000145:classification / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000145:classification / Q000175:diagnosis*; D012372:ROC Curve; D015203:Reproducibility of Results; D012165:Retinal Ganglion Cells / Q000473:pathology*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence / Q000592:standards*; D014065:Tonometry, Ocular
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