title: Confocal scanning laser ophthalmoscopy classifiers and stereophotograph evaluation for prediction of visual field abnormalities in glaucoma-suspect eyes.
abstract: OBJECTIVE
  To determine whether Heidelberg Retina Tomograph (HRT; Heidelberg Engineering, Dossenheim, Germany) classification techniques and investigational support vector machine (SVM) analyses can detect optic disc abnormalities in glaucoma-suspect eyes before the development of visual field abnormalities.
  
  
  METHODS
  Glaucoma-suspect eyes (n = 226) were classified as converts or nonconverts based on the development of repeatable (either two or three consecutive) standard automated perimetry (SAP)-detected abnormalities over the course of the study (mean follow-up, approximately 4.5 years). Hazard ratios for development of SAP abnormalities were calculated based on baseline classification results, follow-up time, and end point status (convert, nonconvert). Classification techniques applied were HRT classification (HRTC), Moorfields Regression Analysis, forward-selection optimized SVM (SVM fwd) and backward elimination-optimized SVM (SVM back) analysis of HRT data, and stereophotograph assessment.
  
  
  RESULTS
  Univariate analyses indicated that all classification techniques were predictors of the development of two repeatable abnormal SAP results, with hazards ratios (95% confidence interval [CI]) ranging from 1.32 (1.00-1.75) for HRTC to 2.0 (1.48-2.76) for stereophotograph assessment (all P < or = 0.05). Only SVM (SVM fwd and SVM back) analysis of HRT data and stereophotograph assessment were univariate predictors of the development of three repeatable abnormal SAP results, with hazard ratios (95% CI) ranging from 1.73 (1.16-2.82) for SVM fwd to 1.82 (1.19-3.12) for SVM back (both P < 0.007). Multivariate analyses including each classification technique individually in a model with age, baseline SAP pattern standard deviation [PSD], and baseline IOP indicated that all classification techniques except HRTC (P = 0.06) were predictors of the development of two repeatable abnormal SAP results with hazards ratios ranging from 1.30 (0.99, 1.73) for HRTC to 1.90 (1.37, 2.69) for stereophotograph assessment. Only SVM (SVM fwd and SVM back) analysis of HRT data and stereophotograph assessment were significant predictors of the development of three repeatable abnormal SAP results in multivariate analyses; hazard ratios of 1.57 (1.03, 2.59) and 1.70 (1.18, 2.51), respectively. SAP PSD was a significant predictor of two repeatable abnormal SAP results in multivariate models with all classification techniques, with hazard ratios ranging from 3.31 (1.39, 7.89) to 4.70 (2.02, 10.93) per 1-dB increase.
  
  
  CONCLUSIONS
  HRT classifications techniques and stereophotograph assessment can detect optic disc topography abnormalities in glaucoma-suspect eyes before the development of SAP abnormalities. These data support strongly the importance of optic disc examination for early glaucoma diagnosis.
authors.affiliation: Hamilton Glaucoma Center, Department of Ophthalmology, University of California San Diego, La Jolla, 92093-0946, USA. cbowd@eyecenter.ucsd.edu
authors.forename: Christopher
authors.initials: C
authors.lastname: Bowd
authors.forename: Linda M
authors.initials: LM
authors.lastname: Zangwill
authors.forename: Felipe A
authors.initials: FA
authors.lastname: Medeiros
authors.forename: Jiucang
authors.initials: J
authors.lastname: Hao
authors.forename: Kwokleung
authors.initials: K
authors.lastname: Chan
authors.forename: Te-Won
authors.initials: TW
authors.lastname: Lee
authors.forename: Terrence J
authors.initials: TJ
authors.lastname: Sejnowski
authors.forename: Michael H
authors.initials: MH
authors.lastname: Goldbaum
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Sample
authors.forename: Jonathan G
authors.initials: JG
authors.lastname: Crowston
authors.forename: Robert N
authors.initials: RN
authors.lastname: Weinreb
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005901:Glaucoma / Q000175:diagnosis; D006801:Humans; D007429:Intraocular Pressure; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis*; D009887:Ophthalmoscopy / Q000379:methods*; D009898:Optic Disk / Q000473:pathology*; D009901:Optic Nerve Diseases / Q000175:diagnosis*; D010781:Photography / Q000379:methods; D014786:Vision Disorders / Q000175:diagnosis*; D058609:Visual Field Tests; D014794:Visual Fields